Epidemiological characteristics of carbapenem-resistant Enterobacteriaceae collected from 17 hospitals in Nanjing district of China

Transmission dynamics of multidrug resistant Klebsiella pneumoniae from an Indian hospital

OBJECT

The dissemination of Klebsiella pneumoniae is becoming a major concern, as this organism is responsible for a significant proportion of hospital acquired infections. Due to complexity of this organism adequate knowledge on the epidemiology and infection control practices associated with the dissemination is highly required. Therefore, this study designed to include consecutive samples from environment and patients to assess the similarity pattern among isolates from different sources.

METHODOLOGY

We included patients with hospital acquired infections with K. pneumonaie and environment isolates. To obtain the complete sequence forty-eight isolates were sequenced on Illumina MiSeq 250 2 × 250 bp paired end (Illumina, USA) and Nanopore (Oxford). These includes 30 BSI cases, 13 environment and 5 from water. Assembly of good quality reads were prepared using Unicycler. AMR gene detection was done using Resfinder of Abricate and sequence similarity was observed by SNP based phylogenetic analysis.

RESULTS

The most common sequence type of organism among all was ST 231 and ST 395. ST 29 was common between water and clinical isolates. Average (range) number of AMR genes present in clinical isolates were 16 (3-24). The antimicrobial genes belong to 41 classes and fosA was highly prevalent. The frequency of blaNDM was present 55.4 % (27/48) and blaOXA in 61.6 % (30/48). The strain ST 395 and ST 16 carried highest no. of replicons n = 10 and n = 9. The predominant plasmid replicon Col440I (N = 58) followed by IncFII_1_pKP91 (N = 34) and ColRNAI (N = 29). The phylogenetic analysis showed high similarity between clinical and environmental samples.

CONCLUSION

This study concludes that environment play essential role in disseminating the infectious strains of organism resulting in increased rates of hospital acquired infections. Therefore, there is an imperative necessity for implementing infection control practices to prevent the spread of infectious diseases.

Antimicrobial susceptibility of gram-negative strains isolated from bloodstream infections in China: Results from the study for monitoring antimicrobial resistance trends (SMART) 2018-2020

The study aims were to present in vitro susceptibilities of clinical isolates from Gram-negative bacteria bloodstream infections (GNBSI) collected in China. GNBSI isolates were collected from 18 tertiary hospitals in 7 regions of China from 2018 to 2020. Minimum inhibitory concentrations were assessed using a Trek Diagnostic System. Susceptibility was determined using CLSI broth microdilution, and breakpoints were interpreted using CLSI M100 (2021). A total of 1,815 GNBSI strains were collected, with E. coli (42.4%) and Klebsiella pneumoniae (28.6%) being the most prevalent species, followed by P. aeruginosa (6.7%). Susceptibility analyses revealed low susceptibilities (<40%) of ESBL-producing E. coli and K. pneumonia to third-/fourth-generation cephalosporins, monobactamases, and fluoroquinolones. High susceptibilities to colistin (95.0%) and amikacin (81.3%) were found for K. pneumoniae, while Acinetobacter baumannii exhibited a high susceptibility (99.2%) to colistin but a low susceptibility to other antimicrobials (<27.5%). Isolates from ICUs displayed lower drug susceptibility rates of K. pneumoniae and A. baumannii than isolates from non-ICUs (all P < 0.05). Carbapenem-resistant and ESBL-producing K. pneumoniae detection was different across regions (both P < 0.05). E. coli and K. pneumoniae were major contributors to GNBSI, while A. baumannii exhibited severe drug resistance in isolates obtained from ICU departments.

Fecal carriage and molecular characterization of carbapenem-resistant Enterobacteriaceae from hospitalized children in a tertiary hospital of Shandong, China

BACKGROUND

The prevalence of carbapenem-resistant Enterobacteriaceae (CRE) has emerged as a serious public health problem worldwide, and the data on the fecal carriage of CRE strains in hospitalized children remain limited. This study aimed to investigate the molecular characteristics of intestinal colonization of CRE in hospitalized children in Shandong, China.

METHODS

A retrospective study was conducted from August to November 2023. Antimicrobial susceptibility testing was performed by the broth microdilution method. Carbapenemase genes, drug resistance genes, and plasmid replicon types were detected using multiplex real-time PCR and whole-genome sequencing. Multilocus sequence typing (MLST) was used to determine the genetic relationships between strains.

RESULTS

A total of 20 CRE isolates were identified from 432 fecal samples, with a fecal carriage rate of 4.6%. The CRE isolates predominantly consisted of Escherichia coli (E. coli, n = 13) and Klebsiella strains (n = 6). CRE isolates showed a high resistance rate of 90-100% to seven β-lactam antibiotics. Resistance rates for other antibiotics such as trimethoprim-sulfamethoxazole, tetracycline, azithromycin, ciprofloxacin, chloramphenicol, nalidixic acid, and streptomycin were 90, 85, 85, 80, 75, 75, and 75%, respectively. CRE isolates showed low resistance to amikacin (20%), and none of the isolates were resistant to tigecycline. Additionally, the multidrug resistance rate of CRE isolates was 95%. All CRE strains carried sulfonamide antibiotic and β-lactamase resistance genes, of which the most common β-lactamase resistance genes were bla NDM-1 (n = 9), bla NDM-5 (n = 7) and bla OXA-1 (n = 7). Resistance genes to tetracycline and macrolide antibiotics were also widespread among the strains. The study found that IncFIB and IncFII series plasmids were present in 84 and 42% of the CRE strains, respectively. Additionally, Col, IncFIA, IncC, IncHI2, and IncX series plasmids were also detected. MLST analysis revealed diverse sequence types (STs) among CRE isolates, with ST167 being a common ST among E. coli isolates.

CONCLUSION

This study revealed bla NDM E. coli were the dominant isolates in fecal samples of hospitalized children in Shandong Province, with a broad multidrug resistance to antibiotics, emphasizing that infection control measures need to be taken to limit the spread of these strains.

Delving into Macrolide Binding Affinities and Associated Structural Modulations in Erythromycin Esterase C: Insights into the Venus Flytrap Mechanism

Since their inception in antibacterial therapy, macrolide-based antibiotics have significantly shaped the evolutionary pathways of pathogenic bacteria, driving them to develop diverse antimicrobial resistance (AMR) mechanisms. Among these, macrolide esterase, commonly referred to as erythromycin esterase, emerged as a critical defense mechanism, enabling bacteria to detoxify macrolides by hydrolyzing the macrolactone ring within the bacterial cell. In this study, we delve into the intricate interactions and conformational dynamics of erythromycin esterase C (EreC), a key member of the Ere enzyme family. We have focused on three FDA-approved and widely prescribed macrolides─erythromycin, clarithromycin, and azithromycin─by employing classical molecular dynamics, absolute binding free energy calculations, and 2D well-tempered metadynamics simulations to explore their interactions with EreC. To estimate the absolute binding free energies, we have used the recently developed and robust "Streamlined Alchemical Free Energy Perturbation (SAFEP)" protocol. The results from our molecular dynamics simulations and advanced analyses portrayed the crucial role of hydrophobic interactions within the macrolide binding cleft of EreC, along with the significant influence of the minor lobe in facilitating overall structural fluctuation. In silico alanine scanning identified top three hydrophobic residues, i.e., PHE248, MET333, and PHE344, responsible for macrolide binding inside that cleft. According to the free energy calculations, azithromycin and clarithromycin showed greater binding affinities toward EreC than the parent macrolide erythromycin. Moreover, 2D metadynamics simulations along with graph theory-based eigenvector centrality analyses revealed a metastable "semiopen" state during the hypothesized "active loop closure" of the EreC protein triggered by subtle conformational changes of an important histidine residue, HIS289, upon macrolide capture, drawing a fascinating parallel to the renowned "Venus flytrap" mechanism.

Mobile genetic elements contributing to horizontal gene transfer of blaNDM among Escherichia coli in the community setting

OBJECTIVE

To investigate the distribution of carbapenem-resistant Enterobacterales (CRE) in the community and to describe the genomic characteristics.

METHODS

CRE screened from fecal samples in healthy people at the health examination center of a tertiary hospital in China underwent Whole genome sequencing (WGS) to analyze genotypic characteristics of CRE. The flanking DNA sequence of blaNDM-5 and mcr1.1 genes were analyzed by Gcluster software.

RESULTS

A total of 7187 fecal samples were screened, and CRE carriage was detected in 0.4 % of the sampled population. In total, 30 Escherichia coli, one Citrobacter freundii and one Klebsiella aerogene were screened. The 30 carbapenem-resistant Escherichia coli (CREC) isolates displayed slight resistance to amikacin (13.3 %) and aztreonam (20.0 %). All the CRE isolates contained blaNDM, and blaNDM-5 (84.4 %) was the most common one. B1 (n = 11) and A (n = 7) were predominant phylogroups. Furthermore, 34 distinct plasmid replicons, 67 different VFs, 22 distinct STs, 17 different FimH types, 26 O:H serotypes as well as 74 MGEs including 61 insertion sequences and 13 transposons were identified. The flanking DNA sequence analysis of blaNDM-5 and mcr1.1 genes indicates the key role of horizontal transfer of blaNDM-5 in the CRE development evidenced by diverse STs and phylogenetic tree.

CONCLUSION

E. coli was the most predominant CRE isolates in community setting, and blaNDM (blaNDM-5) was the main CHβL encoding genes. The high prevalence of ARGs was associated with high resistance to commonly used antimicrobials. Besides, the genetic diversity of these isolates suggested the key role of blaNDM horizontal transfer in the CRE development. Thus, active screening of blaNDM in communities is particularly important for the prevention and control of CRE.

Virulence plasmid with IroBCDN deletion promoted cross-regional transmission of ST11-KL64 carbapenem-resistant hypervirulent Klebsiella pneumoniae in central China

BACKGROUND

Carbapenem-resistant and hypervirulent Klebsiella pneumoniae (CR-hvKP) caused infections of high mortality and brought a serious impact on public health. This study aims to evaluate the epidemiology, resistance and virulence characteristics of CR-hvKP and to identify potential drivers of cross-regional transmission in different regions of China, in order to provide a basis for developing targeted prevention measures.

METHODS

Clinical K. pneumoniae strains were collected from Jiujiang and Nanchang in Jiangxi province between November 2021 to June 2022. Clinical data of patients (age, sex, source of infection, and diagnosis) were also gathered. We characterized these strains for their genetic relatedness using PFGE, antimicrobial and virulence plasmid structures using whole-genome sequencing, and toxicity using Galleria mellonella infection model.

