Benchmarking of methods for genomic taxonomy

Carbapenemase-producing Enterobacterales and their carbapenemase genes are stably recovered across the wastewater-watershed ecosystem nexus

Carbapenemase-producing Enterobacterales (CPE) have emerged as an important nosocomial threat to hospitalized patients, but CPE can also colonize the enteric microbiota of healthy individuals in the community. We hypothesized that clinically relevant CPE are frequently transported in municipal wastewater flows to treatment plants where they are reduced but not eliminated and are subsequently discharged into nearby surface waters and disseminate in the environment. We sampled untreated influent, treated effluent, and nearby surface waters weekly for a one-year period at a single large metropolitan wastewater treatment plant (WWTP) servicing Columbus, Ohio USA. In addition, we investigated the dissemination of these CPE into the environment and the downstream watershed, including sediment, fish, mammals, waterfowl, crops and soils. CPE were recovered from each (100 %) of the 44 influent samples and from 37 (84 %) effluent samples. We also isolated CPE from 50 % (22/44) of the upstream water, 82 % (36/44) of downstream, and 68 % (30/44) way downstream water. CPE were most commonly Enterobacter spp. expressing the blaKPC-2 genotype, although a variety of other species and genotypes were observed. blaKPC concentration was greatest in the influent (mean = 106 gene copies/100 mL water) and treatment resulted in a 4-log reduction in blaKPC concentration (P < 0.05), which was consistent with reduction in total bacteria concentration. We found 22 of 450 fish vent swabs (4.9 %) carrying CPE, but CPE were not recovered from terrestrial wildlife living in the Scioto watershed. Fish intestinal microbiome maintained approximately 1.5 × 104 copies of blaKPC per gram of feces. Our data support the hypothesized flow of CPE from healthcare settings into surface water and the downstream natural environment via municipal wastewater discharge. Our results suggest that river environments can serve as a reservoir for CPE, facilitating their broader One Health dissemination among surface water, wildlife, agriculture, and ultimately back to humans.

Large-scale phenotypic and genomic analysis of Listeria monocytogenes reveals diversity in the sensitivity to quaternary ammonium compounds but not to peracetic acid

Listeria monocytogenes presents a significant concern for the food industry due to its ability to persist in the food processing environment. One of the factors contributing to its persistence is decreased sensitivity to disinfectants. Our objective was to assess the diversity of L. monocytogenes sensitivity to food industry disinfectants by testing the response of 1,671 L. monocytogenes isolates to quaternary ammonium compounds (QACs) and 414 isolates to peracetic acid (PAA) using broth microdilution and growth curve analysis assays, respectively, and to categorize the isolates into sensitive and tolerant. A high phenotype-genotype concordance (95%) regarding tolerance to QACs was obtained by screening the genomes for the presence of QAC tolerance-associated genes bcrABC, emrE, emrC, and qacH. Based on this high concordance, we assessed the QAC genes' dissemination among publicly available L. monocytogenes genomes (n = 39,196). Overall, QAC genes were found in 23% and 28% of the L. monocytogenes collection in this study and in the global data set, respectively. bcrABC and qacH were the most prevalent genes, with bcrABC being the most detected QAC gene in the USA, while qacH dominated in Europe. No significant differences (P > 0.05) in the PAA tolerance were detected among isolates belonging to different lineages, serogroups, clonal complexes, or isolation sources, highlighting limited variation in the L. monocytogenes sensitivity to this disinfectant. The present work represents the largest testing of L. monocytogenes sensitivity to important food industry disinfectants at the phenotypic and genomic level, revealing diversity in the tolerance to QACs while all isolates showed similar sensitivity to PAA.

IMPORTANCE

Contamination of Listeria monocytogenes within food processing environments is of great concern to the food industry due to challenges in eradicating the isolates once they become established and persistent in the environment. Genetic markers associated with increased tolerance to certain disinfectants have been identified, which alongside other biotic and abiotic factors can favor the persistence of L. monocytogenes in the food production environment. By employing a comprehensive large-scale phenotypic testing and genomic analysis, this study significantly enhances the understanding of the L. monocytogenes tolerance to quaternary ammonium compounds (QACs) and the genetic determinants associated with the increased tolerance. We provide a global overview of the QAC genes prevalence among public L. monocytogenes sequences and their distribution among clonal complexes, isolation sources, and geographical locations. Additionally, our comprehensive screening of the peracetic acid (PAA) sensitivity shows that this disinfectant can be used in the food industry as the lack of variation in sensitivity indicates reliable effect and no apparent possibility for the emergence of tolerance.

Antimicrobial resistance in coagulase negative staphylococci: Genome analysis and role of horizontal gene transfer

Coagulase-negative staphylococci (CNS) are emerging as significant contributors to antimicrobial resistance, yet their genomic characteristics remain incompletely understood. This study presents a whole-genome analysis of 12 multidrug-resistant CNS strains (Staphylococcus epidermidis, Staphylococcus haemolyticus, Staphylococcus hominis) isolated from blood cultures, focusing on antimicrobial resistance genes, mobile genetic elements (MGEs), and horizontal gene transfer (HGT) mechanisms. We identified 22 resistance genes conferring resistance to 11 antimicrobial classes, many of which were plasmid-associated. Notably, we report the first detection of the ISSha1 insertion sequence in S. hominis, along with novel resistance plasmids, including pGO1 and VRSAp in S. haemolyticus and pAMα1 in S. hominis. The identification of bacteriophage-derived sequences in S. haemolyticus and S. hominis suggests a role for phages in genetic exchange. CRISPR sequences and a Cas gene were detected in S. hominis, suggesting a potential but unconfirmed role in restricting gene transfer. Additionally, pGO1 was identified as a conjugative plasmid, while pAMα1 and VRSAp were determined to be mobilizable, reinforcing the role of CNS in resistance dissemination. These results highlight CNS as reservoirs of antimicrobial resistance genes and emphasize the importance of species-specific genomic surveillance. Proactive monitoring of CNS is crucial for controlling antimicrobial resistance in clinical settings.

Repeated biocide treatments cause changes to the microbiome of a food industry floor drain biofilm model

There is a concern about the development of microbial tolerance and resistance to biocides due to their repeated use within the food industry. This study aimed to develop a floor drain biofilm model and test whether repeated biocide treatment would result in increased tolerance to biocides. Culturomics and shotgun metagenomic analysis of 14 drains and 214 bacterial isolates from three industrial food production environments revealed microbiomes with great diversity and complexity, but with the dominance of a few highly abundant taxa, including Pseudomonas. A representative drain biofilm was created (3 days, 15°C) using 31 whole genome sequenced bacterial isolates from 24 genera. The biofilm model represented 47-58% and 76-81% of the microbial abundance observed in the metagenome and viable microbiota, respectively. The biofilm model was exposed on days 3 and 6 to water or different industrial concentrations of benzalkonium chloride (BC), peracetic acid (PAA), or sodium hypochlorite (SH). Analysis of the viable survivors using MALDI-TOF MS and the regrowing biofilms using 16S rRNA amplicon sequencing showed how the diversity of the biofilm decreased but without any change in biocide tolerance as seen in log reductions (CFU/cm2). The use of different biocides did, however, exert significantly different selective pressures on the microbiomes as Citrobacter, Acinetobacter, Aeromonas, and Pseudomonas dominated the biofilm after treatments with SH or PAA, while Serratia and Moraxella dominated after treatments with BC. The dominance of Serratia marcescens could be explained by the carriage of a BC efflux pump (oqxB) and the highest (20 mg/L BC) minimum inhibitory concentration (MIC) result of the drain isolates. In contrast, despite carrying a BC efflux pump (qacH), Listeria monocytogenes ST121 did not show increased survival or presence in the biofilm after BC treatments. Only the highest tested concentration of PAA was able to completely eradicate L. monocytogenes. The developed biofilm model and the repeated biocide treatments enabled a better understanding of how biocides affect the biofilm microbiome. Future research should involve testing biocide rotation strategies to control biofilm regrowth and inactivation of persistent foodborne pathogens in floor drains.

In-vitro activity of the novel β-lactam/β-lactamase inhibitor combinations and cefiderocol against carbapenem-resistant Pseudomonas spp. clinical isolates collected in Switzerland in 2022

To evaluate the in-vitro activity of the novel commercially-available drugs, including meropenem-vaborbactam (MEV), ceftazidime-avibactam (CZA), ceftolozane-tazobactam (C/T), imipenem-relebactam (IPR) as well as cefiderocol (FDC), against carbapenem-resistant Pseudomonas spp. (CRP) isolates. All CRP isolates collected at the Swiss National Reference Laboratory (NARA) over the year 2022 (n = 170) have been included. Most of these isolates (n = 121) were non-carbapenemase producers. Among the 49 carbapenemase producers, 47 isolates produced metallo-β-lactamases (MBL) including NDM-1 (n = 11), VIM-like (n = 28), IMP-like (n = 7), and both NDM-1 and VIM-2 (n = 1) and two isolates produced the class A carbapenemase GES-5. Susceptibility testing was determined by broth microdilution method (BMD), or disk diffusion test, and results interpreted following EUCAST guidelines. The susceptibility rates for MEV, CZA, C/T and IPR were found to be 41%, 45%, 59% and 58%, respectively, for the whole set of isolates tested. Among non-carbapenemase producers, susceptibility rates for these β-lactam/β-lactamase inhibitors (BL/BLI) combinations were higher, determined at 55%, 61%, 83%, and 82%, respectively. The overall susceptibility of carbapenemase-producing Pseudomonas spp. to novel BL/BLI was relatively low, while 80% of these isolates demonstrated susceptibility to FDC, with a similar proportion (79%) observed among MBL producers. A total of 10 MBL-producing isolates (6%), mainly NDM-1, were found to exhibit resistance to all drugs tested, with the exception of colistin. FDC exhibited an excellent in-vitro activity against this collection of CRP recovered from Switzerland in 2022, including MBL producers. The new BL/BLI combinations displayed significant activity against non-carbapenemase CRP, with IPR and C/T showing the highest susceptibility rates.

Oral colonization of antimicrobial-resistant bacteria in home health care participants and their association with oral and systemic status

Antimicrobial-resistant bacteria (ARBs) are serious global threat because they make it difficult to treat infections with antibiotics. Recently, it has been demonstrated that ARBs are isolated from the oral cavities of elderly individuals in long-term care facilities. Because oral ARBs can cause systemic diseases such as bacteraemia and aspiration pneumonia, more attention must be given to protect the overall health of elderly people. To understand the prevalence of oral ARBs, more studies are needed in addition to previous studies. In this study, we investigated oral ARBs in elderly people receiving home health care (HHC) who had different lifestyles as residents in long-term care facilities. Among 98 HHC participants, Staphylococcus aureus, including 8 methicillin-resistant S. aureus (MRSA) strains, was isolated from 31 participants (31.7%), and 3rd-generation cephalosporin-resistant gram-negative bacteria (GNARB) were isolated from 18 participants (17.8%). An analysis of the relationship between oral ARBs and clinical status revealed that S. aureus/MRSA isolation was correlated with denture condition, while GNARB isolation was correlated with tube feeding. This study is the first comprehensive analysis of ARB carriage in the oral cavities of elderly people in HHCs. These results demonstrate the potential risk of oral ARB carriage and the importance of infection control in HHCs.

