Occurrence of Enterococcus species with virulence markers in an urban flow-influenced tropical recreational beach

Abstract

Median enterococci counts of beach water samples gradually increased at statistically significant levels (χ2: 26.53, df: 4; p<0.0001) with increasing proximity to river influx. The difference in proportion of antibiotic resistant enterococci in beach water and river water samples was statistically significant (p<0.05) for the tested antibiotics with river isolates generally presenting higher resistance frequencies. Virulence genes cyl, esp, gelE and asa were detected at varying frequencies (7.32%, 21.95%, 100% and 63.41% respectively) among river isolates. On the other hand, the prevalence of these genes was lower (0%, 20%, 67.27% and 41.82% respectively) among beach water isolates. Multi-Locus-Sequence-Typing analysis of Enterococcus faecalis presented four sequence types (ST) one of which shared six out of seven tested loci with ST6, a member of the clonal complex of multi-drug resistant strains associated with hospital outbreaks.

Keywords: Antibiotic resistance; Beach water; Enterococcus; Sequence type; Virulence factors.