RESULTS

Among 609 strains, 45 (7.4%) CR-hvKP were identified, while the strains. isolated from Nanchang and Jiujiang accounted for 10.05% (36/358) and 3.59% (9/251). We observed that ST11-KL64 CR-hvKP had an overwhelming epidemic dominance in these two regions. Significant genetic diversity was identified among all ST11-KL64 CR-hvKP cross-regional transmission between Nanchang and Jiujiang and this diversity served as the primary driver of the dissemination of clonal groups. Virulence genes profile revealed that ST11-KL64 CR-hvKP might harbour incomplete pLVPK-like plasmids and primarily evolved from CRKP by acquiring the hypervirulence plasmid. We found the predominance of truncated-IncFIB/IncHI1B type virulence plasmids with a 25 kb fragment deletion that encoded iroBCDN clusters.

CONCLUSION

ST11-KL64 is the most cross-regional prevalent type CR-hvKPs in Jiangxi province, which mainly evolved from CRKPs by acquiring a truncated-IncHI1B/IncFIB virulence plasmid with the deletion of iroBCDN. Stricter surveillance and control measures are urgently needed to prevent the epidemic transmission of ST11-KL64 CR-hvKP.

New Delhi metallo-β-lactamases among extensively drug-resistant clinical isolates from Lahore, Pakistan

Aim: The study determines rates of carbapenem resistance (CR) and frequency of blaNDM in multidrug-resistance (MDR) or extensive drug resistance (XDR), and evaluates the potential of phenotypic tests for detecting NDM production. Materials & methods: Singleplex PCR was used to detect blaNDM. Phenotypic tests, including combination disc test (CDST) and modified Hodge test (MHT), were evaluated for NDM production. Results: Among 338 CR isolates, 47.63% were MDR, whereas 52.36% were XDR with 53.25% carrying blaNDM. MHT was found to be discriminative for detecting NDM production, whereas no significant association was observed for CDST. Conclusion: The high incidence of CR and MDR and XDR isolates possessing blaNDM presents an impending threat in therapeutics. Limitations of phenotypic tests suggest better testing, including molecular detection of the enzyme.

Real-time genomic epidemiologic investigation of a multispecies plasmid-associated hospital outbreak of NDM-5-producing Enterobacterales infections

OBJECTIVES

New Delhi metallo-β-lactamase (NDM) is an emergent mechanism of carbapenem resistance associated with high mortality and limited treatment options. Because the blaNDM resistance gene is often carried on plasmids, traditional infection prevention and control (IP&C) surveillance methods and reactive whole genome sequencing (WGS) may not detect plasmid transfer in multispecies outbreaks.

METHODS

Initial outbreak detection of NDM-producing Enterobacterales identified at an acute care hospital occurred via traditional IP&C methods and was supplemented by real-time WGS surveillance performed weekly. To resolve NDM-encoding plasmids, we performed long-read sequencing and constructed hybrid assemblies. WGS data for suspected outbreaks was shared with the IP&C team for assessment and intervention.

RESULTS

We observed a multispecies outbreak of NDM-5-producing Enterobacterales isolated from 15 patients between February 2021 and February 2023. The 19 clinical and surveillance isolates sequenced included 7 bacterial species encoding the same NDM-5 plasmid. WGS surveillance and epidemiologic investigation characterized 10 horizontal plasmid transfer events and 6 bacterial transmission events between patients in varying hospital units.

CONCLUSIONS

Our investigation revealed a complex, multispecies outbreak of NDM involving multiple plasmid transfer and bacterial transmission events. We highlight the utility of combining traditional IP&C and prospective genomic methods in identifying and containing plasmid-associated outbreaks.

Whole genome sequence-based molecular characterization of blood isolates of carbapenem-resistant Enterobacter cloacae complex from ICU patients in Kolkata, India, during 2017-2022: emergence of phylogenetically heterogeneous Enterobacter hormaechei subsp. xiangfangensis

Blood-borne infections caused by the carbapenem-resistant Enterobacter cloacae complex (CR-ECC) are major public threats with respect to the challenges encountered during treatment. This study describes the whole genome sequencing-based molecular characteristics of blood isolates (n = 70) of CR-ECC from patients admitted to the intensive care unit of tertiary care hospitals in Kolkata, India, during 2017-2022 with respect to species identification, antimicrobial resistance (AMR) profiling, mechanism of drug resistance, and molecular subtypes. Vitek2 MALDI and species-specific PCR identified Enterobacter hormaechei subsp. xiangfangensis (47.14%) as the emerging CR-ECC subspecies in Kolkata. The predominating carbapenemase and extended-spectrum β-lactamase genes found were blaNDM-1 (51.42%) and blaCTX-M-15 (27%), respectively. Besides, blaNDM-4, blaNDM-5, blaNDM-7, blaCMH-3, blaSFO-1, blaOXA-181, blaOXA-232, blaKPC-3, and blaDHA-7 genes were also detected, which were not previously reported from India. A multitude of Class 1 integrons (including In180, In4874, In4887, and In4888, which were novel) and plasmid replicon types (IncFIB, IncFII, IncX3, IncHI1-HI2, IncC, and IncR) involved in AMR dissemination were identified. Reverse transcription-PCR and western blot revealed that carbapenem resistance in non-carbapenemase-producing CR-ECC isolates was contributed by elevated levels of ampC, overexpression of acrAB, and loss of ompF. A total of 30 distinct sequence types (STs) were ascertained by multi-locus sequence typing; of which, ST2011, ST2018, ST2055, ST2721, and ST2722 were novel STs. Pulsed-field gel electrophoresis analysis showed heterogeneity (69 pulsotypes with a similarity coefficient of 48.40%) among the circulating isolates, suggesting multiple reservoirs of infections in humans. Phylogenetically and genetically diverse CR-ECC with multiple AMR mechanisms mandates close monitoring of nosocomial infections caused by these isolates to forestall the transmission and dissemination of AMR.IMPORTANCEThe emergence and extensive dissemination of the carbapenem-resistant Enterobacter cloacae complex (CR-ECC) have positioned it as a critical nosocomial global pathogen. The dearth of a comprehensive molecular study pertaining to CR-ECC necessitated this study, which is the first of its kind from India. Characterization of blood isolates of CR-ECC over the last 6 years revealed Enterobacter hormaechei subsp. xiangfangensis as the most prevalent subsp., exhibiting resistance to almost all antibiotics currently in use and harboring diverse transmissible carbapenemase genes. Besides the predominating blaNDM-1 and blaCTX-M-15, we document diverse carbapenemase and AmpC genes, such as blaNDM-4, blaNDM-7, blaOXA-181, blaOXA-232, blaKPC-3, blaCMH-3, blaSFO-1, and blaDHA-7, in CR-ECC, which were not previously reported from India. Furthermore, novel integrons and sequence types were identified. Our findings emphasize the need for strengthened vigilance for molecular epidemiological surveillance of CR-ECC due to the presence of epidemic clones with a phylogenetically diverse and wide array of antimicrobial resistance genes in vulnerable populations.

Difference analysis and characteristics of incompatibility group plasmid replicons in gram-negative bacteria with different antimicrobial phenotypes in Henan, China

BACKGROUND

Multi-drug-resistant organisms (MDROs) in gram-negative bacteria have caused a global epidemic, especially the bacterial resistance to carbapenem agents. Plasmid is the common vehicle for carrying antimicrobial resistance genes (ARGs), and the transmission of plasmids is also one of the important reasons for the emergence of MDROs. Different incompatibility group plasmid replicons are highly correlated with the acquisition, dissemination, and evolution of resistance genes. Based on this, the study aims to identify relevant characteristics of various plasmids and provide a theoretical foundation for clinical anti-infection treatment.

METHODS

330 gram-negative strains with different antimicrobial phenotypes from a tertiary hospital in Henan Province were included in this study to clarify the difference in incompatibility group plasmid replicons. Additionally, we combined the information from the PLSDB database to elaborate on the potential association between different plasmid replicons and ARGs. The VITEK mass spectrometer was used for species identification, and the VITEK-compact 2 automatic microbial system was used for the antimicrobial susceptibility test (AST). PCR-based replicon typing (PBRT) detected the plasmid profiles, and thirty-three different plasmid replicons were determined. All the carbapenem-resistant organisms (CROs) were tested for the carbapenemase genes.

RESULTS

21 plasmid replicon types were detected in this experiment, with the highest prevalence of IncFII, IncFIB, IncR, and IncFIA. Notably, the detection rate of IncX3 plasmids in CROs is higher, which is different in strains with other antimicrobial phenotypes. The number of plasmid replicons they carried increased with the strain resistance increase. Enterobacterales took a higher number of plasmid replicons than other gram-negative bacteria. The same strain tends to have more than one plasmid replicon type. IncF-type plasmids tend to be associated with MDROs. Combined with PLSDB database analysis, IncFII and IncX3 are critical platforms for taking blaKPC-2 and blaNDM.

CONCLUSIONS

MDROs tend to carry more complex plasmid replicons compared with non-MDROs. The plasmid replicons that are predominantly prevalent and associated with ARGs differ in various species. The wide distribution of IncF-type plasmids and their close association with MDROs should deserve our attention. Further investigation into the critical role of plasmids in the carriage, evolution, and transmission of ARGs is needed.

Genomic Characterization of Escherichia coli Co-Producing KPC-2 and NDM-5 Carbapenemases Isolated from Intensive Care Unit in a Chinese Hospital

Background: Around the world, carbapenemase-producing Escherichia coli is becoming more prevalent. The purpose of this research was to analyze the whole plasmid sequences from YL03 isolates of the E. coli strain that produce both KPC-2 and NDM-5 carbapenemases. Materials and Methods: Whole-genome sequencing (WGS) and analysis of E. coli strain YL03, which was isolated from a wound sample, was performed by Illumina Novaseq 6000 and Pacific Biosciences Sequel (PacBio, Menlo Park, CA) sequencers. Following that, the WGS results were used to predict and analyze the YL03 genome composition and function. A complete gene sequence for YL03 with the accession number CP093551 has been uploaded to GenBank. Results: The results showed that YL03 co-carried five resistance genes, which included blaKPC-2, blaNDM-5, blaTEM-1B, blaCTX-M-14, and mdf(A). Furthermore, three resistance plasmids were found in YL03: pYL03-KPC, pYL03-NDM, and pYL03-CTX. Among them, the 53 kb-long pYL03-KPC plasmid belonging to the IncP, carried the replicase gene (repA) and the carbapenemase gene (blaKPC-2). The blaKPC-2 gene was flanked by a composite transposon-like element (Tn3-[Tn3] tnpR-ISKpn27 blaKPC--ISKpn6). Conclusions: The YL03 strain co-carried blaKPC-2 and blaNDM-5 and had a unique multidrug resistance plasmid containing blaKPC-2.

