Molecular Characterization of a Widespread, Pathogenic, and Antibiotic Resistance-Receptive Enterococcus faecalis Lineage and Dissemination of Its Putative Pathogenicity Island

Baylor College of Medicine, Houston, Texas, United States
Journal of Bacteriology (Impact Factor: 2.81). 09/2005; 187(16):5709-18. DOI: 10.1128/JB.187.16.5709-5718.2005
Source: PubMed


Enterococcus faecalis, a common cause of endocarditis and known for its capacity to transfer antibiotic resistance to other pathogens, has recently
emerged as an important, multidrug-resistant nosocomial pathogen. However, knowledge of its lineages and the potential of
particular clones of this species to disseminate and cause disease is limited. Using a nine-gene multilocus sequence typing
(MLST) scheme, we identified an evolving and widespread clonal complex of E. faecalis that has caused outbreaks and life-threatening infections. Moreover, this unusual clonal complex was found to contain isolates
of unexpected relatedness, including the first known U.S. vancomycin-resistant enterococcus (E. faecalis strain V583), the first known penicillinase-producing (Bla+) E. faecalis isolate, and the previously described widespread clone of penicillinase producers, a trait found in <0.1% of E. faecalis isolates. All members of this clonal cluster (designated as BVE for Bla+ Vanr endocarditis) were found to contain a previously described putative pathogenicity island (PAI). Further analysis of this
PAI demonstrated its dissemination worldwide, albeit with considerable variability, confirmed its association with clinical
isolates, and found a common insertion site in different clonal lineages. PAI deletions, MLST, and the uncommon resistances
were used to predict the evolution of the BVE clonal cluster. The finding of a virulent and highly successful clonal complex
of E. faecalis with different members resistant to the primary therapies of choice, ampicillin and vancomycin, has important implications
for the evolution of virulence and successful lineages and for public health monitoring and control.

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Available from: George Weinstock, Jul 29, 2014
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    • "Penicillin resistance in E. faecalis is rare and if occurring linked to certain clonal lineages expressing beta-lactamases similar or identical to the S. aureus penicillinase (Nallapareddy et al., 2005; Ruiz-Garbajosa et al., 2006; McBride et al., 2007). Penicillin resistance in E. faecium is mediated via point mutations in the housekeeping pbp5 gene leading to reduced penicillin binding to the expressed protein (Jureen et al., 2004; Rice et al., 2004; Rice et al., 2009). "

    Full-text · Chapter · Apr 2012
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    • "Nevertheless, some E. faecalis clones, like ST6, ST9, ST28 and ST40, represented by at least 10 isolates in the database ( are clearly enriched (>70% of isolates) among hospitalized patients and are distributed world wide (McBride et al., 2007; Nallapareddy et al., 2005; Ruiz-Garbajosa et al., 2006; Freitas et al., 2009; Solheim et al., 2009; Damani et al., 2010; Lopez et al., 2010; Lester et al., 2010; Kawalec et al., 2007; Sun et al., 2009; McBride et al., 2009). "
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    ABSTRACT: Infections caused by multiresistant Gram-positive bacteria represent a major health burden in the community as well as in hospitalized patients. Staphylococcus aureus, Enterococcus faecalis and Enterococcus faecium are well-known pathogens of hospitalized patients, frequently linked with resistance against multiple antibiotics, compromising effective therapy. Streptococcus pneumoniae and Streptococcus pyogenes are important pathogens in the community and S. aureus has recently emerged as an important community-acquired pathogen. Population genetic studies reveal that recombination prevails as a driving force of genetic diversity in E. faecium, E. faecalis, S. pneumoniae and S. pyogenes, and thus, these species are weakly clonal. Although recombination has a relatively modest role driving the genetic variation of the core genome of S. aureus, the horizontal acquisition of resistance and virulence genes plays a key role in the emergence of new clinically relevant clones in this species. In this review, we discuss the population genetics of E. faecium, E. faecalis, S. pneumoniae, S. pyogenes and S. aureus. Knowledge of the population structure of these pathogens is not only highly relevant for (molecular) epidemiological research but also for identifying the genetic variation that underlies changes in clinical behaviour, to improve our understanding of the pathogenic behaviour of particular clones and to identify novel targets for vaccines or immunotherapy.
    Full-text · Article · Jun 2011 · FEMS microbiology reviews
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    • "However, infections caused by E. hirae and E. casseliflavus may also occur and warrant attention [52]. In addition, enterococci are regarded as important reservoirs of antibiotic resistance and virulence genes that are often found on mobile genetic elements [22,27,30,52]. "
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    ABSTRACT: Extensive use of antibiotics as growth promoters in the livestock industry constitutes strong selection pressure for evolution and selection of antibiotic resistant bacterial strains. Unfortunately, the microbial ecology and spread of these bacteria in the agricultural, urban, and suburban environments are poorly understood. Insects such as house flies (Musca domestica) and German cockroaches (Blattella germanica) can move freely between animal waste and food and may play a significant role in the dissemination of antibiotic resistant bacteria within and between animal production farms and from farms to residential settings. Enterococci from the digestive tract of house flies (n = 162), and feces of German cockroaches (n = 83) and pigs (n = 119), collected from two commercial swine farms were isolated, quantified, identified, and screened for antibiotic resistance and virulence. The majority of samples (93.7%) were positive for enterococci with concentrations 4.2 ± 0.7 × 10⁴ CFU/house fly, 5.5 ± 1.1 × 10⁶ CFU/g of cockroach feces, and 3.2 ± 0.8 × 10⁵ CFU/g of pig feces. Among all the identified isolates (n = 639) Enterococcus faecalis was the most common (55.5%), followed by E. hirae (24.9%), E. faecium (12.8%), and E. casseliflavus (6.7%). E. faecalis was most prevalent in house flies and cockroaches, and E. hirae was most common in pig feces. Our data showed that multi-drug (mainly tetracycline and erythromycin) resistant enterococci were common from all three sources and frequently carried antibiotic resistance genes including tet(M) and erm(B) and Tn916/1545 transposon family. E. faecalis frequently harbored virulence factors gelE, esp, and asa1. PFGE analysis of selected E. faecalis and E. faecium isolates demonstrated that cockroaches and house flies shared some of the same enterococcal clones that were detected in the swine manure indicating that insects acquired enterococci from swine manure. This study shows that house flies and German cockroaches in the confined swine production environment likely serve as vectors and/or reservoirs of antibiotic resistant and potentially virulent enterococci and consequently may play an important role in animal and public health.
    Full-text · Article · Jan 2011 · BMC Microbiology
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