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c Escherichia coli isolates (n ‫؍‬ 300) collected from six sites in subtropical Brisbane, Australia, prior to and after storm events were tested for the presence of 11 virulence genes (VGs) specific to diarrheagenic pathotypes. The presence of eaeA, stx 1 , stx 2 , and ehxA genes specific for the enterohemorrhagic E. coli (EHEC) pathotype was detected in 56%, 6%, 10%, and 13% of isolates, respectively. The VGs astA (69%) and aggR (29%), carried by enteroaggregative (EAEC) pathotypes, were frequently detected in E. coli isolates. The enteropathogenic E. coli (EPEC) gene bfp was detected in 24% of isolates. In addition, enteroinvasive E. coli (EIEC) VG ipaH was also detected in 14% of isolates. During dry periods, isolates belonging to the EAEC pathotype were most commonly detected (23%), followed by EHEC (11%) and EPEC (11%). Conversely, a more uniform prevalence of pathotypes, EPEC (14%), EAEC (12%), EIEC (10%), EHEC (7%), and ETEC (7%), was observed after the storm events. The results of this study highlight the widespread occurrence of potentially diarrheagenic pathotypes in the urban aquatic ecosystems. While the presence of VGs in E. coli isolates alone is insufficient to determine pathogenicity, the presence of diarrheagenic E. coli pathotypes in high frequency after the storm events could lead to increased health risks if untreated storm water were to be used for nonpotable purposes and recreational activities. Storm events can result in mobilization and transport of fecal contaminants from point sources, such as urban wastewater treatment plants, and nonpoint sources, in particular animal fecal material, to receiving water bodies. The presence of fecal contamination in rivers, lakes, and creeks can lead to the degradation of water quality and subsequently result in the water becoming unfit for potable/nonpotable uses, aquaculture, and recreational activities such as swimming and fishing (1-4).Escherichia coli and Enterococcus spp. commonly found in mammalian feces have been traditionally used as indicators of fecal pollution in fresh and marine waters (5, 6). After storm events, a severalfold increase in the fecal indicator bacteria (FIB) numbers occur in the surface waters (7-9). There may be several sources of E. coli that contribute to sudden increases in numbers of this bacterium in waterways, including sewage overflows, farm animals, pets, and birds. The elevated microbial contaminants in storm runoff (7, 10) and subsequently in receiving water bodies may pose a serious public health risk. Disease outbreaks related to exposure to contaminated freshwater are well documented (11)(12)(13)(14). Exposure to recreational water has been linked to high numbers (21 out of 31) of reported E. coli O157:H7 disease outbreaks in the United States from 1982 to 2002 (15). Despite the significant disease burden linked to contaminated water exposure, the prevalence of E. coli pathotypes in the urban aquatic environment is not well characterized.The majority of E. coli strains are commensal; however, some strains have ...

In this study, the microbiological quality of household tap water samples fed from rainwater tanks was assessed by monitoring the numbers of Escherichia coli bacteria and enterococci from 24 households in Southeast Queensland (SEQ), Australia. Quantitative PCR (qPCR) was also used for the quantitative detection of zoonotic pathogens in water samples from rainwater tanks and connected household taps. The numbers of zoonotic pathogens were also estimated in fecal samples from possums and various species of birds by using qPCR, as possums and birds are considered to be the potential sources of fecal contamination in roofharvested rainwater (RHRW). Among the 24 households, 63% of rainwater tank and 58% of connected household tap water (CHTW) samples contained E. coli and exceeded Australian drinking water guidelines of <1 CFU E. coli per 100 ml water. Similarly, 92% of rainwater tanks and 83% of CHTW samples also contained enterococci. In all, 21%, 4%, and 13% of rainwater tank samples contained Campylobacter spp., Salmonella spp., and Giardia lamblia, respectively. Similarly, 21% of rainwater tank and 13% of CHTW samples contained Campylobacter spp. and G. lamblia, respectively. The number of E. coli (P ‫؍‬ 0.78), Enterococcus (P ‫؍‬ 0.64), Campylobacter (P ‫؍‬ 0.44), and G. lamblia (P ‫؍‬ 0.50) cells in rainwater tanks did not differ significantly from the numbers observed in the CHTW samples. Among the 40 possum fecal samples tested, Campylobacter spp., Cryptosporidium parvum, and G. lamblia were detected in 60%, 13%, and 30% of samples, respectively. Among the 38 bird fecal samples tested, Campylobacter spp., Salmonella spp., C. parvum, and G. lamblia were detected in 24%, 11%, 5%, and 13% of the samples, respectively. Household tap water samples fed from rainwater tanks tested in the study appeared to be highly variable. Regular cleaning of roofs and gutters, along with pruning of overhanging tree branches, might also prove effective in reducing animal fecal contamination of rainwater tanks.

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