Dataset Information

Identification of Novel Conjugative Plasmids with Multiple Copies of fosB that Confer High-Level Fosfomycin Resistance to Vancomycin-Resistant Enterococci.

ABSTRACT: To further characterize the fosB-carrying plasmids of 19 vancomycin-resistant enterococci, the complete sequences of the fosB- and vanA-containing plasmids of Enterococcus faecium (pEMA120) and E. avium (pEA19081) were obtained by single-molecule, real-time sequencing. We found that these two plasmids are essentially identical (99.99% nucleotide sequence identity), which proved the possibility of interspecies transmission. Comparative analysis of the plasmids revealed that the backbone of pEMA120 is 99% similar to a conjugative fosB-negative E. faecium plasmid, pZB18. There is a traE disrupted in the transfer region of pEMA120, in comparison to pZB18 with an intact traE. The difference of their transfer frequencies between pEMA120 and pZB18 suggests this interruption of traE might affect conjugative transfer. Two copies of the fosB gene linked to a tnpA gene, forming an ISL3-like transposon, were found at separate locations within pEMA120, which had not been reported previously. These two fosB-carrying transposons were confirmed to form circular intermediates by inverse PCR. The hybridization of plasmid DNA digested by BsaI, having restriction site within the fosB sequence, demonstrated that the presence of multiple copies of fosB per plasmid is common. The total copy number of the fosB gene as revealed by qRT-PCR did not correlate with fosfomycin MICs or growth rates at sub-MICs of fosfomycin in different transconjugants. From susceptibility tests, the fosB gene, regardless of the copy number, conferred high fosfomycin MICs that ranged from 16384 to 65536 ?g/ml. This first complete nucleotide sequence of a plasmid carrying two copies of fosB in VRE suggests that the fosB gene can transfer to multiple loci of plasmids by the ISL3 family transposase TnpA, possibly in the form of circular intermediates, leading to the dissemination of high fosfomycin resistance in VRE.

SUBMITTER: Sun L

PROVIDER: S-EPMC5559704 | biostudies-literature | 2017

REPOSITORIES: biostudies-literature

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Identification of Novel Conjugative Plasmids with Multiple Copies of fosB that Confer High-Level Fosfomycin Resistance to Vancomycin-Resistant Enterococci.

Sun Lingyan L Zhang Ping P Qu Tingting T Chen Yan Y Hua Xiaoting X Shi Keren K Yu Yunsong Y

Frontiers in microbiology 20170815

To further characterize the fosB-carrying plasmids of 19 vancomycin-resistant enterococci, the complete sequences of the fosB- and vanA-containing plasmids of Enterococcus faecium (pEMA120) and E. avium (pEA19081) were obtained by single-molecule, real-time sequencing. We found that these two plasmids are essentially identical (99.99% nucleotide sequence identity), which proved the possibility of interspecies transmission. Comparative analysis of the plasmids r ...[more]

PMID: 28861056

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Project description:UNLABELLED:Nosocomial outbreaks of vancomycin-resistant Enterococcus faecium (VREfm) are thought to occur by transmission of VREfm between patients, predicting that infection control interventions will limit cross-transmission. Despite implementation of such strategies, the incidence of VREfm infections continues to rise. We aimed to use genomics to better understand the epidemiology of E. faecium within a large hospital and investigate the reasons for failure of infection control strategies. Whole-genome sequencing was performed on 61 E. faecium (36 VREfm) isolates, predominately from blood cultures collected at a single hospital between 1998 and 2009, and on five vanB-positive anaerobic commensal bacteria isolated from human feces. Phylogenomic analysis and precise mapping of the vanB gene, which contains the Tn1549 transposon, showed that at least 18 of the 36 VREfm isolates had acquired the transposon via independent insertion events, indicating de novo generation of VREfm rather than cross-transmission. Furthermore, Tn1549 sequences found in 15 of the 36 VREfm isolates were the same as the Tn1549 sequence from one of the gut anaerobes. National and international comparator E. faecium isolates were phylogenetically interspersed with isolates from our hospital, suggesting that our findings might be globally representative. These data demonstrate that VREfm generation within a patient is common, presumably occurring in the human bowel during antibiotic therapy, and help explain our inability to reduce VREfm infections. A recommendation from our findings is that infection control practices should include screening patients for specific hospital clones of vancomycin-susceptible E. faecium rather than just VREfm. IMPORTANCE:Enterococcus faecium is an increasingly important human pathogen causing predominantly antibiotic-resistant infections in hospitalized patients. Large amounts of health care funding are spent trying to control antibiotic-resistant bacteria in hospitals globally, yet in many institutions around the world, vancomycin-resistant E. faecium (VREfm) infections continue to rise. The new findings from this study help explain the failures of our current approaches to controlling vanB VREfm in health care institutions. Given the importance of this bacterium as a cause of hospital-acquired infections and the difficulties faced by infection control units in trying to prevent colonization in their institutions, the novel findings from this study provide evidence that a new approach to controlling VREfm in hospitals is required. In particular, more attention should be given to understanding the epidemiology of hospital-adapted vancomycin-susceptible E. faecium, and patients at higher risk for de novo generation of VREfm need to be identified and optimally managed.

Dataset Information

Identification of Novel Conjugative Plasmids with Multiple Copies of fosB that Confer High-Level Fosfomycin Resistance to Vancomycin-Resistant Enterococci.

Publications

Identification of Novel Conjugative Plasmids with Multiple Copies of <i>fosB</i> that Confer High-Level Fosfomycin Resistance to Vancomycin-Resistant Enterococci.

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