In vitro activity of cefiderocol, a siderophore cephalosporin, against carbapenem-resistant hypervirulent Klebsiella pneumoniae in China

Cefiderocol is a siderophore cephalosporin that binds ferric iron and utilizes iron transporters to cross the cell membrane. Hypervirulent Klebsiella pneumoniae (hvKp) is known to produce more siderophores; in this case, the uptake of cefiderocol may be decreased. Therefore, the objective of this study was to evaluate the in vitro activity of cefiderocol against hvKp isolates. A total of 320 carbapenem-resistant K. pneumoniae (CRKp) isolates were collected in China between 2014 and 2022, including 171 carbapenem-resistant hvKp (CR-hvKp) and 149 carbapenem-resistant classical K. pneumoniae (CR-cKp). Quantitative detection of siderophores showed that the average siderophore production of CR-hvKp (234.6 mg/L) was significantly higher than that of CR-cKp (68.9 mg/L, P < 0.001). The overall cefiderocol resistance rate of CR-hvKp and CR-cKp was 5.8% (10/171) and 2.7% (4/149), respectively. The non-susceptible rates of both cefiderocol and siderophore production of CR-hvKp isolates were higher than those of CR-cKp in either NDM-1- or KPC-2-producing groups. The MIC90 and MIC50 for CR-hvKp and CR-cKp were 8 mg/L and 2 mg/L and 4 mg/L and 1 mg/L, respectively. The cumulative cefiderocol MIC distribution for CR-hvKp was significantly lower than that of CR-cKp isolates (P = 0.003). KL64 and KL47 consisted of 53.9% (83/154) and 75.7% (53/70) of the ST11 CR-hvKp and CR-cKp, respectively, and the former had significantly higher siderophore production. In summary, cefiderocol might be less effective against CR-hvKp compared with CR-cKp isolates, highlighting the need for caution regarding the prevalence of cefiderocol-resistant K. pneumoniae strains, particularly in CR-hvKp isolates.

Survival of clinical and environmental carbapenem-resistant Klebsiella pneumoniae ST147 in surface water

Carbapenem-resistant Klebsiella pneumoniae represents a healthcare threat, already disseminated in the environment. This study aimed to compare the behaviour of a clinical and an environmental K. pneumoniae strain (multilocus sequence type ST147) harbouring the gene blaKPC-3 in water. The abundance of the genes phoE (specific for K. pneumoniae) and blaKPC-3 was monitored by quantitative PCR in urban runoff water and sterile ultra-pure water microcosms, aiming to assess survival, blaKPC-3 persistence, and the effect of the native water microbiota. In sterile ultra-pure water, the abundance of cultivable K. pneumoniae and blaKPC-3 gene did not change over the incubation period (8 days). In contrast, in urban runoff, the K. pneumoniae and the genes phoE and blaKPC genes decreased by up to 3 log-units. These results suggest that K. pneumoniae were outcompeted by the native microbiota of the urban runoff water and that the decay of blaKPC-3 gene was due to host death, rather than to gene loss. The study highlights that although native microbiota is essential to hamper the persistence of non-native bacteria, carbapenemase producing K. pneumoniae can survive in urban runoff water for at least one week.

Infection with Carbapenem-resistant Hypervirulent Klebsiella Pneumoniae: clinical, virulence and molecular epidemiological characteristics

BACKGROUND

Carbapenem-resistant hypervirulent Klebsiella pneumoniae (CR-hvKP) is gradually becoming the dominant nosocomial pathogens in the healthcare setting.

METHODS

A retrospective study was conducted on patients with CR-KP from July 2021 to May 2022 in a teaching hospital. We identified bacterial isolates, collected the clinical data, and performed antimicrobial susceptibility testing, hypermucoviscosity string test, antimicrobial and virulence-associated genotype, as well as multi-locus sequence typing. CR-hvKP was defined as the presence of some combination of rmpA and/or rmpA2 with iucA, iroB, or peg-344. SPSS was used for data analysis. Univariate logistic regression analyses were used for risk factor and all statistically significant variables were included in the multivariate model. Statistical significance was taken to be P < 0.05.

RESULTS

A total of 69 non-duplicated CR-KP isolates were collected, 27 of which were CR-hvKP. Out of the 69 CR-KP strains under investigation, they were distributed across 14 distinct sequence types (STs), wherein ST11 exhibited the highest prevalence, constituting 65.2% (45/69) of the overall isolates. The principal carbapenemase genes identified encompassed blakpc-2, blaNDM-1, and blaOXA-48, with blakpc-2 prevailing as the predominant type, accounting for 73.9% (51/69). A total of 69 CR-KP strains showed high resistance to common clinical antibiotics, with the exception of ceftazidime/avibactam. The ST11 (P = 0.040), ST65 (P = 0.030) and blakpc-2 ST11 clones (P = 0.010) were found to be highly related to hvKp. Regarding the host, tracheal intubation (P = 0.008), intracranial infection (P = 0.020) and neutrophil count (P = 0.049) were significantly higher in the patients with CR-hvKP. Multivariate analysis showed tracheal intubation to be an independent risk factor for CR-hvKP infection (P = 0.030, OR = 4.131). According to the clinical data we collected, tracheal intubation was performed mainly in the elderly with severe underlying diseases, which implied that CR-hvKP has become prevalent among elderly patients with comorbidities.

CONCLUSIONS

The prevalence of CR-hvKP may be higher than expected in the healthcare setting. CR-hvKP is gradually becoming the dominant nosocomial pathogen, and its prevalence and treatment will be a major challenge. It is essential to enhance clinical awareness and management of CR-hvKP infection.

Distribution of ß-Lactamase Genes Among Multidrug-Resistant and Extended-Spectrum ß-Lactamase-Producing Diarrheagenic Escherichia coli from Under-Five Children in Ethiopia

Purpose

Escherichia coli strains that produce extended-spectrum ß-lactamase (ESBL) and carbapenemase are among the major threats to global health. The objective of the present study was to determine the distribution of ß-lactamase genes among multidrug-resistant (MDR) and ESBL-producing Diarrheagenic E. coli (DEC) pathotypes isolated from under-five children in Ethiopia.

Patients and Methods

A cross-sectional study was conducted in Addis Ababa and Debre Berhan, Ethiopia. It was a health-facility-based study and conducted between December 2020 and August 2021. A total of 476 under-five children participated in the study. DEC pathotypes were detected by conventional Polymerase Chain Reaction (PCR) assay. After evaluating the antimicrobial susceptibility profile of the DEC strains by disk diffusion method, confirmation test was done for ESBL and carbapenemase production. ß-lactamase encoding genes were identified from phenotypically ESBLs and carbapenemase positive DEC strains using PCR assay.

Results

In total, 183 DEC pathotypes were isolated from the 476 under-five children. Seventy-nine (43%, 79/183) MDR-DEC pathotypes were identified. MDR was common among enteroaggregative E. coli (EAEC) (58%, 44/76), followed by enterotoxigenic E. coli (ETEC) (44%, 17/39)) and enteroinvasive E. coli (EIEC) (30%, 7/23). Phenotypically, a total of 30 MDR-DEC pathotypes (16.4%, 30/183) were tested positive for ESBLs. Few ETEC (5.1%, 2/39) and EAEC (2.6%, 2/76) were carbapenemase producers. The predominant β-lactamase genes identified was blaTEM (80%, 24/30) followed by blaCTX-M (73%, 22/30), blaSHV (60%, 18/30), blaNDM (13%, 4/30), and blaOXA-48 (13%, 4/30). Majority of the ß-lactamase encoding genes were detected in EAEC (50%) and ETEC (20%). Co-existence of different β-lactamase genes was found in the present study.

Conclusion

The blaTEM, blaCTX-M, blaSHV, blaNDM, and blaOXA-48, that are associated with serious and urgent threats globally, were detected in diarrheagenic E. coli isolates from under-five children in Ethiopia. This study also revealed the coexistence of the β-lactamase genes.

Dissemination and characteristics of carbapenem-resistant Klebsiella pneumoniae in nine district hospitals in southwestern China

Background

Carbapenem-resistant Klebsiella pneumoniae (CRKP) is epidemically transmitted globally, but few studies focused on the prevalence in district-level hospitals. In this study, we investigated CRKP strains collected from nine district hospitals from September 2019 to September 2020, aiming to determine the resistance mechanisms, virulence profiles, and molecular epidemiological characteristics of CRKP in district hospitals in Southwest China.

Methods

A total of 51 CRKP strains were collected from 9 district-level hospitals. Matrix-assisted laser desorption/ionization-time of flight mass spectrometer was used for strain identification review, and the micro-broth dilution method was used for antibiotic sensitivity detection. Molecular epidemiological investigation of strains was performed by multilocus sequence typing (MLST) and pulsed-field gel electrophoresis (PFGE) methods. PCR and efflux pump inhibition tests were used to detect CRKP resistance mechanisms. PCR and serum killing tests were used to detect capsular serotype, virulence-related genes, and virulence validation.

Results

The CRKP strains in district hospitals presented high levels of MIC50 and MIC90 in carbapenem antibiotics especially ertapenem and meropenem. A total of 90.2% (46/51) CRKP strains were detected as carbapenemase producers, and the proportion of strains co-expressing carbapenemases was 11.8% (6/51). All CRKP strains were grouped into eight MLST types, and ST11 was the most prevalent genotype. A total of 11.8% (6/51) CRKP isolates were positive for the string test, and three strains of hypervirulent and carbapenem-resistant K. pneumoniae (HV-CRKP) were positive in serum killing test. The molecular typing of all the CRKP isolates was grouped into 29 different PFGE patterns, and 40 ST11 isolates belonged to 20 different PFGE clusters.

