Extended-spectrum β-lactamases in Gram Negative Bacteria

Silver Nanoparticles as Antibacterials: Synthesis, Characterization, and Molecular Simulations Against β-Lactamase-Producing Enterobacter and Salmonella spp

Multidrug resistance poses a threat to public health all over the world. Evidences suggest that third-generation antibiotic resistance mediated by extended-spectrum beta-lactamases (ESBLs) in all Enterobacteriaceae species, especially in Enterobacter and Salmonella. In this study, silver nanoparticles (AgNPs) were synthesized and characterized using sol-gel synthesis and powder X-ray diffraction. It was shown that clinical isolates were sensitive to AgNPs. The MIC and MBC, time-dependent growth inhibition test as well as well diffusion agar techniques. ESBL generation was examined using these approaches. There was a low MIC value of 500 μg/ml for Enterobacter and Salmonella. 1000 μg/ml of AgNPs inhibited the development of microorganisms. The antibacterial effect of AgNPs was slow but dependent on concentration and duration. At a concentration of 100 μg/ml, the inhibition zone for Enterobacter was 22 mm, whereas that for Salmonella was 20 mm. Further, molecular docking employed to explore the binding affinity between AgNPs and the active site of beta-lactamase and compare it with reference. Results revealed a very strong score (- 26.79 kcal/mol). Next, MD simulation was performed. The MD simulation results showed a stable interaction between beta-lactamase-nanocluster. Experimental and computational results elucidate the molecular mechanism of anti-bacterial activity of AgNPs to fight against bacterial infections.

Characterization of extended-spectrum beta-lactamase-producing Enterobacteriaceae from recreational water in Athens, GA, using an undergraduate laboratory module

We present a laboratory module that uses isolation of antibiotic-resistant bacteria from locally collected stream water samples to introduce undergraduate students to basic microbiological culture-based and molecular techniques. This module also educates them on the global public health threat of antibiotic-resistant organisms. Through eight laboratory sessions, students are involved in quality testing of water sources from their neighborhoods, followed by isolation of extended-spectrum beta-lactamase-producing Enterobacteriaceae. By the end of the module, students should be able to isolate Enterobacteriaceae from the environment using selective and differential media, identify isolates using biochemical tests, characterize antibiotic resistance phenotypes using Kirby Bauer and MIC tests, and evaluate the presence of select beta-lactamase genes of interest using PCR. To complement laboratory sessions, students participated in a weekly flipped classroom session with collaborative peer discussions and activities to reinforce concepts applied in the laboratory. Learning outcomes were measured over four semesters with concept checks, in-lecture activities, exams, and laboratory reports. We hypothesized that more than 50% of the student population would achieve each learning objective through the implementation of this authentic research laboratory module. Here, we highlight specific questions used to assess learning objective comprehension and demonstrate that each learning objective was achieved by 65%-100% of the student population. We present a ready-to-adapt module with flexible resources that can be implemented in courses across disciplines in biology, microbiology, environmental sciences, and public health.

Therapeutic potential of novel phages with antibiotic combinations against ESBL-producing and carbapenem-resistant Escherichia Coli

OBJECTIVES

The emergence of extended-spectrum β-lactamase (ESBL)-producing E. coli and carbapenem-resistant E. coli (CREC) is a significant global health challenge. This study focuses on isolating and characterizing two novel phages, EC.W1-9 and EC.W15-4, and investigating their efficacy with antibiotics against these resistant E. coli.

METHODS

In vivo experiments were conducted using BALB/c mice, and E.coli isolates were collected, cultured, and evaluated for antibiotic susceptibility. Phages were isolated from hospital sewage and prepared to infect the E. coli.

RESULTS

The isolated phages, EC.W1-9 and EC.W15-4, belonged to the Podoviridae and Straboviridae families, and lack integrase or toxin-coding genes, indicating safety for therapeutic use. The combination of these phages significently enhanced their lytic ability, lysing 61.7% of 60 E. coli isolates, compared to 41.6%-55% lysis by individual phages. Furthermore, the phage combination demonstrated 100% susceptibility against different E. coli sequence types, including ST73, ST648, ST2311, ST405, ST7962, ST131, ST13003, and ST167. Additionally, synergy between antibiotics and phage combinations improved susceptibility rates to 73.3% for ESBL producers and 54% for CREC. The combined treatment of isolated phages and antibiotics significantly increased survival rates in BALB/c mice exposed to resistant STs of E.coli, including ST131, ST648, and ST410. Survival rates against ST131 increased by approximately 75% and 50% compared to treatment individual phages. Combined treatment with two phages and antibiotics resulted in 75-100% survival against E. coli ST410 and 100% survival against ST648 CONCLUSIONS: This study highlights the therapeutic importance of phage and phage-antibiotic combinations in combating ESBL-producing E. coli and CREC isolates.

Public health threat of antimicrobial resistance and virulence genes in Escherichia coli from human-chicken transmission in Egypt

Escherichia coli (E. coli) infections cause significant losses in the poultry industry and pose zoonotic risks due to rising antimicrobial resistance (AMR) and virulence factors. This study investigates E. coli prevalence, AMR, and virulence genes (papC, vgrG1, iss) in Egyptian chickens and farm workers. A total of 35 dead chickens from 14 flocks and 17 farm workers urine samples were examined bacteriologically to investigate E. coli presence followed by biochemical identification. Antimicrobial susceptibility testing was performed on 14 antibiotics using the disk diffusion method on Mueller-Hinton agar, following 'Clinical and Laboratory Standards Institute (CLSI) (2020) guidelines with Extended-spectrum β-lactamase (ESBL) activity evaluated via the Double Disc Synergy Test (DDST) with ceftazidime, cefotaxime, and their clavulanate combinations following CLSI protocols. virulence genes were detected through polymerase chain reaction (PCR) and phylogenetic analysis of the vgrG1 gene evaluated genetic relatedness between the chicken and human isolates. The study analysed 52 samples, identifying E. coli in 18 chicken organs (51.4%) and 11 human urine samples (64.7%), with no significant difference. various antimicrobic sensitivity profiles were identified phenotypically among all isolates in which 29 isolates, 58.6% were ESBL-producing, and 96.5% exhibited multidrug resistance (MDR), with chicken isolates showing higher resistance overall. virulence genes were detected in similar proportions across the isolates highlighting significant public health risks due to resistant and virulent E. coli. This study emphasized the public health risks of multidrug-resistant E. coli with virulence genes, highlighting potential zoonotic transmission and antibiotic use and food safety.

Rapid identification of carbapenemases and in vitro synergy testing of ceftazidime-avibactam with aztreonam in extensively drug-resistant gram-negative pathogens: Establishing the realm of promise

This study evaluated the effectiveness of ceftazidime-avibactam (CZA) alone and in combination with aztreonam (ATM) against 50 extensively drug-resistant (XDR) Gram-negative bacteria (GNB) isolates using disk stacking method. New Delhi metallo-beta-lactamase (NDM) was the predominant carbapenemase, detected in 50 % of isolates showing synergy. The CZA-ATM combination demonstrated synergy in 40 % of isolates, with 75 % of patients receiving this combination achieving microbiological clearance. This simple, rapid synergy testing method can guide effective therapeutic decisions in resource-limited settings.

In silico genomic insights into bacteriophages infecting ESBL-producing Escherichia coli from human, animal, and environmental sources

BACKGROUND

The emergence of antimicrobial resistance (AMR) in Escherichia coli, particularly extended-spectrum beta-lactamase-producing E. coli (ESBL-EC), is a global public health concern. Bacteriophages (phages) play a significant role in bacterial evolution and the spread of antibiotic resistance genes (ARGs). This study investigates prophages integrated within ESBL-EC genomes to assess their diversity, gene content, and potential contributions to ESBL-EC persistence across human, animal, and environmental reservoirs. Between May and December 2020, a cross-sectional study was conducted in Abuja and Lagos, collecting 448 stool, cecal, and environmental samples from abattoir workers, slaughtered cattle, and the abattoir environment. ESBL-EC genomes from these samples, obtained in an earlier study, were analyzed for phage regions using PHASTER. Intact prophages were analyzed in silico using computational tools to detect ARGs, ESBL genes, virulence factors, and heavy metal resistance. Their genomic relationships were examined with statistical significance of p < 0.05.

RESULTS

Out of 448 samples, ESBL-EC prevalence was 21.7% (97/448). Among 97 ESBL-EC isolates, 646 prophage regions were detected, with 30% (194/646) classified as intact phages. Among the 158 phages with genus assignments, Punavirus was the most prevalent (60.1%). Escherichia was the most frequent predicted host (308/646), particularly in cattle (n = 143) and human (n = 124) sources. Among ESBL-EC genomes, 83.5% (81/97) with intact phages carried phage-associated ARGs, 76.3% (74/97) carried phage-associated ESBL genes, 18.6% (18/97) harbored phage-associated virulence factors, 15.5% (15/97) contained phage-associated plasmids, and 10.3% (10/97) had heavy metal resistance. The most prevalent phage-associated ARGs detected were qnrS1 (73/81) and blaCTX-M-15 (72/81). Two isolates recovered from abattoir workers carried two phage-like plasmids, each harboring either tet(A) or blaCTX-M-55 gene. The predominant phage lifestyles were temperate (n = 182), mainly in the Peduoviridae family, and lytic (n = 12) in the Punavirus genus.

CONCLUSION

This is the first study in Nigeria to characterize phages in ESBL-EC isolates at the One Health interface. The presence of intact phages in humans, animals, and the environment underscores the complex interactions shaping phage ecology. The discovery of ARGs, virulence genes, and heavy metal resistance within prophages suggests a potential role in AMR dissemination. Future research should focus on elucidating mechanisms of ARG transfer mediated by phages in One Health settings.

Multidrug-Resistant Uropathogens in Companion Animals: A Comprehensive Study from Clinical Cases and a Genomic Analysis of a CTX-M-14-Producing Escherichia coli ST354, a Leading Cause of Urinary Tract Infections

Urinary tract infections (UTIs) are common in small animals, posing significant clinical challenges due to their recurrence and discomfort. This study investigated the bacterial causes and antimicrobial resistance patterns of UTIs in dogs and cats presented to an important Veterinary Teaching Hospital in São Paulo, Brazil, the largest city in Latin America. Samples were collected from 31 dogs and 9 cats via ultrasound-guided cystocentesis. Bacterial cultures were performed, species identification was accomplished with matrix-assisted laser desorption ionization-time of flight mass spectrometry, and antimicrobial susceptibility testing was done using the Kirby-Bauer method. Escherichia coli was the most frequently isolated pathogen, accounting for 27.9% of cases, followed by Staphylococcus pseudintermedius, Proteus mirabilis, and Klebsiella pneumoniae. Ampicillin resistance was observed in 70.4% of enterobacteria, with many E. coli strains exhibiting multidrug resistance. Whole-genome sequencing of an extended-spectrum beta-lactamase-producing uropathogenic Escherichia coli strain from a feline patient was performed; it was identified as ST354, a leading cause of UTIs worldwide in humans and animals, carrying the blaCTX-M-14 gene and other resistance determinants. Phylogenetic analysis indicated genetic proximity between this strain and others from Brazilian poultry and environmental sources. These findings emphasize the need for antimicrobial resistance surveillance in veterinary UTIs and advocate for stricter antibiotic stewardship to inform diagnostic and therapeutic approaches within a One Health perspective.

