Research Article
Virulence Genes among Enterococcus faecalis and Enterococcus
faecium Isolated from Coastal Beaches and Human and
Nonhuman Sources in Southern California and Puerto Rico
Donna M. Ferguson,
1
Ginamary Negrón Talavera,
2
Luis A. Ríos Hernández,
2
Stephen B. Weisberg,
3
Richard F. Ambrose,
1
and Jennifer A. Jay
4
1
Department of Environmental Health Sciences, University of California, Los Angeles, Room 46-081 CHS, P.O. Box 951772,
Los Angeles, CA 90095-1772, USA
2
University of Puerto Rico at Mayaguez, Biology Building, Road 108, Km 1, Mayaguez, PR 00680, USA
3
Southern California Coastal Water Research Project, 3535 Harbor Boulevard, Suite 110, Costa Mesa, CA 92626, USA
4
Department of Civil and Environmental Engineering, University of California, Los Angeles, 5732H Boelter Hall, Los Angeles,
CA 90095-1593, USA
Correspondence should be addressed to Donna M. Ferguson; dferguson@netchino.com
Received 22 November 2015; Revised 8 March 2016; Accepted 21 March 2016
Academic Editor: Nongnuch Vanittanakom
Copyright © 2016 Donna M. Ferguson et al. his is an open access article distributed under the Creative Commons Attribution
License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly
cited.
Most Enterococcus faecalis and E. faecium are harmless to humans; however, strains harboring virulence genes, including esp, gelE,
cylA, asa1, and hyl, have been associated with human infections. E. faecalis and E. faecium are present in beach waters worldwide,
yet little is known about their virulence potential. Here, multiplex PCR was used to compare the distribution of virulence genes
among E. faecalis and E. faecium isolated from beaches in Southern California and Puerto Rico to isolates from potential sources
including humans, animals, birds, and plants. All ive virulence genes were found in E. faecalis and E. faecium from beach water,
mostly among E. faecalis. gelE was the most common among isolates from all source types. here was a lower incidence of asa1,
esp, cylA, and hyl genes among isolates from beach water, sewage, septage, urban runof, sea wrack, and eelgrass as compared to
human isolates, indicating that virulent strains of E. faecalis and E. faecium may not be widely disseminated at beaches. A higher
frequency of asa1 and esp among E. faecalis from dogs and of asa1 among birds (mostly seagull) suggests that further studies on the
distribution and virulence potential of strains carrying these genes may be warranted.
1. Introduction
Enterococcus faecalis and Enterococcus faecium are commonly
found in the intestinal tracts of humans and animals and also
ubiquitous in the environment [1]. While generally consid-
ered to be harmless, certain strains of E. faecalis and E. fae-
cium are among the leading causes of nosocomial infections
including urinary tract infections, abdominal and wound
infections, endocarditis, and bacteremia [2–5]. E. faecalis and
E. faecium isolated from patients in hospital settings have
been shown to harbor a higher frequency of gelE (gelatinase),
asa1 (aggregation substance), esp (enterococcal surface pro-
tein), cylA (cytolysin activator), and hyl (glycoside-hydrolase)
as compared to strains found in nonhospitalized individuals,
animals, and food [6–12]. Commensal, that is, harmless, E.
faecalis and E. faecium can become opportunistic pathogens
by acquiring antibiotic resistant and putative virulent genes
from other bacteria via horizontal gene transfer [2, 4, 13–17].
E. faecalis and E. faecium are among the most common
species of enterococci found in the beach environment [18–
21]. Enterococci found in the beach environment can include
naturalized populations existing in soil and vegetation as
well as strains from humans, sewage, animals, birds, reptiles,
and insects [1]. Presumably, potentially pathogenic E. faecalis
and E. faecium in human fecal waste would harbor higher
numbers of virulence genes as compared to strains from
animal and environmental sources.
Hindawi Publishing Corporation
Journal of Pathogens
Volume 2016, Article ID 3437214, 7 pages
http://dx.doi.org/10.1155/2016/3437214