Dataset Information

Deciphering Heteroresistance to Colistin in a Klebsiella pneumoniae Isolate from Marseille, France.

ABSTRACT: Here, we report the description of a colistin-heteroresistant Klebsiella pneumoniae isolate fortuitously isolated from the stool sample of a patient with suspicion of tuberculosis in a public hospital of Marseille, France. In the colistin-resistant subpopulation, a mutation in the mgrB gene leading to a premature stop codon was found, and the hypermucoviscous phenotype was lost. Susceptibility to other antibiotics remained unchanged. To our knowledge, this is the first identification of such a colistin-heteroresistant Klebsiella pneumoniae isolate in France.

SUBMITTER: Bardet L

PROVIDER: S-EPMC5444162 | biostudies-literature | 2017 Jun

REPOSITORIES: biostudies-literature

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Deciphering Heteroresistance to Colistin in a Klebsiella pneumoniae Isolate from Marseille, France.

Bardet Lucie L Baron Sophie S Leangapichart Thongpan T Okdah Liliane L Diene Seydina M SM Rolain Jean-Marc JM

Antimicrobial agents and chemotherapy 20170524 6

Here, we report the description of a colistin-heteroresistant <i>Klebsiella pneumoniae</i> isolate fortuitously isolated from the stool sample of a patient with suspicion of tuberculosis in a public hospital of Marseille, France. In the colistin-resistant subpopulation, a mutation in the <i>mgrB</i> gene leading to a premature stop codon was found, and the hypermucoviscous phenotype was lost. Susceptibility to other antibiotics remained unchanged. To our knowledge, this is the first identificati ...[more]

PMID: 28416544

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Project description:Klebsiella pneumoniae is emerging as an important nosocomial pathogen due to its rapidly increasing multidrug resistance, which has led to a renewed interest in polymyxin antibiotics, such as colistin, as antibiotics of last resort. However, heteroresistance (i.e., the presence of a subpopulation of resistant bacteria in an otherwise susceptible culture) may hamper the effectiveness of colistin treatment in patients. In a previous study, we showed that colistin resistance among extended-spectrum-beta-lactamase (ESBL)-producing K. pneumoniae isolates emerged after the introduction of selective digestive tract decontamination (SDD) in an intensive care unit (ICU). In this study, we investigated heteroresistance to colistin among ESBL-producing K. pneumoniae isolates by using population analysis profiles (PAPs). We used whole-genome sequencing (WGS) to identify the mutations that were associated with the emergence of colistin resistance in these K. pneumoniae isolates. We found five heteroresistant subpopulations, with colistin MICs ranging from 8 to 64 mg/liter, which were derived from five clonally related, colistin-susceptible clinical isolates. WGS revealed the presence of mutations in the lpxM, mgrB, phoQ, and yciM genes in colistin-resistant K. pneumoniae isolates. In two strains, mgrB was inactivated by an IS3-like or ISKpn14 insertion sequence element. Complementation in trans with the wild-type mgrB gene resulted in these strains reverting to colistin susceptibility. The MICs for colistin-susceptible strains increased 2- to 4-fold in the presence of the mutated phoQ, lpxM, and yciM alleles. In conclusion, the present study indicates that heteroresistant K. pneumoniae subpopulations may be selected for upon exposure to colistin. Mutations in mgrB and phoQ have previously been associated with colistin resistance, but we provide experimental evidence for roles of mutations in the yciM and lpxM genes in the emergence of colistin resistance in K. pneumoniae.

Project description:Colistin has been considered a last-line option for the treatment of infections caused by carbapenem-resistant Klebsiella pneumoniae (CRKP). Heterogeneous resistance to colistin leads to unexplained clinical colistin treatment failure for CRKP. Our study aimed to investigate the extent of colistin heteroresistance among CRKP strains in China. A total of 455 colistin-susceptible strains, collected from six tertiary care hospitals in China, were characterized. The overall rate of colistin heteroresistance was 6.2%, as determined by the population analysis profiles (PAPs). Genomic analysis revealed that 60.7% of the colistin-heteroresistant isolates belonged to the epidemic sequence type 11 (ST11) clone. Single-nucleotide polymorphisms (SNPs) suggested that 6 ST5216 strains shared the same origin. Each of the subpopulations had a ≥8-fold decrease in colistin MIC in the presence of carbonyl cyanide m-chlorophenylhydrazone (CCCP), which indicated that heteroresistance could be suppressed by an efflux pump inhibitor. In addition, our results suggested that the PhoPQ pathway plays an important role in the mechanisms of heteroresistance. IMPORTANCE The problem of CRKP has raised alarms concerning global health. Our study enriches the epidemiological study of colistin heteroresistance among CRKP strains in China, where the prevalence of this phenomenon was previously unknown. Importantly, colistin-heteroresistant strains may cause the failure of clinical treatment with colistin, even if the clinical laboratory reports that the strains are sensitive. The commonly used broth microdilution method is unable to detect this special phenomenon. Additionally, our results indicate that efflux pumps play a major role in colistin heteroresistance, and inhibitors can effectively reverse it. Our study is the first to provide a detailed analysis of the prevalence of colistin heteroresistance in China, as well as an analysis of the genetic mechanisms of this phenomenon.

Dataset Information

Deciphering Heteroresistance to Colistin in a Klebsiella pneumoniae Isolate from Marseille, France.

Publications

Deciphering Heteroresistance to Colistin in a Klebsiella pneumoniae Isolate from Marseille, France.

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