AHM-1: An Inclusion to the Arsenal of β-Lactam Resistance in Clostridioides difficile

This study delves into a newly discovered MBL (metallo-β-lactamase) in Clostridioides difficile, a formidable pathogen known for causing nosocomial infections and exhibiting resistance to antimicrobial agents. The primary objective was to unravel its structure-function relationship. This research establishes the enzyme AHM-1 as a subclass B3-like MBL. Experimental results reveal that the enzyme's active site consists of two Zn2+ atoms exhibiting tetrahedral and trigonal bipyramidal coordination, similar to B1 and B3 MBLs. Notably, within its active site, it exhibits a lower binding capacity for other transition metal ions such as Fe2+, Mn2+, and Ni2+ compared to Zn2+. The zinc-binding sites of B1 and B3 MBLs contain strictly conserved His116-His118-His196 and Asp120-Cys221/His121-His263. The absence of all the conserved residues except His116, Asp120, and His121 in the Zn-binding site distinctly separates this enzyme from these two MBL subclasses. Conserved zinc binding motifs present in B1 and B3 MBLs are H-X-H-X-D and H-X-H-X-D-H, respectively. The presence of the H-X-D-X-D-H motif in the enzyme, similar to that in B3 enzymes, along with sequence and structural analysis, places this new enzyme closer to the enzymes belonging to the B3 subclass. This study also identifies the likely catalytic residues responsible for its β-lactamase activity, similar to B3 MBLs. In contrast to MBLs, this enzyme displays hydrolytic activity toward aztreonam. It also shows higher catalytic efficiency toward higher generation cephalosporins. This study thus underscores the significance of a novel enzyme with β-lactamase activity in Clostridioides difficile, highlighting its potential implications for clinical treatment due to its disparities from conventional MBLs.

Bacterial burden and drug-resistant bacteria in healthcare workers' mobile phones: a study in Puerto Rican outpatient clinics

Background

Mobile phones used by healthcare workers (HCWs) in hospitals are significant reservoirs of drug-resistant bacteria responsible for hospital-acquired infections (HAIs).

Aim

The objective of this study was to assess the level of contamination with such bacteria in outpatient clinics.

Methods

Swabs from 83 HCWs' mobile phones were processed using standard biochemical and enzymatic procedures to identify pathogenic bacteria. β-Lactamase tests, antimicrobial susceptibility tests, screening for extended-spectrum β-lactamase (ESBL), and carbapenemase production were performed according to CLSI guidelines. Molecular detection of multi-drug-resistant genes (mecA in Staphylococcus aureus and kpc/ndm carbapenemases in Klebsiella pneumoniae and Acinetobacter spp.) was performed using multiplex real-time polymerase chain reaction.

Findings

The overall prevalence of mobile phone contamination with one or more bacteria was 100%. A total of 51 Gram-positive and 44 Gram-negative isolates, including 20 coagulase-negative staphylococci (CoNS), 20 S. aureus (0 meticillin-resistant S. aureus), 11 Acinetobacter spp. and 10 K. pneumoniae were isolated. β-Lactamase production was detected in 45% of CoNS and 30% of S. aureus. Panton-Valentine Leukocidin (PVL) toxin gene in S. aureus was found in 20% (4/20) of the isolates. Twenty (20%) and 13% of the Acinetobacter spp. and K. pneumoniae isolates, respectively, were ESBL but not carbapenemase producers.

Conclusions

The presence of HAI-causing organisms on mobile phones used by HCWs in outpatient clinics necessitates the implementation of infection control measures to mitigate the risk of cross-contamination in critical healthcare settings.

An insight into newly emerging avian pathogenic E. coli serogroups, biofilm formation, ESBLs and integron detection and in vivo pathogenicity in chicken

Bacterial diseases alone or in combination with other pathogens lead to significant economic losses in poultry globally including India. One of these diseases is avian colibacillosis which is caused by avian pathogenic Escherichia coli (APEC). The present study sought to isolate and characterize using in vivo and in vitro assays E. coli recovered from poultry diagnosed with colibacillosis. A total of 55 E. coli isolates were recovered from tissues of 55 broiler flocks affected with colibacillosis by using standard microbiological techniques, Vitek 2 Compact system and polymerase chain reaction. Out of 55 E. coli isolates, 50 (90.9 %) were characterized as APEC by multiplex PCR using a set of five virulence genes. On serotyping, 16 (32 %) APEC isolates were serogrouped as O26 followed by O98 (28 %), O120 (14 %), O11 (12 %), O135 (8 %) and O17 (4 %). The antimicrobial susceptibility testing of E. coli isolates revealed high antibiotic resistance against imipenem, tetracycline, ciprofloxacin and levofloxacin (96 % each). Interestingly all the 50 suspect APEC isolates were found to be multiple drug resistant (MDR) and the antimicrobial profiling indicated that these isolates could be classified into 38 resistotypes. Moreover, 10 (20 %) isolates were ESBL producers as per phenotypic characterization using combined disk diffusion test. On genotypic characterization of ESBLs, 31 (62 %) isolates were found positive for the blaTEM gene, whereas, 34 (68 %) isolates carried intI1 gene. On assessment for biofilm formation at 72 h incubation, thirteen (26 %) isolates were found to be strong biofilm producers, whereas nine (18 %) and twenty-eight (56 %) isolates were moderate and weak biofilm producers, respectively. Later, the LD50 of one MDR and strong biofilm producing isolate (APEC-P02) was calculated by in vivo oral challenge study in day old broiler chicks. The findings of this study demonstrated that LD50 of APEC-P02 isolate was 1.12 × 108 CFU/ml. The unexpectedly high prevalence of O11, O126, O98, O120 and O135 isolates suggest that there may be emergent serogroups causing colibacillosis in India. The current oral challenge study seems to be the first of its kind in India to estimate the LD50 of a multidrug resistant biofilm producer APEC isolate in day-old chicks.

Monitoring Antibiotic Resistance in Wastewater: Findings from Three Treatment Plants in Sicily, Italy

Antimicrobial resistance (AMR) poses a global public health threat. Wastewater analysis provides valuable insights into antimicrobial resistance genes (ARGs), identifying sources and trends and evaluating AMR control measures. Between February 2022 and March 2023, pre-treatment urban wastewater samples were collected weekly from treatment plants in Pantano D'Arci, Siracusa, and Giarre (Sicily, Italy). Monthly composite DNA extracts were prepared by combining weekly subsamples from each site, yielding 42 composite samples-14 from each treatment plant. Real-time PCR analysis targeted specific ARGs, including blaSHV, erm(A), erm(B), blaOXA, blaNDM, blaVIM, blaTEM, and blaCTX-M. The preliminary findings revealed that blaERM-B, blaOXA, blaTEM, and blaCTX-M were present in all samples, with erm(B) (median value: 8.51; range: 1.67-30.93), blaSHV (0.78; 0.00-6.36), and blaTEM (0.72; 0.34-4.30) showing the highest relative abundance. These results underscore the importance of integrating ARG data with broader research to understand the persistence and proliferation mechanisms of ARGs in wastewater environments. Future studies should employ metagenomic analyses to profile resistomes in urban, hospital, agricultural, and farm wastewater. Comparing these profiles will help identify contamination pathways and inform the development of targeted ARG surveillance programs. Monitoring shifts in ARG abundance could signal cross-sectoral contamination, enabling more effective AMR control strategies.

Antibiotic Resistance Profiles and Genomic Analysis of Endophytic Bacteria Isolates from Wild Edible Fungi in Yunnan

The use of antibiotics has led to the emergence of antibiotic resistance, posing significant challenges in the prevention, control, and treatment of microbial diseases, while threatening public health, the environment, and food safety. In this study, the antibiotic resistance phenotypes and genotypes of 56 endophytic bacteria isolates from three species of wild edible fungi in Yunnan were analyzed using the Kirby-Bauer disk diffusion method and PCR amplification. The results revealed that all isolates were sensitive to ofloxacin, but resistance was observed against 17 other antibiotics. Specifically, 55, 53, and 51 isolates exhibited resistance to amoxicillin, penicillin, and vancomycin, respectively. Antibiotic resistance gene (ARG) detection indicated that the sulfonamide sul1 gene had the highest detection rate (53.57%). Excluding the ARG that was not detected, the lowest detection rates were the sulfonamide sul2 and sul3 genes, both at 1.79%. Among six tetracycline resistance genes, only tetK and tetM were detected. For β-lactam antibiotics, blaTEM, blaVIM, and blaSHV genes were present, while blaOXA was absent. In aminoglycoside resistance genes, aadB was not detected, while detection rates for aac(3')-IIa, acrB, and aadA1 were 3.57%, 1.79%, and 37.5%, respectively. The chloramphenicol Cat gene was detected at a rate of 14.29%, whereas floR was absent. For polypeptide resistance, VanC was detected at 3.57%, with EmgrB not detected. All three quinolone genes were detected, with detection rates of 8.92% for GyrA, 39.29% for GyrB, and 37.5% for ParC. Through phylogenetic analysis, 12 isolates that are closely related to ten common foodborne pathogenic bacteria were further selected for whole-genome sequencing and assembly. Gene annotations revealed that each isolate contained more than 15 ARGs and over 30 virulence factors. Notably, the detection rate of antibiotic resistance phenotypes was higher than that of genotypes, highlighting the importance of studying phenotypic antibiotic resistance that lacks identifiable ARGs. This study enriches the research on endophytes in wild edible fungi and provides new data for microbial ecology and antibiotic resistance research. It also offers critical insights for monitoring microbial antibiotic resistance in wild edible fungi and potentially other food sources, contributing to more effective strategies for ecological protection, sustainable agricultural development, and public health security.

Extended-spectrum β-lactamases genes in Gram-negative isolates from an urban river in Nicaragua

Limited resources and inadequate surveillance systems in developing countries have hindered research on antibiotic resistance gene transfer in aquatic environments. In this context, our study aimed to identify extended-spectrum beta-lactamase gene variants in Gram-negative isolates from the Tipitapa River-a significant Central America ecosystem. Samples were collected and assessed for key water parameters: dissolved oxygen, electrical conductivity, pH, and temperature. We employed a mix of microbiological, biochemical and molecular techniques, including multiplex PCR and sequencing, to characterize bacteria and determine the bla gene variants. Water quality parameters indicated areas impacted by human activities with high mineralization and eutrophication conditions. Among the bacteria analyzed, 48% belonged to the Enterobacteriaceae family, and a significant 88% displayed extended-spectrum beta-lactamases. Sequencing revealed four distinct bla gene variants in 84% of the isolates: bla-SHV-24, bla-SHV-13, bla-TEM-1, and bla-TEM-116, with bla-SHV-24 being the most common (47.62%). This is the first report of bla gene variants in the Tipitapa River, revealing their presence in globally concerning bacteria. The robust methodology enhances surveillance, enables geographic profiling of bla gene variants, and improves our understanding of biochemical patterns and gene transmission dynamics, providing essential insights into the global distribution of antibiotic resistance genes in Central America's natural waters.

