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... gut, possess very subtle virulence traits that are not easily identified (20). Several traits that may contribute to enhanced virulence have been identified in E. faecalis. The E. faecalis cytolysin =-=(10, 23, 26)-=- lyses a broad range of eukaryotic and prokaryotic cells, is usually plasmid encoded (22), and enhances the virulence of E. faecalis in animal models (5, 21, 24, 25, 27). Aggregation substance mediate...

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... dissemination of resistance determinants encoded by the transposon. Moreover, studies performed with animals indicate that the hemolysin determinant is a virulence factor for enterococcal infections =-=(29)-=-. Insertions resulting in the hyperhemolytic phenotype have been shown to yield bacteria that are more virulent than nonhemolytic or normally hemolytic isogenic strains. An open reading frame within t...

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...ntal Medicine, The Scripps Research Institute, La Jolla, California 92037 Enterococci are gram-positive constituents of the normal human microflora, typically colonizing the intestinal tract and skin =-=(34, 47)-=-. However, these organisms are capable of causing disease as opportunistic pathogens, mainly in immunocompromised patients (35, 58). The problem of enterococcal infection has been aggravated by the em...

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...drugs from cells (23). Enterococci are gram-positive commensal bacteria that normally inhabit the gastrointestinal tracts of almost all animals and are the most abundant gram-positive cocci in humans =-=(10, 22)-=-. Once regarded as a bacterial genus of little consequence in infectious diseases, the enterococci are increasingly recognized as the leading nosocomial pathogens because they cause serious diseases s...

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...arranting their increased study. The specific determinants that are proposed to contribute to the virulence of E. faecalis are not universally present, and expression of the cognate genes is variable =-=(21, 37)-=-. For example, in a recent study of 106 clonally diverse strains of E. faecalis the metallopeptidase gelatinase (GelE) was shown to be expressed in less than 60% of 106 genotypically positive isolates...

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... of the frequency of occurrence of the other species. The emergence of enterococci during the last decade has resulted mostly from their antimicrobial resistance and less from their virulence factors =-=(17)-=-. The antimicrobial resistance spans different antimicrobial groups, including �-lactam antibiotics, macrolides, aminoglycosides, and glycopeptides. Glycopeptide-resistant enterococci (GRE), first des...

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...lay an important role in vivo. Enterococci rank among leading causes of nosocomial bacteremia and urinary tract infection (51) and are also a leading cause of community-acquired subacute endocarditis =-=(33)-=-. Enterococcal factors that contribute to the pathogenesis of disease have been identified. The cytolysin of Enterococcus faecalis contributes to enterococcal virulence in all models studied (7, 29, 3...

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...ns, with the exception of cytolysin. Cytolysin is a two-peptide lantibiotic found in E. faecalis (17). It is the only peptide bacteriocin isolated from enterococci with cytolytic (hemolytic) activity =-=(56, 61, 70)-=-. Cytolysin is a virulence factor, and consequently, it is not considered useful as an antimicrobial agent. It is interesting that the cytolysin-encoding genes are found not only in Enterococcus isola...

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...dstream infections with E. faecalis can occur due to contamination of intravenous catheters, ascending urinary tract infections following catheterization, intravenous drug abuse, or abdominal surgery =-=(2, 4, 12, 17, 25, 26, 31, 33)-=-. Many studies have focused on demonstrating that the presence of specific virulence factors such as aggregation substance, cytolysin, surface protein EspA, and extracellular superoxide production are...

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...0 11 bacterial cells/gram feces [3,4]. Enterococci are the predominant Gram-positive cocci found within this niche, and in humans they can be isolated at concentrations of 10 5 to 10 7 CFU/gram feces =-=[5,6]-=-. Bacteriophage induction in response to environmental cues is emerging as one strategy for enterococcal colonization and control in the intestinal ecosystem [7]. The presence of enterococci in the co...