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In recent years, the emergence of bla OXA -encoding Escherichia coli (E. coli) poses a significant threat to human health. Here, we systematically analyzed the global geographic distribution and genetic characteristics of 328 bla OXA -positive E. coli plasmids based on NCBI database. Twelve bla OXA variants have been discovered, with bla OXA-1 (57.93%) being the most common, followed by bla OXA-10 (11.28%) and bla OXA-48 (10.67%). Our results suggested that bla OXA -positive E. coli plasmids were widespread in 40 countries, mainly in China, the United States, and Spain. MLST analysis showed that ST2, ST43, and ST471 were the top three host STs for bla OXA -positive plasmids, deserving continuing attention in future surveillance program. Network analysis revealed a correlation between different bla OXA variants and specific antibiotic resistance genes, such as bla OXA-1 and aac (6')-Ib-cr (95.79%), bla OXA-181 and qnrS1 (87.88%). The frequent detection of aminoglycosides-, carbapenems- and even colistin-related resistance genes in bla OXA -positive plasmids highlights their multidrug-resistant potential. Additionally, bla OXA -positive plasmids were further divided into eight clades, clade I-VIII. Each clade displayed specificity in replicon types and conjugative transfer elements. Different bla OXA variants were associated with specific plasmid lineages, such as bla OXA-1 and IncFII plasmids in clade II, and bla OXA-48 and IncL plasmids in clade I. Overall, our findings provide a comprehensive insight into bla OXA -positive plasmids in E. coli, highlighting the role of plasmids in bla OXA dissemination in E. coli., (© 2024. The Author(s), under exclusive licence to Springer Nature B.V.)

Bacterial resistance to β-lactams is mainly attributed to CTX-M-type extended-spectrum β-lactamases (ESBLs). However, the predominant sequence type (ST) of bla CTX-M -carrying Escherichia coli (bla CTX-M -Ec) in chickens, an important food animal, in China and its contribution to human β-lactam resistance are not investigated. In this study, approximately 1808 chicken-derived strains collected from 10 provinces from 2012 to 2020 were screened for bla CTX-M -Ec, and 222 bla CTX-M -Ec were identified. Antimicrobial susceptibility tests, whole genome sequencing and conjugation experiment were performed. All quality-controlled 136 chicken-derived bla CTX-M -Ec and 1193 human-derived bla CTX-M -Ec genomes were downloaded from NCBI and EnteroBase to comprehensively analyze the prevalence of bla CTX-M -Ec in China. bla CTX-M-55 (153/358, 42.7% in chicken isolates; 312/1193, 26.2% in human isolates) and bla CTX-M-14 (92/358, 25.7% in chicken isolates; 450/1193, 37.7% in human isolates) were dominant in bla CTX-M -Ec. The STs of bla CTX-M -Ec were diverse and scattered, with ST155 (n = 21) and ST152 (n = 120) being the most abundant in chicken- and human-derived isolates, respectively. Few examples indicated that chicken- and human-derived bla CTX-M -Ec have 10 or less core genome single nucleotide polymorphisms (cgSNPs). Genetic environment analysis indicated that ISEcp1, IS26 and IS903B were closely associated with bla CTX-M transfer. The almost identical pc61-55 and pM-64-1161 indicated the possibility of plasmid-mediated transmission of bla CTX-M between humans and chickens. Although the genomes of most bla CTX-M -Ec isolated from chickens and humans were quite different, the prevalence and genetic environment of bla CTX-M variants in both hosts were convergent. CTX-M-mediated resistance is more likely to spread through horizontal gene transmission than bacterial clones., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Enterobacteria that produce extended-spectrum β-lactamase (ESBL) such as Escherichia coli (E. coli) are common in our environment and known to cause serious health implications in humans and animals. β-lactam antibiotics such as penicillins, cephalosporins and monobactams are the most commonly used anti-bacterials in both humans and animals, however, Gram negative bacteria (such as E. coli) that produces extended-spectrum β-lactamases (ESBLs) have the ability to hydrolyze most β-lactams therefore making them resistant to β-lactam antibiotics. Recent extensive researches on the epidemiology and genetic characteristics of extended-spectrum β-lactamase (ESBL)-producing E. coli reported the existence of ESBL-producing E. coli in humans, companion animals and poultry. Therefore, this experiment was performed to investigate the prevalence and genetic characteristics of β-lactamase producing E. coli isolated from beef cattle farms in the Sichuan-Chongqing circle of China. Phenotypic confirmation of ESBL-producing E. coli was performed using the double disk synergy test. Polymerase Chain Reaction (PCR) was used to detect bla CTX-M , bla SHV and bla TEM gene codes, then after, isolates were divided into different phylogenetic groups and multi-locus sequence typing (MLST). The results showed that out of the 222 E. coli strains isolated from the beef cattle, 102 strains showed ESBL phenotypes. The PCR results showed that bla CTX-M was the predominant ESBL gene identified among the E. coli strains with 21 (9.5%) isolates having this gene, followed by bla SHV which was found in 18 (8.1%) isolates. The majority of these ESBL positive isolates were assigned to phylogroup A (19.8%) followed by phylogroup B1 (13.5%). In addition, from the MLST results on ESBL positive isolates (n = 30) we identified 19 STs, ST398 (ST398cplx) and ST7130 which were the prevalent population (20%). In conclusion, the high prevalence of CTX-M, and SHV in the study confirmed its association with E. coli infection; therefore, this calls for health concerns on ESBL-producing E. coli. As far as we know, this is the first comprehensive research report relating to ESBL-producing E. coli incidence in Chinese beef cattle.

Asparaginase (Asp) is one of the most important drugs for treating acute lymphoblastic leukemia (ALL). However, off-protocol Asp administration (OPAA) or hypersensitivity may disturb its pharmacokinetic profile. In this retrospective study, we sought to determine whether OPAA and hypersensitivity to Escherichia coli asparaginase (E coli Asp) impaired extramedullary relapse prevention in a pediatric ALL cohort treated according to SCMC-ALL-2005 protocol from 2005 to 2014 at the Shanghai Children's Medical Center (SCMC). In total, 676 patients were enrolled in this study, including 369 with OPAA and 60 exhibiting hypersensitivity to E coli Asp. At the end of the most recent follow-up, 58 patients had extramedullary relapse. The 5-year cumulative extramedullary relapse incidence in patients with OPAA was 11.01%, whereas that in patients without OPAA was 5.28% (P = .0036). Moreover, the 5-year cumulative extramedullary relapse incidence in patients that exhibited hypersensitivity to E coli Asp was 16.48%, whereas that in patients without hypersensitivity was 7.59% (P = .0195). Concerning the relapse site, OPAA not only increased central nervous system (CNS) relapse but testicular relapse as well. Based on Fine and Gray multivariate analysis, OPAA and hypersensitivity to Asp were independent risk factors for extramedullary relapse. In conclusion, to prevent extramedullary relapse of ALL, adequate duration to administrate Asp was more important than the total dosage, and more attention should be paid to Asp inadequate due to hypersensitivity., (© 2021 Union for International Cancer Control.)

Carbapenem-resistant Enterobacteriaceae (CRE) have been rapidly increasing among animals in many countries and have been a great threat to public health. Horse riding is becoming increasingly popular worldwide; however, reports of CRE producing NDM or KPC-2, two prevalent types of carbapenemases, from horses of equestrian club are extremely scarce and KPC-2-producing Klebsiella pneumoniae in animals is still rarely characterized. In this study, we identified four NDM-5-producing Escherichia coli isolates from horses in equestrian club in Qingdao, China, and one horse possessing NDM-5-producing E. coli also carried ST11 KPC-2-producing K. pneumoniae. Transferability of the plasmids producing carbapenemases was determined by conjugation, and the sequences of all CRE isolates and their transconjugants were then analysed by using whole-genome sequencing. bla NDM-5 was located on a highly similar ~ 46 kb self-transmissible IncX3 plasmid in all isolates, and these plasmids were nearly identical to IncX3 plasmids from different bacterial species of clinical patients in several countries, even including plasmid from clinical E. coli in Qingdao, China. The chromosome of the ST11 K. pneumoniae in this study was highly similar to ST11 clinical K. pneumoniae reported worldwide including the ST11 KPC-2-producing WCHKP020098 from Chengdu, China, and the bla KPC-2 -bearing plasmid in our study was a novel F33:A-:B- non-conjugative multidrug resistance plasmid. The presence of CRE from horses in equestrian club is alarming due to the potential for transmitting these isolates to humans during horse riding, and the prevalence of CRE among equestrian clubs in the whole country requires further monitoring., (© 2020 Blackwell Verlag GmbH.)

