A NEW Escherichia coli O-group, O159, associated with outbreaks of enteritis in infants.

An outbreak of enteritis occurred amongst babies in a nursery unit. 25 babies were affected and 5 required intravenous therapy; there were not fatalities. From 24 of the 25 babies affected, an Escherichia coli with a previously undescribed O-antigen was isolated. An outbreak of diarrhoea had taken place in the same hospital a year before and re-examiniation of cultures of E. coli isolated at that time showed that 5 of the 15 babies affected had been excreting E. coli with the same O-antigen. Isolates from 10 of the babies were tested for enterotoxin production in the infant mouse model and 4 gave a positive response. The new O-antigen has been accepted into the international serotyping scheme and has been designated E. coli O159.