Dataset Information

Plasmid Dynamics in KPC-Positive Klebsiella pneumoniae during Long-Term Patient Colonization.

ABSTRACT: UNLABELLED:Carbapenem-resistant Klebsiella pneumoniae strains are formidable hospital pathogens that pose a serious threat to patients around the globe due to a rising incidence in health care facilities, high mortality rates associated with infection, and potential to spread antibiotic resistance to other bacterial species, such as Escherichia coli Over 6 months in 2011, 17 patients at the National Institutes of Health (NIH) Clinical Center became colonized with a highly virulent, transmissible carbapenem-resistant strain of K. pneumoniae Our real-time genomic sequencing tracked patient-to-patient routes of transmission and informed epidemiologists' actions to monitor and control this outbreak. Two of these patients remained colonized with carbapenemase-producing organisms for at least 2 to 4 years, providing the opportunity to undertake a focused genomic study of long-term colonization with antibiotic-resistant bacteria. Whole-genome sequencing studies shed light on the underlying complex microbial colonization, including mixed or evolving bacterial populations and gain or loss of plasmids. Isolates from NIH patient 15 showed complex plasmid rearrangements, leaving the chromosome and the blaKPC-carrying plasmid intact but rearranging the two other plasmids of this outbreak strain. NIH patient 16 has shown continuous colonization with blaKPC-positive organisms across multiple time points spanning 2011 to 2015. Genomic studies defined a complex pattern of succession and plasmid transmission across two different K. pneumoniae sequence types and an E. coli isolate. These findings demonstrate the utility of genomic methods for understanding strain succession, genome plasticity, and long-term carriage of antibiotic-resistant organisms. IMPORTANCE:In 2011, the NIH Clinical Center had a nosocomial outbreak involving 19 patients who became colonized or infected with blaKPC-positive Klebsiella pneumoniae Patients who have intestinal colonization with blaKPC-positive K. pneumoniae are at risk for developing infections that are difficult or nearly impossible to treat with existing antibiotic options. Two of those patients remained colonized with blaKPC-positive Klebsiella pneumoniae for over a year, leading to the initiation of a detailed genomic analysis exploring mixed colonization, plasmid recombination, and plasmid diversification. Whole-genome sequence analysis identified a variety of changes, both subtle and large, in the blaKPC-positive organisms. Long-term colonization of patients with blaKPC-positive Klebsiella pneumoniae creates new opportunities for horizontal gene transfer of plasmids encoding antibiotic resistance genes and poses complications for the delivery of health care.

SUBMITTER: Conlan S

PROVIDER: S-EPMC4937214 | biostudies-literature | 2016 Jun

REPOSITORIES: biostudies-literature

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Plasmid Dynamics in KPC-Positive Klebsiella pneumoniae during Long-Term Patient Colonization.

Conlan Sean S Park Morgan M Deming Clayton C Thomas Pamela J PJ Young Alice C AC Coleman Holly H Sison Christina C Weingarten Rebecca A RA Lau Anna F AF Dekker John P JP Palmore Tara N TN Frank Karen M KM Segre Julia A JA

mBio 20160628 3

<h4>Unlabelled</h4>Carbapenem-resistant Klebsiella pneumoniae strains are formidable hospital pathogens that pose a serious threat to patients around the globe due to a rising incidence in health care facilities, high mortality rates associated with infection, and potential to spread antibiotic resistance to other bacterial species, such as Escherichia coli Over 6 months in 2011, 17 patients at the National Institutes of Health (NIH) Clinical Center became colonized with a highly virulent, trans ...[more]

PMID: 27353756

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Project description:Enterococcus faecium is a gut commensal of humans and animals. In addition, it has recently emerged as an important nosocomial pathogen through the acquisition of genetic elements that confer resistance to antibiotics and virulence. We performed a whole-genome sequencing-based study on 96 multidrug-resistant E. faecium strains that asymptomatically colonized five patients with the aim of describing the genome dynamics of this species. The patients were hospitalized on multiple occasions and isolates were collected over periods ranging from 15 months to 6.5 years. Ninety-five of the sequenced isolates belonged to E. faecium clade A1, which was previously determined to be responsible for the vast majority of clinical infections. The clade A1 strains clustered into six clonal groups of highly similar isolates, three of which consisted entirely of isolates from a single patient. We also found evidence of concurrent colonization of patients by multiple distinct lineages and transfer of strains between patients during hospitalization. We estimated the evolutionary rate of two clonal groups that each colonized single patients at 12.6 and 25.2 single-nucleotide polymorphisms (SNPs)/genome/year. A detailed analysis of the accessory genome of one of the clonal groups revealed considerable variation due to gene gain and loss events, including the chromosomal acquisition of a 37 kbp prophage and the loss of an element containing carbohydrate metabolism-related genes. We determined the presence and location of 12 different insertion sequence (IS) elements, with ISEfa5 showing a unique pattern of location in 24 of the 25 isolates, suggesting widespread ISEfa5 excision and insertion into the genome during gut colonization. Our findings show that the E. faecium genome is highly dynamic during asymptomatic colonization of the human gut. We observed considerable genomic flexibility due to frequent horizontal gene transfer and recombination, which can contribute to the generation of genetic diversity within the species and, ultimately, can contribute to its success as a nosocomial pathogen.

Project description:Background:Identification of gut microbiota features associated with antibiotic-resistant bacterial colonization may reveal new infection prevention targets. Methods:We conducted a matched, case-control study of long-term acute care hospital (LTACH) patients to identify gut microbiota and clinical features associated with colonization by Klebsiella pneumoniae carbapenemase-producing Klebsiella pneumoniae (KPC-Kp), an urgent antibiotic resistance threat. Fecal or rectal swab specimens were collected and tested for KPC-Kp; 16S rRNA gene-based sequencing was performed. Comparisons were made between cases and controls in calibration and validation subsamples using microbiota similarity indices, logistic regression, and unit-weighted predictive models. Results:Case (n = 32) and control (n = 99) patients had distinct fecal microbiota communities, but neither microbiota diversity nor inherent clustering into community types distinguished case and control specimens. Comparison of differentially abundant operational taxonomic units (OTUs) revealed 1 OTU associated with case status in both calibration (n = 51) and validation (n = 80) subsamples that matched the canonical KPC-Kp strain ST258. Permutation analysis using the presence or absence of OTUs and hierarchical logistic regression identified 2 OTUs (belonging to genus Desulfovibrio and family Ruminococcaceae) associated with KPC-Kp colonization. Among clinical variables, the presence of a decubitus ulcer alone was independently and consistently associated with case status. Combining the presence of the OTUs Desulfovibrio and Ruminococcaceae with decubitus ulcer increased the likelihood of KPC-Kp colonization to >38% in a unit-weighted predictive model. Conclusions:We identified microbiota and clinical features that distinguished KPC-Kp gut colonization in LTACH patients, a population particularly susceptible to KPC-Kp infection. These features may warrant further investigation as markers of risk for KPC-Kp colonization.

Dataset Information

Plasmid Dynamics in KPC-Positive Klebsiella pneumoniae during Long-Term Patient Colonization.

Publications

Plasmid Dynamics in KPC-Positive Klebsiella pneumoniae during Long-Term Patient Colonization.

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