April 21, 2020  |  

An Outbreak of KPC-Producing Klebsiella pneumoniae Linked with an Index Case of Community-Acquired KPC-Producing Isolate: Epidemiological Investigation and Whole Genome Sequencing Analysis.

Aims: A hospital outbreak of Klebsiella pneumoniae carbapenemase (KPC)-producing Klebsiella pneumoniae (KPN) linked with an index case of community-acquired infection occurred in an urban tertiary care hospital in Seoul, South Korea. Therefore, we performed an outbreak investigation and whole genome sequencing (WGS) analysis to trace the outbreak and investigate the molecular characteristics of the isolates. Results: From October 2014 to January 2015, we identified a cluster of three patients in the neurosurgery ward with sputum cultures positive for carbapenem-resistant KPN. An epidemiological investigation, including pulsed-field gel electrophoresis analysis was performed to trace the origins of this outbreak. The index patient’s infection was community acquired. Active surveillance cultures using perirectal swabbing from exposed patients, identified one additional patient with KPC-producing KPN colonization. WGS analyses using PacBio RSII instruments were performed for four linked isolates. WGS revealed a genetic linkage of the four isolates belonging to the same sequence type (ST307). All KPN isolates harbored conjugative resistance plasmids, which has blaKPC-2 carbapenemase genes contained within the Tn4401 “a” isoform and other resistance genes. However, WGS showed only three isolates among four KPC-producing KPN were originated from a common origin. Conclusions: This report demonstrates the challenge that KPC-2-producing KPN with the conjugative resistance plasmid may spread not only in hospitals but also in community, and WGS can help to accurately characterize the outbreak.


April 21, 2020  |  

Plasmid-encoded tet(X) genes that confer high-level tigecycline resistance in Escherichia coli.

Tigecycline is one of the last-resort antibiotics to treat complicated infections caused by both multidrug-resistant Gram-negative and Gram-positive bacteria1. Tigecycline resistance has sporadically occurred in recent years, primarily due to chromosome-encoding mechanisms, such as overexpression of efflux pumps and ribosome protection2,3. Here, we report the emergence of the plasmid-mediated mobile tigecycline resistance mechanism Tet(X4) in Escherichia coli isolates from China, which is capable of degrading all tetracyclines, including tigecycline and the US FDA newly approved eravacycline. The tet(X4)-harbouring IncQ1 plasmid is highly transferable, and can be successfully mobilized and stabilized in recipient clinical and laboratory strains of Enterobacteriaceae bacteria. It is noteworthy that tet(X4)-positive E.?coli strains, including isolates co-harbouring mcr-1, have been widely detected in pigs, chickens, soil and dust samples in China. In vivo murine models demonstrated that the presence of Tet(X4) led to tigecycline treatment failure. Consequently, the emergence of plasmid-mediated Tet(X4) challenges the clinical efficacy of the entire family of tetracycline antibiotics. Importantly, our study raises concern that the plasmid-mediated tigecycline resistance may further spread into various ecological niches and into clinical high-risk pathogens. Collective efforts are in urgent need to preserve the potency of these essential antibiotics.


April 21, 2020  |  

Integrating multiple genomic technologies to investigate an outbreak of carbapenemase-producing Enterobacter hormaechei