Père David's deer ( Elaphurus davidianus or milu) is an endangered species, and the prevalence of antimicrobial resistance (AMR) such as mcr-1 -positive strains among them has been unknown. In this study, we aimed to investigate the genomic characterizations of mcr-1 -positive strains and provide insight into the dissemination of AMR in nature reserve settings. Sixty-seven mcr-1 -positive Escherichia coli isolates from 97 fecal samples were identified by PCR and found resistant to colistin. The prevalence of β-lactam resistance was very high, and there were 64 mcr-1 -positive isolates containing β-lactamase genes. Transconjugants of 66 mcr-1 -positive isolates were acquired through conjugation experiments. PCR-based replicon typing (PBRT) showed that 44 strains harbored IncI2 mcr-1 -bearing plasmids, eight strains harbored IncX4 mcr-1 -carrying plasmids, and 14 strains harbored IncHI2 mcr-1 -positive plasmids. Notably, mcr-1 was located in the chromosome of LD27-1. Clonal dissemination and horizontal dissemination of mcr-1 by plasmids coexist. We first report the prevalence of plasmid-mediated mcr-1 in E. coli from Père David's deer in China. mcr-1 -bearing IncI2 plasmid was the most frequent plasmid type, and the first IncI2 plasmid harboring both bla CTX-M-132 and mcr-1 is characterized here. Our results support the implication of Père David's deer as a potential reservoir for MCR-1-producing E. coli IMPORTANCE still represents a threat to global public health. Père David's deer is a highly endangered species originating in China, and many deer are currently being raised in captivity for gradual reintroduction to the wild. If this species carries AMR bacteria, it will pose a potential threat to the environment. Therefore, research on the dissemination of mcr-1 gene is widely reported around the world and has been identified on various plasmids with different replicon types. Resistance to the last-line antibiotic colistin mediated by mcr-1 from Père David's deer is of great significance. This is the first study to investigate the microbiological and genomic surveillance of MCR-1-producing bacteria colonized among Père David's deer in China, and we uncovered a high prevalence of MCR-1-producing mcr-1 -positive E. coli from Père David's deer is of great significance. This is the first study to investigate the microbiological and genomic surveillance of MCR-1-producing bacteria colonized among Père David's deer in China, and we uncovered a high prevalence of MCR-1-producing E. coli The importance of constant surveillance for AMR bacteria in nature reserve settings is emphasized., (Copyright © 2020 Lu et al.)

Carbapenem resistance in Enterobacteriaceae members has become a major challenge, and the genetic environment of blaKPC, encoding Klebsiella pneumoniae carbapenemases, has not been fully clarified in China. In this study, we aimed to explore the genetic environment of blaKPC in 25 carbapenem-resistant E. coli isolates from hospitals in Hangzhou Province, China. Antimicrobial susceptibility against 22 common antimicrobial agents was tested. Polymerase chain reaction (PCR) analysis was performed for screening of the resistent genes, such as blaKPC, blaCTX-M, blaTEM, blaSHV, blaNDM, qnrA, qnrB, qnrS, aac(6')-Ib, armA and rmtB. The genetic environment of blaKPC were determinedin one isolate. blaKPC was detected by PCR in all the clinical E. coli isolates. There were no strains carrying blaNDM, qnrA and armA. The genetic environment of blaKPC showed that blaKPC dissemination is plasmid mediated and that it is located in the Tn3-Tn4401 transposon complex. Encoding of blaKPC-2 was responsible for carbapenem resistance in the 25 E. coli isolates. The genetic environment of blaKPC was characterized by the Tn3-Tn4401 complex. Our findings may provide a theoretical basis for clinical drug-resistance monitoring, anti-infection treatment and hospital infection control., (© FEMS 2020.)

Objectives: To characterize the colistin-resistant bacterial population in the gut and assess diversity of mcr-1 transmission within a single individual., Methods: Large numbers of isolates (>100 colonies/chicken cecum sample) were collected from nine randomly selected mcr-1-positive chickens in China and used for comprehensive microbiological, molecular and comparative genomics analyses., Results: Of 1273 colonies, 968 were mcr-1 positive (962 Escherichia coli, two Escherichia fergusonii, two Klebsiella pneumoniae and two Klebsiella quasipneumoniae). One to six colistin-resistant species and three to 10 E. coli pulsed-field gel electrophoresis (PFGE) clusters could be identified from each sample. Whole-genome sequencing (WGS) analysis of the representative E. coli strains revealed three to nine sequence types observed in a single chicken host. The mcr-1 genes are located in either chromosomes or plasmids of different types, including IncI2 (n=30), IncHI2 (n=14), IncX4 (n=4), p0111(n=2) and IncHI1(n=1). Strikingly, in single cecum samples, one to five Inc type plasmids harbouring mcr-1 could be identified. Great diversity was also observed for the same IncI2 plasmid within a single chicken host. In addition, up to eight genetic contexts of the mcr-1 gene occurred within a single chicken., Conclusions: There is extensive heterogeneity and flexibility of mcr-1 transmission in chicken gut due to bacterial species differences, distant clonal relatedness of isolates, many types and variations of mcr-positive plasmids, and the flexible genetic context of the mcr-1 gene. These compelling findings indicate that the gut is a 'melting pot' for active horizontal transfer of the mcr-1 gene., (Copyright © 2019 Elsevier B.V. and International Society of Chemotherapy. All rights reserved.)

The aim of this study was to investigate the occurrence and genomic characteristics of extended-spectrum-β-lactamase-producing Escherichia coli (ESBL-EC) in fennec fox imported from Sudan to China. We screened 88 fecal samples from fennec fox for ESBL-EC, using cefotaxime- and meropenem-supplemented selective medium. Antimicrobial susceptibility testing was performed by the agar dilution method except for colistin and tigecycline; for colistin and tigecycline, testing was conducted by the broth microdilution method. ESBL-EC bacteria were sequenced, and their genomes were characterized. Plasmid conjugation, S1 nuclease pulsed-field gel electrophoresis (PFGE), and Southern blotting were performed for a MCR-1-producing isolate. The genetic environment of mcr-1 and ESBL genes was also investigated. A total of 29 ESBL-EC bacteria were isolated from 88 fennec fox (32.9%), while no carbapenemase producers were found. The most prevalent genotypes were the bla CTX-M-55 and bla CTX-M-14 genes, followed by bla CTX-M-15 and bla CTX-M-64 were both located on a 65-kb IncI2 plasmid. This study reports for the first time the occurrence of ESBL-EC in fennec fox. The high prevalence of ESBL producers and the occurrence of MCR-1 producer in fennec fox imported into China from Sudan are unexpected. In addition, it clearly demonstrated that commensal mcr-1 gene was detected in isolate EcFF273. Conjugation analysis confirmed that the mcr-1 gene was transferable. S1 PFGE, Southern blotting, and whole-genome sequencing revealed that mcr-1 and bla CTX-M-64 were both located on a 65-kb IncI2 plasmid. This study reports for the first time the occurrence of ESBL-EC in fennec fox. The high prevalence of ESBL producers and the occurrence of MCR-1 producer in fennec fox imported into China from Sudan are unexpected. In addition, it clearly demonstrated that commensal E. coli strains can be reservoirs of bla CTX-M on wild animals. No data were available on the prevalence of antimicrobial resistance (AMR) among wild animals imported into China. This is the first study to investigate the microbiological and genomics surveillance investigation of ESBL colonization among fennec fox ( mcr-1 ) imported from Sudan to China, and we uncovered a high prevalence of ESBL-EC. Furthermore, the underlying mechanism of colistin resistance in an isolate that harbored Enterobacteriaceae family. IMPORTANCE The extended-spectrum-β-lactamase (ESBL)-producing members of the Enterobacteriaceae family are a global concern for both animal and human health. There is some information indicating a high prevalence of ESBL producers in food animals. Moreover, there have been an increasing number of reports on ESBL-producing strains resistant to the last-resort antibiotic colistin with the global dissemination of the plasmid-mediated mcr-1 gene, which is believed to have originated in animal breeding. However, little is known regarding the burden of ESBL-producing Enterobacteriaceae on wild animals. No data were available on the prevalence of antimicrobial resistance (AMR) among wild animals imported into China. This is the first study to investigate the microbiological and genomics surveillance investigation of ESBL colonization among fennec fox ( Vulpes zerda ) imported from Sudan to China, and we uncovered a high prevalence of ESBL-EC. Furthermore, the underlying mechanism of colistin resistance in an isolate that harbored mcr-1 was also investigated. Results of characterization and analysis of 29 ESBL-producing E. coli may have important implications on our understanding of the transmission dynamics of these bacteria. We emphasize the importance of improved multisectoral surveillance for colistin-resistant E. coli in this region., (Copyright © 2019 Feng et al.)