Prevalence and Molecular Characterization of Carbapenemase-Producing Multidrug-Resistant Bacteria in Diabetic Foot Ulcer Infections

Background: Diabetic foot ulcers (DFUs) represent severe complications in diabetic patients, often leading to chronic infections and potentially resulting in nontraumatic lower-limb amputations. The increasing incidence of multidrug-resistant (MDR) bacteria in DFUs complicates treatment strategies and worsens patient prognosis. Among these pathogens, carbapenemase-producing pathogens have emerged as particularly concerning owing to their resistance to β-lactam antibiotics, including carbapenems. Methods: This study evaluated the prevalence of MDR bacteria, specifically carbapenemase-producing pathogens, in DFU infections. A total of 200 clinical isolates from DFU patients were analyzed via phenotypic assays, including the modified Hodge test (MHT) and the Carba NP test, alongside molecular techniques to detect carbapenemase-encoding genes (blaKPC, blaNDM, blaVIM, blaIMP, and blaOXA-48). Results: Among the isolates, 51.7% were confirmed to be carbapenemase producers. The key identified pathogens included Klebsiella pneumoniae, Pseudomonas aeruginosa, Acinetobacter baumannii, and Escherichia coli. The most commonly detected carbapenemase genes were blaKPC (27.6%) and blaNDM (24.1%). Carbapenemase-producing isolates presented high resistance to β-lactam antibiotics, whereas non-carbapenemase-producing isolates presented resistance through mechanisms such as porin loss and efflux pumps. Conclusions: The findings of this study highlight the significant burden of MDR infections, particularly carbapenemase-producing organisms, in DFUs. MDR infections were strongly associated with critical clinical parameters, including pyrexia (p = 0.017), recent antibiotic use (p = 0.003), and the severity of infections. Notably, the need for minor amputations was much higher in MDR cases (p < 0.001), as was the need for major amputations (p < 0.001). MDR infections were also strongly associated with polymicrobial infections (p < 0.001). Furthermore, Wagner ulcer grade ≥II was more common in MDR cases (p = 0.002). These results emphasize the urgent need for enhanced microbiological surveillance and the development of tailored antimicrobial strategies to combat MDR pathogens effectively. Given the high prevalence of carbapenem resistance, there is an immediate need to explore novel therapeutic options to improve clinical outcomes for diabetic patients with DFUs.

Seasonal Determination of Antibiotic-Resistant Microorganisms and Ciprofloxacin Residues in Pork and Chicken Meats Collected from Fresh Markets in Chiang Mai, Northern Thailand

Antibiotic-resistant bacteria are usually found in food-producing animals worldwide. Ciprofloxacin, an antibiotic, can lead to antibiotic residues in food products, posing health risks to consumers and contributing to the development of antimicrobial resistance. Foodborne illnesses occur when adequate attention is not paid to food hygiene and safety, raising the potential for resistant bacteria to spread to humans through the food chain. This study aims to determine the presence of antibiotic-resistant organism contamination and ciprofloxacin residue in raw pork and chicken. Forty-three pork and 33 chicken meat samples were collected from fresh markets in Chiang Mai, Thailand. Antibiotic-resistant organisms were detected by microbial culture and identified by MALDITOF-MS. The antimicrobial sensitivity tests were used to confirm antibiotic resistance. The ciprofloxacin was detected by using an immunochromatographic-based test kit for screening. The results found Extended Spectrum β-lactamase (ESBL)-producing E. coli and K. pneumoniae were detected at 46.51% and 9.30% in pork and 69.70% and 6.06% in chicken meat samples, respectively. Moreover, ciprofloxacin residues were detected in nine samples (11.84%). Based on this study's findings, the people who are involved in the food chain must be concerned about food safety and food hygiene.

Occurrence of multidrug-resistant ESBL-producing Enterobacteriaceae in livestock and in silico identification of probable catalytic domains in circulating ESBL variants

This study was conducted to detect the occurrence and phenotypic resistance pattern of extended spectrum beta-lactamase (ESBL)-producing Enterobacteriaceae in livestock using docking-based analysis to reveal the classes of antibiotics against which ESBL-producers are active. Rectal swabs from healthy cattle (n = 100), goats (n = 88), and pigs (n = 66) were collected from backyard farms in Andaman and Nicobar Island (India). In total, 304 isolates comprising Escherichia coli (131), Salmonella (75), and Klebsiella pneumoniae (98) were recovered. The phenotypic resistance pattern showed that the highest resistance was found against erythromycin, followed by ampicillin/cloxacillin, ciprofloxacin, amoxicillin/clavulanic acid, and oxytetracycline. Screening of the isolates demonstrated maximum presence of blaTEM-Type, followed by blaCTX-M-Type, and blaSHV-Type. Sequence homology revealed the presence of CTX-M-15, SHV-228, SHV-40, and TEM-82. The possible interactions of CTX-M-15 with cephalosporins and SHV with carbapenems have been identified by docking analysis. The study revealed the occurrence of ESBL-producers with circulating emerging ESBL variants like SHV-40, along with the common variants with clinical relevance (CTX-M-15, TEM-82), highlighting the potential role of livestock as reservoirs for antimicrobial resistance genes. Identifying these ESBLs in livestock is crucial for understanding their contribution to the dissemination of antimicrobial resistant bacteria into the human food chain.

A plasmid with the bla CTX-M gene enhances the fitness of Escherichia coli strains under laboratory conditions

Antimicrobial resistance (AMR) is a major threat to global public health that continues to grow owing to selective pressure caused by the use and overuse of antimicrobial drugs. Resistance spread by plasmids is of special concern, as they can mediate a wide distribution of AMR genes, including those encoding extended-spectrum β-lactamases (ESBLs). The CTX-M family of ESBLs has rapidly spread worldwide, playing a large role in the declining effectiveness of third-generation cephalosporins. This rapid spread across the planet is puzzling given that plasmids carrying AMR genes have been hypothesized to incur a fitness cost to their hosts in the absence of antibiotics. Here, we focus on a WT plasmid that carries the bla CTX-M 55 ESBL gene. We examine its conjugation rates and use head-to-head competitions to assay its associated fitness costs in both laboratory and wild Escherichia coli strains. We found that the wild strains exhibit intermediate conjugation levels, falling between two high-conjugation and two low-conjugation laboratory strains, the latter being older and more ancestral. We also show that the plasmid increases the fitness of both WT and lab strains when grown in lysogeny broth and Davis-Mingioli media without antibiotics, which might stem from metabolic benefits conferred on the host, or from interactions between the host and the rifampicin-resistant mutation we used as a selective marker. Laboratory strains displayed higher conjugation frequencies compared to WT strains. The exception was a low-passage K-12 strain, suggesting that prolonged laboratory cultivation may have compromised bacterial defences against plasmids. Despite low transfer rates among WT E. coli, the plasmid carried low fitness cost in minimal medium but conferred improved fitness in enriched medium, indicating a complex interplay between plasmids, host genetics and environmental conditions. Our findings reveal an intricate relationship between plasmid carriage and bacterial fitness. Moreover, they show that resistance plasmids can confer adaptive advantages to their hosts beyond AMR. Altogether, these results highlight that a closer study of plasmid dynamics is critical for developing a secure understanding of how they evolve and affect bacterial adaptability that is necessary for combating resistance spread.

Wastewater microbiology: occurrence and prevalence of antibiotic-resistant extended-spectrum β-lactamase-producing Enterobacteriaceae in the district wastewater system

Extended spectrum β-lactamase (ESBL)-producing Enterobacteriaceae, including Klebsiella pneumoniae and Escherichia coli, pose a serious risk to human health because of antibiotic resistance. Wastewater serves as a reservoir for these bacteria, contributing to the evolution and transmission of antibiotic-resistant strains. The research aims to identify ESBL bacterium in wastewater samples from District Kohat. K. pneumoniae and E. coli were confirmed as ESBL-producing bacteria through a comprehensive array of diagnostic procedures, including Gram staining, biochemical analyses, and antibiotic susceptibility testing. Fecal coliform count (FCC) analyses revealed varying microorganism levels. Both E. coli and K. pneumoniae isolates showed ESBL enzyme expression, indicating antibiotic resistance. Resistance patterns included ciprofloxacin, ampicillin, cefotaxime, cefoxitin, and amoxicillin-clavulanic acid for both species. E. coli displayed higher sensitivity for chloramphenicol, trimethoprim- sulfamethoxazole, and gentamicin. Ceftazidime minimum inhibitory concentration results showed E. coli's higher resistance. The study accentuates the presence of antibiotic-resistant strains, emphasizing the value of effective wastewater treatment. The study provides crucial insights into microbial characteristics, fecal contamination, ESBL production, and antibiotic resistance in E. coli and K. pneumoniae isolates, advocating for monitoring and mitigation strategies.

Prevalence, Determinants, and Antibiotic Resistance Patterns of Urinary Tract Infections in Antenatal Women in an Urban Resettlement Colony and Slum in Delhi, India: A Cross-sectional Study

BACKGROUND

Urinary tract infection (UTI) is the most common bacterial infection occurring in pregnant women with untreated, recurrent, and inadequately treated bacteriuria accentuating the risk of multiple adverse fetal and maternal health outcomes. The study objective was to determine the proportion of UTIs and their predictors along with antibiotic resistance patterns of causative organisms in pregnant women.

MATERIALS AND METHODS

This cross-sectional study was conducted among 348 pregnant women in an urban resettlement and slum colony. Urine samples were examined through semi-quantitative culture on plated Mac Conkey and blood agar. Antibiotic susceptibility testing was done on Muller Hinton agar using the modified Stokes' disc diffusion method.

RESULTS

At least one symptom related to UTI was reported by 35.7% (95% CI: 30.7-41.1) of the participants. The proportion of pregnant women detected having UTI on urine culture was 7.4% (n = 24, 95% CI: 5.1-10.8) with 13 (54.2%) asymptomatic and 11 (45.8%) symptomatic cases. Overcrowding was a significant predictor of UTI. The most common organisms detected were Escherichia coli (n = 12), Klebsiella pneumoniae (n = 7), Staphylococcus aureus (n = 3), and Acinetobacter species (n = 2).

CONCLUSIONS

The use of individual toilets and active screening for UTI through culture and sensitivity testing in pregnant women should be promoted in low-resource settings irrespective of symptoms. The initiation of presumptive antibiotic therapy for UTI cases in pregnant women should be restricted to painful micturition due to high false positivity of other symptoms with Nitrofurantoin being a likely preferred drug for empirical administration due to its low resistance pattern among isolated organisms.

