Occurrence of Intestinal and Extraintestinal Virulence Genes in Escherichia coli Isolates from Rainwater Tanks in Southeast Queensland, Australia

Ahmed, Warish; Hodgers, Leonie; Masters, Nicole; Sidhu, J. P. S.; Katouli, Mohammad; Toze, Simon

doi:10.1128/aem.06047-11

Cited by 41 publications

(37 citation statements)

References 53 publications

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“…isolated from rainwater tank samples (Ahmed et al . , ). Certain E. coli strains from rainwater tank samples harbouring virulence genes were identical to those found in possum and bird faeces (Ahmed et al .…”

Section: Discussionmentioning

confidence: 99%

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Inactivation of faecal indicator bacteria in a roof-captured rainwater system under ambient meteorological conditions

et al. 2013

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Aims: In this study, faecal indicator bacteria (FIB) namely Escherichia coli and Enterococcus spp. were seeded into slurries of possum faeces and placed on the roof and in the gutter of a roof-captured rainwater (RCR) system. The persistence of FIB in these circumstances was determined under ambient climatic conditions. FIB persistence was also determined under in situ conditions in tank water using diffusion chambers. Methods and Results: The numbers of surviving FIB at different time intervals were enumerated using culture-based methods. Both FIB were rapidly inactivated on the roof under sunlight conditions (T 90 = 2 h) compared with shade conditions (T 90 = 9-53 h). Significant differences were observed between sunlight and shade conditions on the roof for both T 90 values of E. coli (P < 0Á001) and Enterococcus spp. (P < 0Á001). E. coli showed biphasic inactivation patterns under both clean and unclean gutter conditions. Enterococcus spp., however, showed rapid inactivation (T 90 = 2 h for the clean gutter and T 90 = 6 h for the unclean gutter) compared with E. coli (T 90 = 22 h for the clean gutter and T 90 = 20 h for the unclean gutter). Significant differences were also observed between the T 90 values of E. coli and Enterococcus spp. for both clean (P < 0Á001) and unclean (P < 0Á001) gutters. Both E. coli and Enterococcus spp. showed nonlinear biphasic inactivation in tank water. Significant difference was observed between the T 90 value of E. coli inactivation compared with Enterococcus spp. (P < 0Á001) in the tank water. Conclusions: In this study, FIB were observed to survive longer (T 90 = 9-53 h) on the roof under shade conditions compared with sunlight conditions (T 90 = 2 h). If there is a rainfall event within two to three days after the deposition of faecal maters on the roof, it is highly likely that FIB would be transported to the tank water. When introduced into the tank, a relatively slow inactivation process may take place (T 90 = 38-72 h). Significance and Impact of the Study: The presence of FIB in water indicates faecal pollution and potential presence of enteric pathogens. Therefore, the information on the resilience of FIB, as obtained in this study, can be used for indirect assessment of health risks associated with using roof-captured rainwater for potable and nonpotable purposes.

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Section: Discussionmentioning

confidence: 99%

“…Recent studies have also reported the presence of clinically significant virulence genes associated with FIB in rainwater tank samples in SEQ (Ahmed et al . , ). Questions have, therefore, arisen regarding the persistence of FIB and pathogens in rainwater tank samples as well as in faecal deposits on the roof and in the gutter.…”

Section: Introductionmentioning

confidence: 99%

Inactivation of faecal indicator bacteria in a roof-captured rainwater system under ambient meteorological conditions

et al. 2013

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“…The majority of the environmental strains carrying estII and eltA genes also harbored genes such as hlyA and iroN E.coli , which are responsible for acquisition of iron and are commonly found among UPEC strains. Recently a number of studies have detected the presence of these and other VGs belonging to UPEC in surface and rain tank waters (1). Similarly, Masters et al (38) found a high level of these and other VGs in all three water types.…”

Section: Discussionmentioning

confidence: 99%

Pathogenic Escherichia coli Found in Sewage Treatment Plants and Environmental Waters

