Putative new heat-stable cytotoxic and enterotoxic factors in culture supernatant of Escherichia coli isolated from drinking water

Abstract

Enteric infections caused by the ingestion of contaminated water, especially by Escherichia coli, are important to define the virulence properties of these bacteria. Due to frequent infantile diarrhea in the city of Ouro Preto, Minas Gerais state, Brazil, the phenotypic and genotypic diarrheagenic properties of E. coli isolated from drinking water were studied. The culture supernatants of 39 (40%) among a total of 97 E. coli isolates from drinking water were positive by suckling mouse assay and induced cytotoxic effects on Vero cells. The enterotoxic and cytotoxic activities were present in the fraction with less than 10 kDa and were not lost when heated up to 60°C and 100°C for 30 minutes. PCR assays showed that among these 39 Vero cytotoxigenic E. coli, four (10.2%) were positive for ST II (estB) and two (5%) positive for αHly (hlyA). Gene amplification of SLT (stx 1, stx 2), ST I (estA), LT (eltI, eltII), EAST1 (astA), EHly (enhly) and plasmidencoded enterotoxin (pet) were not observed. This heat-stable cytotoxic enterotoxin of E. coli is probably a new putative diarrheagenic virulence factor, as a toxin presenting these characteristics has not yet been described.

Shiga toxin-producing Escherichia coli in drinking water supplies of north Paraná State, Brazil

“…However, STEC has not been commonly detected in drinking water samples in Brazil (Ribeiro et al . ). The recovery of an E. coli O157:H7 strain from a private well located on rural area of São Paulo State (Katsuya et al .…”

“…The occurrence of STEC in drinking water sources has been reported worldwide (Halabi et al 2008;Ram et al 2008), as well as waterborne outbreaks of disease caused by this pathotype (Hrudey et al 2003;Mccall et al 2010;Lienemann et al 2011). However, STEC has not been commonly detected in drinking water samples in Brazil (Ribeiro et al 2011). The recovery of an E. coli O157:H7 strain from a private well located on rural area of São Paulo State (Katsuya et al 1998) was so far the only report of isolation of this pathogen from water sources in this country.…”

Origins and environmental mobility of antibiotic resistance genes, virulence factors and bacteria in a tidal creek's watershed

“…Eight VGs representing enterohemorrhagic (EHEC), enterotoxigenic (ETEC), enteropathogenic (EPEC), extraintestinal pathogenic (ExPEC) and enteroaggregative (EAEC) pathogens were targeted in the study (Ribeiro et al . , Sharma et al . , Yamamoto and Echeverrio ) as shown in Table S2.…”