Genotyping of extended-spectrum beta-lactamase-producing Escherichia coli isolated from wastewater of dairy farms in East Java, Indonesia

Background and Aim

Extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli in dairy farm wastewater represents a significant threat to environmental and public health due to the dissemination of antibiotic-resistance genes. This study investigates the molecular profiles of ESBL-producing E. coli isolates harboring bla CTX-M, bla TEM, and bla SHV genes from dairy farm wastewater in East Java, Indonesia.

Materials and Methods

Wastewater samples (n = 342) were collected from six major dairy regions in East Java: Pasuruan, Malang, Tulungagung, Blitar, Batu, and Kediri. The samples underwent bacterial isolation, identification, and ESBL phenotypic screening using the double-disk synergy test (DDST). Molecular genotyping of bla CTX-M, bla TEM, and bla SHV was conducted using a polymerase chain reaction.

Results

Of the samples, 69.30% (237/342) tested positive for E. coli, with 32.91% (78/237) identified as ESBL producers through DDST. Molecular genotyping confirmed ESBL genes in 28.20% (22/78) of the isolates. The genotypic distribution was 77.2% (17/22) bla TEM, 4.5% (1/22) bla CTX-M, 9.0% (2/22) bla TEM + bla SHV, and 9.0% (2/22) bla TEM + bla CTX-M. These findings highlight the dominance of bla TEM and the presence of multi-gene combinations in East Java's dairy farm wastewater.

Conclusion

The identified molecular profiles underscore dairy farm wastewater as a critical reservoir for antibiotic resistance genes, particularly bla TEM. Addressing this issue necessitates stringent antimicrobial use policies, improved wastewater management, and enhanced biosecurity measures. These findings support a One Health approach to mitigate environmental and public health risks associated with AMR.

Susceptibility of various Gram-negative bacteria to antibacterial agents: SMART in China 2019-2020

BACKGROUND

The Study for Monitoring Antimicrobial Resistance Trends (SMART) is an international surveillance program longitudinally monitoring aerobic and facultative Gram-negative bacteria (GNB) involvement in infections and their antimicrobial resistance profiles. Here the incidence and resistance patterns of Chinese GNB isolates from bloodstream infections (BSI), intraabdominal infections (IAI), respiratory tract infections (RTI) and urinary tract infections (UTI) to commonly used antibacterial agents has been updated. 4,975 GNB isolates collected from 22 hospitals across 7 regions of China from 2019 to 2020 were analyzed. Antimicrobial minimum inhibitory concentrations were assessed using broth microdilution, and susceptibility interpretations followed the breakpoints of European Committee on Antimicrobial Susceptibility Testing 2022 or Clinical and Laboratory Standards Institute.

RESULTS

This study affirmed that Escherichia coli (Ec) was the most commonly identified GNB (32.1%) and then Klebsiella pneumoniae (Kp) (25.3%), Pseudomonas aeruginosa (Pa) (13.9%) and Acinetobacter baumannii (10.5%). The detection rates of carbapenem-resistant (CR) Enterobacterales varied across major infection sites, ranging from 10.3% in UTI to 18.9% in RTI. Specifically, the detection rates of CR-Kp and CR-Pa ranged from 16.2% in IAI to 35.8% in UTI and from 16.1% in UTI to 38.0% in RTI, respectively. Extended-spectrum β-lactamases (ESBL)-producing Ec and Kp bacteria exhibited over 91.7% susceptibility to carbapenems and at least 87.8% susceptibility to amikacin and colistin, but showed lower susceptibility to piperacillin/tazobactam (57.5-86.2%), levofloxacin (10.8-39.7%) and aztreonam (15.3-27.6%) across different infection sources. Amikacin showed higher efficacy against CR strains compared to other commonly used antibacterial drugs, with 80.0% susceptibility against CR-Ec and 82.3% susceptibility against CR-Pa, while only 36.3% susceptibility was observed against CR-Kp.

CONCLUSIONS

The study found varying incidences of CR isolates in Chinese hospitals. Treatment options remained limited due to resistance to multiple antibacterial agents. Carbapenems demonstrated effective antimicrobial in vitro activity against ESBL-producing Enterobacterales found in BSI, IAI, UTI and RTI, outperforming broad-spectrum cephalosporins and other β-lactamase inhibitors.

Leveraging bacteria-inspired nanomaterials for targeted controlling biofilm and virulence properties of Pseudomonas aeruginosa

Pseudomonas aeruginosa is an opportunistic pathogen designated as a high-priority pathogen because of its role in major healthcare-associated and nosocomial infections. Biofilm production by these bacteria is one of the adaptive resistance mechanisms to traditional antibiotics, making treatment challenging, especially for immunocompromised patients. P. aeruginosa also produces a variety of virulence factors, which aid in invasion, adhesion, persistence, and immune system protection. Recent advances in nanotechnology-based therapy, notably the application of bioinspired metal and metal-oxide nanomaterials, have been seen as a viable way to control P. aeruginosa biofilm and virulence. Because of its ease of growth and culture, synthesizing metal and metal-oxide nanomaterials using bacterial species has become one of the most environmentally benign green synthesis options. The application of bacterial-inspired nanomaterials is particularly successful for targeted control of P. aeruginosa infection due to interactions with cell membrane components and transport systems. This paper delves into and provides a complete overview of the application of bacterial-inspired metal and metal-oxide nanomaterials to treat P. aeruginosa infection by targeting biofilm and virulence characteristics. The review focused on synthesizing and applying gold, silver, copper, iron, magnetite, and zinc oxide nanomaterials to mitigate P. aeruginosa biofilm and virulence. The underlying mechanism of these metal and metal-oxide nanoparticles in relation to biofilm and virulence features has also been thoroughly discussed. The current review introduces novel approaches to treating and controlling drug-resistant P. aeruginosa using bacterial-inspired nanomaterials as a targeted therapeutic strategy.

Distribution and Antimicrobial Resistance of Complicated Intraabdominal Infection Pathogens in Two Tertiary Hospitals in Egypt

Background: Management of complicated intraabdominal infections (cIAIs) requires containment of the source and appropriate initial antimicrobial therapy. Identifying the local data is important to guide the empirical selection of antimicrobial therapy. In this study, we aimed to describe the pathogen distribution and antimicrobial resistance of cIAI. Methods: In two major tertiary care hospitals in Egypt, we enrolled patients who met the case definition of cIAI from October 2022 to September 2023. Blood cultures were performed using the BACTAlert system (BioMerieux, Marcy l'Etoile, France). A culture of aspirated fluid, resected material, or debridement of the infection site was performed. Identification of pathogens and antimicrobial susceptibility testing were conducted by the VITEK-2 system (BioMerieux, Marcy l'Etoile, France). Gram-negative resistance genes were identified by PCR and confirmed by whole bacterial genome sequencing using the Nextera XT DNA Library Preparation Kit and sequencing with the MiSeq Reagent Kit 600 v3 (Illumina, USA) on the Illumina MiSeq. Results: We enrolled 423 patients, 275 (65.01%) males. The median age was 61.35 (range 25-72 years). We studied 452 recovered bacterial isolates. Gram-negative bacteria were the vast majority, dominated by E. coli, followed by Klebsiella pneumoniae, Pseudomonas aeruginosa, Acinetobacter baumannii, and Proteus mirabilis (33.6%, 30.5%, 13.7%, 13%, and 5.4%, respectively). High rates of resistance were detected to third- and fourth-generation cephalosporins and fluoroquinolones. No resistance was detected to colistin. Resistance to amikacin and tigecycline was low among all isolates. Resistance to meropenem and ceftazidime/avibactam was moderate. ESBL genes were common in E. coli and K. pneumoniae. CTX-M15 gene was the most frequent. Among Enterobacterales, blaOXA-48 and blaNDM were the most prevalent carbapenemase genes. Pseudomonas aeruginosa isolates harbored a wide variety of carbapenemase genes (OXA, NDM, VIM, SIM, GIM, SPM, IMP, AIM), dominated by metallo-beta-lactamases. In 20.6% of isolates, we identified two or more resistance genes. Conclusion: High resistance rates were detected to third- and fourth-generation cephalosporins and fluoroquinolones. Amikacin and tigecyclines were the most active antimicrobials. Our data call for urgent implementation of antimicrobial stewardship programs and reinforcement of infection control.

Occurrence, Multidrug Resistance, and Multilocus Sequence Typing of Extended-Spectrum Beta-Lactamase/AmpC-Producing Escherichia coli from Farmed Eggs

The present study evaluated the occurrence, antibiogram profile, and sequence types (STs) of multidrug resistant (MDR) Escherichia coli from freshly laid eggs (n = 480), feed (n = 24), water (n = 24), poultry droppings (n = 24), and hand swab samples (n = 10) collected from 24 deep litter (DL) and caged poultry layer farms (12 per category) across Punjab, India. The overall E. coli contamination rate in DL and cage farms was 32% (95% confidence intervals [CI], 26.6-37.8%) and 16.7% (95% CI, 12.6-21.6%), respectively. The logistic regression analysis revealed that the DL system had higher odds of occurrence (odds ratio [OR]) of extended-spectrum beta-lactamase (ESBL) (2.195, 95% CI, 1.065, 4.522) and ESBL/AmpC coproducers (2.69, 95% CI, 1.122, 6.45) compared to the cage system. Additionally, isolates from the DL were 4.065 (95% CI, 1.477, 11.188) times more tetracycline resistant compared to the latter; however, resistance to amoxyclavulanate (OR, 0.437; 95% CI, 0.209, 0.912), and ampicillin (OR, 0.343; 95% CI, 0.163, 0.720) was lesser in DL system. Notably, around 97.7% and 87.2% of the isolates from the DL and cage system were MDR, with the DL system having 6.439 (95% CI, 1.246, 33.283) times more chances of harboring MDR E. coli. Additionally, among the resistance genes, the DL system demonstrated significantly high presence of blaAmpC (56%), qnrA/B/S (42.3%), and tetA/B (30.6%). Furthermore, multilocus sequence typing of 11 MDR isolates (n = 5, DL, and 6, cage) revealed the presence of 10 STs, of which ST10, ST155, and ST156 were found to be of public health importance. Therefore, the present study highlights the burden of MDR, ESBL, and AmpC-producing E. coli on poultry eggs and farm environment, which could be carried over to human handlers and consumers upon direct contact during handling and processing.

Innovative approaches in phenotypic beta-lactamase detection for personalised infection management

Beta-lactamase-producing Enterobacteriaceae present a significant therapeutic challenge. Current developments in phenotypic diagnostics focus primarily on rapid minimum inhibitory concentration (MIC) determination. There is a requirement for rapid phenotypic diagnostics to improve antimicrobial susceptibility tests (AST) and aid prescribing decisions. Phenotypic AST are limited in their ability to characterise beta-lactamase-producing Enterobacteriaceae in detail. Despite advances in rapid AST, gaps and opportunities remain for developing additional diagnostic approaches that facilitate personalised antimicrobial prescribing. In this perspective, we highlight the state-of-the-art in beta-lactamase detection, identify gaps in current practice, and discuss barriers for innovation within this field.