NDM-1-producing Enterobacteriaceae are multidrug-resistant bacteria, also called superbacteria, that have become important global human health threats in recent years. However, data about NDM-1-producing bacteria in animals are rare. In this study, an NDM-1-producing Escherichia coli isolate (designated E120413) was obtained from pigs in Henan province, China in 2012. The susceptibility of E. coli E120413 to antimicrobial agents was determined using Kirby-Bauer disk diffusion and micro-dilution methods. Susceptibility tests indicated that E. coli E120413 was resistant to almost all common antibiotics with high MIC values obtained for most antibiotics tested. E. coli E120413 was detected in the heart, liver, spleen, lung, kidney, brain, stomach, duodenum, mesenteric lymph nodes, and fecal samples of piglets in both cohabitation and experimental groups and the bacteria persisted for more than 2 weeks. However, no obvious clinical symptoms or serious pathological lesions were observed. This is the first investigation of NDM-1-producing E. coli isolate from pigs in China. Although no significant pathological lesions were observed, NDM-1-producing E. coli was found to be highly transmissible and to cause persistent infection in pigs., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Objects: The retrospective study aimed to determine the prevalence rate and antimicrobial susceptibility of extended-spectrum beta-lactamases (ESBLs)-producing Klebsiella pneumoniae and Escherichia coli in 2013-2017 at a single center in China., Methods: Klebsiella pneumoniae and Escherichia coli data were collected from the microbiological laboratory. VITEK 2 compact system was used for the identification and antimicrobial susceptibility testing. ESBL status was determined as per the Clinical and Laboratory Standards Institute (CLSI) protocols microdilution method., Results: Among a total of 2774 strains of Klebsiella pneumoniae and 2154 strains of Escherichia coli, 15.79% and 36.86% were found to be ESBL producers, respectively. In all patients infected by ESBLs-producing strains, those over 60 years accounted for the largest proportion. Infection by ESBLs-producing Klebsiella pneumoniae was more common in male, while that by ESBLs-producing Escherichia coli was more common in female. Urine and respiratory secretions were the most common sources of ESBLs-producing strains; however, ESBLs-producing strains from urine had been significantly declined. No carbapenem-resistant isolate was found, and all ESBLs-producing strains were resistant to ceftriaxone, aztreonam, and piperacillin. There were no differences in resistance rates between ESBLs-producing Escherichia coli and Klebsiella pneumoniae to ceftazidime and cefepime; however, ESBLs-producing Klebsiella pneumoniae showed higher resistance rates to piperacillin/tazobactam, amikacin, gentamicin, and co-trimoxazole compared with ESBLs-producing Escherichia coli., Conclusion: Different ESBLs-producing organisms have their own epidemiological characteristics, and the resistance of ESBLs-producing Klebsiella pneumoniae and Escherichia coli is different even to the same antibiotics. Therefore, it is important to continuously monitor the status of ESBLs-producing organisms, and an improved antimicrobial stewardship and infection control are much required.

Background: The emergence of carbapenem-resistant Enterobacteriaceae strains has posed a severe threat to public health in recent years. The mobile elements carrying the New Delhi metallo-β-lactqtamase (NDM) gene have been regarded as the major mechanism leading to the rapid increase of carbapenem-resistant Enterobacteriaceae strains isolated from clinics and animals., Results: We describe an NDM-5-producing Escherichia coli strain, ECCRA-119 (sequence type 156 [ST156]), isolated from a poultry farm in Zhejiang, China. ECCRA-119 is a multidrug-resistant (MDR) isolate that exhibited resistance to 27 antimicrobial compounds, including imipenem and meropenem, as detected by antimicrobial susceptibility testing (AST). The complete genome sequence of the ECCRA-119 isolate was also obtained using the PacBio RS II platform. Eleven acquired resistance genes were identified in the chromosome; four were detected in plasmid pTB201, while six were detected in plasmid pTB202. Importantly, the carbapenem-resistant gene bla NDM-5 was detected in the IncX3 plasmid pTB203. In addition, seven virulence genes and one metal-resistance gene were also detected. The results of conjugation experiments and the transfer regions identification indicated that the bla NDM-5 -harboring plasmid pTB203 could be transferred between E. coli strains., Conclusions: The results reflected the severe bacterial resistance in a poultry farm in Zhejiang province and increased our understanding of the presence and transmission of the bla NDM-5 gene.

Objectives: To investigate the prevalence and molecular characteristics of ESBL-producing Escherichia coli (ESBL-EC) in faecal samples from dairy cows in China., Methods: In total, 651 faecal samples were collected from cows distributed among the 10 provinces of China. Potential ESBL-EC isolates were cultured on selective medium. The clonal relatedness of the ESBL-EC isolates was assessed using MLST. WGS was conducted on 3 mcr-positive isolates and 14 additional randomly selected ESBL-EC isolates. Southern blot, S1-PFGE and conjugation were performed for mcr-1-carrying isolates. The genetic environment of the pMCR-JLF4 plasmid was also analysed., Results: In total, 290 unique ESBL-EC isolates were detected from 284 cows (43.6%). Alleles of CTX-M were observed in 94.1% (273/290) of all isolates. The most prevalent genotypes observed in this study were blaCTX-M-14, blaCTX-M-15, blaCTX-M-17 and blaCTX-M-55. Differentiation of 79 STs with a polyclonal structure was accomplished using MLST. Clonal complex 10 was the most prevalent major complex detected here. Furthermore, the mcr-1 gene was detected in three isolates. The complete sequence of the mcr-1-containing pMCR-JLF4 was determined. The plasmid was 66.7 kb in length, with a genetic structure of nikA-nikB-mcr-1-pap2. Conjugation analysis confirmed that the mcr-1 gene in pMCR-JLF4 was transferable without the assistance of the ISApl1 gene., Conclusions: The data presented here suggest high prevalence of ESBL-EC in Chinese cow farms. Furthermore, it was clearly demonstrated that commensal E. coli strains can be reservoirs of blaCTX-M genes, potentially contributing to the dissemination and transfer of the mcr-1 gene to pathogenic bacteria among cows.

Objectives: Although bla NDM-1 has been widely detected in various Enterobacteriaceae clinical isolates, multiple bla NDM-1 colonisations within the same patient remain rare. The aim of the study was to describe a patient with respiratory tract colonisation with NDM-1-producing Escherichia coli and Citrobacter freundii during hospitalisation in China., Methods: Two carbapenem-resistant isolates were analysed. Antimicrobial susceptibility testing, metallo-β-lactamase production, conjugation assay, plasmid analysis and molecular typing were performed., Results: The two clinical isolates carried the bla NDM-1 gene and showed resistance to carbapenems. S1 nuclease pulsed-field gel electrophoresis (S1-PFGE) revealed that E. coli NB753 harboured a plasmid of ca. 80kb, and C. freundii NB865 harboured three plasmids (ca. 70, 80 and 135kb). Southern blot and Inc replicon typing further demonstrated that both isolates carried the bla NDM-1 gene on a self-transferrable IncX3 plasmid. Moreover, the two NDM-producing plasmids were conjugative and the transconjugants showed increased resistance to carbapenems., Conclusion: An NDM-1-encoding plasmid harboured by various clinical isolates in a single patient is worrying considering that this plasmid may be widespread in our hospital. Furthermore, the threat of carbapenemase-producing bacterial epidemics should be closely monitored. However, a limitation of this study was the extremely small sample size., (Copyright © 2018 International Society for Chemotherapy of Infection and Cancer. Published by Elsevier Ltd. All rights reserved.)