Carbapenem-resistant Enterobacteriaceae (CRE) represent one of the most urgent threats to human health posed by antibiotic resistant bacteria. Enterobacter hormaechei and other members of the Enterobacter cloacae complex are the most commonly encountered Enterobacter spp. within clinical settings, responsible for numerous outbreaks and ultimately poorer patient outcomes. Here we applied three complementary whole genome sequencing (WGS) technologies to characterise a hospital cluster of blaIMP-4 carbapenemase-producing E. hormaechei.In response to a suspected CRE outbreak in 2015 within an Intensive Care Unit (ICU)/Burns Unit in a Brisbane tertiary referral hospital we used Illumina sequencing to determine that all outbreak isolates were sequence type (ST)90 and near-identical at the core genome level. Comparison to publicly available data unequivocally linked all 10 isolates to a 2013 isolate from the same ward, confirming the hospital environment as the most likely original source of infection in the 2015 cases. No clonal relationship was found to IMP-4-producing isolates identified from other local hospitals. However, using Pacific Biosciences long-read sequencing we were able to resolve the complete context of the blaIMP-4 gene, which was found to be on a large IncHI2 plasmid carried by all IMP-4-producing isolates. Continued surveillance of the hospital environment was carried out using Oxford Nanopore long-read sequencing, which was able to rapidly resolve the true relationship of subsequent isolates to the initial outbreak. Shotgun metagenomic sequencing of environmental samples also found evidence of ST90 E. hormaechei and the IncHI2 plasmid within the hospital plumbing.Overall, our strategic application of three WGS technologies provided an in-depth analysis of the outbreak, including the transmission dynamics of a carbapenemase-producing E. hormaechei cluster, identification of possible hospital reservoirs and the full context of blaIMP-4 on a multidrug resistant IncHI2 plasmid that appears to be widely distributed in Australia.


April 21, 2020  |  

Increased prevalence of Escherichia coli strains from food carrying blaNDM and mcr-1-bearing plasmids that structurally resemble those of clinical strains, China, 2015 to 2017.

Introduction: Emergence of resistance determinants of blaNDM and mcr-1 has undermined the antimicrobial effectiveness of the last line drugs carbapenems and colistin. Aim: This work aimed to assess the prevalence of blaNDM and mcr-1 in E. coli strains collected from food in Shenzhen, China, during the period 2015 to 2017. Methods: Multidrug-resistant E. coli strains were isolated from food samples. Plasmids encoding mcr-1 or blaNDM genes were characterised and compared with plasmids found in clinical isolates.ResultsAmong 1,166 non-repeated cephalosporin-resistant E. coli strains isolated from 2,147 food samples, 390 and 42, respectively, were resistant to colistin and meropenem, with five strains being resistant to both agents. The rate of resistance to colistin increased significantly (p?


April 21, 2020  |  

The blaNDM-1-Carrying IncA/C2 Plasmid Underlies Structural Alterations and Cointegrate Formation In Vivo.

In 2012, a carbapenemase-producing Salmonella enterica serovar Corvallis isolate carrying a blaNDM-1 multiresistance IncA/C2 plasmid, apart from IncHI2 and ColE-like plasmids, was detected in a wild bird in Germany. In a recent broiler chicken infection study, we observed transfer of this blaNDM-1-carrying IncA/C2 plasmid to other Enterobacteriaceae Here, we focused on the stability of this plasmid and gained insight into the type and frequency of its structural alterations after an in vivo passage in a broiler chicken infection study.Copyright © 2019 Hadziabdic et al.


April 21, 2020  |  

Klebsiella quasipneumoniae Provides a Window into Carbapenemase Gene Transfer, Plasmid Rearrangements, and Patient Interactions with the Hospital Environment.

Several emerging pathogens have arisen as a result of selection pressures exerted by modern health care. Klebsiella quasipneumoniae was recently defined as a new species, yet its prevalence, niche, and propensity to acquire antimicrobial resistance genes are not fully described. We have been tracking inter- and intraspecies transmission of the Klebsiella pneumoniae carbapenemase (KPC) gene, blaKPC, between bacteria isolated from a single institution. We applied a combination of Illumina and PacBio whole-genome sequencing to identify and compare K. quasipneumoniae from patients and the hospital environment over 10- and 5-year periods, respectively. There were 32 blaKPC-positive K. quasipneumoniae isolates, all of which were identified as K. pneumoniae in the clinical microbiology laboratory, from 8 patients and 11 sink drains, with evidence for seven separate blaKPC plasmid acquisitions. Analysis of a single subclade of K. quasipneumoniae subsp. quasipneumoniae (n?=?23 isolates) from three patients and six rooms demonstrated seeding of a sink by a patient, subsequent persistence of the strain in the hospital environment, and then possible transmission to another patient. Longitudinal analysis of this strain demonstrated the acquisition of two unique blaKPC plasmids and then subsequent within-strain genetic rearrangement through transposition and homologous recombination. Our analysis highlights the apparent molecular propensity of K. quasipneumoniae to persist in the environment as well as acquire carbapenemase plasmids from other species and enabled an assessment of the genetic rearrangements which may facilitate horizontal transmission of carbapenemases. Copyright © 2019 Mathers et al.


