Affiliation:
1. Department of Civil & Environmental Engineering, Environmental Engineering & Science, Stanford University, Stanford, California, USA
2. NOAA Southwest Fisheries Science Center, La Jolla, California, USA
Abstract
ABSTRACT
This report documents the presence of fecal indicators and bacterial pathogens in sand at 53 California marine beaches using both culture-dependent and -independent (PCR and quantitative PCR [QPCR]) methods. Fecal indicator bacteria were widespread in California beach sand, with
Escherichia coli
and enterococci detected at 68% and 94% of the beaches surveyed, respectively. Somatic coliphages and a
Bacteroidales
human-specific fecal marker were detected at 43% and 13% of the beaches, respectively. Dry sand samples from almost 30% of the beaches contained at least one of the following pathogens:
Salmonella
spp.,
Campylobacter
spp.,
Staphylococcus aureus
, and methicillin-resistant
Staphylococcus aureus
(MRSA), which were detected at 15%, 13%, 14%, and 3% of tested beaches, respectively. Fecal indicators and pathogens were poorly correlated to one another and to land cover. Sands were dry at the time of collection, and those with relatively high moisture tended to have higher concentrations or a more frequent occurrence of both indicators and pathogens. Using culture-dependent assays, fecal indicators decayed faster than pathogens in microcosm experiments using unaltered beach sand seeded with sewage and assessed by culture-dependent assays. The following order of persistence was observed (listed from most to least persistent):
Campylobacter
>
Salmonella
> somatic coliphages > enterococci >
E. coli
> F
+
phages. In contrast, pathogens decayed faster than fecal indicators in culture-independent assays: enterococci >
Bacteroidales
human-specific marker >
Salmonella
>
Campylobacter
. Microcosm experiments demonstrated that both indicators and pathogens were mobilized by wetting with seawater. Decay rates measured by QPCR were lower than those measured with culture-dependent methods. Enterococcal persistence and possible growth were observed for wetted microcosms relative to unwetted controls.
Publisher
American Society for Microbiology
Subject
Ecology,Applied Microbiology and Biotechnology,Food Science,Biotechnology
Cited by
84 articles.
订阅此论文施引文献
订阅此论文施引文献,注册后可以免费订阅5篇论文的施引文献,订阅后可以查看论文全部施引文献