Additive Effects of Natural Plant Extracts/Essential Oils and Probiotics as an Antipathogenic Topical Skin Patch Solution for Acne and Eczema

This work leverages the additive antipathogenic effects of natural extracts/essential oils (EOs) and probiotics for the treatment of acne vulgaris associated with Cutibacterium acnes (C. acnes) and eczema complicated by secondary infections with Staphylococcus aureus (S. aureus). Six probiotic strains and various extracts/EOs were evaluated in a large screening to evaluate their potential against both pathogens. Lacticaseibacillus paracasei PCB003 was able to inhibit the growth of both pathogens. For extracts/EOs, Oregano EO had the best antipathogenic effects on both pathogens and did not show any adverse impact on the growth of probiotics, making it suitable for simultaneous use. Using Lactiplantibacillus plantarum PCB011 as a probiotic model, five material formulations were assessed for their suitability to protect probiotic cells within freeze-dried topical patches. Alginate and trehalose (ALG+TRE) and thermoplastic starch (TPS) had the highest probiotic survivability, with ALG+TRE chosen as the final patch material as it was more robust. PCB003 and PCB011 were individually incorporated into the ALG+TRE freeze-dried matrix to form a 6 mm patch; both ALG+TRE (PCB003) and ALG+TRE (PCB011) patches, when used individually, successfully inhibited C. acnes growth by 4.7 and 6.0 mm, respectively, surpassing the performance of commercially available acne patches. The additive effect with 30% Oregano EO further improved pathogen inhibition. For S. aureus, the incorporation of 30% Oregano EO to ALG+TRE (PCB003) increased the size of the inhibition zone more than 10-fold. For C. acnes, the ALG+TRE (PCB003) patch with 30% Oregano EO demonstrated an inhibition zone of 16.3 mm, and the ALG+TRE (PCB011) patch with 30% Oregano EO achieved a 14.3 mm inhibition zone. Genomic analysis confirmed that PCB003 and PCB011 lack antimicrobial resistance determinants, ensuring safety. This study successfully combined probiotics and natural agents to create effective dermatological antipathogenic patches.

Whole-Genome Shotgun Sequencing from Chicken Clinical Tracheal Samples for Bacterial and Novel Bacteriophage Identification

A whole-genome shotgun sequencing (sWGS) approach was applied to chicken clinical tracheal swab samples during metagenomics investigations to identify possible microorganisms among poultry with respiratory diseases. After applying shotgun sequencing, Ornithobacterium rhinotracheale (ORT) and a putative prophage candidate were found in one of the swab samples. A multi-locus sequence typing (MLST) scheme of the ORT genome involved the adk, aroE, fumC, gdhA, pgi, and pmi genes. Antibiotic resistant analysis demonstrated tetracycline-resistan t ribosomal protection protein, tetQ, the aminoglycoside-(3)-acetyltransferase IV gene, aminoglycoside antibiotic inactivation and macrolide resistance, and the ermX gene in the ORT genome. A putative prophage candidate was predicted using Prophage Hunter and PHAST, while BLAST analyses were utilized to identify genes encoding bacteriophage proteins. Interestingly, genes encoding endolysins were detected in bacteriophage genomes. The gene products encoded in the prophage sequence were most closely related to bacteriophages in the N4-like family among the Authographiviridae in the Caudovirales. This study demonstrates the potential of sWGS for the rapid detection and characterization of etiologic agents found in clinical samples.

Genomic diversity and evolutionary patterns of Edwardsiella ictaluri affecting farmed striped catfish (Pangasianodon hypophthalmus) in Vietnam over 20 years

Edwardsiella ictaluri continues to pose a significant risk to the health and production of striped catfish (Pangasianodon hypophthalmus) in Vietnam. Whilst recent advances in genomic sequencing provide an insight into the global genomic diversity of this important fish pathogen, genome-wide analysis of Vietnamese isolates recovered over time is lacking. In this study, we used a whole-genome sequencing approach to compare the genomes of 31 E. ictaluri isolates recovered over a 20-year period (2001-2021) and performed comparative genomic analysis to explore temporal changes in genome diversity, population structure and mechanisms driving pathogenesis and antimicrobial resistance. Our findings revealed an open pan-genome with 4148 genes and a core genome (3 060 genes) accounting for over two-thirds of the genome. Moreover, we found the genomes sequenced to classify into two distinct lineages and estimated the ancestral origin of these lineages within Vietnam to date back to the 1950s. Plasmids were highly prevalent in Vietnamese E. ictaluri, with isolates harbouring up to four plasmids within their genome. Further, a diverse mobilome was observed with nine different plasmid types detected across the genome collection. Exploration of putative plasmids revealed a diverse set of antimicrobial resistance genes (ARGs) against key antibiotics used in Vietnamese aquaculture and virulence genes associated with protein secretion systems. Correlation analysis revealed the total number of ARGs detected in genomes to increase with isolate recovery time. Whilst the number of virulence genes remained relatively stable, temporal variation was noted in several virulence factors related to motility and immune system modulation. Findings from this study highlight the need for continued genomic surveillance to monitor changes in antimicrobial resistance and pathogenesis, to help inform the development of disease control and management strategies.

Brucella ceti in Common Dolphins (Delphinus delphis) in Portugal-Characterization of First Isolates

This study investigates Brucella ceti infection in marine mammals stranded along the Lisbon and Tagus Valley coast between 2022 and mid-2024, marking the first report of Brucella presence in Portuguese waters. Out of 59 examined marine mammals, B. ceti was isolated in three common dolphins (5.1%), a prevalence rate consistent with previous studies from other coastlines. PCR-based detection indicated a higher infection rate (23.7%), suggesting an underestimation of the prevalence of B. ceti infection in this population. Multi-locus Sequence Typing (MLST) and Multiple-Locus Variable-Number Tandem-Repeat Analysis (MLVA) revealed distinct genetic profiles and close relationships to B. ceti strains from the Atlantic, supporting the hypothesis of specific host-adapted lineages in dolphins. Virulence genes, including those for host interaction (bspE, btpB) and intracellular survival (virB7, vceA), were consistent across isolates, highlighting the pathogenic potential. Additionally, antimicrobial resistance (AMR) genes, such as mprF and efflux proteins (bepC-G), were also identified. These findings underscore the need for further research and surveillance to understand B. ceti transmission, host range, and impacts on Atlantic cetaceans, as well as to develop effective diagnostic and management strategies to mitigate infection risks in marine environments.

ESBL- and pAmpC-producing Enterobacterales from Swedish dogs and cats 2017-2021: a retrospective study

BACKGROUND

Antibiotic resistant bacteria are a threat to both human and animal health. Of special concern are resistance mechanisms that are transmissible between bacteria, such as extended-spectrum beta-lactamases (ESBL) and plasmid-mediated AmpC (pAmpC). ESBL/AmpC resistance is also of importance as it confers resistance to beta-lactam antibiotics including third generation cephalosporins. The Swedish Veterinary Agency (former English name National Veterinary Institute) performs confirmatory testing of suspected ESBL-/pAmpC-producing Enterobacterales. The aim of this study is to describe the clinical background, antibiotic susceptibility, and genetic relationships of confirmed isolates from dogs and cats in Sweden from 2017 to 2021.

RESULTS

The study includes 92 isolates of ESBL/pAmpC-producing bacteria from 82 dogs, and 28 isolates from 23 cats. Escherichia coli was the most commonly isolated bacteria, and the most frequent sampling site was the urinary tract. From eight dogs and two cats, ESBL/pAmpC-producing bacteria were isolated on more than one occasion. Multi-resistance was more than twice as common in samples from dogs (50%) than in samples from cats (22%). Among dogs, sequence type (ST) 131 and ST372 were the dominant strains and blaCMY-2 and blaCTX-M-15 the dominant genes conferring reduced susceptibility to third-generation cephalosporins. Among cats, ST73 was the dominant strain and blaCTX-M-15 the dominant gene.

CONCLUSIONS

Monitoring the resistance patterns and genetic relationships of bacteria over time is important to follow the results of measures taken to reduce resistance. Knowledge of the appropriate antibiotic usage is also crucial. In this study, a variety of STs and ESBL/pAmpC-genes were detected among the isolates. There were available antibiotics likely effective for treatment in all cases, based on resistance pattern, infection site and host species.

A Longitudinal Study on Campylobacter spp. in an Integrated Broiler Complex in the Southeast Region of the United States: Prevalence and Phylogenetic Analysis

Poultry meat products are considered the major contributors to Campylobacteriosis in humans. The objective of this study was to determine the prevalence status, critical entry points, and movement patterns of Campylobacter spp. along different stages of an integrated broiler complex. To isolate bacteria and perform phylogenetic analysis, a total of 790 environmental samples were collected from 38 production houses, a hatchery, 6 transport trucks, and a processing plant of a commercial broiler complex. Odds ratio and 95% confidence intervals were compared among different stages and sample types (α = 0.05). Altogether 17% (137/790) of samples and 61% (23/38) of production houses were positive for Campylobacter spp. Similarly, 34% (46/135) of samples were identified as Campylobacter jejuni (C. jejuni), and 61% (83/135) were identified as Campylobacter coli (C. coli). The odds of Campylobacter spp. detection in broiler farms' surroundings were 4 times (1.88-8.26; 95% CLs) more likely as compared to parent pullets and breeder farms' surroundings (p = 0.0004). Similarly, among different sample types, the odds of Campylobacter spp. detection in boot swabs and sponge-stick swabs were more likely as compared to fly paper samples (p ≤ 0.0024). In addition, the odds of Campylobacter spp. detection in postpick whole carcass rinses were 4 times (1.99-7.59; 95% CLs) more likely as compared to postchill carcass rinses (p = 0.0004). The phylogeny results of both C. jejuni and C. coli indicate multiple critical entry points of bacterial strains along the chain and suggest the possibility of transmission of Campylobacter spp. from broiler grow-out flocks through transport and to final raw products (29%) in the processing plant. The results indicate potential risks of foodborne infections in consumers from ingestion of contaminated raw or undercooked poultry meat. Therefore, a comprehensive control strategy may be essential to reduce or eliminate Campylobacter spp. or other zoonotic pathogens from the poultry food chain.

Tracing the transmission of carbapenem-resistant Enterobacterales at the patient: ward environmental nexus

INTRODUCTION

Colonisation and infection with Carbapenem-resistant Enterobacterales (CRE) in healthcare settings poses significant risks, especially for vulnerable patients. Genomic analysis can be used to trace transmission routes, supporting antimicrobial stewardship and informing infection control strategies. Here we used genomic analysis to track the movement and transmission of CREs within clinical and environmental samples.

METHODS

25 isolates were cultured from clinical patient samples or swabs, that tested positive for OXA-48-like variants using the NG-Test® CARBA-5 test and whole genome sequenced (WGS) using Oxford Nanopore Technologies (ONT). 158 swabs and 52 wastewater samples were collected from the ward environment. 60 isolates (matching clinical isolate genera; Klebsiella, Enterobacter, Citrobacter and Escherichia) were isolated from the environmental samples using selective agar. Metagenomic sequencing was undertaken on 36 environmental wastewater and swab samples.