Antimicrobial resistance and prevalence of extended-spectrum beta-lactamase-producing Klebsiella species in East Tennessee dairy farms

Klebsiella species commonly reside in dairy cattle guts and are consistently exposed to beta-lactam antibiotics, including ceftiofur, which are frequently used on the U.S. dairy farms. This may impose selection pressure and result in the emergence of extended-spectrum beta-lactamase (ESBL)-producing strains. However, information on the status and antimicrobial resistance (AMR) profile of ESBL-Klebsiella spp. in the U.S. dairy farms is largely unknown. This study aimed to determine the prevalence and AMR profile of ESBL-Klebsiella spp. and the factors affecting their occurrence in dairy cattle farms. Rectal fecal samples (n = 508) and manure, feed, and water samples (n = 64) were collected from 14 dairy farms in Tennessee. Samples were directly plated on CHROMagar ESBL, and presumptive Klebsiella spp. were confirmed using matrix-assisted laser desorption/ionization-time of flight mass spectrometry. Antimicrobial susceptibility testing was performed on the isolates against panels of 14 antimicrobial agents from 10 classes using minimum inhibitory concentration. Of 572 samples, 57 (10%) were positive for ESBL-Klebsiella spp. The fecal prevalence of ESBL-Klebsiella spp. was 7.2% (95% CI: 6.5-8.0). The herd-level fecal prevalence of ESBL-Klebsiella spp. was 35.7% (95% CI: 12.7-64.8). The fecal prevalence of ESBL-Klebsiella spp. was significantly higher in calves than in cows and higher in cows with higher parity (≥3) as compared to cows with low parity (P < 0.001). Most (96.5%, n = 57) ESBL-Klebsiella spp. were resistant to ceftriaxone. The highest level of acquired co-resistance to ceftriaxone in ESBL-Klebsiella spp. was to sulfisoxazole (66.7%; 38/57). About 19% of ESBL-Klebsiella spp. were multidrug resistant. The presence of ESBL-producing Klebsiella spp. in dairy cattle, feed, and water obtained from troughs could play a crucial epidemiological role in maintaining and spreading the bacteria on farms and serving as a point source of transmission.

IMPORTANCE

We collected 572 samples from dairy farms, including rectal feces, manure, feed, and water. We isolated and identified extended-spectrum beta-lactamase (ESBL)-Klebsiella spp. and conducted an antimicrobial susceptibility test and analyzed different variables that may be associated with ESBL-Klebsiella spp. in dairy farms. The results of our study shed light on how ESBL-Klebsiella spp. are maintained through fecal-oral routes in dairy farms and possibly exit from the farm into the environment. We determine the prevalence of ESBL-Klebsiella spp. and their antimicrobial susceptibility profiles, underscoring their potential as a vehicle for multiple resistance gene dissemination within dairy farm settings. We also collected data on variables affecting their occurrence and spread in dairy farms. These findings have significant implications in determining sources of community-acquired ESBL-Enterobacteriaceae infections and designing appropriate control measures to prevent their spread from food animal production systems to humans, animals, and environments.

Pharmacokinetic parameters of CAZ-AVI in the normal lung and in models of pneumonia: lessons for treatment optimization in critical care

The spread of multidrug-resistant Gram-negative bacterial infections is a significant issue for worldwide public health. Gram-negative organisms regularly develop resistance to antibiotics, especially to β-lactam antimicrobials, which can drastically restrict the number of therapies. A third-generation cephalosporin and the non-β-lactam β-lactamase inhibitor avibactam, which exhibits broad-spectrum β-lactamase inhibition in vitro, are combined to form ceftazidime-avibactam (CAZ-AVI). In this narrative review, we summarize data on pharmacokinetic (PK) parameters for CAZ-AVI in both animal and human models of pneumonia, as well as in healthy individuals. We assessed current literature performing an extensive search of the literature, using as search words 'CAZ-AVI', 'pharmacokinetics', 'pneumonia', 'lung', and 'epithelial lining fluid'. Overall, lung exposure studies of CAZ-AVI revealed that the epithelial lining fluid penetration ranges between 30% and 35% of plasma concentration. Despite the fair lung penetration of CAZ-AVI, this antimicrobial agent has a pivotal role in managing patients with multi-drug resistant Gram-negative pneumonia, however further studies are needed to better assess its PK profile.

More than just the gene: investigating expression using a non-native plasmid and host and its impact on resistance conferred by β-lactamase OXA-58 isolated from a hospital wastewater microbiome

With the escalation of hospital-acquired infections by multidrug resistant bacteria, understanding antibiotic resistance is of paramount importance. This study focuses on the β-lactamase gene, blaOXA-58, an important resistance determinant identified in a patient-facing hospital wastewater system. This study aimed to characterize the behaviour of the OXA-58 enzyme when expressed using a non-native plasmid and expression host. blaOXA-58 was cloned using a pET28a(+)/Escherichia coli BL21(DE3) expression system. Nitrocefin hydrolysis and antimicrobial susceptibility of OXA-58-producing cells were assessed against penicillin G, ampicillin, meropenem, and amoxicillin. blaOXA-58 conferred resistance to amoxicillin, penicillin G, and ampicillin, but not to meropenem. This was unexpected given OXA-58's annotation as a carbapenemase. The presence of meropenem also reduced nitrocefin hydrolysis, suggesting it acts as a competitive inhibitor of the OXA-58 enzyme. This study elucidates the phenotypic resistance conferred by an antimicrobial resistance gene (ARG) obtained from a clinically relevant setting and reveals that successful functional expression of ARGs is multifaceted. This study challenges the reliability of predicting antimicrobial resistance based solely on gene sequence alone, and serves as a reminder of the intricate interplay between genetics and structural factors in understanding resistance profiles across different host environments.

Prevalence of Extended-Spectrum Beta-Lactamase-Producing Enterobacteriaceae and Associated Clinical Implications at the University Teaching Hospital of Kigali in Rwanda

Extended spectrum beta-lactamase (ESBL)-producing Enterobacteriaceae poses a global problem and complicates therapeutic choices. The paucity of data in resource-poor countries undermines the understanding of the problem's extent, and cases of antimicrobial treatment failure continue to accumulate. This study aimed to determine the prevalence and clinical implications of ESBL-producers at the University Teaching Hospital of Kigali in Rwanda. A 1-year cross-sectional retrospective study was conducted on Escherichia coli and Klebsiella pneumoniae isolated in blood and urine from January 1 to December 31, 2022. In total, 1,283 isolates were recorded. The results showed an overall prevalence of ESBL phenotypes at 300/1,283 (23.4%). Extended spectrum beta-lactamase-positive E. coli was more frequently detected than K. pneumoniae in both urine (20.6% versus 10.1%) and blood (8.8% versus 6.2%). These isolates were 100% resistant to amoxicillin-clavulanic acid, third-generation cephalosporins, piperacillin, sulbactam ampicillin, ampicillin, cefuroxime, and cefoxitin. The least resistance was observed to amikacin (18%), meropenem (10%), and polymyxin B (3%). Hospital stays ranging from 8 to 21 days were the most frequent, and the mortality rate was 10.3% in patients with ESBL cases, which was more than double the general hospital mortality rate in the same period. In conclusion, our findings indicate a high prevalence of ESBL phenotypes, high antibiotic resistance rates, prolonged hospital stays, and an increased mortality rate. These findings suggest the need for continued surveillance, planning appropriate interventions, and caution during empirical therapy.

Efficacy of aspergillomarasmine A/meropenem combinations with and without avibactam against bacterial strains producing multiple β-lactamases

The effectiveness of β-lactam antibiotics is increasingly threatened by resistant bacteria that harbor hydrolytic β-lactamase enzymes. Depending on the class of β-lactamase present, β-lactam hydrolysis can occur through one of two general molecular mechanisms. Metallo-β-lactamases (MBLs) require active site Zn2+ ions, whereas serine-β-lactamases (SBLs) deploy a catalytic serine residue. The result in both cases is drug inactivation via the opening of the β-lactam warhead of the antibiotic. MBLs confer resistance to most β-lactams and are non-susceptible to SBL inhibitors, including recently approved diazabicyclooctanes, such as avibactam; consequently, these enzymes represent a growing threat to public health. Aspergillomarasmine A (AMA), a fungal natural product, can rescue the activity of the β-lactam antibiotic meropenem against MBL-expressing bacterial strains. However, the effectiveness of this β-lactam/β-lactamase inhibitor combination against bacteria producing multiple β-lactamases remains unknown. We systematically investigated the efficacy of AMA/meropenem combination therapy with and without avibactam against 10 Escherichia coli and 10 Klebsiella pneumoniae laboratory strains tandemly expressing single MBL and SBL enzymes. Cell-based assays demonstrated that laboratory strains producing NDM-1 and KPC-2 carbapenemases were resistant to the AMA/meropenem combination but became drug-susceptible upon adding avibactam. We also probed these combinations against 30 clinical isolates expressing multiple β-lactamases. E. coli, Enterobacter cloacae, and K. pneumoniae clinical isolates were more susceptible to AMA, avibactam, and meropenem than Pseudomonas aeruginosa and Acinetobacter baumannii isolates. Overall, the results demonstrate that a triple combination of AMA/avibactam/meropenem has potential for empirical treatment of infections caused by multiple β-lactamase-producing bacteria, especially Enterobacterales.

Prevalence of CTX-M types among ESBL-producing pathogenic Escherichia coli isolates from foodborne diarrheal patients in Gyeonggi-do, South Korea

Prevalence and characteristics of extended-spectrum β-lactamase (ESBL)-producing pathogenic Escherichia coli from foodborne diarrheal patients were studied. Analysis of 495 E. coli isolates revealed that 80 isolates were ESBL-producing pathogenic E. coli, and enteroaggregative E. coli and enterotoxigenic E. coli were two of the most prevalent pathotypes. In silico Clermont phylo-typing of the 80 ESBL-producing E. coli showed that phylogroup A (49/80) and D (22/80) were the predominant phylogroups. The average nucleotide identity analysis of ESBL-producing E. coli disclosed that they could be grouped into two phylogenetic groups; 25 A and 55 B groups. All strains, except one, harbored the blaCTX-M gene. All CTX-M-15 type ESBL-producing strains also carried qnrS, a plasmid-mediated quinolone resistance gene (PMQR). These results suggest that the diversity of ESBL-producing E. coli is high and that co-existence of blaCTX-M-15 and qnrS genes is widespread, highlighting their high risk of antibiotic-resistance spreading in infectious disease outbreaks.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10068-024-01549-5.