Anastasi

Matthews

Stratton

et al. 2012

Appl Environ Microbiol

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cWe previously demonstrated that some Escherichia coli strains with uropathogenic properties survived treatment stages of sewage treatment plants (STPs), suggesting that they may be released into the environment. We investigated the presence of such strains in the surrounding environmental waters of four STPs from which these persistent strains were isolated. In all, 264 E. coli isolates were collected from 129 receiving water sites in a 20-km radius surrounding STPs. We also included 93 E. coli strains collected from 18 animal species for comparison. Isolates were typed using a high-resolution biochemical fingerprinting method (the PhPlate system), and grouped into common (C) types. One hundred forty-seven (56%) environmental isolates were identical to strains found in STPs' final effluents. Of these, 140 (95%) carried virulence genes (VGs) associated with intestinal pathogenic E. coli (IPEC) or uropathogenic E. coli (UPEC) and were found in a variety of sites within areas sampled. Of the remaining 117 environmental strains not identical to STP strains, 105 belonged to 18 C types and 102 of them carried VGs found among IPEC or UPEC strains. These strains belonged mainly to phylogenetic groups A (A0 and A1) and B1 and to a lesser extent B2 2 , B2 3 , D1, and D2. Eight of 18 environmental C types, comprising 50 isolates, were also identical to bird strains. The presence of a high percentage of environmental E. coli in waters near STPs carrying VGs associated with IPEC and UPEC suggests that they may have derived from STP effluents and other nonpoint sources.

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“…The detection of the intimin eae gene in EPEC could indicate the presence of Shiga-toxin producing E. coli, since this gene is found in more than one pathotype (34). The ingestion of EPEC, however, causes watery diarrhea that is associated with vomiting and low fever (12), whereas EHEC represents one of the most pathogenic E. coli groups that have the ability to cause bloody diarrhea, with little or no fever.…”

Section: Discussionmentioning

confidence: 99%

Prevalence of Virulence Genes Associated with Pathogenic Escherichia coli Strains Isolated from Domestically Harvested Rainwater during Low- and High-Rainfall Periods

Dobrowsky

Deventer

Kwaadsteniet

et al. 2014

Appl Environ Microbiol

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bThe possible health risks associated with the consumption of harvested rainwater remains one of the major obstacles hampering its large-scale implementation in water limited countries such as South Africa. Rainwater tank samples collected on eight occasions during the low-and high-rainfall periods (March to August 2012) in Kleinmond, South Africa, were monitored for the presence of virulence genes associated with Escherichia coli. The identity of presumptive E. coli isolates in rainwater samples collected from 10 domestic rainwater harvesting (DRWH) tanks throughout the sampling period was confirmed through universal 16S rRNA PCR with subsequent sequencing and phylogenetic analysis. Species-specific primers were also used to routinely screen for the virulent genes, aggR, stx, eae, and ipaH found in enteroaggregative E. coli (EAEC), enterohemorrhagic E. coli (EHEC), enteropathogenic E. coli (EPEC), and enteroinvasive E. coli, respectively, in the rainwater samples. Of the 92 E. coli strains isolated from the rainwater using culture based techniques, 6% were presumptively positively identified as E. coli O157:H7 using 16S rRNA. Furthermore, virulent pathogenic E. coli genes were detected in 3% (EPEC and EHEC) and 16% (EAEC) of the 80 rainwater samples collected during the sampling period from the 10 DRWH tanks. This study thus contributes valuable information to the limited data available regarding the ongoing prevalence of virulent pathotypes of E. coli in harvested rainwater during a longitudinal study in a high-population-density, periurban setting.

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Occurrence of Intestinal and Extraintestinal Virulence Genes in Escherichia coli Isolates from Rainwater Tanks in Southeast Queensland, Australia

Cited by 41 publications

References 53 publications

Inactivation of faecal indicator bacteria in a roof-captured rainwater system under ambient meteorological conditions

Inactivation of faecal indicator bacteria in a roof-captured rainwater system under ambient meteorological conditions

Pathogenic Escherichia coli Found in Sewage Treatment Plants and Environmental Waters

Prevalence of Virulence Genes Associated with Pathogenic Escherichia coli Strains Isolated from Domestically Harvested Rainwater during Low- and High-Rainfall Periods

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