Objectives: The aim of this study was to investigate the prevalence and characterisation of OXA-48-like-producing Enterobacteriaceae in Henan Province, China., Methods: A total of 339 carbapenem-non-susceptible clinical Enterobacteriaceae isolates [imipenem or meropenem minimum inhibitory concentration (MIC) of >1μg/mL] obtained between January 2013 and December 2016 were screened for the presence of the bla OXA-48-like gene by PCR and sequencing. Antimicrobial susceptibility to various antimicrobials agents was examined by MIC testing. Multilocus sequence typing (MLST) was performed for bacterial genotyping. The plasmid pEC21-OXA-181 was transformed into Escherichia coli DH5α by electroporation and was sequenced using an Illumina MiSeq platform, followed by subsequent annotation and genetic analysis., Results: Among the 339 carbapenem-non-susceptible Enterobacteriaceae isolates, only one (0.3%) E. coli strain EC21, belonging to ST410, was positive for bla OXA-181 , a variant of bla OXA-48 . This OXA-181-producing E. coli, recovered from a patient without a history of foreign travel, was obtained earlier than the first reported bla OXA-181 -positive E. coli (WCHEC14828) in Sichuan Province, China. Plasmid analysis revealed that bla OXA-181 together with the quinolone resistance gene qnrS1 was carried by an IS26-flanked composite transposon on a 51-kb IncX3-type plasmid., Conclusions: These findings indicate the emergence of OXA-181-producing E. coli in China earlier than previously thought. The bla OXA-181 gene is associated with the widely disseminated potentially endemic E. coli ST410 clone and is carried by an IncX3 plasmid, a common vehicle for spreading NDM-type carbapenemases, which might promote the further dissemination of bla OXA-181 among the Enterobacteriaceae in China., (Copyright © 2018 International Society for Chemotherapy of Infection and Cancer. Published by Elsevier Ltd. All rights reserved.)

Aim: To characterize extended-spectrum β-lactamase-producing Escherichia coli harboring the colistin resistance gene mcr-1 from human fecal samples collected in 2012 in a rural area of Shandong province, PR China., Materials & Methods: Whole-genome sequencing and antimicrobial susceptibility testing was performed on 25 mcr-1-positive isolates to determine carriage of antibiotic resistance and virulence genes, diversity and antibiotic resistance profiles., Results: The isolates were highly genetically diverse and carried a large variety of different antibiotic resistance genes. The multidrug-resistance rate was high (96%). Virulence genes associated with intestinal pathogenic E. coli were carried by 32% of the isolates., Conclusion: Further monitoring of the epidemiological situation is necessary to ensure a preparedness for potential emergence of novel, difficult-to-treat strains and awareness of available treatment options.

Background: Extended-spectrum β-lactamases (ESBLs)-producing Escherichia coli (E. coli) isolates in environment water become progressively a potential threat to public health, while the detailed information about the ESBL-producing E. coli isolates in the rivers and lakes in Northwest China is scarce. In the present study, it was aimed to characterize the ESBL-producing E. coli isolated from the surface waters in Northwest China., Results: A total of 2686 E. coli isolates were obtained from eleven rivers and lakes in Northwest China to screen for ESBL producers. Seventy-six (2.8%) isolates were classified as ESBL producers, and phylogenic groups D and A accounted for 59.2% of the ESBL producers. CTX-Ms were the predominant ESBLs genotype, and they were represented by seven bla CTX-M subtypes. bla CTX-M-14 was the most prevalent specific CTX-M gene, followed by bla CTX-M-9 , bla CTX-M-123 , bla CTX-M-15 , bla CTX-M-27, bla CTX-M-1 and bla CTX-M-65 . Moreover, 54 of the 76 ESBL producers carried at least one plasmid-mediated quinolone resistance (PMQR) gene, and aac(6')-Ib-cr was predominant. The overall occurrence of virulence factors ranged from 1.3% (eae) to 48.7% (traT). Thirty-seven sequence types (STs) were confirmed among the 76 ESBL producers, and the predominant was ST10, which was represented by 10 isolates; importantly, clone B2-ST131, associated with severe infections in humans and animals, was detected three times., Conclusion: The prevalence of ESBL-producing E. coli from the rivers and lakes in Northwest China was low (2.8%), and the extraintestinal pathogenic E. coli (ExPEC) pathotype was the most commonly detected on the basis of the virulence factor profiles. 76.3% of ESBL producers harbored more than one β-lactamase gene, and bla CTX-M-14 was the predominant genotype. Notably, one ST131 isolate from Gaogan Canal simultaneously harbored bla CTX-M-9 , bla CTX-M-15 , bla CTX-M-123 , bla KPC-2 , bla NDM-1 , bla OXA-2 as well as the PMQR genes qnrA, qnrS and aac(6')-Ib-cr.

The aim of this study was to identify risk factors for extended-spectrum β-lactamase (ESBL)-producing Escherichia coli (E coli) bloodstream infection (BSI) among carriers hospitalized between March 2011 and June 2016 at the ICU of the West China Hospital.The cases were patients with at least 1 episode of ESBL-producing E coli BSI within 1 week after a positive rectal swab. Controls were selected randomly 1:2 among ESBL-producing E coli rectal carriers who did not develop BSI.Among 19,429 ICU patients, 9015 (46.4%) had a positive rectal swab for ESBL-producing E coli. Of them, 42 (0.5%) were diagnosed with ESBL-producing E coli BSI. The in-hospital mortality was higher for the BSI patients compared with controls (19.1% vs. 6.0%, P = .031). In the past 72 hours, patients in case group were more likely to use penicillin (odds ratio [OR] = 12.076; 95% confidence interval [CI]: 1.397-104.251, P = .02), cephalosporin (OR = 6.900; 95% CI: 1.493-31.852, P = .01), and carbapenem (OR = 5.422; 95% CI: 1.228-23.907, P = .03) as compared to patients in control group. Also, when compared to patients in control group, patients in case group were likely to stay for a longer time in ICU before positive rectal swab test (OR = 1.041, 95% CI: 1.009-1.075, P = .01) and have higher maximum body temperature before positive rectal swab (OR = 8.014; 95% CI: 2.408-26.620, P = .001).Bacteremia owing to ESBL-producing E coli was associated with high antimicrobial exposure, hospital stay, and maximum body temperature.

Objectives: To evaluate the prevalence of clinical mcr-1-positive Escherichia coli and Klebsiella pneumoniae and characterize the antimicrobial resistance profiles of mcr-1-positive E. coli and mcr-1-negative E. coli in China., Methods: A total of 6264 clinical E. coli (n = 3854) and K. pneumoniae (n = 2410) were collected from hospitalized patients from 18 to 20 hospitals as part of the China Antimicrobial Resistance Surveillance Trial (CARST) between January 2007 and June 2016. PCR was used to screen for the mcr-1 gene among all isolates. Antibiotic susceptibility testing was performed using the broth microdilution method. mcr-1-positive pathogens were then characterized by MLST and minimum spanning tree analysis using the BURST algorithm for related STs., Results: We examined 39 (0.62%) clinical isolates of mcr-1-positive E. coli and K. pneumoniae over a 10 year period. Resistance to antimicrobial agents was significantly more severe in mcr-1-positive isolates than mcr-1-negative isolates, particularly piperacillin (P = 0.008), amikacin (P < 0.0001), nitrofurantoin (P < 0.004) and fosfomycin (P < 0.0001). Among mcr-1-carrying isolates, ESBL production was as high as 84.6% (33 of 39) and 92.3% (36 of 39) of them displayed an MDR phenotype. STs suggested ubiquitous dissemination of mcr-1-carrying pathogens., Conclusions: mcr-1-carrying E. coli and K. pneumoniae displayed a lower prevalence and abundant phylogenetic diversity in mainland China. mcr-1-positive E. coli showed significant differences in antimicrobial resistance profiles compared with mcr-1-negative E. coli strains, suggesting physicians may consider prescribing different antibiotics when faced with infections caused by mcr-1-positive pathogens.

