Epidemiological and bacteriological investigation of enterohemorrhagic Escherichia coli infection in the Chugoku-Shikoku area

Abstract

We investigated the occurring tendency of enterohemorrhagic Escherichia coli (EHEC) infection in the prefectural and municipal public health institutes in the Chugoku-Shikoku area from 1996 to 1999, and the bacteriological characteristics of EHEC isolated from these cases. Consequently, epidemiological analysis of the EHEC infection in this district was performed. 22 outbreaks in the various facilities showed the tendency occurred in infants and aged groups, and the serotypes of EHEC isolated from these outbreaks were O26, O111 etc. as well as O157. In 4 cases, EHEC were isolated from specimens of buckwheat noodles, salad, sand box, and goat feces, and these were determined as the source of infection. In 898 sporadic cases, including familial infection, the EHEC isolates were classified into 24 serotypes, and the genotypes of EHEC O157:H7 isolates by pulsed-field gel electrophoresis (PFGE) also varied. Moreover, since many asymptomatic carriers were detected in the adult group with familial infection, the existence of healthy carriers is as important as the source of infection. The drug-resistance test of EHEC isolates showed that 24% of the 924 isolates were resistant to drugs.