Abstract
BackgroundAfter E. coli O157, E. coli O26 is the second most prevalent enterohaemorrhagic E. coli (EHEC) serotype identified in cases of foodborne illness in Australia and throughout the world. E. coli O26 associated foodborne outbreaks have drawn attention to the survival capabilities of this organism in a range of environments. The aim of the present study was to assess the ability of E. coli O26 to survive the effects of disinfectants, acids and antimicrobials and investigate the possible influence of virulence genes in survival and persistence of E. coli O26 from human and cattle sources from Australia.ResultsInitial characterization indicated that E. coli O26 are a genetically diverse group that were shown to belong to a number of pathotypes. Overall, 86.4% of isolates were susceptible to all antimicrobials tested with no significant differences in resistance observed between pathotypes. A representative subset of isolates (n = 40) were selected to determine their ability to survive disinfectants at proposed industry working concentrations and acid stress. Profoam, Kwiksan 22, and Topactive DES. were able to inhibit the growth of 100% of isolates. The remaining three disinfectants (Dairy Chlor 12.5%, Envirosan and Maxifoam) were not effective against the subset of 40 E. coli O26. Finally, elevated MICs (1,024 to 4,096 μg/ml) of acetic, propionic, lactic, and citric acids were determined for the majority of the isolates (85%).ConclusionsAustralian E. coli O26 isolates belong to a range of pathotypes that harbor differing virulence markers. Despite this, their response to antimicrobials, disinfectants and acids is similar confirming that stress response appears unrelated to the presence of EHEC virulence markers. Notwithstanding, the tolerance to disinfectants and the elevated acid MICs for EHEC and the other E. coli O26 pathotypes examined in this study may contribute to bacterial colonization on food contact surfaces and subsequent foodborne illness caused by this pathogen.
Highlights
After E. coli O157, E. coli O26 is the second most prevalent enterohaemorrhagic E. coli (EHEC) serotype identified in cases of foodborne illness in Australia and throughout the world
Enterohaemorrhagic Escherichia coli (EHEC) strains have been associated with a number of food-borne outbreaks which have led to life threatening sequelae such as hemolytic uremic-syndrome (HUS) and hemolytic colitis (HC) [1,2,3]
Among the non-O157 serotypes, E. coli O26:H11 is one of the major serotypes of concern [3, 6]. It is not completely understood which suite of bacterial virulence determinants are most necessary for E. coli O26 to cause disease in humans, isolates recovered from human clinical samples typically possess
Summary
After E. coli O157, E. coli O26 is the second most prevalent enterohaemorrhagic E. coli (EHEC) serotype identified in cases of foodborne illness in Australia and throughout the world. Epidemiological surveillance indicates that E. coli of O157:H7 serotype is the most frequently It is not completely understood which suite of bacterial virulence determinants are most necessary for E. coli O26 to cause disease in humans, isolates recovered from human clinical samples typically possess. It has been recognised that cattle represent a major reservoir of E. coli O26 [11,12,13] Exposure to this pathogen can occur by a variety of routes including contact with animals on farms, consumption of contaminated meat, milk and its derivatives, water, spinach, sliced watermelon, clover sprouts, blueberries and strawberries [11, 14,15,16,17,18,19,20]. Multistate outbreaks of EHEC O26 infections in the USA have been reported by the CDC in 2010, 2011, 2013 and 2015 [16, 17, 28]
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