Objectives: This study characterised a bla NDM-1 -producing Escherichia coli isolate from a companion dog., Methods: The E. coli strain was isolated from a surveillance study of carbapenem-resistant Gram-negative bacteria from companion animals in the Animal Teaching Hospital of China Agricultural University (Beijing, China) in 2013. Species identification was performed using an API 20E system and matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOF/MS). Minimum inhibitory concentrations (MICs) of various antimicrobial agents were determined by agar dilution. Multilocus sequence typing (MLST) was performed and various carbapenemase genes, including bla NDM , bla IMP , bla VIM , bla SME , bla IMI , bla KPC , bla GES , bla SPM , bla GIM , bla NMC , bla DIM , bla SIM , bla OXA-23 , bla OXA-24 , bla OXA-48 , bla OXA-51 and bla OXA-58 were screened by PCR. S1 nuclease pulsed-field gel electrophoresis (S1-PFGE) and Southern blotting as well as a modified random primer walking strategy were performed to analyse the location and genetic environment of bla NDM-1 ., Results: An E. coli isolate belonging to ST167 was found to be positive for the bla NDM-1 gene and exhibited resistance to β-lactams, tetracycline, gentamicin, fosfomycin and ciprofloxacin. The bla NDM-1 gene in this strain was located on an ca. 150-kb plasmid and the flanking sequences of the bla NDM-1 -carrying region (a common gene cluster, ΔISAba125-bla NDM-1 -ble-trpF-ΔdsbC) exhibited >99% identity to the corresponding regions of bla CTX-M-15 -harboring plasmids in nosocomial E. coli ST131 isolates., Conclusions: This is the first report of bla NDM-1 -producing ST167 E. coli in a companion dog. Companion animals harbouring carbapenemase-producing isolates are an upcoming public health threat and it is worthy paying attention to the emergence of carbapenem resistance in companion animals., (Copyright © 2017 International Society for Chemotherapy of Infection and Cancer. Published by Elsevier Ltd. All rights reserved.)

The emergence and dissemination of carbapenem-resistant Escherichia coli (E. coli) strains is a main risk for global public health, but little is known of carbapenemase producing E. coli in Henan, China. The study was undertaken to investigate the prevalence and mechanism of carbapenem-resistant E. coli strains in a hospital in Xinxiang, Henan, China, 2014. A total of 5 carbapenemase-producing E. coli strains were screened from 1014 isolates. We found that they were all resistant to meropenem and imipenem. Amikacin showed the best sensitivity, with gentamicin coming up next. The positive rate of bla NDM was 80% (4/5). The sequencing results showed that two isolates belonged to bla NDM-1 whereas other 2 isolates carried the bla NDM-5. Other carbapenemase genes including bla IMP , bla VIM , bla KPC and bla OXA-48 were not detected. The bla CTX-M-15, bla TEM-1, sul2, aad, and aac(6")-Ib-cr were also detected. MLST analysis showed that NDM-producing E. coli were sporadic. Conjugation test indicated bla NDM was the principal resistance mechanism of carbapenem-resistant E. coli in the hospital, Henan, China.NDM was the principal resistance mechanism of carbapenem-resistant E. coli in the hospital, Henan, China., (Copyright © 2017. Published by Elsevier Ltd.)

Extended-spectrum beta-lactamase-producing Escherichia coli (ESBL-EC) strains are emerging around the world as a source of resistance to β-lactam antibiotics such as ampicillin, cefotaxime, and ceftazidime. mcr-1 is a novel plasmid-mediated gene conferring resistance to colistin. The aim of this study was to investigate the prevalence of ESBL-EC mcr-1 of chicken origin in the different provinces of China during 2008-2014. Overall, 341 of 821 isolates were determined to be ESBL-EC strains, and the proportion of ESBL-positive strains almost doubled from 2008 to 2014. The findings of our study revealed regional differences, with significantly more ESBL-EC isolates from stockbreeding in concentrated poultry industry areas in Shandong than from the other four provinces. The ESBL type analysis showed that bla CTX-M was the most prevalent ESBL-encoding gene (92.7%). In total, twelve subtypes of CTX-M genes were detected, among which, bla CTX-M-55 (34.3%) and bla CTX-M-65 (17.9%) were the major identified genotypes. In addition, bla TEM and pAmpC genes were carried by 86.0% and 8.5% of isolates, respectively. In this study, we also observed 44 E. coli isolates with multiple ST types (ST46, ST1286, ST10, ST29, ST101, and ST354) carrying mcr-1, and the majority of mcr-1-carrying plasmids were IncI2. The whole-genome sequencing analysis indicated the co-existence of bla CTX-M and mcr-1 in ESBL-EC of both animal and human origin, and phylogenetic analysis further revealed their close relationship, especially several isolates sharing a small number of SNPs, which suggested the increasing trend of co-existence and transmission of ESBL and mcr-1 in both clinical medicine and veterinary medicine.

Six imported pigs originating from Guangdong, Henan, and Hunan provinces in China during October 2015 to February 2017 were cultured and found to be positive for meropenem-resistant Escherichia coli The samples yielded 9 E. coli isolates of diverse sequence types carrying bla NDM-5 on IncX3 (8 isolates from 5 farms) or IncFII (1 isolate from 1 farm) plasmids. The mcr-1 gene was coharbored by 4 isolates. The IncX3 plasmids (∼46 kb) carrying bla NDM-5 were identical or nearly identical to each other., (Copyright © 2018 American Society for Microbiology.)

Fosfomycin in combination with various antibiotics represents an excellent clinically efficacious regimen for the treatment of urinary tract infections (UTIs) caused by extended-spectrum β-lactamase (ESBL)-producing Escherichia coli. Underlying mechanisms of fosfomycin resistance remain largely uncharacterised. To investigate the antibacterial efficacy of fosfomycin against ESBL-producing E. coli, 356 non-repetitive ESBL-producing E. coli clinical isolates were collected from urine specimens from patients with UTI in Wenzhou, China, from January 2011 to December 2015. Antimicrobial sensitivity testing indicated that 6.7% (24/356) of the ESBL-producing E. coli strains were resistant to fosfomycin. The fosA3 gene encoding a fosfomycin-modifying enzyme was detected in 20 isolates by PCR and sequencing, alone or in combination with other ESBL determinants. Conjugation experiments and Southern blotting demonstrated that 70% (14/20) of the fosA3-positive isolates possessed transferable plasmids (ca. 54.2 kb) co-harbouring the ESBL resistance gene bla CTX-M and the fosfomycin resistance gene fosA3. Among the four fosfomycin-resistant fosA3-negative E. coli isolates, three contained amino acid substitutions (Ile28Asn and Phe30Leu in MurA and Leu297Phe in GlpT). The results indicate that presence of the fosA3 gene is the primary mechanism of fosfomycin resistance in ESBL-producing E. coli isolates in Wenzhou, China. In addition, a plasmid (ca. 54.2 kb) co-harbouring fosA3 and bla CTX-M genes is horizontally transferable. Furthermore, a low degree of homology in the fosfomycin-resistant E. coli was confirmed using multilocus sequence typing (MLST), suggesting that there is no obvious phenomenon of clonal dissemination., (Copyright © 2017 Elsevier B.V. and International Society of Chemotherapy. All rights reserved.)