April 21, 2020  |  

Conjugal Transfer, Whole-Genome Sequencing, and Plasmid Analysis of Four mcr-1-Bearing Isolates from U.S. Patients.

Four Enterobacteriaceae clinical isolates bearing mcr-1 gene-harboring plasmids were characterized. All isolates demonstrated the ability to transfer colistin resistance to Escherichia coli; plasmids were stable in conjugants after multiple passages on nonselective media. mcr-1 was located on an IncX4 (n?=?3) or IncN (n?=?1) plasmid. The IncN plasmid harbored 13 additional antimicrobial resistance genes. Results indicate that the mcr-1-bearing plasmids in this study were highly transferable in vitro and stable in the recipients.This is a work of the U.S. Government and is not subject to copyright protection in the United States. Foreign copyrights may apply.


April 21, 2020  |  

Detection of VIM-1-Producing Enterobacter cloacae and Salmonella enterica Serovars Infantis and Goldcoast at a Breeding Pig Farm in Germany in 2017 and Their Molecular Relationship to Former VIM-1-Producing S. Infantis Isolates in German Livestock Production.

In 2011, VIM-1-producing Salmonella enterica serovar Infantis and Escherichia coli were isolated for the first time in four German livestock farms. In 2015/2016, highly related isolates were identified in German pig production. This raised the issue of potential reservoirs for these isolates, the relation of their mobile genetic elements, and potential links between the different affected farms/facilities. In a piglet-producing farm suspicious for being linked to some blaVIM-1 findings in Germany, fecal and environmental samples were examined for the presence of carbapenemase-producing Enterobacteriaceae and Salmonella spp. Newly discovered isolates were subjected to Illumina whole-genome sequencing (WGS) and S1 pulsed-field gel electrophoresis (PFGE) hybridization experiments. WGS data of these isolates were compared with those for the previously isolated VIM-1-producing Salmonella Infantis isolates from pigs and poultry. Among 103 samples, one Salmonella Goldcoast isolate, one Salmonella Infantis isolate, and one Enterobacter cloacae isolate carrying the blaVIM-1 gene were detected. Comparative WGS analysis revealed that the blaVIM-1 gene was part of a particular Tn21-like transposable element in all isolates. It was located on IncHI2 (ST1) plasmids of ~290 to 300?kb with a backbone highly similar (98 to 100%) to that of reference pSE15-SA01028. SNP analysis revealed a close relationship of all VIM-1-positive S Infantis isolates described since 2011. The findings of this study demonstrate that the occurrence of the blaVIM-1 gene in German livestock is restricted neither to a certain bacterial species nor to a certain Salmonella serovar but is linked to a particular Tn21-like transposable element located on transferable pSE15-SA01028-like IncHI2 (ST1) plasmids, being present in all of the investigated isolates from 2011 to 2017.IMPORTANCE Carbapenems are considered one of few remaining treatment options against multidrug-resistant Gram-negative pathogens in human clinical settings. The occurrence of carbapenemase-producing Enterobacteriaceae in livestock and food is a major public health concern. Particularly the occurrence of VIM-1-producing Salmonella Infantis in livestock farms is worrisome, as this zoonotic pathogen is one of the main causes for human salmonellosis in Europe. Investigations on the epidemiology of those carbapenemase-producing isolates and associated mobile genetic elements through an in-depth molecular characterization are indispensable to understand the transmission of carbapenemase-producing Enterobacteriaceae along the food chain and between different populations to develop strategies to prevent their further spread.Copyright © 2019 Roschanski et al.