Conclusion

CRKP strains showed high-level antibiotic resistance and virulence phenotype in district hospitals in Southwest China, which suggested that we should immediately pay attention to the rapid dissemination of the CRKP in regional hospitals. Our study will provide new insights into the epidemiology of CRKP in regional hospitals, which will help regional hospitals develop nosocomial infection prevention and control policies tailored to local conditions.

Characterization of ST11 and ST15 Carbapenem-Resistant Hypervirulent Klebsiella pneumoniae from Patients with Ventilator-Associated Pneumonia

Background

The prevalence of carbapenem-resistant hypervirulent Klebsiella pneumoniae (hv-CRKP) is a serious public threat globally. Here, we performed clinical, molecular, and phenotypic monitoring of hv-CRKP strains isolated from the intensive care unit (ICU) to offer evidence for prevention and control in hospitals.

Methods

Data analysis of ICU patients suffering from ventilator-associated pneumonia (VAP) because of hv-CRKP infection, admitted at the Chinese Teaching Hospital between March 2019 and September 2021 was performed. Patients' antibiotic-resistance genes, virulence-associated genes, and capsular serotypes of these isolates were detected. Homology analysis of the strains was performed by MLST and PFGE. Six different strains were tested for their virulence traits using the serum killing test and the Galleria mellonella infection assay. For whole genome sequencing, KP3 was selected as a representative strain.

Results

Clinical data of 19 hv-CRKP-VAP patients were collected and their hv-CRKP were isolated, including 10 of ST11-KL64, 4 of ST15-KL112, 2 of ST11-KL47, 1 of ST15-KL19, 1 of ST17-KL140, and 1 of ST48-KL62. Four ST15 and 8 ST11 isolates revealed high homology, respectively. Most strains carried the carbapenemase gene blaKPC-2 (14/19, 73.68%), followed by blaOXA-232 (4/19, 21.05%). All strains were resistant to almost all the antibiotics except polymyxin and tigacycline. Ten patients were treated with polymyxin or tigacycline based on their susceptibility results, and unfortunately 6 patients died. All strains exhibited a hyper-viscous phenotype, and the majority (17/19, 89.47%) of them contained rmpA and rmpA2. The serum killing test showed that KP9 was resistant to normal healthy serum, others were intermediately or highly sensitive. G. mellonella larvae infection assay suggested that the strains in this study were hypervirulent.

Conclusion

This study highlights the dominant strain and molecular epidemiology of hv-CRKP in a hospital in China. We should pay more attention to the effect of hv-CRKP on VAP, strengthen monitoring and control transmission.

Genomic Epidemiologic Investigation of a Multispecies Hospital Outbreak of NDM-5-Producing Enterobacterales Infections

Background

New Delhi metallo-β-lactamase (NDM) represents an emergent mechanism of carbapenem resistance associated with high mortality and limited antimicrobial treatment options. Because the blaNDM resistance gene is often carried on plasmids, traditional infection prevention and control (IP&C) surveillance methods like speciation, antimicrobial resistance testing, and reactive whole genome sequencing (WGS) may not detect plasmid transfer in multispecies outbreaks.

Methods

Initial outbreak detection of NDM-producing Enterobacterales identified at an acute care hospital occurred via traditional IP&C methods and was supplemented by real-time WGS surveillance, which was performed weekly using the Illumina platform. To resolve NDM-encoding plasmids, we performed long-read Oxford Nanopore sequencing and constructed hybrid assemblies using Illumina and Nanopore sequencing data. Reports of relatedness between NDM-producing organisms and reactive WGS for suspected outbreaks were shared with the IP&C team for assessment and intervention.

Findings

We observed a multispecies outbreak of NDM-5-producing Enterobacterales isolated from 15 patients between February 2021 and February 2023. The 19 clinical and surveillance isolates sequenced included seven bacterial species and each encoded the same NDM-5 plasmid, which showed high homology to NDM plasmids previously observed in Asia. WGS surveillance and epidemiologic investigation characterized ten horizontal plasmid transfer events and six bacterial transmission events between patients housed in varying hospital units. Transmission prevention focused on enhanced observation and adherence to basic infection prevention measures.

Interpretation

Our investigation revealed a complex, multispecies outbreak of NDM that involved multiple plasmid transfer and bacterial transmission events, increasing the complexity of outbreak identification and transmission prevention. Our investigation highlights the utility of combining traditional IP&C and prospective genomic methods in identifying and containing plasmid-associated outbreaks.

Funding

This work was funded in part by the National Institute of Allergy and Infectious Diseases, National Institutes of Health (NIH) (R01AI127472) (R21AI1783691).

Molecular eidemiology of carbapenem-resistant Enterobacter cloacae complex in a tertiary hospital in Shandong, China

BACKGROUND

The increasing incidence and prevalence of carbapenem-resistant Enterobacter cloacae complex (CREC) poses great challenges to infection prevention and disease treatment. However, much remains unknown about the clinical characteristics of CREC isolates. Our objective was to characterize antimicrobial resistance and, carbapenemase production in CREC with 36 CREC isolates collected from a tertiary hospital in Shandong, China.

RESULTS

Three types of carbapenemases (NDM, IMP and VIM) were detected in these isolates. Among them, NDM carbapenemases were most prevalent, with a 61.2% (22/36) detection rate for NDM-1, 27.8% (10/36) for NDM-5 and 2.8% (1/36) for NDM-7. IMP-4 was found in two isolates and VIM-1 in only one isolate. The MLST analysis identified 12 different sequence types (STs), of which ST171 (27.8%) was the most prevalent, followed by ST418 (25.0%). ST171 isolates had significantly higher rates of resistance than other STs to gentamicin and tobramycin (Ps < 0.05), and lower rates of resistance to aztreonam than ST418 and other STs (Ps < 0.05). Among 17 carbapenemase-encoding genes, the bla_NDM-5 gene was more frequently detected in ST171 than in ST418 and other isolates (Ps < 0.05). In contrast, the bla_NDM-1 gene was more frequently seen in ST418 than in ST171 isolates. One novel ST (ST1965) was identified, which carried the bla_NDM-1 gene.

CONCLUSION

NDM-5 produced by ST171 and NDM-1 carbapenemase produced by ST418 were the leading cause of CREC in this hospital. This study enhances the understanding of CREC strains and helps improve infection control and treatment in hospitals.

The Antibacterial Activity of Rhazya stricta Extracts against Klebsiella pneumoniae Isolated from Some Soil Invertebrates at High Altitudes

Klebsiella is a common dangerous pathogen for humans and animals and is widely present in the digestive system. The genus Klebsiella is ubiquitous, as it is endemic to surface water, soil, and sewage. In this study, 70 samples were obtained from soil-dwelling invertebrates from September 2021 to March 2022 from Taif and Shafa in different altitudinal regions of Saudi Arabia. Fifteen of these samples were identified as Klebsiella spp. The Klebsiella isolates were genetically identified as Klebsiella pneumoniae using rDNA sequencing. The antimicrobial susceptibility of the Klebsiella isolates was determined. Amplification of virulence genes was performed using PCR. In this study, 16S rDNA sequencing showed a similarity from 98% to 100% with related K. pneumonia from the NCBI database, and the sequences were deposited in the NCBI GenBank under accession numbers ON077036 to ON077050. The growth inhibition properties of ethanolic and methanolic extracts of the medicinal plant Rhazya stricta's leaves against K. pneumoniae strains using the minimum inhibitory concentration (MIC) method and disc diffusion were evaluated. In addition, the biofilm inhibitory potential of these extracts was investigated using crystal violet. HPLC analysis identified 19 components divided into 6 flavonoids, 11 phenolic acids, stilbene (resveratrol), and quinol, and revealed variations in the number of components and their quantities between extracts. Both extracts demonstrated interesting antibacterial properties against K. pneumoniae isolates. The 2 extracts also showed strong biofilm inhibitory activities, with percentages of inhibition extending from 81.5% to 98.7% and from 35.1% to 85.8% for the ethanolic and methanolic extracts, respectively. Rhazya stricta leaf extract revealed powerful antibacterial and antibiofilm activities against K. pneumoniae isolates and could be a good candidate for the treatment or prevention of K. pneumonia-related infections.

Identification and Characterization of Plasmids and Genes from Carbapenemase-Producing Klebsiella pneumoniae in Makkah Province, Saudi Arabia

Klebsiella pneumoniae (K. pneumoniae) is involved in several hospital and community-acquired infections. The prevalence of K. pneumoniae-producing-carbapenemase (KPC) resistance genes rapidly increases and threatens public health worldwide. This study aimed to assess the antibiotic resistance level of K. pneumoniae isolates from Makkah Province, Saudi Arabia, during the Islamic ‘Umrah’ ritual and to identify the plasmid types, presence of genes associated with carbapenem hydrolyzing enzymes, and virulence factors. The phenotypic and genotypic analyses based on the minimum inhibitory concentration (MIC), biofilm formation, PCR, and characterization of KPC-encoding plasmids based on the replicon typing technique (PBRT) were explored. The results showed that most isolates were resistant to carbapenem antibiotics and other antibiotics classes. This study identified sixteen different replicons of plasmids in the isolates and multiple genes encoding carbapenem factors, with blaVIM and blaOXA-48 being the most prevalent genes identified in the isolates. However, none of the isolates exhibited positivity for the KPC production activity. In addition, this study also identified six virulence-related genes, including kfu, wabG, uge, rmpA, fimH, and a capsular polysaccharide (CPS). Together, the data reported in this study indicate that the isolated K. pneumoniae during the pilgrimage in Makkah were all resistant to carbapenem antibiotics. Although the isolates lacked KPC production activity, they carried multiple carbapenem-resistant genes and virulence factors, which could drive their resistant phenotype. The need for specialized methods for KPC detection, monitoring the possibility of nosocomial transmission, and diverse therapeutic alternatives are necessary for controlling the spreading of KPC. This study can serve as a reference for clinicians and researchers on types of K. pneumoniae commonly found during religious gathering seasons in Saudi Arabia.

A matrix management of prevention and control for carbapenem-resistant Enterobacteriaceae in an urban compact medical union

PURPOSE

To understand the epidemiological characteristics of nosocomial infection of carbapenem-resistant Enterobacteriaceae (CRE) in an urban medical union includes 10 medical hospitals with different number of beds in China.

METHODS

Epidemiological data on age, department, and infection of CRE cases detected from January 2014 to December 2021 were collected via a real-time hospital-infection monitoring system or manually for subsequent characterization. A multi-departmental and multi-disciplinary matrix (MMM) management of CRE was established and implemented within a medical union.