RESULTS

21/25 (84%) clinical isolates had > 1 blaOXA gene and 19/25 (76%) harboured > 1 blaNDM gene. Enterobacterales were most commonly isolated from environmental wastewater samples 27/52 (51.9%), then stick swabs 5/43 (11.6%) and sponge swabs 5/115 (4.3%). 11/60 (18%) environmental isolates harboured > 1 blaOXA gene and 1.9% (1/60) harboured blaNDM-1. blaOXA genes were found in 2/36 (5.5%) metagenomic environmental samples.

CONCLUSIONS

Potential for putative patient-patient and patient-ward transmission was shown. Metagenomic sampling needs optimization to improve sensitivity.

Screening and Genomic Profiling of Antimicrobial Bacteria Sourced from Poultry Slaughterhouse Effluents: Bacteriocin Production and Safety Evaluation

Background/Objectives: Antimicrobial-resistant (AMR) pathogens represent a serious threat to public health, particularly in food production systems where antibiotic use remains widespread. As a result, alternative antimicrobial treatments to antibiotics are essential for effectively managing bacterial infections. This study aimed to identify and characterize novel antimicrobial peptides produced by bacteria, known as bacteriocins, as well as to recognize safe bacteriocin-producing strains, sourced from poultry slaughterhouse effluents. Methods: A total of 864 bacterial isolates were collected across eight stages of a poultry slaughter line and screened for antimicrobial activity against Gram-positive and Gram-negative indicator strains. Whole-genome sequencing (WGS) was performed on 12 selected strains, including Enterococcus faecium (6 isolates), Lactococcus lactis (1 isolate), Lactococcus garvieae (1 isolate) and Escherichia coli (4 isolates). The presence of bacteriocin gene clusters (BGC), antibiotic resistance genes (ARG), and virulence factors (VF) was analyzed. The antimicrobial activity of a novel bacteriocin was further evaluated using in vitro cell-free protein synthesis (IV-CFPS). Results: WGS revealed multiple BGCs, including a novel class IId bacteriocin, lactococcin P1A (LcnP1A), in L. lactis SWD9. LcnP1A showed antimicrobial activity against various indicator strains, including Listeria monocytogenes. While most bacteriocin-encoding strains harbored ARGs and VFs, E. faecium SWG6 was notable for its absence of ARGs and minimal VFs, highlighting its potential as a probiotic. Conclusions: These findings underscore the importance of discovering novel bacteriocins and safer bacteriocin producing strains to address antimicrobial resistance in the food chain. Further research would validate the efficacy of both the novel lactococcin P1A bacteriocin and the E. faecium SWG6 isolate for application in processed food and animal production systems.

Re-sensitization of imipenem-resistant Pseudomonas aeruginosa and restoration of cephalosporins susceptibility in Enterobacteriaceae by recombinant Esterase B

Sphingobium sp. SM42 Esterase B (EstB) is an enzyme with a dual function in degrading dibutyl phthalate and catalyzing the cleavage of the C-S bond in C3-sidechains of the dihydrothiazine ring of cephalosporins, generating more active β-lactam derivatives. Global prokaryotic genome analysis revealed the existence of a gene identical to estB in Pseudomonas aeruginosa strain PS1 suggesting a horizontal gene transfer event involving estB. To investigate the effect of ectopic expression of EstB in the periplasm of P. aeruginosa and several Enterobacteriaceae on antibiotic susceptibility levels, plasmid, pEstB, carrying a recombinant EstB fused with the signal peptide from Escherichia coli outer membrane protein A (OmpA) for periplasmic localization was constructed. The expression of EstB in the periplasm of P. aeruginosa and the Enterobacteriaceae: E. coli, Klebsiella pneumoniae, and Salmonella enterica serovar Typhi, increased susceptibility to carbapenems and cephalosporins. EstB reversed the imipenem resistance of P. aeruginosa ΔmexS and restored the changes in susceptibility to cephalosporins conferred by the downregulation of the outer membrane proteins, OmpK35 and OmpK36, in K. pneumoniae ΔramR-ompK36 to wild-type level. The introduction of EstB to the periplasmic space of Gram-negative bacteria can increase carbapenem and cephalosporin susceptibility.

Chromosomally located blaCMH in Enterobacter cloacae complex across human-bird-environment interfaces: A one-health perspective

To improve the understanding of antimicrobial resistance (AMR) in migratory birds derived-Enterobacter cloacae (E. cloacae) complex and its spread at the human-bird-environment interface, we isolated 11 strains of third-generation cephalosporin-resistant E. cloacae from 1003 specimens from 29 migratory bird species over two years in Chongming, Shanghai, China. The comprehensive analysis incorporated second- and third-generation sequencing techniques and extensive bioinformatic analysis. Four human-associated E. cloacae sequence types (STs), including ST432, ST412, ST1, and ST639, were found in migratory birds. We confirmed that the blaCMH-4 and blaCMH-6 genes were the major genotypes of the β-lactamase resistance genes in E. cloacae found in migratory birds. In addition, a thorough genomic analysis was performed on a global collection of 398 E. cloacae isolates carrying the blaCMH gene from 46 different countries. China had the highest proportion with 19.10 % (76/398), followed by Singapore with 18.34 % (73/398), Nigeria with 15.83 % (63/398), and the USA with 14.07 % (56/398). The first transmission of E. cloacae carrying blaCMH-4 and blaCMH-6 was defined around 1894 and 1549, respectively. Time-based phylogenetic analysis revealed that host jumps among humans, birds, and the environment led to the emergence of modern strains with ESBL- and carbapenem-resistant genes from about 2004 to 2016. The detection rate of insertion sequences (IS) of E. cloacae carrying blaCMH from human sources is higher than that from migratory bird sources, which is related to the different genetic environments caused by antibiotic selective pressure. It is crucial to have a comprehensive understanding of the characteristics exhibited by blaCMH producing E. cloacae in different ecological environments. Our results contribute to the effective monitoring and implementation of proactive strategies to reduce the spread of multidrug-resistant E. cloacae.

Whole genome sequencing reveals circulation of potentially virulent Listeria innocua strains with novel genomic features in cattle farm environments in Dhaka, Bangladesh

Through the last decade, Listeria spp. has been detected in food and environmental samples in Bangladesh. However, the genomic information of this bacterium that prevails in the country remains scarce. This study analyzed the complete genome sequences of two Listeria spp. isolates obtained from cow dung and their drinking water collected from a cattle farm in Dhaka, Bangladesh. Both the isolates were identified as Listeria innocua, which shared almost identical genomic features. The genome sequences demonstrated the presence of 13 virulence genes associated with invasion (iap/cwhA, gtcA, and lpeA), surface protein anchoring (lspA), adherence (fbpA, and lap), intracellular survival (lplA1, and prsA2), peptidoglycan modification (oatA, and pdgA), and heat stress (clpC, clpE, and clpP). Additionally, the gene fosX, conferring resistance to fosfomycin, and two copper resistance-associated genes, copC and csoR, were identified in both. The genome sequences also revealed two plasmid replicons, rep25 and rep32, along with three insertion sequences [ISLmo3 (CP022021), ISLmo7 (CP006611), ISS1N (M37395)]. Notably, a composite transposon [CN_8789_ISS1N (M37395)], was detected in both L. innocua isolates, representing the first documented occurrence of this particular composite transposon in any reported Listeria species. Furthermore, the genomes contained four prophage regions [Listeria phage LP-030-2 (NC_021539), Listeria phage vB_LmoS_188 (NC_028871), Listeria phage A118 (NC_003216) and Escherichia phage RCS47 (NC_042128)]. Two CRISPR arrays were also identified, one belonging to the family type II-A. Multilocus Sequence Typing (MLST) analysis classified the L. innocua isolates of the same sequence type, ST-637. Single nucleotide polymorphism (SNP) analysis uncovered the presence of 231-340 SNPs between the L. innocua isolates and their closely related global lineage. In contrast, only 42 SNPs were identified between the two isolates, suggesting a potential transmission of L. innocua between cow dung and cattle farm water. The presence of L. innocua isolates harboring virulence genes associated with ruminant infection in the cattle farm environment of Bangladesh raises significant concerns about the potential presence of other human and animal pathogens. This poses a serious threat to the cattle farming industry. Additionally, the genomic analysis of the L. innocua isolates enhances our understanding of the evolutionary dynamics of Listeria species.

Genome sequencing and comparative genomic analysis of bovine mastitis-associated non-aureus staphylococci and mammaliicocci (NASM) strains from India

We describe the whole-genome sequencing and comparative genomic analysis of 22 mastitis-associated NASM strains isolated from India. The mean genome size of the strains was 2.55 Mbp, with an average GC content of 32.2%. We identified 14 different sequence types (STs) among the 22 NASM strains. Of these, ST1 and ST6 of S. chromogenes were exclusively associated with bovine mastitis. Genome-wide SNP-based minimum spanning tree revealed the intricate phylogenetic relationships among NASM strains from India, categorizing them into five major clades. Interestingly, mastitis-associated strains formed separate subclades in all the NASM species studied, indicating distinct host-specific co-evolution. The study identified 32 antimicrobial resistance (AMR) genes and 53 virulence-associated genes, providing insights into the genetic factors that could contribute to the pathogenicity of NASM species. Some virulence and AMR genes were found in the predicted genomic islands, suggesting possible horizontal transfer events.

Isolation, Genomics-Based and Biochemical Characterization of Bacteriocinogenic Bacteria and Their Bacteriocins, Sourced from the Gastrointestinal Tract of Meat-Producing Pigs

Antimicrobial resistance (AMR) poses a significant challenge to animal production due to the widespread use of antibiotics. Therefore, there is an urgent need for alternative antimicrobial strategies to effectively manage bacterial infections, protect animal health, and reduce reliance on antibiotics. This study evaluated the use of emerging approaches and procedures for the isolation, identification, and characterization of bacteriocin-producing bacteria and their bacteriocins, sourced from the gastrointestinal tract (GIT) of meat-producing pigs. Out of 2056 isolates screened against Gram-positive and Gram-negative indicator strains, 20 of the most active antimicrobial isolates were subjected to whole genome sequencing (WGS) for the prediction of coding DNA sequences (CDS) and the identification of bacteriocin gene clusters (BGC) and their functions. The use of an in vitro cell-free protein synthesis (IV-CFPS) protocol and the design of an IV-CFPS coupled to a split-intein mediated ligation (IV-CFPS/SIML) procedure made possible the evaluation of the production and antimicrobial activity of described and putatively novel bacteriocins. A colony MALDI-TOF MS procedure assisted in the identification of class I, II, and III lanthipeptides. MALDI-TOF MS and a targeted proteomics, combined with a massive peptide analysis (LC-MS/MS) approach, has proven valuable for the identification and biochemical characterization of previously described and novel bacteriocins encoded by the isolated bacteriocin-producing strains.