Antibiotic Resistance Profiles of Extended-Spectrum β-Lactamase (ESBL)- and Metallo-β-Lactamase (MBL)-Producing Klebsiella pneumoniae Isolates From Diabetic Foot Ulcers: Implications for Treatment Strategies

Background Diabetic foot ulcers (DFUs) are prevalent complications of diabetes mellitus, often leading to severe infections and adverse clinical outcomes. Klebsiella pneumoniae, a gram-negative bacterium, has emerged as a significant causative agent in DFU infections, raising concerns due to its increasing antibiotic resistance, particularly in extended-spectrum β-lactamase (ESBL) and metallo-β-lactamase (MBL) production. Aim This study aimed to comprehensively assess the prevalence, antibiotic resistance profiles, and clinical correlates of ESBL- and MBL-producing K. pneumoniae isolates specifically derived from DFUs. Methods A cross-sectional observational study was conducted at Krishna Vishwa Vidyapeeth from January 2023 to June 2023, involving 126 patients diagnosed with DFUs. Clinical and demographic data were collected, and wound swabs underwent microbiological analysis. Phenotypic detection methods were employed to identify ESBL and MBL production, followed by standardized antibiotic susceptibility testing. Results Among the 126 isolates tested, 36 (28.6%) were identified as ESBL-producing and 21 (16.7%) as MBL-producing strains. ESBL-producing isolates exhibited high resistance rates to antibiotics such as ampicillin (92.3%), amoxicillin-acid (84.6%), and cephalosporins, including ceftriaxone (76.9%), and cefepime (73.8%). MBL-producing isolates demonstrated even broader resistance profiles, including resistance to fluoroquinolones (ciprofloxacin, 60.0%; levofloxacin, 57.1%), aminoglycosides (gentamicin, 42.9%), and carbapenems (meropenem, 38.1%; imipenem, 35.7%). Conclusion This study identifies a significant prevalence of ESBL- and MBL-producing K. pneumoniae in DFUs, showcasing high antibiotic resistance rates. Comorbidities correlate significantly with the presence of resistant isolates, necessitating treatment strategies for effective management.

Molecular Characteristics of Cephalosporin Resistant Escherichia coli and Klebsiella pneumoniae Isolated from Children in a Tertiary Care Centre of Central Kerala, India

Aims:

The study was aimed to determine the molecular characteristics of extended-spectrum beta-lactamases (ESBL) producing cephalosporin-resistant Escherichia coli and Klebsiella pneumoniae isolated from children below ten years of age.

Background:

Geographically diverse variations in the prevalence of ESBL genes were reported. No data were available on the prevalence of ESBL genes in central Kerala, India, among children below 10 years of age.

Methods:

A cross-sectional study was performed to analyze ESBL genes in cephalosporin-re-sistant E. coli and K. pneumoniae strains isolated from samples received in the Microbiology la-boratory of a tertiary care centre during the period between May 2021 and July 2022. The strains showed that ESBL + cephalosporin resistance was subjected to PCR-based genotyping for the genes such as bla (beta-lactamase) CTX-M-1, blaCTX-M-15, blaCTX-M-U, blaTEM, blaPER and SHV.

Results:

Among the total 228 samples analyzed, 136 (60%) had no growth. Ninety-two (40 %) samples showed growth of E. coli and K. pneumoniae. Among the isolates that showed growth, 39 (42%) were sensitive, and the remaining 53 (57%) were resistant to third-generation cephalospor-ins. Among the isolates showed resistance, 22 (42%) were ESBL positive and 31 (58%) were ESBL negative. Among the positive ESBL, nine E. coli strains (60%) were positive for CTX-M-15 and CTX-M-1. CTX-M-15 and CTX-M-U were present in six (85%) K. pneumoniae with ESBL +.

Conclusion:

E. coli and K. pneumoniae isolated from specimens of children below ten years of age showed 41-42% ESBL producers. Prevalent ESBL-producing genes in E. coli were CTX-M-15 and CTX-M-1. CTX-M-15 and CTX-M-U were prevalent in ESBL-producing K. pneumoniae.

Bacterial profiles, antibiotic susceptibility patterns, and associated factors of symptomatic urinary tract infections among symptomatic university students at Haramaya University, Eastern Ethiopia: Cross-sectional study

Urinary tract infection (UTI) is a highly prevalent infection that can affect individuals of all ages, posing a significant risk to global health in terms of both morbidity and mortality. The emergence of multidrug-resistant bacteria adds to the complexity of this public health issue. There is limited data on the current study area. Therefore, this study aimed to determine the bacterial profiles, antibiotic susceptibility patterns, and associated factors of UTIs among symptomatic university students at Haramaya University, Eastern Ethiopia from May 10 to June 15, 2021. A cross-sectional study was conducted among 281 Haramaya University students. A systematic random sampling technique was used to select the study participants. Data were collected using a self-administered questionnaire. Ten to 15 mL of midstream urine samples were collected aseptically from patients. Standard microbiological techniques were used for bacterial identifications and drug susceptibility testing. The association between dependent and independent variables was determined by the logistics regression model. Variables with a P-value of <.05 were considered statistically significant. The overall prevalence of UTI among university students was 18.1% (95% confidence interval [CI]: 13.5-23.1). The most frequently isolated bacteria were Escherichia coli (33.3%) and Staphylococcus epidermidis (29.4%). Gram-negative bacteria demonstrated high resistance against ceftazidime (100%), penicillin (96%), ampicillin (92%), and tetracycline (71%). Similarly, gram-positive bacteria exhibited significant resistance to ceftazidime (100%) and ampicillin (81%). Multidrug-resistant isolates constituted an overall prevalence of 35 (68.6%) (95% CI: 63.6-73.6). Furthermore, year of study (adjusted odds ratios [AOR] = 2.66; 95% CI: 1.23-5.76), history of UTI (AOR = 2.57; 95% CI: 1.10-6.00), and sexual activity (AOR = 0.08; 95% CI: 0.02-0.39) were identified as factors. In this study, university students exhibited a higher prevalence of UTI compared to previous studies conducted in Africa. The most commonly identified bacteria causing UTIs were E coli, followed by S epidermidis. Factors such as the year of the study, presence of flank pain, history of previous UTIs, and frequency of sexual activity were found to be associated with UTIs. All the isolates have acquired resistance to the majority of commonly prescribed antibiotics. It is crucial to regularly monitor UTIs and the proliferation of antibiotic-resistant bacteria among university students.

Extended-spectrum beta-lactamase-producing Escherichia coli and Klebsiella pneumoniae: insights from a tertiary hospital in Southern Thailand

Broad-spectrum ampicillin-resistant and third-generation cephalosporin-resistant Enterobacteriaceae, particularly Escherichia coli and Klebsiella pneumoniae that have pathological features in humans, have become a global concern. This study aimed to investigate the prevalence, antimicrobial susceptibility, and molecular genetic features of extended-spectrum beta-lactamase (ESBL)-producing E. coli and K. pneumoniae isolates in Southern Thailand. Between January and August 2021, samples (n = 199) were collected from a tertiary care hospital in Southern Thailand. ESBL and AmpC-lactamase genes were identified using multiplex polymerase chain reaction (PCR). The genetic relationship between ESBL-producing E. coli and K. pneumoniae was determined using the enterobacterial repetitive intergenic consensus (ERIC) polymerase chain reaction. ESBL-producing E. coli and K. pneumoniae isolates were mostly collected from catheter urine samples of infected female patients. The ESBL production prevalence was highest in the medical wards (n = 75, 37.7%), followed by that in surgical wards (n = 64, 32.2%) and operating rooms (n = 19, 9.5%). Antimicrobial susceptibility analysis revealed that all isolates were resistant to ampicillin, cefotaxime, ceftazidime, ceftriaxone, and cefuroxime; 79.4% were resistant to ciprofloxacin; and 64.3% were resistant to trimethoprim-sulfamethoxazole. In ESBL-producing K. pneumoniae and E. coli, blaTEM (n = 57, 72.2%) and blaCTX-M (n = 61, 50.8%) genes were prominent; however, no blaVEB, blaGES, or blaPER were found in any of these isolates. Furthermore, only ESBL-producing K. pneumoniae had co-harbored blaTEM and blaSHV genes at 11.6%. The ERIC-PCR pattern of multidrug-resistant ESBL-producing strains demonstrated that the isolates were clonally related (95%). Notably, the presence of multidrug-resistant and extremely resistant ESBL producers was 83.4% and 16.6%, respectively. This study highlights the presence of blaTEM, blaCTX-M, and co-harbored genes in ESBL-producing bacterial isolates from hospitalized patients, which are associated with considerable resistance to beta-lactamase and third-generation cephalosporins.

IMPORTANCE

We advocate for evidence-based guidelines and antimicrobial stewardship programs to encourage rational and appropriate antibiotic use, ultimately reducing the selection pressure for drug-resistant bacteria and lowering the likelihood of ESBL-producing bacterial infections.

Distribution of extended-spectrum β-lactamase producing Escherichia coli genes in an integrated poultry-fish farming system in Bogor, Indonesia

Background and Aim

The excessive use of antimicrobials in livestock farming leads to the emergence and dissemination of antimicrobial-resistant organisms. This study aimed to detect extended-spectrum β-lactamase (ESBL)-producing Escherichia coli genes in integrated poultry-fish farms in Bogor, Indonesia.

Materials and Methods

A total of 256 samples were collected from six poultry-fish farms. One hundred and seventy-five chicken cloaca swabs, 60 fish skin swabs, six pond water samples, and 15 farmer's hand swabs. ESBL-producing E. coli was confirmed through double-disk diffusion. The specific primers and probe genes for quantitative polymerase chain reaction detection of ESBL-producing E. coli targeted blaTEM, blaCTX-M, blaSHV, and blaOXA-48 genes.

Results

Among the 256 samples tested, 145 (56.6%) were positive for E. coli, and 67.6% (98/145) were identified as ESBL-producing E. coli. The most ESBL-producing E. coli isolates were obtained from chicken cloaca (78.3%, 72/92), followed by pond water (66.7%, 4/6), fish skin (47.6%, 20/42), and farmer's hand swabs (40%, 2/5). About 100% of the isolates carried the genes blaTEM and blaCTX-M, whereas 17.3% and 24.5% carried blaSHV and blaOXA-48, respectively.

Conclusion

ESBL-producing E. coli genes were investigated in chicken cloaca, fish, pond water, and farmers' hands within an interconnected poultry-fish farming operation. The ESBL-producing E. coli in chickens can transfer resistant genes to aquatic environments. The transfer could harm other aquatic species and food chains, potentially threatening human health.

First Report on the Occurrence and Antibiotic Resistance Profile of Colistin-Resistant Escherichia coli in Raw Beef and Cow Feces in Vietnam

Colistin-resistant Escherichia coli (COE) has been recently recognized as a serious threat to animal and human health. This study aimed to determine the prevalence and antibiotic resistance profile of COE isolated from raw beef and cow feces in Vietnam. Our results showed that 16% (16/100) and 32% (32/100) of raw beef and cow feces samples were positive for COE, respectively. A total of 48 COE strains were isolated, with 16 originating from raw beef and 32 from cow feces samples. The antibiotic susceptibility test revealed that the COE isolates were highly resistant to ampicillin, tetracycline, florfenicol, trimethoprim/sulfamethoxazole, streptomycin, and nalidixic acid, with resistance rates ranging from 66.67% to 87.5%. In addition, 87.5% of the isolates were identified to be multidrug-resistant strains. Further molecular characterization indicated that all COE isolates carried the mcr-1 gene, with 16 of them also harboring blaCTX-M-55 genes. Taken together, the findings in this study demonstrate that raw beef and cow feces are important sources of COE, which can be potentially transmitted to humans through the food chain.