RESULTS

A total of 1327 cases of CRE infection were detected during the 8 years, of which 352 were due to nosocomial infection, with an infection morbidity of 0.046% and a resistance rate of 10.79%. The morbidity of CRE infection showed a trend of year-to-year fluctuation. The morbidity of CRE infection was significantly higher in winter and spring than that in summer and autumn, significantly higher in men than in women (χ² ​= ​55.891, p ​< ​0.001), and 3 times higher in elderly patients ≥65 years old than in patients <65 years old (χ² ​= ​117.517, p ​< ​0.001). The morbidity of CRE infection after intervention with MMM management decreased significantly from 0.071% to 0.042% (χ² ​= ​15.628, p ​< ​0.001).

CONCLUSIONS

CRE prevention and control practice should be adapted to seasonal variations, gender and age differences. The effective prevention and control of CRE nosocomial infections can be achieved by implementing MMM management within a medical association.

Epidemiology of carbapenem-resistant Klebsiella pneumoniae ST15 of producing KPC-2, SHV-106 and CTX-M-15 in Anhui, China

Background:

It is well known that carbapenem-resistant Klebsiella pneumoniae (CRKP) has become a more problematic public health issue due to its widespread spread worldwide. In China, ST11-type CRKP is the most prevalent CRKP, but ST15-type CRKP, a recently prevalent high-risk clone, has emerged widely throughout China, posing a serious public health risk. Therefore, we conducted an epidemiological of an outbreak of ST15 CRKP of producing CTX-M-15, KPC-2 and SHV-106 in a tertiary hospital in Anhui, China, to Understanding the potential risks of the current STT15 CRKP outbreak.

Results:

From July 2021 to December 2021, 13 ST15 CRKP isolates were identified by collecting non-repeated clinical multidrug-resistant isolates, with all capsular typing of serotype KL19. All ST15 CRKP isolates were resistant to cephalosporins, carbapenems and quinolones, but were sensitive to amikacin, tigecycline and polymyxin B. In addition, isolates carried bla_SHV−106 (100%), bla_KPC−2 (69%), bla_CTX−M−15 (69%), bla_TEM−1B (69%), bla_OXA−1 (62%) and bla_LAP−2 (8%), as well as iron chelators (iutA, ybt, fyuA, ent, fepA, irp1, irp2, 100%) were detected. In phenotyping experiments, all ST15 CRKP exhibited lower growth rates than NTUH-K2044, and all ST15 CRKP did not exhibit mucoviscositty characteristics. However, in the Galleria mellonella infection model, isolates 21081212, 21081241 and 21091216 were more lethal than the hypervirulent isolates NTUH-K2044. Sequencing results showed that the genetic environment surrounding the genes bla_SHV−106, bla_KPC−2, bla_CTX−M−15, bla_OXA−1 and bla_TEM−1B were all identical in the ST15 CRKP isolates. Phylogenetic analysis showed that 13 ST15 CRKP isolates were divided into three subgroups, and when placed in global analysis, 10 of them were highly homologous to isolates from Jiangsu, two were highly homologous to isolates from Zhejiang, and one was homologous to an isolate from an unlabelled region.

Conclusion:

Our research shows that ST15 CRKP, which carries multiple β-lactamases genes and siderophores-encoding genes, may be evolving to hypervirulence and may have spread widely in localised areas. Therefore, environmental surveillance and clinical infection control in hospitals should be strengthened to prevent further spread of ST15 CRKP.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12866-022-02672-1.

Assessing Colistin Resistance by Phenotypic and Molecular Methods in Carbapenem-resistant Enterobacterales in a Tertiary Care Hospital in Pakistan

Introduction

Members of Enterobacterales are very common pathogens, which continue to show resistance to many antibiotics. Carbapenem performed well for some time. Colistin was the final hope for the carbapenem-resistant Enterobacterales, but resistance against it has virtually tied the clinician's hands, especially when it comes to treating critically ill patients.

Purpose

Detection of colistin resistance by the agar method as well as by the polymerase chain reaction (mobilized colistin resistance-1 gene) in carbapenem-resistant Enterobacterales.

Materials and Methods

A cross-sectional study from Dec 2019 to Dec 2020 was conducted at the Department of Microbiology, Army Medical College, National University of Medical Sciences Rawalpindi Pakistan. Antimicrobial susceptibility of Enterobacterales was determined according to the Kirby-Bauer disc diffusion method except for colistin. Colistin agar was used, in concentrations of 2 µg/mL and 4 µg/mL. Results were interpreted according to Clinical and Laboratory Standards Institute guidelines 2020. Mobilized colistin-resistant-1 gene in the carbapenem resistant Enterobacterales was detected by performing real-time polymerase chain reaction assay.

Results

Among the 172 carbapenem-resistant Enterobacterales 18 isolates were resistant using the colistin agar test. Whereas by molecular method colistin resistance was detected among 10 isolates that carried mobilized colistin resistance 1 gene, making the frequency of the MCR-1 gene 5.81%. Seventy percent of isolates were from paired blood samples. Eight patients, from whom the colistin resistant gene was isolated expired.

Conclusion

Colistin resistance is a very serious issue and should not be missed in a clinical microbiology laboratory. The phenotypic agar test method is an excellent option for routine use, as it combines ease of performance with affordable cost. However, molecular methods are essential for the detection of mobilized colistin resistance gene (1-9) for epidemiological purposes.

ST11 Carbapenem-Resistant Klebsiella pneumoniae Clone Harboring blaNDM Replaced a blaKPC Clone in a Tertiary Hospital in China

The nosocomial spread of carbapenem-resistant Enterobacterales (CRE) is extremely common, resulting in severe burdens on healthcare systems. In particular, the high-risk Klebsiella pneumoniae ST11 strain has a wide endemic area in China. The current study describes the results of continuous monitoring of CRE genotypes and phenotypes in a tertiary hospital in North China from 2012 to 2020. A total of 160 isolates were collected, including 109 Klebsiella. pneumoniae (68.13%), 29 Escherichia coli (26.60%), 12 Enterobacter cloacae (7.50%), and 10 other strains (6.25%). A total of 149 carbapenemase genes were detected, of which blaKPC-2 (51.0%) was the most common, followed by blaNDM-1 (22.82%), and blaNDM-5 (23.49%). Based on multi-locus sequence typing, the ST11 strain (66.1%) dominates K. pneumoniae, followed by ST15 (13.8%). Interestingly, the proportion of blaNDM (22.2%, 16/72) in ST11 K. pneumoniae was significantly increased in 2018−2019. Hence, whole-genome sequencing was performed on ST11 K. pneumoniae. Growth curves and in vitro competition experiments showed that K. pneumoniae carrying blaNDM exhibited a stronger growth rate (p < 0.001) and competition index (p < 0.001) than K. pneumoniae carrying blaKPC. Moreover, K. pneumoniae carrying blaNDM had a stronger biofilm-forming ability than K. pneumoniae carrying blaKPC (t = 6.578; p < 0.001). K. pneumoniae carrying blaKPC exhibited increased defense against bactericidal activity than K. pneumoniae carrying blaNDM. Thus, ST11 K. pneumoniae carrying blaNDM has strong adaptability and can locally replace K. pneumoniae carrying blaKPC to become an epidemic strain. Based on these findings, infection control and preventive measures should focus on the high-risk ST11-K. pneumoniae strain.

Hybrid IncFIA/FIB/FIC(FII) plasmid co-carrying blaNDM-5 and fosA3 from an Escherichia coli ST117 strain of retail chicken

Carbapenems and fosfomycin are important antibiotics used to treat Enterobacteriaceae-associated infections. This study aimed to characterize the co-resistance and co-dissemination mechanism of carbapenem and fosfomycin resistance in an Escherichia coli ST117 strain isolated from retail chicken meat. Antimicrobial susceptibility testing showed that an E. coli CS18F strain had a multidrug resistance profile, including carbapenem and fosfomycin resistance. The presence of bla_NDM-5 and fosA3 genes was confirmed by PCR and Sanger sequencing. The bla_NDM-5 and fosA3 genes were successfully transferred to the recipient strain E. coli J53 via conjugation, and the transconjugants had elevated minimum inhibitory concentrations (MICs) for meropenem and fosfomycin. Whole genome sequencing (WGS) of E. coli CS18F revealed that bla_NDM-5 and fosA3 were colocalized on an IncFIA/FIB/FIC(FII) type plasmid of 189,141 bp, which was designated as pCS18F-NDM-Fos. A novel structure with five IS26 sequences flanking the multiple drug resistance region (MDRR) was identified, and three copies of IS26 were found to be flanked bla_NDM-5, fosA3, dfrA12, aadA2, and sul1. Three types of translocation units (TUs) were identified by PCR, containing either the resistance gene bla_NDM-5 and an IS26 sequence, fosA3, and an IS26 sequence, or both, indicating their potential co-transfer via TUs. Thus, this is an unprecedented report of the presence of a plasmid co-carrying bla_NDM-5 and fosA3 and TUs potentially mediating their simultaneous transfer.

Outbreak of IncX8 Plasmid-Mediated KPC-3-Producing Enterobacterales Infection, China

Carbapenem-resistant Enterobacterales (CRE) infection is highly endemic in China; Klebsiella pneumoniae carbapenemase (KPC) 2-producing CRE is the most common, whereas KPC-3-producing CRE is rare. We report an outbreak of KPC-3-producing Enterobacterales infection in China. During August 2020-June 2021, 25 bla_KPC-3-positive Enterobacteriale isolates were detected from 24 patients in China. Whole-genome sequencing analysis revealed that the bla_KPC-3 genes were harbored by IncX8 plasmids. The outbreak involved clonal expansion of KPC-3-producing Serratia marcescens and transmission of bla_KPC-3 plasmids across different species. The bla_KPC-3 plasmids demonstrated high conjugation frequencies (10^-3 to 10^-4). A Galleria mellonella infection model showed that 2 sequence type 65 K2 K. pneumoniae strains containing bla_KPC-3 plasmids were highly virulent. A ceftazidime/avibactam in vitro selection assay indicated that the KPC-3-producing strains can readily develop resistance. The spread of bla_KPC-3-harboring IncX8 plasmids and these KPC-3 strains should be closely monitored in China and globally.