Characterization of neurologic disease-associated Streptococcus suis strains within the United States swine herd and use of diagnostic tools

Streptococcus suis negatively impacts swine health, posing diagnostic and preventative challenges. S. suis can induce disease and also quietly reside on mucosal surfaces. The limited use of diagnostic tools to identify disease-associated strains and rule out differential diagnoses, alongside the complex ecology of S. suis, poses significant challenges in comprehending this important pathogen and defining pathotypes. This study evaluated 2,379 S. suis central nervous system (CNS) isolates from diagnostic submissions between 2015 and 2019. Isolates originating from submissions with histologic evidence of CNS infection (n = 1,032) were further characterized by standard and advanced diagnostic techniques. We identified 29 S. suis serotypes and 4 reclassified serotypes as putative causes of CNS disease. Among these, serotypes 1 and 7 emerged as the predominant putative causes of CNS infection (32% of submissions). Furthermore, 51 sequence types (STs), of which 15 were novel, were detected with ST1 predominating. Through whole-genome sequencing of 145 isolates, we observed that five commonly used virulence-associated genes (VAGs; epf, mrp, sly, ofs, and srtF) were not present in most disease-associated isolates, and matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) yielded false-positive results in 7% of isolates. These data indicate that (i) clinical signs and site of isolation alone are insufficient for defining a pathotype, (ii) S. suis serotypes and STs associated with CNS infection are more diverse than previously reported, (iii) MALDI-TOF MS may need to be supplemented with additional diagnostic tools for precise S. suis identification, and (iv) VAGs remain an unreliable means for identifying isolates associated with CNS disease.IMPORTANCEStreptococcus suis is an important and complex systemic bacterial pathogen of swine. Characterization of S. suis strains originating from pigs with histologic confirmation of neurologic disease is limited. Review of swine diagnostic submissions revealed that fewer than half of cases from which S. suis was isolated from the brain had histologic evidence of neurologic disease. This finding demonstrates that clinical signs and site of isolation alone are not sufficient for identifying a neurologic disease-associated strain. Characterization of strains originating from cases with evidence of disease using classic and advanced diagnostic techniques revealed that neurologic disease-associated strains are diverse and commonly lack genes previously associated with virulence.

Assessment of the activity and mechanisms of resistance to cefiderocol and combinations of β-lactams and the novel β-lactamase inhibitors avibactam, taniborbactam, zidebactam, nacubactam, xeruborbactam, and ANT3310 in emerging double-carbapenemase-producing Enterobacterales

We aimed to investigate the activity of and mechanisms of resistance to cefiderocol and innovative β-lactam/β-lactamase inhibitor combinations in a nationwide collection of double-carbapenemase-producing Enterobacterales. In all, 57 clinical isolates co-producing two carbapenemases collected from Spanish hospitals during the period 2017-2022 were analyzed. Minimum inhibitory concentration (MIC) values for ceftazidime, ceftazidime/avibactam, aztreonam, aztreonam/avibactam, aztreonam/nacubactam, cefiderocol, cefepime, cefepime/taniborbactam, cefepime/zidebactam, cefepime/nacubactam, imipenem, imipenem/relebactam, meropenem, meropenem/vaborbactam, meropenem/xeruborbactam, and meropenem/ANT3310 were determined by reference broth microdilution. Genetic drivers of resistance were analyzed by whole-genome sequencing (WGS). The collection covered nine carbapenemase associations: VIM + OXA-48 (21/57), NDM + OXA-48 (11/57), KPC + VIM (10/57), KPC + OXA-48 (6/57), IMP + OXA-48 (3/57), NDM + KPC (2/57), NDM + VIM (2/57), NDM + GES (1/57), and KPC + IMP (1/57). Ceftazidime/avibactam, imipenem/relebactam, and meropenem/vaborbactam were the least active options. Aztreonam/avibactam and aztreonam/nacubactam were active against the whole collection and yielded MIC50/MIC90 values of ≤0.25/0.5 mg/L and 1/2 mg/L, respectively. Cefepime/zidebactam (56/57 susceptible), meropenem/xeruborbactam (56/57 susceptible), cefepime/nacubactam (55/57 susceptible), and cefiderocol (53/57 susceptible) were also highly active, with MIC50/MIC90 values ranging from ≤0.25-2 mg/L to 2-4 mg/L, respectively. Meropenem/ANT3310 (MIC50/MIC90 = 0.5/≥64 mg/L; 47/57 susceptible) and cefepime/taniborbactam (MIC50/MIC90 = 0.5/16 mg/L; 44/57 susceptible) also retained high levels of activity, although they were affected by NDM-type enzymes in combination with porin deficiency. Our findings highlight that cefiderocol and combinations of β-lactams and the novel β-lactamase inhibitors avibactam, nacubactam, taniborbactam, zidebactam, xeruborbactam, and ANT3310 show promising activity against double-carbapenemase-producing Enterobacterales.

Assessment and genomic analysis of Salmonella and Campylobacter from different stages of an integrated no-antibiotics-ever (NAE) broiler complex: a longitudinal study

The objective of this study was to determine prevalence and perform genomic analysis of Salmonella spp. and Campylobacter spp. isolated from different stages of an integrated NAE broiler complex. Environmental samples were screened with 3M-Molecular Detection System (MDS) and MDS positive samples were further processed for confirmation of results and identification. Core genome-based phylogenies were built for both bacteria isolated from this study along with selected NCBI genomes. The odds ratios and 95% confidence limits were compared among stages and sample types (α < 0.05) using multivariable model. Based on MDS results, 4% and 18% of total samples were positive for Salmonella spp. and Campylobacter spp. respectively. The odds of Salmonella detection in hatchery samples were 2.58 times as likely as compared to its detection in production farms' samples (P = 0.151) while the odds of Campylobacter detection in production farms' samples were 32.19 times as likely as its detection in hatchery (P = 0.0015). Similarly, the odds of Campylobacter detection in boot swabs, soil, water, and miscellaneous samples were statistically significant (P < 0.05) as compared with fly paper as reference group. The serovars identified for Salmonella were Typhimurium, Barranquilla, Liverpool, Kentucky, Enteritidis, Luciana, and Rough_O:r:1,5. For Campylobacter, the species identified were Campylobacter jejuni and Campylobacter coli. Phylogeny results show close genetic relatedness among bacterial strains isolated from different locations within the same stage and between different stages. The results show possibility of multiple entry points of such bacteria entering broiler complex and can potentially contaminate the final raw product in the processing plant. It suggests the need for a comprehensive control strategy with strict biosecurity measures and best management practices to minimize or eliminate such pathogens from the poultry food chain.

Wastewater and environmental sampling holds potential for antimicrobial resistance surveillance in food-producing animals - a pilot study in South African abattoirs

Antimicrobial resistance (AMR) poses a significant global One Health challenge that causes increased mortality and a high financial burden. Animal production contributes to AMR, as more than half of antimicrobials are used in food-producing animals globally. There is a growing body of literature on AMR in food-producing animals in African countries, but the surveillance practices across countries vary considerably. This pilot study aims to explore the potential of wastewater and environmental surveillance (WES) of AMR and its extension to the veterinary field. Floor drainage swab (n = 18, 3/abattoir) and wastewater (n = 16, 2-3/abattoir) samples were collected from six South African abattoirs that handle various animal species, including cattle, sheep, pig, and poultry. The samples were tested for Extended-Spectrum Beta-Lactamase (ESBL) and Carbapenemase-producing Enterobacterales, Methicillin-Resistant Staphylococcus aureus (MRSA), Vancomycin-resistant Enterococci (VRE), and Candida auris by using selective culturing and MALDI-TOF MS identification. The phenotype of all presumptive ESBL-producing Escherichia coli (n = 60) and Klebsiella pneumoniae (n = 24) isolates was confirmed with a disk diffusion test, and a subset (15 and 6 isolates, respectively), were further characterized by whole-genome sequencing. In total, 314 isolates (0-12 isolates/sample) withstood MALDI-TOF MS, from which 37 species were identified, E. coli and K. pneumoniae among the most abundant. Most E. coli (n = 48/60; 80%) and all K. pneumoniae isolates were recovered from the floor drainage samples, while 21 presumptive carbapenem-resistant Acinetobacter spp. isolates were isolated equally from floor drainage and wastewater samples. MRSA, VRE, or C. auris were not found. All characterized E. coli and K. pneumoniae isolates represented ESBL-phenotype. Genomic analyses revealed multiple sequence types (ST) of E. coli (n = 10) and K. pneumoniae (n = 5), including STs associated with food-producing animals globally, such as E. coli ST48 and ST10 and K. pneumoniae ST101. Common beta-lactamases linked to food-producing animals, such as bla CTX-M-55 and bla CTX-M-15, were detected. The presence of food-production-animal-associated ESBL-gene-carrying E. coli and K. pneumoniae in an abattoir environment and wastewater indicates the potential of WES in the surveillance of AMR in food-producing animals. Furthermore, the results of this pilot study encourage studying the topic further with refined methodologies.

A Longitudinal Study of Escherichia coli Clinical Isolates from the Tracheal Aspirates of a Paediatric Patient-Strain Type Similar to Pandemic ST131

Escherichia coli is a Gram-negative bacterium and part of the intestinal microbiota. However, it can cause various diarrhoeal illnesses, i.e., traveller's diarrhoea, dysentery, and extraintestinal infections when the bacteria are translocated from the intestine to other organs, such as urinary tract infections, abdominal and pelvic infections, pneumonia, bacteraemia, and meningitis. It is also an important pathogen in intensive care units where cross-infection may cause intrahospital spread with serious consequences. Within this study, four E. coli isolates from the tracheal aspirates of a tracheotomised paediatric patient on chronic respiratory support were analysed and compared for antibiotic resistance and virulence potential. Genomes of all four isolates (5381a, 5381b, 5681, 5848) were sequenced using Oxford Nanopore Technology. According to PFGE analysis, the clones of isolates 5681 and 5848 were highly similar, and differ from 5381a and 5381b which were isolated first chronologically. All four E. coli isolates belonged to an unknown sequence type, related to the E. coli ST131, a pandemic clone that is evolving rapidly with increasing levels of antimicrobial resistance. All four E. coli isolates in this study exhibited a multidrug-resistant phenotype as, according to MIC data, they were resistant to ceftriaxone, ciprofloxacin, doxycycline, minocycline, and tetracycline. In addition, principal component analyses revealed that isolates 5681 and 5848, which were recovered later than 5381a and 5381b (two weeks and three weeks, respectively) possessed more complex antibiotic resistance genes and virulence profiles, which is concerning considering the short time period during which the strains were isolated.

Molecular epidemiology of extended-spectrum beta-lactamase-producing-Klebsiella species in East Tennessee dairy cattle farms

Introduction

The rising prevalence of Extended-Spectrum Beta-Lactamase (ESBL)-producing Klebsiella species (spp.) poses a significant threat to human and animal health and environmental safety. To address this pressing issue, a comprehensive study was undertaken to elucidate the burden and dissemination mechanisms of ESBL-Klebsiella spp. in dairy cattle farms.

Methods

Fifty-seven Klebsiella species were isolated on CHROMagar™ ESBL plates and confirmed with MADLI-TOF MS and whole genome sequenced from 14 dairy farms.

