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

Abstract

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.

A review on physicochemical and microbiological contamination of roof-harvested rainwater in urban areas

“…Apart from these, other studies assessing the quality of harvested rainwater are available for different parts of the world: Lye (1987) in Kentucky-USA, Fujioka et al (1991) in Hawaii, Coombes et al (2000) in NSW-Australia, Handia (2005) in Zambia, Hernandes and Vieira (2005) in Southeast Brazil, Peters et al (2008) in Bermuda, Ahmed et al (2009) in SEQAustralia, Daoud et al (2011) in Palestine, Gikas and Tsihrintzis (2012) in Northeast Greece, Shuster et al (2013) in Ohio-USA, Van der Sterren et al (2013) in Sydney, and Dobrowsky et al (2014aDobrowsky et al ( , 2014b in WC-South Africa. Finally, a summary of the reports on the chemical and biological quality of harvested rainwater tanks can be found in Kwaadsteniet et al (2013).…”

Public health risks associated with Enteroaggregative Escherichia coli (EAEC) as a food‐borne pathogen

“…Genes from the ETEC, EPEC and STEC pathotypes were detected consistently, but genes from the EIEC and EAEC pathotypes were only found occasionally, and never in the rainy season or in winter (Akter et al, 2013). EAEC was found in 16% of 80 samples from domestic rainwater harvest tanks during a longitudinal study in a high-population-density, urban setting and in river water samples in South Africa (Obi et al, 2004;Dobrowsky et al, 2014). In a study of pre-treated water in a drinking water treatment plant in Taiwan, EAEC-associated genes were found in 3.6% of 55 water samples, alongside with high levels of other potentially pathogenic E. coli (Huang et al, 2011).…”

White Teeth and Healthy Skeletons for All: The Path to Universal Fluoride-Free Drinking Water in Tanzania

“…Moreover, in fluoride prone areas such as AERV, rainwater is expected to have lower concentrations of toxic geogenic contaminants such as F, U, As, and heavy metals than groundwater. However, a number of studies have shown that rainwater may contain potentially toxic physicochemical and microbial contaminants [69][70][71][72][73][74].…”

“…The bulk of contaminants reported in rainwater are often acquired from atmospheric deposition, roof materials, and conveyance and storage facilities [69][70][71][72][73][74]. A study by Gwenzi et al [75] presents a detailed discussion of the occurrence of various contaminants in roof rainwater, and the key factors influencing its quality, including nature and age of roof materials, weather conditions and land use practices.…”