Dataset Information

Dissemination of multiple drug resistance genes by class 1 integrons in Klebsiella pneumoniae isolates from four countries: a comparative study.

ABSTRACT: A comparative genetic analysis of 42 clinical Klebsiella pneumoniae isolates, resistant to two or more antibiotics belonging to the broad-spectrum ?-lactam group, sourced from Sydney, Australia, and three South American countries is presented. The study focuses on the genetic contexts of class 1 integrons, mobilizable genetic elements best known for their role in the rapid evolution of antibiotic resistance among Gram-negative pathogens. It was found that the class 1 integrons in this cohort were located in a number of different genetic contexts with clear regional differences. In Sydney, IS26-associated Tn21-like transposons on IncL/M plasmids contribute greatly to the dispersal of integron-associated multiple-drug-resistant (MDR) loci. In contrast, in the South American countries, Tn1696-like transposons on an IncA/C plasmid(s) appeared to be disseminating a characteristic MDR region. A range of mobile genetic elements is clearly being recruited by clinically important mobile class 1 integrons, and these elements appear to be becoming more common with time. This in turn is driving the evolution of complex and laterally mobile MDR units and may further complicate antibiotic therapy.

SUBMITTER: Roy Chowdhury P

PROVIDER: S-EPMC3122386 | biostudies-literature | 2011 Jul

REPOSITORIES: biostudies-literature

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Dissemination of multiple drug resistance genes by class 1 integrons in Klebsiella pneumoniae isolates from four countries: a comparative study.

Roy Chowdhury Piklu P Ingold Ana A Vanegas Natasha N Martínez Elena E Merlino John J Merkier Andrea Karina AK Castro Mercedes M González Rocha Gerardo G Borthagaray Graciela G Centrón Daniela D Bello Toledo Helia H Márquez Carolina M CM Stokes H W HW

Antimicrobial agents and chemotherapy 20110425 7

A comparative genetic analysis of 42 clinical Klebsiella pneumoniae isolates, resistant to two or more antibiotics belonging to the broad-spectrum β-lactam group, sourced from Sydney, Australia, and three South American countries is presented. The study focuses on the genetic contexts of class 1 integrons, mobilizable genetic elements best known for their role in the rapid evolution of antibiotic resistance among Gram-negative pathogens. It was found that the class 1 integrons in this cohort wer ...[more]

PMID: 21518841

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Project description:NDM-5 carbapenemase was mainly identified in Escherichia coli, while the rapid transmission of bla NDM-5 among Enterobacteriaceae has raised serious public attention. This study identified 14 NDM-5-producing Klebsiella pneumoniae isolates from 107 carbapenem-resistant K. pneumoniae isolates, recovered from blood, urine, and normally sterile body fluids of pediatric patients from January 2016 to December 2018. All NDM-5-producing isolates were highly resistant to ?-lactams, while tigecycline and polymyxin B exhibited excellent antimicrobial activity. These 14 strains belonged to 9 different sequence types (STs) and displayed various pulsed-field gel electrophoresis (PFGE) patterns, suggesting that they were not clonally related. S1-PFGE followed by Southern blotting showed that the bla NDM-5 gene was located on an ?46-kb IncX3 plasmid in all strains. All bla NDM-5-carrying plasmids were successfully transferred into recipient E. coli J53. PCR-based sequencing demonstrated that all of the bla NDM-5-carrying plasmids shared highly similar backbones, with nucleotide sequence identity of >99%. Moreover, this plasmid displayed high sequence similarity to the previously reported epidemic IncX3 bla NDM-5-carrying plasmids, with dynamic changes observed only in bla NDM-5-surrounding elements. Interestingly, the IncX3 bla NDM-5-carrying plasmids showed strong stability in clinical isolates when cultured in antibiotic-free medium. However, after the conjugation inhibitor linoleic acid was added, a gradual increase in the level of IncX3 plasmid loss could be observed. Clinical isolates displayed 10% to 15% bla NDM-5-carrying plasmid loss after coculture with linoleic acid for 5?days. These results showed that the IncX3 plasmid facilitated the dissemination of bla NDM-5 among multiclonal K. pneumoniae strains in children and that conjugal transfer contributed significantly to IncX3 plasmid stability within K. pneumoniae IMPORTANCE The emergence and spread of New Delhi metallo-?-lactamase (NDM)-producing Enterobacteriaceae have been a serious challenge to public health, and NDM-5 shows increased resistance to carbapenems compared with other variants. NDM-5 has been identified mostly in E. coli but has rarely been described in K. pneumoniae and other Enterobacteriaceae isolates. Here, we present the dissemination of highly similar 46-kb IncX3 bla NDM-5-carrying plasmids among multiclonal K. pneumoniae strains in children, highlighting the horizontal gene transfer of bla NDM-5 among K. pneumoniae strains via the IncX3 plasmid. Moreover, the IncX3 bla NDM-5-carrying plasmids displayed strong stability in clinical strains when cultured in antibiotic-free medium, and the plasmid maintenance was attributed partly to conjugal transfer. Plasmid conjugation is mediated by the type IV secretion system (T4SS), and T4SS is conserved among all epidemic IncX3 bla NDM-5-carrying plasmids. Therefore, combining conjugation inhibition and promotion of plasmid loss would be an effective strategy to limit the conjugation-assisted persistence of IncX3 bla NDM-5-carrying plasmids.