Results and discussion

Six families of beta-lactamase (bla) (bla CTX-M, bla SHV, bla TEM, bla OXY, bla OXA, and bla SED) were detected in ESBL-Klebsiella spp. genomes. Most (73%) of isolates had the first three types of beta-lactamase genes, with bla SHV being the most frequent, followed by bla CTX-M. Most (93%) isolates harbored two or more bla genes. The isolates were genotypically MDR, with 26 distinct types of antibiotic resistance genes (ARGs) and point mutations in gyrA, gyrB, and parC genes. The genomes also harbored 22 different plasmid replicon types, including three novel IncFII. The IncFII and Col440I plasmids were the most frequent and were associated with bla CTXM-27 and qnrB19 genes, respectively. Eighteen distinct sequence types (STs), including eight isolates with novel STs of K. pneumoniae, were detected. The most frequently occurring STs were ST353 (n = 8), ST469 (n = 6), and the novel ST7501 (n = 6). Clusters of ESBL-Klebsiella strains with identical STs, plasmids, and ARGs were detected in multiple farms, suggesting possible clonal expansion. The same ESBL variant was linked to identical plasmids in different Klebsiella STs in some farms, suggesting horizontal spread of the resistance gene. The high burden and dual spread mechanism of ESBL genes in Klebsiella species, combined with the emergence of novel sequence types, could swiftly increase the prevalence of ESBL-Klebsiella spp., posing significant risks to human, animal, and environmental health. Immediate action is needed to implement rigorous surveillance and control measures to mitigate this risk.

First identification and genomic features of multidrug-resistant Citrobacter freundii ST669 strain isolated from a domesticated duck in Bangladesh

Objectives

Citrobacter freundii is a prevalent source of nosocomial infections and a well-known cause of diarrheal diseases. In recent years, it has also become increasingly resistant to various antimicrobials. In this study, we screened and characterized a multidrug-resistant (MDR) C. freundii isolate obtained from a domesticated diseased duck to better understand the genetic features, molecular epidemiology, and underlying factors linked to the antimicrobial resistance genes (ARGs) and virulence factor genes (VFGs) of the isolate.

Methods

The C. freundii BAU_TM8 strain was isolated using culturing, staining, biochemical, polymerase chain reaction, and Matrix-assisted laser desorption/ionization-time of flight methods. The MDR properties of the strain were determined by a disk diffusion test. The genomic sequence of C. freundii BAU_TM8 was performed using the Illumina NextSeq2000 platform. The ARGs, VFGs, and genomic functional characteristics of the C. freundii BAU_TM8 strain were identified using several open-source databases.

Results

The sequence type of this strain was ST669, and the pathogenicity index of the strain was 0.919. Moreover, the strain had an estimated genome length of 5,797,806 bp, harboring 62 contigs, a G + C content of 54.32 %, and five contig L50s with an N50 value of 443,947 bp. Using phylogenetic analysis, this strain was closely related to two strains isolated from human and environmental samples in the USA and China despite huge geographical distances. The C. freundii BAU_TM8 strain consisted of 40 AGRs encoding resistance to 19 antimicrobial categories, e.g., fluoroquinolones, macrolides, folate pathway antagonists, aminoglycosides, tetracyclines, cephalosporins, and others. According to the phenotypic assay and genome sequence, the sensitivity and specificity of resistance profiles of the strain were 100 % and 20 %, respectively. Moreover, the virulence factor database detected 66 VFGs in this strain. This strain contained 1581 subsystems, having 33 % subsystem coverage and 2275 genes encoding amino acid derivatives, carbohydrate metabolism, protein metabolism, cofactors, vitamins, prosthetic groups, pigments, respiration, motility and chemotaxis, stress response, DNA metabolism, nucleosides and nucleotides, and others.

Conclusions

To the best of our knowledge, this is the first WGS report of C. freundii from a domesticated duck in Bangladesh. The ubiquitous occurrence of ARGs and VFGs in the C. freundii BAU_TM8 strain detected in this study highlights the growing concern about antimicrobial resistance in humans, animals, and environments.

Complete genome sequence of the OXA-48-producing Klebsiella pneumoniae strain 11978

We announce the complete genome sequence of Klebsiella pneumoniae strain 11978 isolated from a patient hospitalized in Turkey in 2001. The genome belongs to sequence type 14 and includes three plasmids. Notably, it presents an IncL plasmid carrying blaOXA-48, which demonstrated global success in terms of dissemination.

Enteroaggregative Escherichia coli: Frequent, yet underdiagnosed pathotype among E. coli O111 strains isolated from children with gastrointestinal disorders in the Czech Republic

Enteroaggregative Escherichia coli (EAEC) strains including those of serogroup O111 are important causes of diarrhea in children. In the Czech Republic, no information is available on the etiological role of EAEC in pediatric diarrhea due to the lack of their targeted surveillance. To fill this gap, we determined the proportion of EAEC among E. coli O111 isolates from children with gastrointestinal disorders ≤ 2 years of age submitted to the National Reference Laboratory for E. coli and Shigella during 2013-2022. EAEC accounted for 177 of 384 (46.1 %) E. coli O111 isolates, being the second most frequent E. coli O111 pathotype. Most of them (75.7 %) were typical EAEC that carried aggR, usually with aaiC and aatA marker genes; the remaining 24.3 % were atypical EAEC that lacked aggR but carried aaiC and/or aatA. Whole genome sequencing of 11 typical and two atypical EAEC O111 strains demonstrated differences in serotypes, sequence types (ST), virulence gene profiles, and the core genomes between these two groups. Typical EAEC O111:H21/ST40 strains resembled by their virulence profiles including the presence of the aggregative adherence fimbriae V (AAF/V)-encoding cluster to such strains from other countries and clustered with them in the core genome multilocus sequence typing (cgMLST). Atypical EAEC O111:H12/ST10 strains lacked virulence genes of typical EAEC and differed from them in cgMLST. All tested EAEC O111 strains displayed stacked-brick aggregative adherence to human intestinal epithelial cells. The AAF/V-encoding cluster was located on a plasmid of 95,749 bp or 93,286 bp (pAAO111) which also carried aggR, aap, aar, sepA, and aat cluster. EAEC O111 strains were resistant to antibiotics, in particular to aminopenicillins and cephalosporins; 88.3 % produced AmpC β-lactamase, and 4.1 % extended spectrum β-lactamase. We conclude that EAEC are frequent among E. coli O111 strains isolated from children with gastrointestinal disorders in the Czech Republic. To reliably assess the etiological role of EAEC in pediatric diarrhea, a serotype-independent, PCR-based pathotype surveillance system needs to be implemented in the future.

Genomic epidemiology of multidrug-resistant clinical Acinetobacter baumannii in Bangladesh

The rising frequency of multidrug-resistant (MDR) Acinetobacter baumannii infections represents a significant public health challenge in Bangladesh. Genomic analysis of bacterial pathogens enhances surveillance and control efforts by providing insights into genetic diversity, antimicrobial resistance (AMR) profiles, and transmission dynamics. In this study, we conducted a comprehensive bioinformatic analysis of 82 whole-genome sequences (WGS) of A. baumannii from Bangladesh to understand their genomic epidemiological characteristics. WGS of the MDR and biofilm-forming A. baumannii strain S1C revealed the presence of 28 AMR genes, predicting its pathogenicity and classification within sequence type ST2. Multi-locus sequence typing (MLST) genotyping suggested heterogeneity in the distribution of clinical A. baumannii strains in Bangladesh, with a predominance of ST575. The resistome diversity was evident from the detection of 82 different AMR genes, with antibiotic inactivation being the most prevalent resistance mechanism. All strains were predicted to be multidrug-resistant. The observed virulence genes were associated with immune evasion, biofilm formation, adherence, nutrient acquisition, effector delivery, and other mechanisms. Mobile genetic elements carrying AMR genes were predicted in 68.29% (N = 56) of the genomes. The "open" state of the pan-genome and a high proportion of accessory genes highlighted the genome plasticity and diversity of A. baumannii in Bangladesh. Additionally, phylogenomic analysis indicated clustering of A. baumannii strains into three separate clades according to sequence type. In summary, our findings offer detailed insights into the genomic landscape of A. baumannii in Bangladesh, contributing to our understanding of its epidemiology and pathogenicity and informing strategies to combat this pathogen.

Sensitivity and specificity of Nanopore sequencing for detecting carbapenem and 3rd-generation cephalosporin-resistant Enterobacteriaceae in urine samples: Real-time simulation with public antimicrobial resistance gene database

Objectives

To evaluate the accuracy of beta-lactamase gene detection directly from urine samples by Nanopore sequencing.

Methods

DNA was extracted from bacterial pellets in spun urine. The purified DNA was then sequenced in native form by a Nanopore sequencer (MinION) to identify the organisms and beta-lactamase genes. Results were compared to routine urine cultures and standard antimicrobial susceptibility tests (AST).

Results

We processed 60 urine samples of which routine cultures grew Enterobacteriaceae, including 28 carbapenem-resistant (CRE), 17 extended-spectrum beta-lactamase (ESBL) or AmpC producing, and 15 non-ESBL/AmpC phenotypes. We excluded 7 samples with extremely low DNA amounts (<1 ng/μl) for a final case of 53 in total. The sensitivity of antimicrobial resistance gene detection within 6 h, the optimal duration from real-time simulation, of Nanopore sequencing for the diagnosis of carbapenem-resistant and ceftriaxone-resistant phenotypes was 73.9 % (95%CI 56.0-91.9 %) and 81.1 % (95%CI 68.5-93.7 %), while the specificity was 96.7 % (95%CI 90.2-100.0 %) and 56.3 % (95%CI 31.9-80.6 %), respectively. The median times for MinION to generate DNA reads containing carbapenemase and ESBL/AmpC genes were 93 min (IQR 17-245.5) and 99 min (IQR 31.25-269.75) after sequencing commencement, respectively.

Conclusions

Nanopore sequencing can identify bacterial genotypic resistance in urine and may enable clinicians to adjust antimicrobial therapy earlier than routine AST.

Investigating genomic diversity of Staphylococcus aureus associated with pediatric atopic dermatitis in South Africa

Importance

Staphylococcus aureus frequently colonizes the skin and nose of patients with atopic dermatitis (AD), a disease associated with skin barrier dysfunction and chronic cutaneous inflammation. Published genomic studies on AD-associated S. aureus in pediatric populations in sub-Saharan Africa are limited.

Objectives

To investigate the phenotypic and genomic diversity of S. aureus in children with and without AD during early childhood.

Data setting and participants

A cross-sectional study of 220 children (aged 9-38 months) with AD (cases) and without AD (controls) from Cape Town and Umtata, South Africa.

Main outcomes and measures

S. aureus phenotypic and genomic diversity were investigated using whole-genome sequencing, antibiotic susceptibility testing and biofilm microtiter assay.

