Frequency and distribution of diarrhoeagenic Escherichia coli strains isolated from pediatric patients with diarrhoea in Bosnia and Herzegovina.

Diarrhoeal disease is a major cause of illness and death among infants and young children worldwide. Among the Escherichia coli (E. coli) causing intestinal diseases, there are six well-described categories: enteroaggregative E. coli (EAEC), diffusely adherent E. coli (DAEC), enteroinvasive E. coli (EIEC), enteropathogenic E. coli (EPEC), enterohaemorrhagic E. coli (EHEC) and enterotoxigenic E. coli (ETEC). The aim of the present study was to investigate the relative contribution of different groups of diarrhoeagenic E. coli (DEC) in paediatric patients with diarrhoea. Clinical stool specimens from 380 children with diarrhoea, with ages ranging from birth to < 12 years, were selected for the study over a period of 17 months (August 2007 to December 2008). The study showed that 85/380 children (22%) had diarrhoea due to diarrhoeagenic E. coli. The most prevalent was enteropathogenic E. coli (EPEC) isolated from 46/85 paediatric patients (54%), followed by enterotoxigenic (ETEC) isolated from 19/85 (22.3%), enterohaemorrhagic (EHEC) from 18/85 (21.1%) and enteroinvasive (EIEC) from 2/85 patients (2.3%). The most prevalent serotypes of EPEC were O86:K61 and O44:K74 isolated from 10/46 (21.7%), O128:K67 from 6/46 patients (13%), followed by O158:K- and O126:K71 isolated from 4/46 patients (8.6%). Among the ETEC the most prevalent serotypes were O78:K80 isolated from 10/19 (56.7%) and O25:K11 from 9/19 patients (47.3%), especially during the first twelve months: 9/19 patients (47.3%). The most prevalent EHEC strain found in this study was O145:K- and O103:K-: 5/18 patients (27.8%). Two isolated strains of EIEC belong to serotype O164:K-. The average age of the patients was 2 years. Two patients with bloody diarrhoea had EHEC serotype O157:H7 which progressed to haemolytic-uremic syndrome (HUS). Our study shows that diarrhoeagenic E. coli is a significant causal agent of diarrhoeal diseases in paediatric patients in Bosnia and Herzegovina. This study is the first report about the frequency and most common serotypes of DEC in Bosnia and Herzegovina. Additionally, it is the first report of cases with an O157:K- infection which progressed to HUS, a serious and potentially fatal illness.