April 21, 2020  |  

Spreading Patterns of NDM-Producing Enterobacteriaceae in Clinical and Environmental Settings in Yangon, Myanmar.

The spread of carbapenemase-producing Enterobacteriaceae (CPE), contributing to widespread carbapenem resistance, has become a global concern. However, the specific dissemination patterns of carbapenemase genes have not been intensively investigated in developing countries, including Myanmar, where NDM-type carbapenemases are spreading in clinical settings. In the present study, we phenotypically and genetically characterized 91 CPE isolates obtained from clinical (n = 77) and environmental (n = 14) samples in Yangon, Myanmar. We determined the dissemination of plasmids harboring genes encoding NDM-1 and its variants using whole-genome sequencing and plasmid analysis. IncFII plasmids harboring blaNDM-5 and IncX3 plasmids harboring blaNDM-4 or blaNDM-7 were the most prevalent plasmid types identified among the isolates. The IncFII plasmids were predominantly carried by clinical isolates of Escherichia coli, and their clonal expansion was observed within the same ward of a hospital. In contrast, the IncX3 plasmids were found in phylogenetically divergent isolates from clinical and environmental samples classified into nine species, suggesting widespread dissemination of plasmids via horizontal transfer. Half of the environmental isolates were found to possess IncX3 plasmids, and this type of plasmid was confirmed to transfer more effectively to recipient organisms at a relatively low temperature (25°C) compared to the IncFII plasmid. Moreover, various other plasmid types were identified harboring blaNDM-1, including IncFIB, IncFII, IncL/M, and IncA/C2, among clinical isolates of Klebsiella pneumoniae or Enterobacter cloacae complex. Overall, our results highlight three distinct patterns of the dissemination of blaNDM-harboring plasmids among CPE isolates in Myanmar, contributing to a better understanding of their molecular epidemiology and dissemination in a setting of endemicity.Copyright © 2019 American Society for Microbiology.


April 21, 2020  |  

Diverse Vectors and Mechanisms Spread New Delhi Metallo-ß-Lactamases among Carbapenem-Resistant Enterobacteriaceae in the Greater Boston Area.

New Delhi metallo-beta-lactamases (NDMs) are an uncommon but emerging cause of carbapenem resistance in the United States. Genomic factors promoting their domestic spread remain poorly characterized. A prospective genomic surveillance program among Boston-area hospitals identified multiple new occurrences of NDM-carrying strains of Escherichia coli and Enterobacter cloacae complex in inpatient and outpatient settings, representing the first occurrences of NDM-mediated resistance since initiating genomic surveillance in 2011. Cases included domestic patients with no international exposures. PacBio sequencing of isolates identified strain characteristics, resistance genes, and the complement of mobile vectors mediating spread. Analyses revealed a common 3,114-bp region containing the blaNDM gene, with carriage of this conserved region among unique strains by diverse transposon and plasmid backbones. Functional studies revealed a broad capacity for blaNDM transmission by conjugation, transposition, and complex interplasmid recombination events. NDMs represent a rapidly spreading form of drug resistance that can occur in inpatient and outpatient settings and in patients without international exposures. In contrast to Tn4401-based spread of Klebsiella pneumoniae carbapenemases (KPCs), diverse transposable elements mobilize NDM enzymes, commonly with other resistance genes, enabling naive strains to acquire multi- and extensively drug-resistant profiles with single transposition or plasmid conjugation events. Genomic surveillance provides effective means to rapidly identify these gene-level drivers of resistance and mobilization in order to inform clinical decisions to prevent further spread.Copyright © 2019 American Society for Microbiology.