Results

Of the 124 S. aureus isolates recovered from 220 children, 96 isolates (79 cases and 17 controls) with high-quality sequences were analyzed. Isolates from cases showed greater phenotypic resistance to gentamicin (10%), rifampicin (4%), chloramphenicol (4%), and exhibited multidrug resistance (9%) than in controls. Furthermore, the isolates from cases formed stronger biofilms than those from controls (76% vs. 35%, p = 0.001), but showed no dominance of any virulence factor gene or mobile genetic elements. There was no significant difference in the distribution of immune evasion cluster types between cases and controls. However, IEC type G was identified only among cases.

Conclusion and relevance

AD-associated S. aureus has phenotypic and genetic features that are important for successful pathogenic colonization and survival. Further studies are needed to assess the pathological implications of colonization of various S. aureus lineages in vivo to elucidate their pathological contribution to AD pathogenesis and pathophysiology.

Genomic characterization of methicillin-resistant Staphylococcus aureus isolated from patients attending regional referral hospitals in Tanzania

BACKGROUND

Methicillin-resistant Staphylococcus aureus (MRSA) colonization increases the risk of subsequent infection by MRSA strain complex interlinking between hospital and community-acquired MRSA which increases the chance of drug resistance and severity of the disease.

OBJECTIVE

Genomic characterization of Staphylococcus aures strains isolated from patients attending regional referral hospitals in Tanzania.

METHODOLOGY

A laboratory-based cross-sectional study using short read-based sequencing technology, (Nextseq550,Illumina, Inc. San diego, California, USA). The samples used were collected from patients attending selected regional referral hospitals in Tanzania under the SeqAfrica project. Sequences were analyzed using tools available in the center for genomic and epidemiology server, and visualization of the phylogenetic tree was performed in ITOL 6.0. SPSS 28.0 was used for statistical analysis.

RESULTS

Among 103 sequences of S. aureus, 48.5% (50/103) carry the mecA gene for MRSA. High proportions of MRSA were observed among participants aged between 18 and 34 years (52.4%), in females (54.3%), and among outpatients (60.5%). The majority of observed MRSA carried plasmids rep5a (92.0%), rep16 (90.0%), rep7c (90.0%), rep15 (82.0%), rep19 (80.0%) and rep10 (72.0%). Among all plasmids observed rep5a, rep16, rep20, and repUS70 carried the blaZ gene, rep10 carried the erm(C) gene and rep7a carried the tet(K) gene. MLST and phylogeny analysis reveal high diversity among MRSA. Six different clones were observed circulating at selected regional hospitals and MRSA with ST8 was dominant.

CONCLUSION

The study reveals a significant presence of MRSA in Staphylococcus aureus strains from Tanzanian regional hospitals, with nearly half carrying the mecA gene. MRSA is notably prevalent among young adults, females, and outpatients, showing high genetic diversity and dominance of ST8. Various plasmids carrying resistance genes indicate a complex resistance profile, highlighting the need for targeted interventions to manage MRSA infections in Tanzania.

Genomic Sequence of Streptococcus salivarius MDI13 and Latilactobacillus sakei MEI5: Two Promising Probiotic Strains Isolated from European Hakes (Merluccius merluccius, L.)

Frequently, diseases in aquaculture have been fought indiscriminately with the use of antibiotics, which has led to the development and dissemination of (multiple) antibiotic resistances in bacteria. Consequently, it is necessary to look for alternative and complementary approaches to chemotheraphy that are safe for humans, animals, and the environment, such as the use of probiotics in fish farming. The objective of this work was the Whole-Genome Sequencing (WGS) and bioinformatic and functional analyses of S. salivarius MDI13 and L. sakei MEI5, two LAB strains isolated from the gut of commercial European hakes (M. merluccius, L.) caught in the Northeast Atlantic Ocean. The WGS and bioinformatic and functional analyses confirmed the lack of transferable antibiotic resistance genes, the lack of virulence and pathogenicity issues, and their potentially probiotic characteristics. Specifically, genes involved in adhesion and aggregation, vitamin biosynthesis, and amino acid metabolism were detected in both strains. In addition, genes related to lactic acid production, active metabolism, and/or adaptation to stress and adverse conditions in the host gastrointestinal tract were detected in L. sakei MEI5. Moreover, a gene cluster encoding three bacteriocins (SlvV, BlpK, and BlpE) was identified in the genome of S. salivarius MDI13. The in vitro-synthesized bacteriocin BlpK showed antimicrobial activity against the ichthyopathogens Lc. garvieae and S. parauberis. Altogether, our results suggest that S. salivarius MDI13 and L. sakei MEI5 have a strong potential as probiotics to prevent fish diseases in aquaculture as an appropriate alternative/complementary strategy to the use of antibiotics.

Mycobacterium cosmeticum catheter-related bloodstream infection in an immunocompetent patient: A case report and review of the literature

Background

Mycobacterium cosmeticum is an emerging rapidly growing mycobacteria (RGM) species that has been rarely reported to cause human disease. RGM catheter-related bloodstream infections (CRBSI) are often challenging to treat given the need for line removal, variable species-dependent antimicrobial susceptibility, combination antimicrobial treatment, and historically longer courses of antibiotics.

Case presentation

We present a case of an immunocompetent pediatric patient with severe hemophilia B and M. cosmeticum CRBSI. While the patient's hemophilia B precluded a standard line holiday, he successfully cleared his infection with two line exchanges followed by two weeks of antibiotics.

Conclusions

RGM, including emerging species M. cosmeticum, may be considered in patients with an indolent presentation of CRBSI. Our case suggests source control with shorter courses of antimicrobials can be successful.

Genomic and metagenomic analysis reveals shared resistance genes and mobile genetic elements in E. coli and Klebsiella spp. isolated from hospital patients and hospital wastewater at intra- and inter-genus level

Antimicrobial resistance (AMR) is a global problem that gives serious cause for concern. Hospital wastewater (HWW) is an important link between the clinical setting and the natural environment, and an escape route for pathogens that cause hospital infections, including urinary tract infections (UTI). Bacteria of the genera Escherichia and Klebsiella are common etiological factors of UTI, especially in children, and they can cause short-term infections, as well as chronic conditions. ESBL-producing Escherichia and Klebsiella have also emerged as potential indicators for estimating the burden of antimicrobial resistance under environmental conditions and the spread of AMR between clinical settings and the natural environment. In this study, whole-genome sequencing and the nanopore technology were used to analyze the complete genomes of ESBL-producing E.coli and Klebsiella spp. and the HWW metagenome, and to characterize the mechanisms of AMR. The similarities and differences in the encoded mechanisms of AMR in clinical isolates (causing UTI) and environmental strains (isolated from HWW and the HWW metagenome) were analyzed. Special attention was paid to the genetic context and the mobility of antibiotic resistance genes (ARGs) to determine the common sources and potential transmission of these genes. The results of this study suggest that the spread of drug resistance from healthcare facilities via HWW is not limited to the direct transmission of resistant clonal lines that are typically found in the clinical setting, but it also involves the indirect transfer of mobile elements carrying ARGs between bacteria colonizing various environments. Hospital wastewater could offer a supportive environment for plasmid evolution through the insertion of new ARGs, including typical chromosomal regions. These results indicate that interlined environments (hospital patients - HWW) should be closely monitored to evaluate the potential transmission routes of drug resistance in bacteria.

Isolation and Characterization of Lactic Acid Bacteria With Probiotic Attributes From Different Parts of the Gastrointestinal Tract of Free-living Wild Boars in Hungary

Lactic acid bacteria (LAB) in the microbiota play an important role in human and animal health and, when used as probiotics, can contribute to an increased growth performance in livestock management. Animals living in their native habitat can serve as natural sources of microorganisms, so isolation of LAB strains from wild boars could provide the opportunity to develop effective probiotics to improve production in swine industry. In this study, the probiotic potential of 56 LAB isolates, originated from the ileum, colon, caecum and faeces of 5 wild boars, were assessed in vitro in details. Their taxonomic identity at species level and their antibacterial activity against four representative strains of potentially pathogenic bacteria were determined. The ability to tolerate low pH and bile salt, antibiotic susceptibility, bile salt hydrolase activity and lack of hemolysis were tested. Draft genome sequences of ten Limosilactobacillus mucosae and three Leuconostoc suionicum strains were determined. Bioinformatic analysis excluded the presence of any known acquired antibiotic resistance genes. Three genes, encoding mesentericin B105 and two different bacteriocin-IIc class proteins, as well as two genes with possible involvement in mesentericin secretion (mesE) and transport (mesD) were identified in two L. suionicum strains. Lam29 protein, a component of an ABC transporter with proved function as mucin- and epithelial cell-adhesion factor, and a bile salt hydrolase gene were found in all ten L. mucosae genomes. Comprehensive reconsideration of all data helps to select candidate strains to assess their probiotic potential further in animal experiments.

Characterization and genome mining of Bacillus subtilis BDSA1 isolated from river water in Bangladesh: A promising bacterium with diverse biotechnological applications

The metabolic versatility of Bacillus subtilis makes it useful for a wide range of applications in biotechnology, from bioremediation to industrially important metabolite production. Understanding the molecular attributes of the biocontrol characteristics of B. subtilis is necessary for its tailored use in the environment and industry. Therefore, the present study aimed to conduct phenotypic characterization and whole genome analysis of the B. subtilis BDSA1 isolated from polluted river water from Dhaka, Bangladesh to explore its biotechnological potential. The chromium reduction capacity at 100 ppm Cr (VI) showed that B. subtilis BDSA1 reduced 40 % of Cr (VI) within 24hrs at 37 °C. Exposure of this bacterium to 200 ppm cadmium resulted in 43 % adsorption following one week of incubation at 37 °C. Molecular detection of chrA and czcC gene confirmed chromium and cadmium resistance characteristics of BDSA1. The size of the genome of the B. subtilis BDSA1 was 4.2 Mb with 43.4 % GC content. Genome annotation detected the presence of numerous genes involved in the degradation of xenobiotics, resistance to abiotic stress, production of lytic enzymes, siderophore formation, and plant growth promotion. The assembled genome also carried chromium, cadmium, copper, and arsenic resistance-related genes, notably cadA, czcD, czrA, arsB etc. Genome mining revealed six biosynthetic gene clusters for bacillaene, bacillibacin, bacilysin, subtilosin, fengycin and surfactin. Importantly, BDSA1 was predicted to be non-pathogenic to humans and had only two acquired antimicrobial resistance genes. The pan-genome analysis showed the openness of the B. subtilis pan-genome. Our findings suggested that B. subtilis BDSA1 might be a promising candidate for diverse biotechnological uses.