First Case Report of Detection of Multidrug-Resistant Enterobacter hormaechei in Clinical Sample from an Aborted Ruminant

The emergence of multidrug-resistant (MDR) bacterial strains is one of the significant global challenges with regard to bacterial drug-resistance control. Enterobacter hormaechei organisms belong to the Enterobacter cloacae complex (ECC) and are commonly recognized as causative agents for hospital infections. Recently, a few E. hormaechei MDR strains associated with infection in piglets, calves, and a fox were reported, highlighting the important role of animals and livestock in the emergence and spread of antimicrobial resistance. In this study, the vaginal swab sample from a 5-year-old cow with multiple anamnestic infectious abortions was carefully investigated. The animal was unresponsive to antibiotic therapy recommended by the veterinarian. The MDR bacterial strain isolated from the bovine sample, designated as the Saratov_2019, belonged to Enterobacter hormaechei. The genome-based phylogenetic analysis identified the isolate to be Enterobacter hormaechei subsp. xiangfangensis. The genome of the Saratov_2019 contained a 6364 bp plasmid. Importantly, we revealed the novel sequence type ST1416 and 13 MDR genes correlating with the MDR phenotype in only the chromosome but not the plasmid. These findings indicate that the potential spread of this strain may pose a threat for both animal and human health. The data obtained here support the notion of the important role of livestock in the emergence and spread of antimicrobial resistance, promoting careful investigation of the MDR spectra for livestock-related bacterial isolates. To the best of our knowledge, this is the first report on the association of E. hormaechei subsp. xiangfangensis with the infection of the reproductive system in cattle.

Transmission barrier of the blaKPC plasmid mediated by type I restriction-modification systems in Escherichia coli

BACKGROUND

Transportation of carbapenem-resistant plasmids contributes to carbapenem resistance in Gram-negative bacteria. KPC enzymes are the most clinically important enzymes among carbapenem-resistant Klebsiella pneumoniae, whereas the rate of blaKPC in Escherichia coli is low. The CRISPR-Cas system and restriction-modification system (R-M system) in bacteria defend against invading genomes. Currently, the role of the immune systems in the low rate of KPC-producing E. coli remains unclear.

OBJECTIVES

We investigated the relationship between immune systems and the low detection rate of blaKPC in E. coli.

METHODS

We searched for blaKPC among 1039 E. coli whole genomes available in GenBank using nucleotide BLAST. CRISPR-Cas systems and the R-M system were detected in all strains having the ST as blaKPC-positive strains. Nucleotide BLAST was used to search for protospacers on blaKPC plasmids. A conjugation assay was performed to determine whether the R-M system influences the acquisition of blaKPC plasmids by E. coli.

RESULTS

ST131 was the dominant ST of KPC-producing E. coli and IncN was the main plasmid type (12/32). CRISPR-Cas systems were frequently present in E. coli carrying blaKPC. Furthermore, CRISPR-Cas systems in E. coli didn't target plasmids with blaKPC. Type I R-M systems were rare in KPC-producing E. coli, but significantly over-represented in KPC-negative strains. E. coli DH5α with hsdR deletion accepted blaKPC-carrying plasmids, whereas those with hsdR complementation impeded blaKPC-carrying plasmid conjugation.

CONCLUSIONS

Horizontal transmission of blaKPC occurs among E. coli. The type I R-M system is associated with the defence against blaKPC plasmid transport into E. coli.

Temperature-Regulated IncX3 Plasmid Characteristics and the Role of Plasmid-Encoded H-NS in Thermoregulation

Carbapenem-resistant Enterobacteriaceae (CRE) are a critical public health problem worldwide. Globally, IncX3-type plasmids have emerged as the predominant vehicles carrying the metallo-β-lactamase gene bla NDM. Although bla NDM-bearing IncX3 plasmids have been found in various hosts from diverse environments, whether their transfer and persistence properties vary under different conditions and what factors influence any variation is unknown. By observing the effects of different temperatures on IncX3 plasmid conjugation rates, stability, and effects on host fitness in Escherichia coli, we demonstrate that temperature is an important determinant of plasmid phenotypes. The IncX3 plasmid pGZIncX3 transferred at highest frequencies, was most stable and imposed lower fitness costs at 37°C. Temperature-regulated variation in pGZIncX3 properties involved a thermoregulated plasmid-encoded H-NS-like protein, which was produced at higher levels at 30°C and 42°C and inhibited the expression of type IV secretion system genes involved in conjugation. These findings suggest that bla NDM-bearing IncX3 plasmids are adapted to carriage by enterobacteria that colonize mammalian hosts and could explain the rapid dissemination of these plasmids among human-associated species, particularly in hospital settings.

High Carriage Rate of the Multiple Resistant Plasmids Harboring Quinolone Resistance Genes in Enterobacter spp. Isolated from Healthy Individuals

Antimicrobial-resistant bacteria causing intractable and even fatal infections are a major health concern. Resistant bacteria residing in the intestinal tract of healthy individuals present a silent threat because of frequent transmission via conjugation and transposition. Plasmids harboring quinolone resistance genes are increasingly detected in clinical isolates worldwide. Here, we investigated the molecular epidemiology of plasmid-mediated quinolone resistance (PMQR) in Gram-negative bacteria from healthy service trade workers. From 157 rectal swab samples, 125 ciprofloxacin-resistant strains, including 112 Escherichia coli, 10 Klebsiella pneumoniae, two Proteus mirabilis, and one Citrobacter braakii, were isolated. Multiplex PCR screening identified 39 strains harboring the PMQR genes (including 17 qnr,19 aac(6')-Ib-cr, and 22 oqxA/oqxB). The genome and plasmid sequences of 39 and 31 strains, respectively, were obtained by short- and long-read sequencing. PMQR genes mainly resided in the IncFIB, IncFII, and IncR plasmids, and coexisted with 3-11 other resistance genes. The high PMQR gene carriage rate among Gram-negative bacteria isolated from healthy individuals suggests the high-frequency transmission of these genes via plasmids, along with other resistance genes. Thus, healthy individuals may spread antibiotic-resistant bacterial, highlighting the need for improved monitoring and control of the spread of antibiotic-resistant bacteria and genes in healthy individuals.

In silico Evolution and Comparative Genomic Analysis of IncX3 Plasmids Isolated From China Over Ten Years

IncX3 plasmids are correlated with the dissemination and acquisition of carbapenem resistance in Enterobacteriaceae and have been prevalent in China over the last 10 years. Since the distribution characteristics of IncX3 plasmids across China as well as their evolutionary traits for 10 years remain unclear, here we conducted a retrospective literature review and in silico comparative analysis of IncX3 plasmids in publicly available IncX3 plasmid genomes. IncX3 plasmids distributed in 17 provinces or cities were extracted for analysis, which tend to be specifically associated with hospital-isolated Escherichia coli ST410 from phylogroup A. Although the backbones of IncX3 plasmids have remained highly conservative over the last 10 years, the bla_NDM resistance genetic contexts on these plasmids could fall into five subtypes, among which AR_N1_I has been identified in Enterobacter cloacae174 chromosome and AR_N5_I was simultaneously located on IncF and IncA/C plasmids. This suggests that the bla_NDM resistance gene environment can spread between different plasmids, between different bacterial genera, or between strains and plasmids, highlighting that it is imperative to adopt more stringent infection control measures targeting IncX3 plasmid spread.

Emergence of 16S rRNA methyltransferases among carbapenemase-producing Enterobacterales in Spain studied by whole-genome sequencing

The emergence of 16S rRNA methyltransferases (RMTs) in Gram-negative pathogens bearing other clinically relevant resistance mechanisms, such as carbapenemase-producing Enterobacterales (CPE), is becoming an alarming concern. We investigated the prevalence, antimicrobial susceptibility, resistance mechanisms, molecular epidemiology and genetic support of RMTs in CPE isolates from Spain. This study included a collection of 468 CPE isolates recovered during 2018 from 32 participating Spanish hospitals. MICs were determined using the broth microdilution method, the agar dilution method (fosfomycin) or MIC gradient strips (plazomicin). All isolates were subjected to hybrid whole-genome sequencing (WGS). Sequence types (STs), core genome phylogenetic relatedness, horizontally acquired resistance mechanisms, plasmid analysis and the genetic environment of RMTs were determined in silico from WGS data in all RMT-positive isolates. Among the 468 CPE isolates evaluated, 24 isolates (5.1%) recovered from nine different hospitals spanning five Spanish regions showed resistance to all aminoglycosides and were positive for an RMT (21 RmtF, 2 ArmA and 1 RmtC). All RMT-producers showed high-level resistance to all aminoglycosides, including plazomicin, and in most cases exhibited an extensively drug-resistant susceptibility profile. The RMT-positive isolates showed low genetic diversity and were global clones of Klebsiella pneumoniae (ST147, ST101, ST395) and Enterobacter cloacae (ST93) bearing bla_OXA-48, bla_NDM-1 or bla_VIM-1 carbapenemase genes. RMTs were harboured in five different multidrug resistance plasmids and linked to efficient mobile genetic elements. Our findings highlight that RMTs are emerging among clinical CPE isolates from Spain and their spread should be monitored to preserve the future clinical utility of aminoglycosides and plazomicin.

IncN1 ST7 Epidemic Plasmid Carrying blaIMP-4 in One ST85-Type Klebsiella oxytoca Clinical Isolate with Porin Deficiency

Purpose

Klebsiella oxytoca is an opportunistic pathogen causing nosocomial infections. This study was designed to characterize the genomic features of a carbapenem-resistant K. oxytoca strain and analyze its molecular characteristics.

Materials and Methods

The strain wzx-IMP was isolated from the blood of a 2-year-old girl diagnosed with acute myeloid leukemia-M7. Species identification was performed, and the minimal inhibitory concentration of the strain was measured. Multilocus sequence typing was performed to identify the subtypes of K. oxytoca. The transfer capacity of the blaIMP-4-harboring plasmid was investigated by conjugation experiments, and the genome characteristics of the strain were examined using whole-genome sequencing.

Results

wzx-IMP belongs to the ST85 type and is resistant to imipenem and meropenem, which harbored the blaIMP-4 gene. The blaIMP-4 gene was located in an IS26-associated class 1 integron of pwzx_IMP, which contains conserved IncN1-type backbone regions with a replication gene and its accessory structure for plasmid replication. The blaIMP-4-carrying plasmid in wzx-IMP was successfully transferred to Escherichia coli EC600 by conjugation. Whole-genome sequencing showed that the wzx-IMP isolate included the blaOXY-1-1 gene, accompanied by OmpK36 absence.

