Abundance and characteristics of the recreational water quality indicator bacteria Escherichia coli and enterococci in gull faeces

Abstract

Aims: To evaluate the numbers and selected phenotypic and genotypic characteristics of the faecal indicator bacteria Escherichia coli and enterococci in gull faeces at representative Great Lakes swimming beaches in the United States. Methods and Results: E. coli and enterococci were enumerated in gull faeces by membrane filtration. E. coli genotypes (rep-PCR genomic profiles) and E. coli (Vitek Ò GNI+) and enterococci (API Ò rapid ID 32 Strep and resistance to streptomycin, gentamicin, vancomycin, tetracycline and ampicillin) phenotypes were determined for isolates obtained from gull faeces both early and late in the swimming season. Identical E. coli genotypes were obtained only from single gull faecal samples but most faecal samples yielded more than one genotype (median of eight genotypes for samples with 10 isolates). E. coli isolates from the same site that clustered at ‡85% similarity were from the same sampling date and shared phenotypic characteristics, and at this similarity level there was population overlap between the two geographically isolated beach sites. Enterococcus API Ò profiles varied with sampling date. Gull enterococci displayed wide variation in antibiotic resistance patterns, and high-level resistance to some antibiotics. Conclusions: Gull faeces could be a major contributor of E. coli (10 5 -10 9 CFU g )1 ) and enterococci (10 4 -10 8 CFU g )1 ) to Great Lakes recreational waters. E. coli and enterococci in gull faeces are highly variable with respect to their genotypic and phenotypic characteristics and may exhibit temporal or geographic trends in these features. Significance and Impact of the Study: The high degree of variation in genotypic or phenotypic characteristics of E. coli or enterococci populations within gull hosts will require extensive sampling for adequate characterization, and will influence methods that use these characteristics to determine faecal contamination sources for recreational waters.

Impacts of Migratory Sandhill Cranes (Grus canadensis) on Microbial Water Quality in the Central Platte River, Nebraska, USA

“…These FIB findings are consistent with data generally reported for avian excreta (Geldreich 1978;Byappanahalli et al 2012), but there are known exceptions [e.g., gulls (Gould and Fletcher 1978;Fogarty et al 2003)]. However, E. coli and enterococci provide no clear source attribution data.…”

Influences of natural and anthropogenic factors on surface and groundwater quality in rural and urban areas

“…A variety of animals, both warm-and cold-blooded, contain faecal indicator bacteria in their faeces (Harwood et al 1999;Souza et al 1999;Gordon and Cowling 2003). Humans and animal species contain different numbers and different ratios of E. coli and enterococci in their faeces, although data are contradictory (Geldreich 1978;Alderisio and DeLuca 1999;Fogarty et al 2003;Field 2004;Weaver et al 2005). E. coli and enterococci are not well correlated with pathogenic Salmonella spp.…”

Molecular Detection of Campylobacter spp. in California Gull (Larus californicus) Excreta

“…FIB have also been documented for gull excreta (6,10,18). Total Enterococcus spp., E. coli, E. faecalis, and E. casseliflavus are the prominent FIB species reported from gull excreta (6), and enterococci from gull excreta have been considered a major contributor of recreational water enterococci at Great Lakes areas (10) and a cause of beach closures in southern California.…”