Genomic analysis of carbapenem- and colistin-resistant Klebsiella pneumoniae complex harbouring mcr-8 and mcr-9 from individuals in Thailand

The surge in mobile colistin-resistant genes (mcr) has become an increasing public health concern, especially in carbapenem-resistant Enterobacterales (CRE). Prospective surveillance was conducted to explore the genomic characteristics of clinical CRE isolates harbouring mcr in 2015-2020. In this study, we aimed to examine the genomic characteristics and phonotypes of mcr-8 and mcr-9 harbouring carbapenem-resistant K. pneumoniae complex (CRKpnC). Polymerase chain reaction test and genome analysis identified CRKpnC strain AMR20201034 as K. pneumoniae (CRKP) ST147 and strain AMR20200784 as K. quasipneumoniae (CRKQ) ST476, harbouring mcr-8 and mcr-9, respectively. CRKQ exhibited substitutions in chromosomal-mediated colistin resistance genes (pmrB, pmrC, ramA, and lpxM), while CRKP showed two substitutions in crrB, pmrB, pmrC, lpxM and lapB. Both species showed resistance to colistin, with minimal inhibitory concentrations of 8 µg/ml for mcr-8-carrying CRKP isolate and 32 µg/ml for mcr-9-carrying CRKQ isolate. In addition, CRKP harbouring mcr-8 carried blaNDM, while CRKQ harbouring mcr-9 carried blaIMP, conferring carbapenem resistance. Analysis of plasmid replicon types carrying mcr-8 and mcr-9 showed FIA-FII (96,575 bp) and FIB-HI1B (287,118 bp), respectively. In contrast with the plasmid carrying the carbapenemase genes, the CRKQ carried blaIMP-14 on an IncC plasmid, while the CRKP harboured blaNDM-1 on an FIB plasmid. This finding provides a comprehensive insight into another mcr-carrying CRE from patients in Thailand. The other antimicrobial-resistant genes in the CRKP were blaCTX-M-15, blaSHV-11, blaOXA-1, aac(6')-Ib-cr, aph(3')-VI, ARR-3, qnrS1, oqxA, oqxB, sul1, catB3, fosA, and qacE, while those detected in CRKQ were blaOKP-B-15, qnrA1, oqxA, oqxB, sul1, fosA, and qacE. This observation highlights the importance of strengthening official active surveillance efforts to detect, control, and prevent mcr-harbouring CRE and the need for rational drug use in all sectors.

Genomic characterization and virulence gene profiling of Erysipelothrix rhusiopathiae isolated from widespread muskox mortalities in the Canadian Arctic Archipelago

BACKGROUND

Muskoxen are important ecosystem components and provide food, economic opportunities, and cultural well-being for Indigenous communities in the Canadian Arctic. Between 2010 and 2021, Erysipelothrix rhusiopathiae was isolated from carcasses of muskoxen, caribou, a seal, and an Arctic fox during multiple large scale mortality events in the Canadian Arctic Archipelago. A single strain ('Arctic clone') of E. rhusiopathiae was associated with the mortalities on Banks, Victoria and Prince Patrick Islands, Northwest Territories and Nunavut, Canada (2010-2017). The objectives of this study were to (i) characterize the genomes of E. rhusiopathiae isolates obtained from more recent muskox mortalities in the Canadian Arctic in 2019 and 2021; (ii) identify and compare common virulence traits associated with the core genome and mobile genetic elements (i.e. pathogenicity islands and prophages) among Arctic clone versus other E. rhusiopathiae genomes; and iii) use pan-genome wide association studies (GWAS) to determine unique genetic contents of the Arctic clone that may encode virulence traits and that could be used for diagnostic purposes.

RESULTS

Phylogenetic analyses revealed that the newly sequenced E. rhusiopathiae isolates from Ellesmere Island, Nunavut (2021) also belong to the Arctic clone. Of 17 virulence genes analysed among 28 Arctic clone isolates, four genes - adhesin, rhusiopathiae surface protein-A (rspA), choline binding protein-B (cbpB) and CDP-glycerol glycerophosphotransferase (tagF) - had amino acid sequence variants unique to this clone when compared to 31 other E. rhusiopathiae genomes. These genes encode proteins that facilitate E. rhusiopathiae to attach to the host endothelial cells and form biofilms. GWAS analyses using Scoary found several unique genes to be overrepresented in the Arctic clone.

CONCLUSIONS

The Arctic clone of E. rhusiopathiae was associated with multiple muskox mortalities spanning over a decade and multiple Arctic islands with distances over 1000 km, highlighting the extent of its spatiotemporal spread. This clone possesses unique gene content, as well as amino acid variants in multiple virulence genes that are distinct from the other closely related E. rhusiopathiae isolates. This study establishes an essential foundation on which to investigate whether these differences are correlated with the apparent virulence of this specific clone through in vitro and in vivo studies.

Genome assembly, comparative genomics, and identification of genes/pathways underlying plant growth-promoting traits of an actinobacterial strain, Amycolatopsis sp. (BCA-696)

The draft genome sequence of an agriculturally important actinobacterial species Amycolatopsis sp. BCA-696 was developed and characterized in this study. Amycolatopsis BCA-696 is known for its biocontrol properties against charcoal rot and also for plant growth-promotion (PGP) in several crop species. The next-generation sequencing (NGS)-based draft genome of Amycolatopsis sp. BCA-696 comprised of ~ 9.05 Mb linear chromosome with 68.75% GC content. In total, 8716 protein-coding sequences and 61 RNA-coding sequences were predicted in the genome. This newly developed genome sequence has been also characterized for biosynthetic gene clusters (BGCs) and biosynthetic pathways. Furthermore, we have also reported that the Amycolatopsis sp. BCA-696 produces the glycopeptide antibiotic vancomycin that inhibits the growth of pathogenic gram-positive bacteria. A comparative analysis of the BCA-696 genome with publicly available closely related genomes of 14 strains of Amycolatopsis has also been conducted. The comparative analysis has identified a total of 4733 core and 466 unique orthologous genes present in the BCA-696 genome The unique genes present in BCA-696 was enriched with antibiotic biosynthesis and resistance functions. Genome assembly of the BCA-696 has also provided genes involved in key pathways related to PGP and biocontrol traits such as siderophores, chitinase, and cellulase production.

The Triple Combination of Meropenem, Avibactam, and a Metallo-β-Lactamase Inhibitor Optimizes Antibacterial Coverage Against Different β-Lactamase Producers

This work explores the potential of a triple combination of meropenem (MEM), a novel metallo-β-lactamase (MBL) inhibitor (indole-2-carboxylate 58 (InC58)), and a serine-β-lactamase (SBL) inhibitor (avibactam (AVI)) for broad-spectrum activity against carbapenemase-producing bacteria. A diverse panel comprising MBL- and SBL-producing strains was used for susceptibility testing of the triple combination using the agar dilution method. The frequency of resistance (FoR) to MEM combined with InC58 was investigated. Mutants were sequenced and tested for cross resistance, fitness, and the stability of the resistance phenotype. Compared with the double combinations of MEM plus an SBL or MBL inhibitor, the triple combination extended the spectrum of activity to most of the isolates bearing SBLs (oxacillinase-48 (OXA-48) and Klebsiella pneumoniae carbapenemase-2 (KPC-2)) and MBLs (New Delhi metallo-β-lactamases (NDMs)), although it was not effective against Verona integron-encoded metallo-β-lactamase (VIM)-carrying Pseudomonas aeruginosa (P. aeruginosa) and OXA-23-carrying Acinetobacter baumannii (A. baumannii). The FoR to MEM plus InC58 ranged from 2.22 × 10-7 to 1.13 × 10-6. The resistance correlated with mutations to ompC and comR, affecting porin C and copper permeability, respectively. The mutants manifested a fitness cost, a decreased level of resistance during passage without antibiotic pressure, and cross resistance to another carbapenem (imipenem) and a β-lactamase inhibitor (taniborbactam). In conclusion, compared with the dual combinations, the triple combination of MEM with InC58 and AVI showed a much wider spectrum of activity against different carbapenemase-producing bacteria, revealing a new strategy to combat β-lactamase-mediated antimicrobial resistance.

Genomic Insights into Edwardsiella ictaluri: Molecular Epidemiology and Antimicrobial Resistance in Striped Catfish (Pangasianodon hypophthalmus) Aquaculture in Vietnam

Edwardsiella ictaluri is responsible for causing bacillary necrosis (BNP) in striped catfish (Pangasianodon hypophthalmus) in Vietnam. This study offers a comprehensive genomic characterization of E. ictaluri to enhance understanding of the molecular epidemiology, virulence, and antimicrobial resistance. E. ictaluri isolates were collected from diseased striped catfish in the Mekong Delta. The species was confirmed through PCR. Antimicrobial susceptibility testing was conducted using minimum inhibitory concentrations for commonly used antimicrobials. Thirty representative isolates were selected for whole genome sequencing to delineate their genomic profiles and phylogeny. All strains belonged to ST-26 and exhibited genetic relatedness, differing by a maximum of 90 single nucleotide polymorphisms. Most isolates carried multiple antimicrobial resistance genes, with the tet(A) gene present in 63% and floR in 77% of the genomes. The ESBL gene, blaCTX-M-15, was identified in 30% of the genomes. Three plasmid replicon types were identified: IncA, p0111, and IncQ1. The genomes clustered into two clades based on their virulence gene profile, one group with the T3SS genes and one without. The genetic similarity among Vietnamese isolates suggests that disease spread occurs within the Mekong region, underscoring the importance of source tracking, reservoir identification, and implementation of necessary biosecurity measures to mitigate spread of BNP.

Displacement of Hospital-Acquired, Methicillin-Resistant Staphylococcus aureus Clones by Heterogeneous Community Strains in Kenya over a 13-Year Period

We determined antibiotic susceptibility and employed Oxford Nanopore whole-genome sequencing to explore strain diversity, resistance, and virulence gene carriage among methicillin-resistant Staphylococcus aureus (MRSA) strains from different infection sites and timepoints in a tertiary Kenyan hospital. Ninety-six nonduplicate clinical isolates recovered between 2010 and 2023, identified and tested for antibiotic susceptibility on the VITEK ID/AST platform, were sequenced. Molecular typing, antibiotic resistance, and virulence determinant screening were performed using the relevant bioinformatics tools. The strains, alongside those from previous studies, were stratified into two periods covering 2010-2017 and 2018-2023 and comparisons were made. Mirroring phenotypic profiles, aac(6')-aph(2″) [aminoglycosides]; gyrA (S84L) and grlA (S80Y) [fluoroquinolones]; dfrG [anti-folates]; and tet(K) [tetracycline] resistance determinants dominated the collection. While the proportion of ST239/241-t037-SCCmec III among MRSA reduced from 37.7% to 0% over the investigated period, ST4803-t1476-SCCmec IV and ST152-t355-SCCmec IV were pre-eminent. The prevalence of Panton-Valentine leucocidin (PVL) and arginine catabolic mobile element (ACME) genes was 38% (33/87) and 6.8% (6/87), respectively. We observed the displacement of HA-MRSA ST239/241-t037-SCCmec III with the emergence of ST152-t355-SCCmec IV and a greater clonal heterogeneity. The occurrence of PVL+/ACME+ CA-MRSA in recent years warrants further investigations into their role in the CA-MRSA virulence landscape, in a setting of high PVL prevalence.