Conclusion

We report an ST85-type carbapenem-resistant K. oxytoca strain, which produces blaIMP-4 located in an IncN1-type plasmid and accompanied by OmpK36 porin deficiency.

Multidrug resistance IncC plasmid carrying blaCMY-97 in Shiga toxin-producing Escherichia coli ST215-H54 of ovine origin

CMY-type β-lactamases are the most reported plasmid-mediated AmpC (pAmpC), with the CMY-2-like group being the most clinically relevant described in Escherichia coli at human-animal-environment interface. Shiga toxin-producing E. coli (STEC) lineages are zoonotic pathogens commonly reported causing serious clinical conditions in humans, including severe diarrheagenic diseases. Therefore, this study aimed to investigate a multidrug-resistant (MDR) STEC isolate (A313) recovered from a healthy sheep and carrying mobile bla_CMY-97, that encodes a pAmpC belonging to the CMY-2-like group. The A313 isolate exhibited a MDR profile to clinically relevant antimicrobials (i.e., cephalosporins, aminoglycosides, and fluoroquinolones), but reduced susceptibility to extended-spectrum cephalosporins and aztreonam. Besides, virulence genes (stx2, gad and iutA) were detected in A313, which belonged to ST215/CC10 and phylogenetic group A, whereas the fimH54 was identified. The bla_CMY-97 gene and other antimicrobial resistance determinants [aph(6)-Id, aph(3″)-Ib, aac(3)-IId, aadA5, floR, tetA, sul1, and sul2], as well as genes encoding tolerance to mercury (merRTPCADE), were harbored by an IncC plasmid (named pA313-CMY-97, ~ 176 kb). A novel genetic context of bla_CMY-2-like, in which a 208-bp ISEcp1 was truncated by an IS26 in the opposite orientation upstream of the bla_CMY-97 gene (IS26-∆ISEcp1-bla_CMY-97-blc-sugE-encR), was also identified in pA313-CMY-97. To the best of our knowledge, this is the first report on the acquisition of bla_CMY-97 into a plasmid. Therefore, we reported ovine as reservoir of clinically relevant MDR bacteria carrying mobile bla_CMY-97 with potential for zoonotic transmission.

Prevalence of the NTEKPC-I on IncF Plasmids Among Hypervirulent Klebsiella pneumoniae Isolates in Jiangxi Province, South China

Infection caused by carbapenem-resistant hypervirulent Klebsiella pneumoniae (CR-hvKP) has become a tricky health care threat in China and KPC-2 enzyme is a main factor mediating resistance to carbapenems of K. pneumoniae. Here, we report the characterization of the genetic environment of the blaKPC-2 gene in CR-hvKP clinical isolates from South China. Forty-five non-duplicated CR-hvKP isolates collected in Jiangxi Province from 2018 to 2019 were analyzed. Each of them were multidrug-resistant due to the presence not only of blaKPC-2 gene but also of other resistance determinants, including Metallo-β-lactamases (NDM-1), extended-spectrum β-lactamases (TEM-1, CTX-M-14, SHV-1), and plasmid-mediated quinolone resistance determinants (qnrS, aac(6′)-Ib-cr). After plasmid analyses of PCR-based replicon typing (PBRT), mapping PCR, amplicon sequencing, and whole-genome sequencing (WGS) were used to analyze the genetic environment of the blaKPC-2 gene. PCR analysis of pLVPK-like plasmids, Southern Blot, and mouse lethality assay were used to characterize the virulence phenotype of K. pneumoniae. Multilocus sequence typing (MLST) analysis showed ST11 CR-hvKP was the predominant clone. In conclusion, this is the first analysis of diverse genetic structures blaKPC-2 gene in CR-hvKP isolates from south China. Both the NTEKPC-I on the IncF plasmids and pLVPK-like virulence plasmids make contributions to the formation of CR-hvKP especially ST11 which need more attention.

Shift in the Dominant Sequence Type of Carbapenem-Resistant Klebsiella pneumoniae Bloodstream Infection from ST11 to ST15 at a Medical Center in Northeast China, 2015-2020

Objective

To investigate the clinical characteristics and molecular epidemiology of carbapenem-resistant Klebsiella pneumoniae (CRKP) bloodstream infection at a medical center in northeast China, especially after coronavirus disease (COVID-19) pandemic.

Methods

Fifty-one patients were diagnosed with CRKP bloodstream infection between January 2015 and December 2020, among which 42 isolates were available for further study. Species identification and antibiotic susceptibilities were tested with matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) and VITEK 2 systems. Carbapenemase genes, virulence genes and MLST genes were detected by polymerase chain reaction. Moreover, the string test and serum killing assay were performed to evaluate the virulence of the CRKP isolates.

Results

During the six-year period, the detection rate of CRKP in bloodstream infection showed an increasing trend, with the intensive care unit, hematology and respiratory medicine wards mainly affected. Molecular epidemiology analyses showed that KPC-2 was the dominant carbapenemase gene. In addition, the dominant sequence type (ST) of CRKP shifted from ST11 to ST15 strains, which were all sensitive to amikacin in contrast to the ST11 stains. Furthermore, ST15 CRKP strains were positive for the KfuB virulence gene and more resistant to serum killing compared to the ST11 CRKP strains. Nonetheless, the mortality rate of patients infected with ST11 and ST15 CRKP did not show any significant differences.

Conclusion

A shift in the dominant sequence type of CRKP bloodstream infections from ST11 to ST15 was observed during the years 2015–2020. Compared to ST11, the ST15 CRKP strains showed amikacin sensitivity, positivity for KfuB gene, and serum resistance, which may indicate stronger virulence.

Antibiotic-Resistant Enterobacteriaceae in Wastewater of Abattoirs

Antibiotic-resistant Enterobacteriaceae are regularly detected in livestock. As pathogens, they cause difficult-to-treat infections and, as commensals, they may serve as a source of resistance genes for other bacteria. Slaughterhouses produce significant amounts of wastewater containing antimicrobial-resistant bacteria (AMRB), which are released into the environment. We analyzed the wastewater from seven slaughterhouses (pig and poultry) for extended-spectrum β-lactamase (ESBL)-carrying and colistin-resistant Enterobacteriaceae. AMRB were regularly detected in pig and poultry slaughterhouse wastewaters monitored here. All 25 ESBL-producing bacterial strains (19 E. coli and six K. pneumoniae) isolated from poultry slaughterhouses were multidrug-resistant. In pig slaughterhouses 64% (12 of 21 E. coli [57%] and all four detected K. pneumoniae [100%]) were multidrug-resistant. Regarding colistin, resistant Enterobacteriaceae were detected in 54% of poultry and 21% of pig water samples. Carbapenem resistance was not detected. Resistant bacteria were found directly during discharge of wastewaters from abattoirs into water bodies highlighting the role of slaughterhouses for environmental surface water contamination.

Carbapenemase detection by NG-Test CARBA 5-a rapid immunochromatographic assay in carbapenem-resistant Enterobacterales diagnosis

Background

The global spread of carbapenem-resistant Enterobacterales (CRE) represents a serious public health concern as these organisms are associated with limited treatment options, high mortality rate and rapid transmissibility. The identification of carbapenemase remains a challenge in microbiological laboratories as no single method is perfect when considering cost, carbapenemase coverage, accuracy, handling complexity and TATs together.

Methods

NG-Test CARBA 5 assay and modified carbapenem inactivation method in conjunction with EDTA carbapenem inactivation method (mCIM/eCIM) were challenged with a collection of 299 molecularly characterized CRE isolates in China in order to evaluate the performance in detecting five major carbapenemases (bla_KPC, bla_NDM, bla_VIM, bla_IMP, and bla_OXA-48) among Enterobacterales.

Results

NG-Test CARBA 5 detected all KPC-, NDM-, VIM- and OXA-48-producing isolates perfectly with a weak false-positive signal for NDM in an IMP-4 producer, which makes the specificity for NDM decreases to 99.6%. The overall specificity/sensitivity were 99.9%/100% for NG-Test CARBA 5. mCIM/eCIM achieved high specificity of 100%/100% and sensitivity of 99.6%/97.4%, with one S. marcescens isolate harboring VIM-2 undetected.

Conclusions

Both NG-Test CARBA 5 and mCIM/eCIM showed excellent results in the tested carbapenemase (bla_KPC, bla_NDM, bla_VIM, bla_IMP, and bla_OXA-48) detection compared with molecular genotypic test. As every assay has its own limitations, suitable methods should be combined for the establishment of the CRE diagnostic pathways.

Epidemiological Characterization of Colistin and Carbapenem Resistant Enterobacteriaceae in a Tertiary: A Hospital from Anhui Province

PURPOSE

Antimicrobial resistance, especially carbapenem resistance Enterobacteriaceae and plasmid mediated mobile colistin resistance, is a serious issue worldwide. This study was designed to determine the epidemiological characteristics of plasmid mediated colistin resistance and carbapenem resistant Enterobacteriaceae from tertiary A hospital located in Hefei, China.

METHODS

Totally, 158 carbapenems resistant Enterobacteriaceae (CRE) were screened for antibiotic susceptibility, mcr-1, extended spectrum β-lactamases (ESBLs), metallo-β-lactamases (MBLs), and fosfomycin resistance genes using PCR and sequencing. The sequence types were identified by multilocus sequence typing (MLST). Plasmid profiles were determined by PCR based replicon typing (PBRT), and the plasmid sizes were confirmed by southern blotting.

RESULTS

The isolates showed high MIC50 and MIC90 for all antimicrobials, except tigecycline, meropenem, and colistin. The main Carbapenemase genes were bla KPC-2 (90.5%), bla NDM-1(3.7%), bla OXA-48(5.6%) and fosA3 (14.5%). The bla CTXM-15 found 36.7%, mcr-1 (3.7%) recorded in six isolates. PBRT revealed bla KPC-2 in K. pneumoniae on IncR, IncFII, and IncA/C. bla NDM-1 in E. coli on IncFII, whereas in E. cloacae noticed on IncHI2 plasmid. mcr-1 was recorded among IncFIIK, IncFII, and IncF in E. coli, K. pneumoniae, and E. cloacae. Resistance genes (mcr-1, bla NDM-1, bla KPC-2) harboring plasmids are successfully trans-conjugant to EC-600. A high incidence of ST11 was observed in K. pneumoniae carbapenem resistant isolates. While in E. coli, multiple STs were identified. However, mcr-1 in ST23 was identified for the first time in Anhui Province. Among Enterobacter cloacae, ST270 detected carrying bla NDM-1. Southern-hybridization confirmed the plasmid sizes 35-150kb.

