Diarrheagenic Escherichia coli in acute gastroenteritis in infants in North-West Italy

Enteropathogenic Escherichia coli may cause diarrhoea in infancy, but it is not routinely detected and regarded as a major causative agent. The aim of the present study was to estimate the incidence of enteropathogenic E. coli infection and to investigate its epidemiology and pathogenesis from faecal specimens in infants hospitalized for acute gastroenteritis. Between March 2008 and June 2009, faecal samples were collected and examined to recognize diarrhoeal aetiology, especially for E. coli, by cultural identification and multiplex-PCR. E. coli were isolated in 75 of 160 collected samples (46,88%); 10 samples of which (6,3%) had been positively recognised for pathogenic genes. Data showed that the presence of diarrheagenic E. coli infection was 6.3%, but it becomes 5% considering E. coli as a unique agent responsible for diarrhoea. The datum is not statistically meaningful because of the small sample (p>0,05). Bacterial pathogens were also isolated in 60 samples (37,5% of the total collected samples): 15 Salmonella spp., 8 Klebsiella pneumoniae, 9 Klebsiella oxytoca, 11 Citrobacter freundii, 5 Pseudomonas aeruginosa, 2 Serratia spp., 7 Enterobacter cloacae, 1 Shigella spp., 2 Campylobacter spp. Rotavirus was the predominant pathogenic single etiologic agent identified. It was found in 35 samples (21.88% of the overall collected samples), while Adenovirus, serotypes 40 or 41, was isolated in 2 samples (1.3%). Rotavirus infection was found predominantly in winter with respect to autumn. Data provide an interesting epidemiologic survey of enteropathogenic E. coli, which is not usually detected, although it may have potential clinical implications. Abbreviations: CDEC, detaching E. coli; DAEC, diffusely adherent E. coli; EAggEC, enteroaggregative E. coli; EHEC, enterohaemorrhagic E. coli; EIEC, enteroinvasive E. coli; EPEC, enteropathogenic E. coli; ETEC, enterotoxigenic E. coli.