April 21, 2020  |  

Reconstruction of the genomes of drug-resistant pathogens for outbreak investigation through metagenomic sequencing

Culture-independent methods that target genome fragments have shown promise in identifying certain pathogens, but the holy grail of comprehensive pathogen genome detection from microbiologically complex samples for subsequent forensic analyses remains a challenge. In the context of an investigation of a nosocomial outbreak, we used shotgun metagenomic sequencing of a human fecal sample and a neural network algorithm based on tetranucleotide frequency profiling to reconstruct microbial genomes and tested the same approach using rectal swabs from a second patient. The approach rapidly and readily detected the genome of Klebsiella pneumoniae carbapenemase (KPC)-producing K. pneumoniae in the patient fecal specimen and in the rectal swab sample, achieving a level of strain resolution that was sufficient for confident transmission inference during a highly clonal outbreak. The analysis also detected previously unrecognized colonization of the patient by vancomycin-resistant Enterococcus faecium, another multidrug-resistant bacterium.IMPORTANCE The study results reported here perfectly demonstrate the power and promise of clinical metagenomics to recover genome sequences of important drug-resistant bacteria and to rapidly provide rich data that inform outbreak investigations and treatment decisions, independently of the need to culture the organisms.


April 21, 2020  |  

Klebsiella pneumoniae ST307 with blaOXA-181, South Africa, 2014-2016.

Klebsiella pneumoniae sequence type (ST) 307 is an emerging global antimicrobial drug-resistant clone. We used whole-genome sequencing and PCR to characterize K. pneumoniae ST307 with oxacillinase (OXA) 181 carbapenemase across several private hospitals in South Africa during 2014-2016. The South Africa ST307 belonged to a different clade (clade VI) with unique genomic characteristics when compared with global ST307 (clades I-V). Bayesian evolution analysis showed that clade VI emerged around March 2013 in Gauteng Province, South Africa, and then evolved during 2014 into 2 distinct lineages. K. pneumoniae ST307 clade VI with OXA-181 disseminated over a 15-month period within 42 hospitals in 23 cities across 6 northeastern provinces, affecting 350 patients. The rapid expansion of ST307 was most likely due to intrahospital, interhospital, intercity, and interprovince movements of patients. This study highlights the importance of molecular surveillance for tracking emerging antimicrobial clones.


April 21, 2020  |  

Potential KPC-2 carbapenemase reservoir of environmental Aeromonas hydrophila and Aeromonas caviae isolates from the effluent of an urban wastewater treatment plant in Japan.

Aeromonas hydrophila and Aeromonas caviae adapt to saline water environments and are the most predominant Aeromonas species isolated from estuaries. Here, we isolated antimicrobial-resistant (AMR) Aeromonas strains (A. hydrophila GSH8-2 and A. caviae GSH8M-1) carrying the carabapenemase blaKPC-2 gene from a wastewater treatment plant (WWTP) effluent in Tokyo Bay (Japan) and determined their complete genome sequences. GSH8-2 and GSH8M-1 were classified as newly assigned sequence types ST558 and ST13, suggesting no supportive evidence of clonal dissemination. The strains appear to have acquired blaKPC-2 -positive IncP-6-relative plasmids (pGSH8-2 and pGSH8M-1-2) that share a common backbone with plasmids in Aeromonas sp. ASNIH3 isolated from hospital wastewater in the United States, A. hydrophila WCHAH045096 isolated from sewage in China, other clinical isolates (Klebsiella, Enterobacter and Escherichia coli), and wastewater isolates (Citrobacter, Pseudomonas and other Aeromonas spp.). In addition to blaKPC-2 , pGSH8M-1-2 carries an IS26-mediated composite transposon including a macrolide resistance gene, mph(A). Although Aeromonas species are opportunistic pathogens, they could serve as potential environmental reservoir bacteria for carbapenemase and AMR genes. AMR monitoring from WWTP effluents will contribute to the detection of ongoing AMR dissemination in the environment and might provide an early warning of potential dissemination in clinical settings and communities. © 2019 The Authors. Environmental Microbiology Reports published by Society for Applied Microbiology and John Wiley & Sons Ltd.