CONCLUSION

This study indicates the co-carrying of mcr-1, bla KPC-2, and bla NDM-1 among clinical isolates, the prevalence of different Enterobacteriaceae STs is alarming, especially in E. coli. Holding such a resistance profile is a threat for humans and animals, which may be transferred between the strains through plasmid transfusion. Persistent control actions are immediately necessary to combat this hazard.

Carriage of Carbapenem-Resistant Enterobacterales in Adult Patients Admitted to a University Hospital in Italy

The emerging spread of carbapenemase-producing Enterobacterales (CPE) strains, in particular, Klebsiella pneumoniae and Escherichia coli, has become a significant threat to hospitalized patients. Carbapenemase genes are frequently located on plasmids than can be exchanged among clonal strains, increasing the antibiotic resistance rate. The aim of this study was to determine the prevalence of CPE in patients upon their admission and to analyze selected associated factors. An investigation of the antibiotic resistance and genetic features of circulating CPE was carried out. Phenotypic tests and molecular typing were performed on 48 carbapenemase-producing strains of K. pneumoniae and E. coli collected from rectal swabs of adult patients. Carbapenem-resistance was confirmed by PCR detection of resistance genes. All strains were analyzed by PCR-based replicon typing (PBRT) and multilocus sequence typing (MLST) was performed on a representative isolate of each PBRT profile. More than 50% of the strains were found to be multidrug-resistant, and the bla_KPC gene was detected in all the isolates with the exception of an E. coli strain. A multireplicon status was observed, and the most prevalent profile was FIIK, FIB KQ (33%). MLST analysis revealed the prevalence of sequence type 512 (ST512). This study highlights the importance of screening patients upon their admission to limit the spread of CRE in hospitals.

Fecal Carriage and Molecular Epidemiology of Carbapenem-Resistant Enterobacteriaceae from Inpatient Children in a Pediatric Hospital of Shanghai

Purpose

To determine the epidemiology characteristics of intestinal colonization of carbapenem-resistant Enterobacteriaceae (CRE) among inpatients in a pediatric hospital in China.

Methods

A retrospective study was conducted from April to December 2019. Medical records were reviewed to extract the clinical information. Antimicrobial susceptibility was performed by broth microdilution method. Drug resistance determinants and plasmid types were analyzed using polymerase chain reaction (PCR) assays. Multilocus sequence typing (MLST) and Enterobacterial repetitive intergenic consensus sequences PCR (ERIC-PCR) were employed to determine the genetic relationships between strains.

Results

A total of 90 CRE strains were isolated, with a fecal carriage rate of 8.6% (90/1052), and mainly distributed in E. aerogenes (n=30), K. pneumoniae (n=25) and E. coli (n=23). More than 50% of CRE colonizers had a history of invasive procedures and antibiotic exposures. As high as 91.1% (82/90) of CRE isolates carried carbapenemase genes, with bla_NDM-5 (n=56) being the most common, and mainly found in E. aerogenes (51.8%, 29/56) and E. coli (32.1%, 18/56) isolates, which primarily belonged to ST4 (100%, 29/29) and ST692 (55.6%, 10/18), respectively. Followed by bla_KPC-2 (n=12), and all found in K. pneumoniae ST11 isolates. Other carbapenemase genes including bla_NDM-1, bla_IMP-4 and bla_IMP-26. Meanwhile, ESBL genes (bla_CTX-M, bla_TEM-1 and bla_SHV) and AmpC genes (bla_DHA-1 and bla_EBC) were also detected. All CRE isolates showed high resistance to cephalosporins and carbapenemases (97.8%-100.0%) but remained susceptible to tigecycline (98.9%). IncX3 was a major plasmid type in NDM-containing strains (91.3%), and 91.7% of KPC-2-producing K. pneumoniae harboring IncFII and IncFIB plasmids. The ERIC-PCR revealed that several strains with identical STs were genetically similar.

Conclusion

This study revealed a major intestinal colonization of ST4 NDM-5 E. aerogenes, ST11 KPC-2 K. pneumoniae and ST692 NDM-5 E. coli strains among inpatients in a pediatric hospital. Infection control measures should be implemented immediately to prevent the spread of these strains in clinical settings.

New β-Lactam-β-Lactamase Inhibitor Combinations

The limited armamentarium against drug-resistant Gram-negative bacilli has led to the development of several novel β-lactam-β-lactamase inhibitor combinations (BLBLIs). In this review, we summarize their spectrum of in vitro activities, mechanisms of resistance, and pharmacokinetic-pharmacodynamic (PK-PD) characteristics. A summary of available clinical data is provided per drug. Four approved BLBLIs are discussed in detail. All are options for treating multidrug-resistant (MDR) Enterobacterales and Pseudomonas aeruginosa Ceftazidime-avibactam is a potential drug for treating Enterobacterales producing extended-spectrum β-lactamase (ESBL), Klebsiella pneumoniae carbapenemase (KPC), AmpC, and some class D β-lactamases (OXA-48) in addition to carbapenem-resistant Pseudomonas aeruginosa Ceftolozane-tazobactam is a treatment option mainly for carbapenem-resistant P. aeruginosa (non-carbapenemase producing), with some activity against ESBL-producing Enterobacterales Meropenem-vaborbactam has emerged as treatment option for Enterobacterales producing ESBL, KPC, or AmpC, with similar activity as meropenem against P. aeruginosa Imipenem-relebactam has documented activity against Enterobacterales producing ESBL, KPC, and AmpC, with the combination having some additional activity against P. aeruginosa relative to imipenem. None of these drugs present in vitro activity against Enterobacterales or P. aeruginosa producing metallo-β-lactamase (MBL) or against carbapenemase-producing Acinetobacter baumannii Clinical data regarding the use of these drugs to treat MDR bacteria are limited and rely mostly on nonrandomized studies. An overview on eight BLBLIs in development is also provided. These drugs provide various levels of in vitro coverage of carbapenem-resistant Enterobacterales, with several drugs presenting in vitro activity against MBLs (cefepime-zidebactam, aztreonam-avibactam, meropenem-nacubactam, and cefepime-taniborbactam). Among these drugs, some also present in vitro activity against carbapenem-resistant P. aeruginosa (cefepime-zidebactam and cefepime-taniborbactam) and A. baumannii (cefepime-zidebactam and sulbactam-durlobactam).

Characterization of an New Delhi-Metallo-1-Producing Enterobacter cloacae ST418 Strain from a Patient in Guangzhou, China

New Delhi-Metallo-1-producing (NDM-1-producing) Enterobacter cloacae is one of the highly resistant pathogens affecting the intensive care unit. A previous study reported that ST418 was the main epidemic type of NDM-1-producing E. cloacae in Shenzhen, China. However, few NDM-1-producing carbapenem-resistant Enterobacter cloacae ST418 strains have been described. In this study, we collected and characterized an NDM-1-producing carbapenem-resistant E. cloacae strain, E70, from a patient in Guangzhou. E70 was resistant to multiple antibiotics, including imipenem and meropenem. S1-Pulsed field gel electrophoresis and southern blotting showed that E70 harbored four plasmids and that the bla_NDM-1 gene was located on an ∼50 kb plasmid. Conjugation experiments revealed that the two smaller plasmids were transferable and that transconjugants obtaining one or both plasmids acquired different antimicrobial resistances. Whole-genome sequencing and analysis revealed that E70 belonged to ST418. The bla_NDM-1 and bla_SHV-12 genes coexisted on the 53.7 kb IncX3 plasmid pE70-NDM1, whereas the bla_CTX-M-3 and bla_TEM-1 genes were located on another untyped 26.0 kb plasmid, pE70-TEM1. The bla_NDM-1 plasmids in Enterobacter cloacae ST418 may serve as an important vehicle in the dissemination of NDM, and the coexistence of transferable plasmids increases the possibility of rapid horizontal spread of multidrug resistance genes. Long-term monitoring and detailed study are necessary for the prevention of bla_NDM-1-carrying E. cloacae infection.

Virulence evolution, molecular mechanisms of resistance and prevalence of ST11 carbapenem-resistant Klebsiella pneumoniae in China: A review over the last 10 years

Sequence type 11 (ST11) carbapenem-resistant Klebsiella pneumoniae (CRKP) has become the dominant clone in China. In this review, we trace the prevalence of ST11 CRKP in the China Antimicrobial Surveillance Network (CHINET), the key antimicrobial resistance mechanisms and virulence evolution. The recent emergence of ST11 carbapenem-resistant hypervirulent K. pneumoniae (CR-hvKP) strains in China due to the acquisition of a pLVPK-like virulence plasmid, which may cause severe infections in relatively healthy individuals that are difficult to treat with current antibiotics, has attracted worldwide attention. There is a very close linkage among IncF plasmids, NTE_KPC and ST11 K. pneumoniae in China. Hybrid conjugative virulence plasmids are demonstrated to readily convert a ST11 CRKP strain to a CR-hvKP strain via conjugation. Understanding the molecular evolutionary mechanisms of resistance and virulence-bearing plasmids as well as the prevalence of ST11 CRKP in China allows improved tracking and control of such organisms.

Recent progress of bacterial FtsZ inhibitors with a focus on peptides

In recent years, the rise of antibiotic resistance has become a primary health problem. With the emergence of bacterial resistance, the need to explore and develop novel antibacterial drugs has become increasingly urgent. Filamentous temperature-sensitive mutant Z (FtsZ), a crucial cell division protein of bacteria, has become a vital antibacterial target. FtsZ is a filamentous GTPase; it is highly conserved in bacteria and shares less than 20% sequence identity with the eukaryotic cytoskeleton protein tubulin, indicating that FtsZ-targeting antibacterial agents may have a low cytotoxicity toward eukaryotes. FtsZ can form a dynamic Z-ring in the center of the cell resulting in cell division. Furthermore, disturbance in the assembly of FtsZ may affect cellular dynamics and bacterial cell survival, making it a fascinating target for drug development. This review focuses on the recent discovery of FtsZ inhibitors, including peptides, natural products, and other synthetic small molecules, as well as their mechanism of action, which could facilitate the discovery of novel FtsZ-targeting clinical drugs in the future.