Association Between Biofilm Formation and Extended-Spectrum Beta-Lactamase Production in Klebsiella pneumoniae Isolated from Fresh Fruits and Vegetables

The presence of extended-spectrum beta-lactamase (ESBL)-producing Klebsiella pneumoniae in fresh fruits and vegetables is a growing public health concern. The primary objective of this study was to investigate the relationship between biofilm formation and extended-spectrum β-lactamase (ESBL) production in K. pneumoniae strains obtained from fresh fruits and vegetables. Out of 120 samples analysed, 94 samples (78%) were found to be positive for K. pneumoniae. Among the K. pneumoniae strains isolated, 74.5% were from vegetables, whereas the remaining (25.5%) were from fresh fruits. K. pneumoniae isolates were resistant to at least three different classes of antibiotics, with ceftazidime (90%) and cefotaxime (70%) showing the highest resistance rates. While the high occurrence of ESBL-producing and biofilm-forming K. pneumoniae strains were detected in vegetables (73.5% and 73.7%, respectively), considerable amounts of the same were also found in fresh fruits (26.5% and 26.3%, respectively). The results further showed a statistically significant (P < 0.001) association between biofilm formation and ESBL production in K. pneumoniae strains isolated from fresh fruits and vegetables. Furthermore, the majority (81%) of the ESBL-producing strains harbored the blaCTX-M gene, while a smaller proportion of strains carried the blaTEM gene (30%), blaSHV gene (11%) or blaOXA (8%). This study highlights the potential public health threat posed by K. pneumoniae in fresh fruits and vegetables and emphasizes the need for strict surveillance and control measures.

Antibiotic susceptibility patterns and trends of the gram-negative bacteria isolated from the patients in the emergency departments in China: results of SMART 2016-2019

BACKGROUND

The study aims were to evaluate the species distribution and antimicrobial resistance profile of Gram-negative pathogens isolated from specimens of intra-abdominal infections (IAI), urinary tract infections (UTI), respiratory tract infections (RTI), and blood stream infections (BSI) in emergency departments (EDs) in China.

METHODS

From 2016 to 2019, 656 isolates were collected from 18 hospitals across China. Minimum inhibitory concentrations were determined by CLSI broth microdilution and interpreted according to CLSI M100 (2021) guidelines. In addition, organ-specific weighted incidence antibiograms (OSWIAs) were constructed.

RESULTS

Escherichia coli (E. coli) and Klebsiella pneumoniae (K. pneumoniae) were the most common pathogens isolated from BSI, IAI and UTI, accounting for 80% of the Gram-negative clinical isolates, while Pseudomonas aeruginosa (P. aeruginosa) was mainly isolated from RTI. E. coli showed < 10% resistance rates to amikacin, colistin, ertapenem, imipenem, meropenem and piperacillin/tazobactam. K. pneumoniae exhibited low resistance rates only to colistin (6.4%) and amikacin (17.5%) with resistance rates of 25-29% to carbapenems. P. aeruginosa exhibited low resistance rates only to amikacin (13.4%), colistin (11.6%), and tobramycin (10.8%) with over 30% resistance to all traditional antipseudomonal antimicrobials including ceftazidime, cefepime, carbapenems and levofloxacin. OSWIAs were different at different infection sites. Among them, the susceptibility of RTI to conventional antibiotics was lower than for IAI, UTI or BSI.

CONCLUSIONS

Gram-negative bacteria collected from Chinese EDs exhibited high resistance to commonly used antibiotics. Susceptibilities were organ specific for different infection sites, knowledge which will be useful for guiding empirical therapies in the clinic.

Active surveillance of antimicrobial resistance in companion animals: A pilot study in a Spanish Veterinary Teaching Hospital

The role of small animal veterinary hospitals in the onset and dissemination of antimicrobial-resistant organisms (AMROs) is still not clear, and the implementation of an internal surveillance systems is a cost-effective tool to better understand their impact. The aim of this study was to describe a pilot program of active surveillance in a Spanish Veterinary Teaching Hospital, developed to estimate the detection frequency of AMROs in the commensal flora of patients and in the environment. Surveillance was focused on Methicillin-resistant Staphylococci (MRS), third generation cephalosporins resistant gram-negative bacteria (3GCR-GNB), and carbapenems-resistant gram-negative bacteria (CR-GNB). Oral and perirectal swabs were collected in the same dogs and cats hospitalized > 48 h, at their admission and before their discharge. Out of 50 patients sampled, 24% (12/50) were carriers at admission of at least one of the three investigated AMROs. Twenty-eight percent of patients (14/50) acquired at least one AMRO during the hospital stay. MRS detection frequency at admission was 12% (6/50), while acquisition was 6% (3/50). 3GCR-GNB detection frequency was 14% at admission (7/50) and acquisition 22% (11/50), while CR-GNB detection frequency was 2% at admission (1/50) and acquisition 2% (1/50). Environmental surveillance (98 samples) showed a total detection frequency of 22.4% for MRS (22/98), 2% for 3GCR-GNB and CR-GNB (2/98). Clinical staff' shoe soles showed high detection frequency for MRS (50%). 3GCR Escherichia coli was the most isolated species in patients (n = 17). The results show how active surveillance can be used as a tool to assess the impact of AMROs in veterinary hospitals to subsequently build up tailored control plans based on specific issues.

Antimicrobial Susceptibility Profiles of Klebsiella pneumoniae Strains Collected from Clinical Samples in a Hospital in Southern Italy

Infections caused by antibiotic-resistant bacteria represent a serious threat to global public health. Recently, due to its increased resistance to carbapenems and β-lactams, Klebsiella pneumoniae has become one of the main causes of septicemia, pneumonia, and urinary tract infections. It is crucial to take immediate action and implement effective measures to prevent further spread of this issue. This study aims to report the prevalence and antibiotic resistance rates of K. pneumoniae strains isolated from clinical specimens from 2015 to 2020 at the University Hospital of Salerno, Italy. More than 3,800 isolates were collected from urine cultures, blood cultures, respiratory samples, and others. K. pneumoniae isolates showed broad resistance to penicillin and cephalosporins, and increased susceptibility to fosfomycin and gentamicin. Extended spectrum beta-lactamase (ESBL) isolates accounted for 20-22%. A high percentage of strains tested were resistant to carbapenems, with an average of 40% to meropenem and 44% to ertapenem. The production of ESBLs and resistance to carbapenems is one of the major public health problems. Constant monitoring of drug-resistant isolates is crucial for developing practical approaches in implementing antimicrobial therapy and reducing the spread of K. pneumoniae in nosocomial environments.

A review of the mechanisms that confer antibiotic resistance in pathotypes of E. coli

The dissemination of antibiotic resistance in Escherichia coli poses a significant threat to public health worldwide. This review provides a comprehensive update on the diverse mechanisms employed by E. coli in developing resistance to antibiotics. We primarily focus on pathotypes of E. coli (e.g., uropathogenic E. coli) and investigate the genetic determinants and molecular pathways that confer resistance, shedding light on both well-characterized and recently discovered mechanisms. The most prevalent mechanism continues to be the acquisition of resistance genes through horizontal gene transfer, facilitated by mobile genetic elements such as plasmids and transposons. We discuss the role of extended-spectrum β-lactamases (ESBLs) and carbapenemases in conferring resistance to β-lactam antibiotics, which remain vital in clinical practice. The review covers the key resistant mechanisms, including: 1) Efflux pumps and porin mutations that mediate resistance to a broad spectrum of antibiotics, including fluoroquinolones and aminoglycosides; 2) adaptive strategies employed by E. coli, including biofilm formation, persister cell formation, and the activation of stress response systems, to withstand antibiotic pressure; and 3) the role of regulatory systems in coordinating resistance mechanisms, providing insights into potential targets for therapeutic interventions. Understanding the intricate network of antibiotic resistance mechanisms in E. coli is crucial for the development of effective strategies to combat this growing public health crisis. By clarifying these mechanisms, we aim to pave the way for the design of innovative therapeutic approaches and the implementation of prudent antibiotic stewardship practices to preserve the efficacy of current antibiotics and ensure a sustainable future for healthcare.

Multidrug-Resistant Extended-Spectrum Beta-Lactamase (ESBL)-Producing Escherichia coli in a Dairy Herd: Distribution and Antimicrobial Resistance Profiles

This study investigated the presence, distribution, and antimicrobial resistance profiles of extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli in a dairy herd located in Northern Italy. The feces of clinically healthy calves, their mothers, and the cows treated for mastitis, as well as water, environmental samples, and waste milk were collected and subjected to bacteriological culture on CHROMagarTM ESBL plates. A questionnaire was administered to identify risk factors. The isolates were identified as E. coli by MALDI-TOF MS and subjected to the double-disk synergy test (DDST) and minimal inhibitory concentration (MIC) assay. As a result, ESBL E. coli was isolated from the feces of 28 of 37 (75.67%) calves, the feces of 2 of 3 (66.67%) treated cows, 8 of 14 (57.15%) environmental samples, and waste milk. All ESBL isolates showed multiple resistances and were categorized as multidrug-resistant (MDR). Several risk factors for ESBL E. coli selection and diffusion were identified, including lack of routine cleaning of calf feeding and housing equipment, administration of waste milk to male calves, and blanket dry cow therapy. In conclusion, this study highlighted the presence of MDR, ESBL E. coli in the feces of most dairy calves, and their association with different sample sources. Accordingly, adding to the prudent use of antibiotics, the adoption of adequate farm hygiene and biosecurity measures might also help prevent the spread and transmission of ESBL E. coli within the herd.

Multidrug-resistant clinical K. pneumoniae ST16, ST218, and ST283 and emergence of pandrug-resistant KPC-positive ST6434/K2 lineage in Iraq

BACKGROUND AND AIM

The increasing incidence of Klebsiella pneumoniae infections, both in the community and in hospitals, is a huge health problem. This is due to the increasing resistance of the bacteria to antibiotics and biofilm formation, as well as the presence of a capsule. This study focuses on two main objectives: to survey the most common capsular types in local isolates for the first time in Anbar, Iraq, on molecular level and to distinguish between infectious pathogen strains using multilocus sequence typing (MLST) for more efficient epidemiological and surveillance analysis, in order to determine the source of these strains (invasive or purebred).

METHODOLOGY

Multidrug-resistant (MDR) isolates adapted to genomic extraction and molecular screening of capsular type and MLST, and then to data processing by Pasteur Institut.

RESULTS

For the first time, one isolate was registered as a new strain in the world with ST 6434; the other strains demonstrated as preregistered with ST16, ST218, and ST283. 33% of MDR isolates belonged to the capsular K2 type.

CONCLUSION

The study's findings were not aligned with the global knowledge base about the distribution of capsular type in Asia. To prevent the spread of highly resistant strains, careful monitoring of virulence determinants is necessary in addition to the observation of antibiotic resistance.