Background & Aims: Little is known about aetiology and morbidity and clinical characteristics of pyogenic liver abscess caused by extended-spectrum beta-lactamase-producing Enterobacteriaceae., Methods: An analysis between pyogenic liver abscess patients caused by extended-spectrum beta-lactamase-producing Enterobacteriaceae isolates and those caused by non-extended-spectrum beta-lactamase-producing Enterobacteriaceae was performed., Results: Among 817 pyogenic liver abscess patients, there were 176 patients (21.5%) with pyogenic liver abscess of biliary origin, and 67 pyogenic liver abscess patients (8.2%) caused by extended-spectrum beta-lactamase-producing Enterobacteriaceae isolates (mainly Escherichia coli and Klebsiella pneumoniae). Of 176 pyogenic liver abscess patients related to biliary disorders, there were 48 pyogenic liver abscess patients (27.3%) caused by extended-spectrum beta-lactamase-producing Enterobacteriaceae. Within 67 pyogenic liver abscess patients caused by Enterobacteriaceae expressing extended-spectrum beta-lactamases, the occurrences of 48 pyogenic liver abscess patients (71.6%) were associated with biliary disorders. When compared with pyogenic liver abscess patients caused by non-extended-spectrum beta-lactamase-producing Enterobacteriaceae, there were significantly greater incidences of polymicrobial infections, bacteremia, pulmonary infection, recurrence and death in pyogenic liver abscess patients caused by extended-spectrum beta-lactamase-producing Enterobacteriaceae. Carbapenems remain mainstay drugs against extended-spectrum beta-lactamase-producing E. coli and K. pneumoniae. Independent risk factors for occurrence of pyogenic liver abscess caused by extended-spectrum beta-lactamase-producing Enterobacteriaceae were biliary disorders including extra- and intrahepatic cholangiolithiasis and an abnormal bilioenteric communication between bile and gut, a treatment history of malignancy such as operation and chemotherapy, pulmonary infection, and diabetes mellitus., Conclusions: Pyogenic liver abscess caused by extended-spectrum beta-lactamase-producing Enterobacteriaceae isolates mainly occurs in patients with biliary disorders or with a treatment history of malignancy. The mainstay of treatment remains carbapenems in combination with adequate aspiration or drainage., (© 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Since its initial discovery in China in 2015, the plasmid-mediated colistin resistance gene mcr-1 has been reported in Escherichia coli isolated from clinical samples, animals and meat worldwide. In this study, 706 extended-spectrum β-lactamase (ESBL)-producing E. coli from 411 persons were detected in a collection of faecal samples from 1000 rural residents in three counties in Shandong Province, China. These isolates were screened for mcr-1 and phenotypic colistin resistance. The gene was found in 3.5% of the isolates (from 4.9% of persons) from all three counties. All isolates with phenotypic colistin resistance carried mcr-1. These data indicate that commensal carriage of ESBL-producing E. coli with mcr-1 among persons in rural China was already present in 2012 and that mcr-1 was the most important colistin resistance mechanism. Interventions are necessary to minimise further dissemination of mcr-1, which would limit the future usefulness of colistin as a last-resort antibiotic., (Copyright © 2017 Elsevier B.V. and International Society of Chemotherapy. All rights reserved.)

Introduction: Animals are considered to be reservoirs of extended-spectrum beta-lactamase (ESBL)-producing bacteria, but few epidemiological data on ESBL-producing Escherichia coli urinary tract isolates in pet dogs are available in China., Methodology: This study was conducted to describe the prevalence and characterization of ESBL producers among E. coli urinary tract isolates from pet dogs in Tai'an, China., Results: A total of 118 E. coli were obtained from urinary samples of 80 companion dogs suffering from acute or chronic cystitis, of which three isolates from different dogs were ESBL producers. One isolate from dog A was of phylogroup A/ST410/CTX-M-15/TEM-1; one from dog B was of phylogroup B1/ST533/CTX-M-15/TEM-1; one from dog C was of phylogroup D/ST648/CTX-M-15. All ESBL producers were resistant to ampicillin, cephalexin, cefalotin, cefpodoxime, ceftiofur, enrofloxacin, marbofloxacin, and trimethoprim/sulfamethoxazole, but were susceptible to imipenem and amoxicillin/clavulanic acid. E. coli of ST533 carrying blaCTX-M-15 were first detected in pet dogs in China., Conclusions: Collectively, the findings could expand our knowledge about the prevalence and characterization of ESBL-producing E. coli urinary tract isolates in pet dogs in China.

Fosfomycin has become a therapeutic option in urinary tract infections. We identified 57 fosfomycin-resistant Escherichia coli from 465 urine-derived extended-spectrum β-lactamase (ESBL)-producing isolates from a Chinese hospital during 2010-2014. Of the 57 fosfomycin-resistant isolates, 51 (89·5%) carried fosA3, and one carried fosA1. Divergent pulsed-field gel electrophoresis profiles and multi-locus sequence typing results revealed high clonal diversity in the fosA3-positive isolates. Conjugation experiments showed that the fosA3 genes from 50 isolates were transferable, with IncFII or IncI1 being the most prevalent types of plasmids. The high prevalence of fosA3 was closely associated with that of bla CTX-M. Horizontal transfer, rather than clonal expansion, might play a central role in dissemination. Such strains may constitute an important reservoir of fosA3 and bla CTX-M, which may well be readily disseminated to other potential human pathogens. Since most ESBL-producing E. coli have acquired resistance to fluoroquinolones worldwide, further spread of fosA3 in such E. coli isolates should be monitored closely.

Escherichia coli (E. coli) commonly reside in human intestine and most E. coli strains are harmless, but some serotypes cause serious food poisoning. This study identified and molecularly characterized bla SHV genes from 490 E. coli strains with multi-drug resistance in a hospital population. PCR and molecular cloning and southern blot were performed to assess functions and localizations of this resistant E. coli gene and the pulsed-field gel electrophoresis (PFGE) was utilized to demonstrate the clonal relatedness of the positive E. coli strains. The data showed that 4 of these 490 E. coli strains (4/499, 0.8%) carried bla SHV genes that included EC D2485 (bla SHV-5 ), EC D2487 (bla SHV-5 ), EC D2684 (bla SHV-11 ) and EC D2616 (bla SHV-195, a novel bla SHV ). Analysis of bla SHV open-reading frame showed that bla SHV-5 had a high hydrolysis activity to the broad-spectrum penicillin (ampicillin or piperacillin), ceftazidime, ceftriaxone, cefotaxime and aztreonam. bla SHV-195 and bla SHV-11 had similar resistant characteristics with high hydrolysis activities to ampicillin and piperacillin, but low activities to cephalosporins. Moreover, the two bla SHV-5 genes were located on a transferable plasmid (23kb), whereas the other two bla SHV variants (bla SHV-11 and bla SHV-195 ) seemed to be located in the chromosomal material. Both EC D2485 and EC D2487 clones isolated in 2010 had the same DNA finger printing profile and they might be the siblings of clonal dissemination. The data from the current study suggest that the novel bla SHV and clonal dissemination may be developed, although bla SHV genes were infrequently identified in this hospital population. The results of the work demonstrate the necessity for molecular surveillance in tracking bla SHV -producing strains in large teaching hospital settings and emphasize the need for epidemiological monitoring., (Copyright © 2016 Elsevier B.V. All rights reserved.)

