TITLE:
Survival of Epidemic, Clinical, Faecal and Recreational Beach Enterococci Strains with Putative Virulence Genes in Marine and Fresh Waters
AUTHORS:
Asmat Ahmad, Ayokunle Christopher Dada, Gires Usup
KEYWORDS:
Clinical Enterococci Die-Off, Beach Enterococci Die-Off, Faecal Enterococci Die-Off, Tropical Water Temperature, Marine and Fresh Water, Virulence
JOURNAL NAME:
Journal of Environmental Protection,
Vol.5 No.6,
May
12,
2014
ABSTRACT:
Culturable
faecal coliform, epidemic, clinical, faecal and recreational beach enterococci strains
possessing putative virulence genes were enumerated over the course of 5 weeks to
comparatively assess their persistence in tropical marine and fresh waters. For
the clinical and epidemic strains tested, it took 2.38 ± 0.45 days for a 1-log reduction
(T90) in marine water. A higher T90 average of 2.51 ± 0.08
was observed for the commensal and environmental strains. Generally, lower T90 values of 2.14 ± 0.26 and 2.15 ± 0.16 days respectively were observed for
hospital and community acquired enterococci strains in fresh water mesocosms subjected
to tropical ambient temperature. Beach water enterococci and enterococci recovered
from faeces of humans survived for up to 20 days and 23 days respectively in fresh
and marine waters. The epidemic strain, MMH594, an esp-positive clinical bacteremia
isolate that previously caused multiple infections in a hospital ward outbreak fares
favourably well in tropical marine and fresh aquatic environments. For enterococci,
the decay rate was approximately 13% higher in fresh water than was observed for
marine water. On the contrary, for E. coli,
the decay rate was approximately 17% lower in fresh water than was observed in marine
water. Generally, the whole, the population trends of E. coli and enterococci in fresh and marine water mesocosms did not
reveal any evidence of growth. Our findings suggest that potentially pathogenic
bacteria can resume active growth after three weeks of being harboured by the reservoir-beach
sand and still pose threat to public health.