April 21, 2020  |  

Complete genome sequence of an IMP-8, CTX-M-14, CTX-M-3 and QnrS1 co-producing Enterobacter asburiae isolate from a patient with wound infection.

The aim of this study was to investigate the characteristics and complete genome sequence of an IMP-8, CTX-M-14, CTX-M-3 and QnrS1 co-producing multidrug-resistant Enterobacter asburiae isolate (EN3600) from a patient with wound infection.Species identification was confirmed by matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOF/MS). Carbapenemase genes were identified by PCR and Sanger sequencing. The complete genome sequence of E. asburiae EN3600 was obtained using a PacBio RS II platform. Genome annotation was done by Rapid Annotation using Subsystem Technology (RAST) server. Acquired antimicrobial resistance genes (ARGs) and plasmid replicons were detected using ResFinder 2.1 and PlasmidFinder 1.3, respectively.The genome of E. asburiae EN3600 consists of a 4.8-Mbp chromosome and five plasmids. The annotated genome contains various ARGs conferring resistance to aminoglycosides, ß-lactams, fluoroquinolones, fosfomycin, macrolides, phenicols, rifampicin and sulfonamides. In addition, plasmids of incompatibility (Inc) groups IncHI2A, IncFIB(pECLA), IncFIB(pQil) and IncP1 were identified. The genes blaIMP-8, blaCTX-M-14 and blaCTX-M-3 were located on different plasmids. The blaIMP-8 gene was carried by an 86-kb IncFIB(pQil) plasmid. The blaCTX-M-3 and qnrS1 genes were co-harboured by an IncP1 plasmid. In addition, blaCTX-M-14 was associated with blaTEM-1B, blaOXA-1, catB3 and sul1 genes in a 116-kb non-typeable plasmid.To our knowledge, this is the first complete genome sequence of an E. asburiae isolate co-producing IMP-8, CTX-M-14, CTX-M-3 and QnrS1. This genome may facilitate the understanding of the resistome, pathogenesis and genomic features of Enterobacter cloacae complex (ECC) and will provide valuable information for accurate identification of ECC.Copyright © 2019 International Society for Antimicrobial Chemotherapy. Published by Elsevier Ltd. All rights reserved.


April 21, 2020  |  

Genetic and biochemical characterization of FRI-3, a novel variant of the Ambler class A carbapenemase FRI-1.

To characterize a new variant of the FRI class A carbapenemase isolated from an MDR clinical Enterobacter cloacae isolate.A carbapenem-resistant E. cloacae was isolated from a rectal swab from a patient in an ICU in Southern Germany. Various phenotypic tests confirmed production of a putative class A carbapenemase. The new bla gene variant, blaFRI-3, and its genetic environment were characterized by WGS. Biochemical characterization was performed by heterologous expression in Escherichia coli TOP10 and by purification of the enzyme with subsequent determination of its kinetic parameters.PCR and sequencing carried out for different class A carbapenemase genes confirmed the presence of a novel variant of blaFRI-1. The novel variant was named FRI-3 and exhibited 91%, 96% and 92% amino acid identity to FRI-1, FRI-2 and FRI-4, respectively. E. coli TOP10 expressing blaFRI-3 showed increased resistance to almost all ß-lactams. Comparing the catalytic behaviour of FRI-3 and FRI-1, it was shown that FRI-3 had the same substrate spectrum, but basically hydrolysed ß-lactams less efficiently than FRI-1. WGS data revealed that blaFRI-3 was located on a 111?kb plasmid.The biochemical characterization of FRI-3 illustrates that even a few differences in the amino acid sequence can lead to altered catalytic activities of ß-lactamases belonging to the same family. © The Author(s) 2019. Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy. All rights reserved. For permissions, please email: journals.permissions@oup.com.


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