Objectives: The prevalence and dissemination of diverse NDM-producing bacteria in China was investigated., Methods: We collected 1,162 isolates from 8 cities during December 2013∼May 2015 in China. The NDM-positive strains as well as the NDM genotypes in these sample were detected via Vitek 2 compact system (bioMérieux, France), 16S rRNA gene sequencing, PCR and an S1- pulsed-field gel electrophoresis assay and Southern blot hybridization. The horizontal-transfer capability of the bla NDM gene was assessed by filter mating by using a standard E.coli J53 azide-resistant strain as the recipient., Results: Three genotypes (NDM-1, NDM-3 and NDM-5) of NDM-producing bacteria were identified, among which the NDM-1-positive isolates were the most frequent one. For the first time, we found NDM-5-produing S.typhimurium and NDM-3-produing E.coli in China. We also found that the NDM-positive (especially NDM-3 and NDM-5) strains were completely resistant to nearly all of the antimicrobial drugs utilized and bla NDM was mostly located on diverse plasmids with sizes ranging from 30 to 670kb., Conclusion: Various species of bacteria especially the enteric pathogens with diverse NDM genotypes had spread in China. Hence, an ongoing surveillance of their dissemination is essential to prevent and control the spread of these organisms., (Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Background: Recently, the emergence of multidrug-resistant organisms such as extended-spectrum β-lactamase (ESBL)-producing Enterobacteriaceae has raised considerable concern regarding the appropriate treatment of intra-abdominal infections (IAIs). In this study, we investigated the molecular characteristics of ESBL among clinical isolates of Escherichia coli and Klebsiella pneumoniae causing IAIs and their pattern of antimicrobial resistance, which can provide useful information about the epidemiology and risk factors associated with these infections., Materials and Methods: One hundred sixty-seven E.coli and 47 K. pneumoniae ESBL-producing strains causing IAIs were collected from 9 hospitals in China, during 2012 and 2013. The antimicrobial susceptibility profile of these strains was determined. Polymerase chain reaction and sequencing were performed to identify genes for β-lactamase (blaTEM, blaSHV, blaOXA-1-like, and blaCTX-M). The isolates were also analyzed by pulsed-field gel electrophoresis (PFGE)., Results: In 167 ESBL-producing E. coli strains, 104 strains (62.3%) were positive for CTX-M, and 9 strains (5.39%) were positive for SHV. Among the 47 K. pneumoniae strains, 35 strains (74.5%) were positive for SHV-2a, 12 strains (25.5%) were positive for CTX-M. No TEM-type and OXA-1-like strain was detected among all the ESBL-producing strains. Regarding the CTX-M-positive E. coli and K. pneumoniae strains, CTX-M-15 was the most common genotype in E. coli and K. pneumoniae strains, accounting for 28.7% and 17.0%, respectively, followed by CTX-M-55 accounting for 16.2% and 2.13%, respectively; the remaining genotypes included CTX-M-123 and CTX-M-82. PFGE showed that E.coli and K. pneumoniae ESBL-producing strains causing IAIs were diverse and that emerging resistance may not be due to the dissemination of national clones., Conclusion: The present study revealed that in ESBL-producing strains causing IAIs in China, the most common genotype for E.coli was CTX-M-15 and for K. pneumoniae was SHV-2a. However, there was a wide diversity of strains causing IAIs among the ESBL-producing E. coli and K. pneumoniae., (Copyright © 2016 Elsevier Inc. All rights reserved.)

Objectives: Community-onset bloodstream infections (COBSIs) caused by ESBL-producing Escherichia coli (ESBL-EC) and ESBL-producing Klebsiella pneumoniae (ESBL-KP) are increasing globally. This study aimed to investigate the epidemiology and risk factors of ESBL-EC and ESBL-KP in COBSIs in China., Methods: A prospective, multicentre study was performed in 28 tertiary hospitals from September 2013 to November 2014. All isolates and ESBLs were microbiologically characterized. A statistical analysis of risk factors was performed using binary logistic regression. The trial was registered with ClinicalTrials.gov (NCT01961206)., Results: A total of 919 consecutive episodes of COBSIs were reported and 640 E. coli and 279 K. pneumoniae isolates (non-duplicate) were collected. According to the criteria, 662 (72.0%) cases were classified as having community-acquired bloodstream infections, while the remaining 257 (28.0%) were classified as having healthcare-associated bloodstream infections. The proportions of ESBL producers were 55.5% (355/640) among E. coli isolates and 16.5% (46/279) among K. pneumoniae isolates, respectively. Healthcare-associated infections, obstructive urinary tract disease, previous surgical history and use of a cephalosporin antibiotic within 3 months were independent predictors of COBSIs caused by ESBL-EC. Heart failure was the only independent risk factor for COBSIs due to ESBL-KP. Age was not independently associated with infections caused by ESBL producers. CTX-M-14 was the most common ESBL genotype and was widespread throughout the country., Conclusions: ESBL producers are highly prevalent in COBSIs in China, especially among cases caused by E. coli. For these resistant pathogens, clinicians should consider adequate empirical therapy, and different risk factors for prediction should be used in this country., (© The Author 2016. Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.)

Objectives: To characterize extended-spectrum β-lactamase (ESBL)-producing Escherichia coli isolates from the community, determine their antibiotic sensitivity profiles and quinolone resistance mechanisms, and identify any horizontal transfer of ESBL genes., Methods: One thousand seven hundred thirty-two stool samples were collected from healthy individuals in 6 communities and 2 physical examination centers in Shanghai, China. ESBL-producing E. coli was screened and confirmed by confirmatory test and E. coli-identifying agars. PCR was used to amplify ESBL-encoding genes bla CTX-M , bla TEM , bla SHV genes, and quinolone resistance-relating genes gyrA, gryB, parC, parE, qnrS, aac (6')-Ib-cr, oqxA, and oqxB, followed by sequencing. Antimicrobial susceptibility tests and conjugation assays were also performed., Results: Overall, 528 isolates were identified as ESBL-producing E. coli, and all were positive for bla CTX-M . CTX-M-14 was found most frequently (48.9%). S83L±D87N in gyrA and S80I in parC were the most common topoisomerase mutations. Plasmid-mediated quinolone resistance (PMQR) determinants were also detected, including qnrS1 (11.7%), qnrS2 (3.7%), aac (6')-Ib-cr(12.8%), oqxA(8.5%), and oqxB(11.0%). The rate of multidrug resistance was very high (92.2%). ESBL genes transferred successfully in 39.4% isolates., Conclusions: There is a high prevalence of fecal carriage of ESBL-producing E. coli in the community in Shanghai, with high-level quinolone resistance and CTX-M-14 being the predominant CTX-M enzyme., (Copyright © 2016. Published by Elsevier Inc.)

New Delhi metallo-β-lactamase (NDM)-producing Enterobacteriaceae (NPE) shows prevalence in China. Little is known about the mechanisms related to the spread of NPE. Recently, a total of 51 non-duplicated NPE isolates were collected from a tertiary-care hospital in China and analysed for genetic relatedness by PFGE, antimicrobial susceptibility by Etest and sequence type by multilocus sequence typing. S1-PFGE and Southern blot analysis or PCR amplification were used for plasmid profiling. Between 2014 and 2015, 22 Escherichia coli, 10 Klebsiella pneumoniae, 9 Enterobacter cloacae, 2 Enterobacter aerogenes, 3 Providencia rettgeri, 1 Klebsiella oxytoca, 1 Proteus mirabilis, 1 Citrobacter freundii, 1 Citrobacterwerkmanii and 1 Raoultella planticola were identified as NPE. Results of PFGE and multilocus sequence typing showed that most strains were genetically unrelated. Among the 45 blaNDM-carrying plasmids, there were 25 IncX3 plasmids with a size of about 30 to 50 kb, one 100 kb IncX3 plasmid, 11 IncA/C plasmids with a size range from 70 to 300 kb, six 90 to 120 kb IncB/O plasmids, one IncN plasmid with a size of 100 kb and one 140 kb IncFrep plasmid. An NDM-1-producing isolate of C. werkmanii was identified, which had not been reported previously. An Escherichia coli strain was found acquiring a blaNDM-1-carrying IncFrep plasmid in vivo during infection. In conclusion, an NDM-1-producing isolate of C. werkmanii was identified. An Escherichia coli strain acquired a blaNDM-1-carrying plasmid in vivo. IncX3 and IncA/C plasmids with various sizes might have emerged as the main platforms mediating the spread of the blaNDM genes in China.