Project description:Klebsiella pneumoniae is a major threat to public health, causing significant morbidity and mortality worldwide. The emergence of highly drug-resistant strains is particularly concerning. There has been a recognition and division of Klebsiella pneumoniae into three distinct phylogenetic groups: Klebsiella pneumoniae, Klebsiella variicola, and Klebsiella quasipneumoniae. K. variicola and K. quasipneumoniae have often been described as opportunistic pathogens that have less virulence in humans than K. pneumoniae does. We recently sequenced the genomes of 1,777 extended-spectrum-beta-lactamase (ESBL)-producing K. pneumoniae isolates recovered from human infections and discovered that 28 strains were phylogenetically related to K. variicola and K. quasipneumoniae. Whole-genome sequencing of 95 additional non-ESBL-producing K. pneumoniae isolates recovered from patients found 12 K. quasipneumoniae strains. Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) analysis initially identified all patient isolates as K. pneumoniae, suggesting a potential pitfall in conventional clinical microbiology laboratory identification methods. Whole-genome sequence analysis revealed extensive sharing of core gene content and plasmid replicons among the Klebsiella species. For the first time, strains of both K. variicola and K. quasipneumoniae were found to carry the Klebsiella pneumoniae carbapenemase (KPC) gene, while another K. variicola strain was found to carry the New Delhi metallo-beta-lactamase 1 (NDM-1) gene. K. variicola and K. quasipneumoniae infections were not less virulent than K. pneumoniae infections, as assessed by in-hospital mortality and infection type. We also discovered evidence of homologous recombination in one K. variicola strain, as well as one strain from a novel Klebsiella species, which challenge the current understanding of interrelationships between clades of Klebsiella. IMPORTANCEKlebsiella pneumoniae is a serious human pathogen associated with resistance to multiple antibiotics and high mortality. K. variicola and K. quasipneumoniae are closely related organisms that are generally considered to be less-virulent opportunistic pathogens. We used a large, comprehensive, population-based strain collection and whole-genome sequencing to investigate infections caused by these organisms in our hospital system. We discovered that K. variicola and K. quasipneumoniae isolates are often misidentified as K. pneumoniae by routine clinical microbiology diagnostics and frequently cause severe life-threatening infections similar to K. pneumoniae. The presence of KPC in K. variicola and K. quasipneumoniae strains as well as NDM-1 metallo-beta-lactamase in one K. variicola strain is particularly concerning because these genes confer resistance to many different beta-lactam antibiotics. The sharing of plasmids, as well as evidence of homologous recombination, between these three species of Klebsiella is cause for additional concern.

Dataset Information

Dissemination of multiple drug resistance genes by class 1 integrons in Klebsiella pneumoniae isolates from four countries: a comparative study.

Publications

Dissemination of multiple drug resistance genes by class 1 integrons in Klebsiella pneumoniae isolates from four countries: a comparative study.

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