Phenotypic characterization of ESBL-producing urinary isolates of E. coli and Klebsiella spp. in a tertiary care children's hospital in Nepal

BACKGROUND

The production of extended-spectrum beta-lactamases (ESBLs) among uropathogens, particularly E. coli and Klebsiella spp., poses a severe public health concern. This study explored the epidemiology of ESBL-producing E. coli and Klebsiella spp. isolated from urine samples obtained at a tertiary care children's hospital in Nepal.

METHODS

A cross-sectional study was conducted from August 2016 to February 2017. A total of 745 clean catch urine samples were obtained from pediatric patients under the age of 13 and subjected to semiquantitative culture. E. coli and Klebsiella spp. were identified using standard laboratory protocols. Antibiotic susceptibility testing was performed using the Kirby-Bauer disc diffusion method, and ESBL producers were phenotypically identified using the combined disk method.

RESULTS

Among the bacterial isolates, E. coli predominated, accounting for 139 (81.8%) positive cases. Notably, E. coli showed high susceptibility to nitrofurantoin, with 117 (84.2%) isolates being susceptible. Meanwhile, K. pneumoniae showed high susceptibility to gentamicin, with 21 (91.3%) isolates being susceptible. Of the 163 isolates of E. coli and Klebsiella spp., 62 (38.0%) were identified as multidrug-resistant (MDR), with 42 (25.8%) confirmed as phenotypic ESBL producers. Remarkably, all 41 (100%) ESBL-producing E. coli isolates were susceptible to imipenem.

CONCLUSIONS

The prevalence of ESBL producers among E. coli and K. pneumoniae isolates from pediatric patients underscores the importance of antimicrobial stewardship. Nitrofurantoin and gentamicin emerge as effective empirical treatment choices against these pathogens in children. However, the high rates of multidrug resistance and ESBL production highlight the necessity for routine surveillance, and early detection strategies to manage such infections effectively.

Uncovering the secrets of resistance: An introduction to computational methods in infectious disease research

Antimicrobial resistance (AMR) is a growing global concern with significant implications for infectious disease control and therapeutics development. This chapter presents a comprehensive overview of computational methods in the study of AMR. We explore the prevalence and statistics of AMR, underscoring its alarming impact on public health. The role of AMR in infectious disease outbreaks and its impact on therapeutics development are discussed, emphasizing the need for novel strategies. Resistance mutations are pivotal in AMR, enabling pathogens to evade antimicrobial treatments. We delve into their importance and contribution to the spread of AMR. Experimental methods for quantitatively evaluating resistance mutations are described, along with their limitations. To address these challenges, computational methods provide promising solutions. We highlight the advantages of computational approaches, including rapid analysis of large datasets and prediction of resistance profiles. A comprehensive overview of computational methods for studying AMR is presented, encompassing genomics, proteomics, structural bioinformatics, network analysis, and machine learning algorithms. The strengths and limitations of each method are briefly outlined. Additionally, we introduce ResScan-design, our own computational method, which employs a protein (re)design protocol to identify potential resistance mutations and adaptation signatures in pathogens. Case studies are discussed to showcase the application of ResScan in elucidating hotspot residues, understanding underlying mechanisms, and guiding the design of effective therapies. In conclusion, we emphasize the value of computational methods in understanding and combating AMR. Integration of experimental and computational approaches can expedite the discovery of innovative antimicrobial treatments and mitigate the threat posed by AMR.

Epidemiology and clinical characteristics of patients with healthcare-acquired multidrug-resistant Gram-negative bacilli: a retrospective study from a tertiary care hospital

The numbers of infections caused by Gram-negative bacteria (GNB) that produce extended-spectrum beta-lactamases (ESBLs) and those that are carbapenem resistant, especially Escherichia coli (E. coli) and Klebsiella pneumoniae (K. pneumoniae), are increasing, and these infections are becoming a global public health problem. The aim of this study was to assess the prevalence of infections caused by ESBL-producing and carbapenem-resistant Gram-negative bacilli in patients hospitalized at An-Najah National University Hospital in Nablus, Palestine, and to provide healthcare workers with valuable information on the treatment of these infections. A retrospective cross-sectional investigation was conducted at a large tertiary care teaching hospital. The study included patients admitted to the hospital between January and December 2021, from whom ESBL-producing and carbapenem-resistant Gram-negative bacilli were isolated. The patients' clinical and demographic information was obtained from the hospital information system. In addition, information regarding the bacterial isolates and antibiotic resistance was obtained from the hospital's microbiology laboratory. This study included a total of 188 patients-91 males (48.4%) and 97 females (51.6%). The general surgical ward accounted for the highest proportion of infections (30.9%), followed by the surgical ICU (12.2%). The most common infections were caused by ESBL-producing E. coli, which accounted for 62.8% of the cases. Among them, urinary tract infections caused by this microorganism were the most prevalent (44.7% of patients). Over 50% of the patients (54.2%) had a history of antibiotic use, and 77.8% had been hospitalized within the past three months. ESBL-producing E. coli was significantly isolated from blood cultures (p-value = 0.000), and CR-K. pneumoniae was significantly isolated from endotracheal isolates (p-value = 0.001). This study emphasizes the concerning frequency of healthcare-acquired infections caused by ESBL-producing and carbapenem-resistant GNB in a tertiary care hospital. The substantial prevalence of antibiotic resistance presents considerable obstacles to the successful administration of routinely employed antibiotics. The results highlight the immediate need for improved antimicrobial stewardship and the implementation of infection control strategies to reduce the effects of multidrug-resistant GNB on patient well-being and public health.

Long-term gut colonization with ESBL-producing Escherichia coli in participants without known risk factors from the southeastern United States

We evaluated gut carriage of extended spectrum beta lactamase producing Enterobacteriaceae (ESBL-E) in southeastern U.S. residents without recent in-patient healthcare exposure. Study enrollment was January 2021-February 2022 in Athens, Georgia, U.S. and included a diverse population of 505 adults plus 50 child participants (age 0-5). Based on culture-based screening of stool samples, 4.5% of 555 participants carried ESBL-Es. This is slightly higher than reported in studies conducted 2012-2015, which found carriage rates of 2.5-3.9% in healthy U.S. residents. All ESBL-E confirmed isolates (n=25) were identified as Escherichia coli. Isolates belonged to 11 sequence types, with 48% classified as ST131. Ninety six percent of ESBL-E isolates carried a blaCTX-M gene. Isolated ESBL-Es frequently carried virulence genes as well as multiple classes of antibiotic resistance genes. Long-term colonization was common, with 64% of ESBL-E positive participants testing positive when rescreened three months later. One participant yielded isolates belonging to two different E. coli sequence types that carried blaCTX-M-1 genes on near-identical plasmids, suggesting intra-gut plasmid transfer. Isolation of E. coli on media without antibiotics revealed that ESBL-E. coli typically made up a minor fraction of the overall gut E. coli population, although in some cases they were the dominant strain. ESBL-E carriage was not associated with a significantly different stool microbiome composition. However, some microbial taxa were differentially abundant in ESBL-E carriers. Together, these results suggest that a small subpopulation of US residents are long-term, asymptomatic carriers of ESBL-Es, and may serve as an important reservoir for community spread of these ESBL genes.

Genomic and metabolic versatility of Pseudomonas aeruginosa contributes to its inter-kingdom transmission and survival

Pseudomonas aeruginosa is one of the most versatile bacteria with renowned pathogenicity and extensive drug resistance. The diverse habitats of this bacterium include fresh, saline and drainage waters, soil, moist surfaces, taps, showerheads, pipelines, medical implants, nematodes, insects, plants, animals, birds and humans. The arsenal of virulence factors produced by P. aeruginosa includes pyocyanin, rhamnolipids, siderophores, lytic enzymes, toxins and polysaccharides. All these virulent elements coupled with intrinsic, adaptive and acquired antibiotic resistance facilitate persistent colonization and lethal infections in different hosts. To date, treating pulmonary diseases remains complicated due to the chronic secondary infections triggered by hospital-acquired P. aeruginosa. On the contrary, this bacterium can improve plant growth by suppressing phytopathogens and insects. Notably, P. aeruginosa is one of the very few bacteria capable of trans-kingdom transmission and infection. Transfer of P. aeruginosa strains from plant materials to hospital wards, animals to humans, and humans to their pets occurs relatively often. Recently, we have identified that plant-associated P. aeruginosa strains could be pathologically similar to clinical isolates. In this review, we have highlighted the genomic and metabolic factors that facilitate the dominance of P. aeruginosa across different biological kingdoms and the varying roles of this bacterium in plant and human health.

Incidence of catheter-associated urinary tract infections by Gram-negative bacilli and their ESBL and carbapenemase production in specialized hospitals of Bahir Dar, northwest Ethiopia

BACKGROUND

Catheter-associated urinary tract infections (CAUTIs) due to multidrug-resistant Gram-negative bacilli (GNB) is a common concern globally. Investigating the incidence of CAUTI and associated antibiotic resistance has paramount importance from the health care associated infections perspective. This study therefore assessed the incidence of CAUTIs due to GNB and the production of extended-spectrum beta-lactamase (ESBL) and carbapenemase among inpatients in specialized hospitals of Northwest, Ethiopia.

METHODS

A total of 363 patients with indwelling urinary catheters who were admitted in the hospital for > 48 h were consecutively enrolled and followed from 3 to 18 days. Data were collected through interviewing and review of medical records. Patients who developed at least one of the following: fever (> 38 OC), suprapubic tenderness, or costovertebral angle pain, coupled with a GNB positive urine culture of ≥ 103 CFU/mL with no more than two bacterial species were defined as CAUTI. The ESBL and carbapenemase production were detected and identified by chromogenic medium. Logistic regression analysis was done to identify associated factors.

RESULTS

From 363 patients followed, the incidence rate of CAUTI was 27.8 per 1000 catheter days. Catheterization for ≥ 8 days (AOR = 10.6, 95%CI:1.8-62.1) and hospitalization for > 10 days (AOR = 8.1, 95%CI: 2.4-27.2) were the factors significantly associated with CAUTIs. E. coli (n = 18, 34.6%), Proteus species (n = 7, 13.5%), and P. aeruginosa (n = 6, 11.5%) were the most frequent GNB. Isolates revealed high rates of resistance to amoxicillin-clavulanic acid (100%), cefazolin (n = 51, 98%), ceftazidime (n = 47, 90%) and cefotaxime (n = 46, 88%). Most of the GNB isolates (86.5%) were multidrug-resistant. Overall, 19.2% and 5.8% of GNB isolates were ESBL and carbapenemase producers, respectively.

CONCLUSIONS

Incidence of CAUTI with Gram-negative bacilli is high. As most of the GNB isolates are MDR and showed a super high rate of resistance to amoxicillin-clavulanic and third-generation cephalosporins, empirical treatment with these substances is virtually ineffective in patients with suspected GNB infection in Ethiopia. The expression of ESBL and carbapenemase among GNB isolates is also a concern. Therefore, improved infection prevention and control measures, careful use of catheters and third generation of cephalosporins are needed to improve patient outcomes and reduce the burden of CAUTIs and the spreading of antimicrobial resistance.