Since the first report of bla NDM-1 , 16 bla NDM variants have been identified among Gram-negative bacteria worldwide. Recently, a novel bla NDM variant, bla ST5138 clinical isolate associated with hospital-acquired urinary tract infection from China. NDM-13 , was identified in the chromosome of an ST101 Escherichia coli isolate from Nepal. Here we first reported plasmid-mediated bla NDM-13 in a carbapenem-resistant E. coli -harboring vector circulating in China. In accordance with the structure of pNDM-HN380, pNDM13-DC33 consists of a 33-kb backbone encoding plasmid replication ( bla NDM-13 and bla SHV-12 coexisted on the a ~54 Kb self-transferable plasmid. Compared with NDM-1, NDM-13, NDM-3, and NDM-4 had two amino acid substitutions (D95N and M154L), one amino acid substitution (D95N) and one amino acid substitutions (M154L), respectively. Complete plasmid sequencing showed that bla NDM-13 -harboring plasmid (pNDM13-DC33) was highly similar to the bla NDM-1 -harboring IncX3 plasmid pNDM-HN380, a common bla NDM -harboring vector circulating in China. In accordance with the structure of pNDM-HN380, pNDM13-DC33 consists of a 33-kb backbone encoding plasmid replication ( repB ), stability partitioning, and transfer ( tra, trb , and pil ) functions, and a 21-kb antimicrobial resistance region with high GC content between umuD and mpr genes. In conclusion, the present study is the first report of a plasmid-encoded bla NDM-13 and the complete sequence of a bla NDM-13 -harboring plasmid (pNDM13-DC33). bla NDM-13 maybe originate from bla NDM-1 located on a pNDM-HN380-like plasmid by sequential mutations.

This study reports the increasing prevalence of clinical Escherichia coli of sequence type 167 (ST167) carrying both blaNDM-1 and blaNDM-5 on the conjugative IncX3 plasmid in various parts of China. Close surveillance is needed to monitor the future dissemination of ST167 strains that harbor blaNDM-5 or other blaNDM-like genes., (Copyright © 2016, American Society for Microbiology. All Rights Reserved.)

Objective: Aerobic vaginitis (AV) is a recently proposed term for genital tract infection in women. The diagnosis of AV is mainly based on descriptive diagnostic criteria proposed by Donders and co-workers. The objective of this study is to report AV prevalence in southwest China using an objective assay kit based on preformed enzymes and also to determine its characteristics., Materials and Methods: A total of 1948 outpatients were enrolled and tested by a commercial diagnostic kit to investigate the AV prevalence and characteristics in southwestern China. The study mainly examined the vaginal ecosystem, age distribution, Lactobacillus amount, and changes in pH. Differences within groups were analyzed by Wilcoxon two-sample test., Results: The AV detection rate is 15.40%. The AV patients were usually seen in the sexually active age group of 20-30 years, followed by those in the age group of 30-40 years. The vaginal ecosystems of all the patients studied were absolutely abnormal, and diagnosed to have a combined infection [aerobic vaginitis (AV) + bacterial vaginitis (BV) 61.33%; 184/300]. Aerobic bacteria, especially Staphylococcus aureus and Escherichia coli, were predominantly found in the vaginal samples of these women., Conclusion: AV is a common type of genital infection in southwestern China and is characterized by sexually active age and combined infection predominated by the AV and BV type., (Copyright © 2016. Published by Elsevier B.V.)

Escherichia coli (E. coli) is one of the most frequent and lethal causes of bloodstream infections (BSIs). We carried out a retrospective multicenter study on antimicrobial resistance and phylogenetic background of clinical E. coli isolates recovered from bloodstream in three hospitals in Shanghai. E. coli isolates causing BSIs were consecutively collected between Sept 2013 and Sept 2014. Ninety isolates randomly selected (30 from each hospital) were enrolled in the study. Antimicrobial susceptibility testing was performed by disk diffusion. PCR was used to detect antimicrobial resistance genes coding for β-lactamases (TEM, CTX-M, OXA, etc.), carbapenemases (IMP, VIM, KPC, NDM-1 and OXA-48), and phylogenetic groups. eBURST was applied for analysis of multi-locus sequence typing (MLST). The resistance rates for penicillins, second-generation cephalosporins, fluoroquinolone and tetracyclines were high (>60%). Sixty-one of the 90 (67.8%) strains enrolled produced ESBLs and no carbapenemases were found. Molecular analysis showed that CTX-M-15 (25/61), CTX-M-14 (18/61) and CTX-M-55 (9/61) were the most common ESBLs. Phylogenetic group B2 predominated (43.3%) and exhibited the highest rates of ESBLs production. ST131 (20/90) was the most common sequence type and almost assigned to phylogenetic group B2 (19/20). The following sequence types were ST405 (8/90) and ST69 (5/90). Among 61 ESBL-producers isolates, B2 (26, 42.6%) and ST131 (18, 29.5%) were also the most common phylogenetic group and sequence type. Genetic diversity showed no evidence suggesting a spread of these antimicrobial resistant isolates in the three hospitals. In order to provide more comprehensive and reliable epidemiological information for preventing further dissemination, well-designed and continuous surveillance with more hospitals participating was important.

We report the first occurrence of New Delhi metallo-β-lactamase 5 (NDM-5) in carbapenem-resistant Escherichia coli isolated from blood cultures of three leukemia patients in northern China. These patients had at some time been hospitalized in the hematology department of the same hospital. All isolates were ST167 with identical pulsed-field gel electrophoresis patterns, suggesting a likely hospital transmission., (Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.)

The present study was conducted to gain insights into the occurrence and characteristics of extended-spectrum beta-lactamase- (ESBL-) producing Escherichia coli ( E. coli ) from drinking well water in the rural area of Laiwu, China, and to explore the role of the nearby pit latrine as a contamination source. ESBL-producing E. coli from wells were compared with isolates from pit latrines in the vicinity. The results showed that ESBL-producing E. coli isolates, with the same antibiotic resistance profiles, ESBL genes, phylogenetic group, plasmid replicon types, and enterobacterial repetitive intergenic consensus-polymerase chain reaction (ERIC-PCR) fingerprints, were isolated from well water and the nearby pit latrine in the same courtyard. Therefore, ESBL-producing E. coli in the pit latrine may be a likely contributor to the presence of ESBL-producing E. coli in rural well water., Competing Interests: The authors declare that they have no competing interests regarding the publication of this paper.

Unlabelled: The purpose of this study was to investigate the prevalence and characterization of extended-spectrum beta-lactamases (ESBL)-producing Enterobacteriaceae from spring waters in Mountain Tai of China. ESBL-producing Enterobacteriaceae were found in four out of 50 sampled spring waters (4/50, 8·0%) and a total of 16 non-duplicate ESBL-producing Enterobacteriaceae were obtained, including 13 Escherichia coli (E. coli) and three Klebsiella pneumoniae (Kl. pneumoniae). All 16 nonduplicate ESBL-producing Enterobacteriaceae isolates harboured genes encoding CTX-M ESBLs, among which six expressed CTX-M-15, five produced CTX-M-14, three produced CTX-M-55 and two expressed CTX-M-27. Four multilocus sequence types (ST) were found and ST131 was the dominant type (8/16, 50·0%). Taken together, the contamination of ESBL-producing Enterobacteriaceae were present in spring waters of Mountain Tai., Significance and Impact of the Study: The results indicated that spring waters could become a reservoir of antibiotic resistant bacteria and contribute to the spread of antimicrobial-resistant bacteria via drinking water or food chain. In addition, wastewater discharge of restaurants or hotels may be an important contribution source of antibiotic resistant bacteria in spring waters., (© 2015 The Society for Applied Microbiology.)

Developing reagents with high affinity and specificity are critical to detect the environmental hormones or toxicants. Ribosome display technology has been widely used in functional protein or peptide screening and in directed evolution of protein molecules in vitro. In this study, single-chain variable fragments (scFvs) against bisphenol A (BPA) were selected from a library constructed from splenocytes of non-immunized mice. After five rounds of selection, the selected scFvs bound to BPA with high affinity. Indirect competitive enzyme-linked immunosorbent assay (ELISA) was introduced to screen the antibody affinity and specificity to BPA. The equilibrium dissociation constants (KDS) of one clone was 1.76μM as determined by surface plasmon resonance (SPR). This study indicated that ribosome display can isolate binders to small molecules from a non-immunized naive library without any in vivo steps and can generate recombinant antibodies efficiently and rapidly. In addition, this study provides a methodological framework for detection of small molecules using recombinant antibodies., (Copyright © 2013 Elsevier Inc. All rights reserved.)