Analysis of the Class 1 Integrons, Carbapenemase Genes and Biofilm Formation Genes Occurrence in Acinetobacter baumannii Clinical Isolates

Acinetobacter baumannii is a non-fermentative Gram-negative bacterium that can cause nosocomial infections in critically ill patients. Carbapenem-resistant A. baumannii (CRAB) has spread rapidly in clinical settings and has become a key concern. The main objective of this study was to identify the distribution of integrons and biofilm-formation-related virulence genes in CRAB isolates. A total of 269 A. baumannii isolates (219 isolates of CRAB and 50 isolates of carbapenem-sensitive A. baumannii (CSAB)) were collected. Carbapenemase genes (bla KPC, bla VIM, bla IMP, bla NDM, and bla OXA-23-like) and biofilm-formation-related virulence genes (abal, bfms, bap, and cusE) were screened with PCR. Class 1 integron was screened with PCR, and common promoters and gene cassette arrays were determined with restriction pattern analysis combined with primer walking sequencing. Whole-genome sequencing was conducted, and data were analyzed for a bla OXA-23-like-negative isolate. All 219 CRAB isolates were negative for bla KPC, bla VIM, bla IMP, and bla NDM, while bla OXA-23-like was detected in 218 isolates. The detection rates for abal, bfms, bap, and cusE in 219 CRAB were 93.15%, 63.93%, 88.13%, and 77.63%, respectively. Class 1 integron was detected in 75 CRAB (34.25%) and in 3 CSAB. The single gene cassette array aacA4-catB8-aadA1 with relatively strong PcH2 promoter was detected in class 1 integrons. The bla OXA-23-like-negative CRAB isolate was revealed to be a new sequence type (Oxford 3272, Pasteur 2520) carrying bla OXA-72, bla OXA-259, and bla ADC-26. In conclusion, bla OXA-23-like was the main reason for CRAB's resistance to carbapenems. A new (Oxford 3272, Pasteur 2520) CRAB sequence type carrying the bla OXA-72, bla OXA-259, and bla ADC-26 was reported.

The first case of urosepsis caused by Corynebacterium aurimucosum in an immunocompetent patient

Non-diphtheroid Corynebacterium sepsis is rare and has affected only immunocompromised or particularly predisposed patients so far. We present the first case of urosepsis caused by Corynebacterium aurimucosum in a 67-year-old woman, without any known immunodeficiencies and in absence of any immunosuppressive therapy, admitted to the hospital for fever and acute dyspnea. This work suggests a new approach in evaluating the isolation of Corynebacteria, especially if isolated from blood. In particular, it highlights the potential infectious role of C. aurimucosum (often considered a contaminant and only rarely identified as an etiological agent of infections) and its clinical consequences, detailing also interesting aspects about its microbiological diagnosis and relative therapy and clarifying contrasting data of literature.

Genomic analysis of Salmonella isolated from canal water in Bangkok, Thailand

Antimicrobial resistance (AMR) poses an escalating global public health threat. Canals are essential in Thailand, including the capital city, Bangkok, as agricultural and daily water sources. However, the characteristic and antimicrobial-resistance properties of the bacteria in the urban canals have never been elucidated. This study employed whole genome sequencing to characterize 30 genomes of a causal pathogenic bacteria, Salmonella enterica, isolated from Bangkok canal water between 2016 and 2020. The dominant serotype was Salmonella Agona. In total, 35 AMR genes and 30 chromosomal-mediated gene mutations were identified, in which 21 strains carried both acquired genes and mutations associated with fluoroquinolone resistance. Virulence factors associated with invasion, adhesion, and survival during infection were detected in all study strains. 75.9% of the study stains were multidrug-resistant and all the strains harbored the necessary virulence factors associated with salmonellosis. One strain carried 20 resistance genes, including mcr-3.1, mutations in GyrA, ParC, and ParE, and typhoid toxin-associated genes. Fifteen plasmid replicon types were detected, with Col(pHAD28) being the most common type. Comparative analysis of nine S. Agona from Bangkok and 167 from public databases revealed that specific clonal lineages of S. Agona might have been circulating between canal water and food sources in Thailand and globally. These findings provide insight into potential pathogens in the aquatic ecosystem and support the inclusion of environmental samples into comprehensive AMR surveillance initiatives as part of a One Health approach. This approach aids in comprehending the rise and dissemination of AMR and devising sustainable intervention strategies.IMPORTANCEBangkok is the capital city of Thailand and home to a large canal network that serves the city in various ways. The presence of pathogenic and antimicrobial-resistant Salmonella is alarming and poses a significant public health risk. The present study is the first characterization of the genomic of Salmonella strains from Bangkok canal water. Twenty-two of 29 strains (75.9%) were multidrug-resistant Salmonella and all the strains carried essential virulence factors for pathogenesis. Various plasmid types were identified in these strains, potentially facilitating the horizontal transfer of AMR genes. Additional investigations indicated a potential circulation of S. Agona between canal water and food sources in Thailand. The current study underscores the role of environmental water in an urban city as a reservoir of pathogens and these data obtained can serve as a basis for public health risk assessment and help shape intervention strategies to combat AMR challenges in Thailand.

Short reads-based characterization of pathotype diversity and drug resistance among Escherichia coli isolated from patients attending regional referral hospitals in Tanzania

BACKGROUND

Escherichia coli is known to cause about 2 million deaths annually of which diarrhea infection is leading and typically occurs in children under 5 years old. Although Africa is the most affected region there is little information on their pathotypes diversity and their antimicrobial resistance.

OBJECTIVE

To determine the pathotype diversity and antimicrobial resistance among E. coli from patients attending regional referral hospitals in Tanzania.

MATERIALS AND METHODS

A retrospective cross-section laboratory-based study where a total of 138 archived E. coli isolates collected from 2020 to 2021 from selected regional referral hospitals in Tanzania were sequenced using the Illumina Nextseq550 sequencer platform. Analysis of the sequences was done in the CGE tool for the identification of resistance genes and virulence genes. SPSS version 20 was used to summarize data using frequency and proportion.

RESULTS

Among all 138 sequenced E. coli isolates, the most prevalent observed pathotype virulence genes were of extraintestinal E. coli UPEC fyuA gene 82.6% (114/138) and NMEC irp gene 81.9% (113/138). Most of the E. coli pathotypes observed exist as a hybrid due to gene overlapping, the most prevalent pathotypes observed were NMEC/UPEC hybrid 29.7% (41/138), NMEC/UPEC/EAEC hybrid 26.1% (36/138), NMEC/UPEC/DAEC hybrid 18.1% (25/138) and EAEC 15.2% (21/138). Overall most E. coli carried resistance gene to ampicillin 90.6% (125/138), trimethoprim 85.5% (118/138), tetracycline 79.9% (110/138), ciprofloxacin 76.1% (105/138) and 72.5% (100/138) Nalidixic acid. Hybrid pathotypes were more resistant than non-hybrid pathotypes.

CONCLUSION

Whole genome sequencing reveals the presence of hybrid pathotypes with increased drug resistance among E. coli isolated from regional referral hospitals in Tanzania.

Genomic Characterization of Listeria monocytogenes and Other Listeria Species Isolated from Sea Turtles

Listeria monocytogenes is a ubiquitous pathogen found both in the environment and food. It can cause listeriosis in a wide range of animals as well as in humans. Investigations on presence, spread and virulence are still limited to terrestrial and human environments. Embracing the One Health Approach, investigating the presence and spread of L. monocytogenes in marine ecosystems and among wildlife, would provide us with useful information for human health. This study investigated the presence of L. monocytogenes and Listeria spp. in two species of sea turtles common in the Mediterranean Sea (Caretta caretta and Chelonia mydas). A total of one hundred and sixty-four carcasses of sea turtles (C. caretta n = 161 and C. mydas n = 3) stranded along the Abruzzo, Molise, Campania, and Calabria coasts, were collected. Brain and fecal samples were taken, enriched, and cultured for the detection of Listeria spp. From the specimens collected, strains of L. monocytogenes (brain n = 1, brain and feces n = 1, multiorgan n = 1 and feces n = 1), L. innocua (feces n = 1 and brain n = 1), and L. ivanovii (brain n = 1) were isolated. Typical colonies were isolated for Whole Genome Sequencing (WGS). Virulence genes, disinfectants/metal resistance, and antimicrobial resistance were also investigated. L. monocytogenes, L. innocua, and L. ivanovii were detected in C. caretta, whilst only L. monocytogenes and L. innocua in C. mydas. Notable among the results is the lack of significant differences in gene distribution between human and sea turtle strains. Furthermore, potentially pathogenic strains of L. monocytogenes were found in sea turtles.

Biochemical and molecular characterization of Campylobacter fetus isolates from bulls subjected to bovine genital campylobacteriosis diagnosis in Spain

BACKGROUND

Bovine genital campylobacteriosis (BGC) is caused by Campylobacter fetus subsp. venerealis (Cfv) including its biovar intermedius (Cfvi). This sexually transmitted disease induces early reproductive failure causing considerable economic losses in the cattle industry. Using a collection of well-characterized isolates (n = 13), C. fetus field isolates (n = 64) and saprophytic isolates resembling Campylobacter (n = 75) obtained from smegma samples of breeding bulls, this study evaluated the concordance of the most used phenotypic (H2S production in cysteine medium and 1% glycine tolerance) and molecular (PCR) methods for the diagnosis of BGC and assessed possible cross-reactions in the molecular diagnostic methods.

RESULTS

Characterization at the subspecies level (fetus vs. venerealis) of C. fetus isolated from bull preputial samples using phenotypic and molecular (PCR targeting nahE and ISCfe1) methods showed moderate concordance (κ = 0.462; CI: 0.256-0.669). No cross-reactions were observed with other saprophytic microaerophilic species or with other Campylobacter species that can be present in preputial samples. Whole genome sequencing (WGS) of discrepant isolates showed 100% agreement with PCR identification. For the differentiation of Cfv biovars, comparison of the H2S test (at 72 h and 5 days of incubation) and a PCR targeting the L-cysteine transporter genes showed higher concordance when H2S production was assessed after 5 days (72 h; κ = 0.553, 0.329-0.778 CI vs. 5 days; κ = 0.881, 0.631-1 CI), evidencing the efficacy of a longer incubation time.

CONCLUSIONS

This study confirmed the limitations of biochemical tests to correctly identify C. fetus subspecies and biovars. However, in the case of biovars, when extended incubation times for the H2S test (5 days) were used, phenotypic identification results were significantly improved, although PCR-based methods produced more accurate results. Perfect agreement of WGS with the PCR results and absence of cross-reactions with non-C. fetus saprophytic bacteria from the smegma demonstrated the usefulness of these methods. Nevertheless, the identification of new C. fetus subspecies-specific genes would help to improve BGC diagnosis.

Advances in phage-host interaction prediction: in silico method enhances the development of phage therapies

Phages can specifically recognize and kill bacteria, which lead to important application value of bacteriophage in bacterial identification and typing, livestock aquaculture and treatment of human bacterial infection. Considering the variety of human-infected bacteria and the continuous discovery of numerous pathogenic bacteria, screening suitable therapeutic phages that are capable of infecting pathogens from massive phage databases has been a principal step in phage therapy design. Experimental methods to identify phage-host interaction (PHI) are time-consuming and expensive; high-throughput computational method to predict PHI is therefore a potential substitute. Here, we systemically review bioinformatic methods for predicting PHI, introduce reference databases and in silico models applied in these methods and highlight the strengths and challenges of current tools. Finally, we discuss the application scope and future research direction of computational prediction methods, which contribute to the performance improvement of prediction models and the development of personalized phage therapy.