Serogroup and Verocytotoxin Productivity of Escherichia coli Isolated from Diarrheal Patients in Korea

Kim, Ho Hoon; Kang, Yeon Ho; Kim, Sung Han; Park, Mi Sun; Yu, Jae Yon; Lee, Bok Kwon

Abstract

BACKGROUND
Since 1982, many countries has reported outbreaks or sporadic cases caused by enterohaemorrhagic Escherichia coli (EHEC) serogroup strains, mainly E. coli O157:H7 type strain. However, systemic investigation about EHEC agents, including E. coli O157:H7, have not been done in Korea. Therefore, we investigated serogroup and verotoxin productivity of E. coli strains isolated from diarrheal patients and estimated risk of human infection in comparison with the EHEC strains isolated from cow, pig, and food material in Korea.
METHODS
Diarrheal patient stool samples were collected and E. coli strains were isolated, according to biochemical characteristics. In order to isolate E. coli O157:H7, D-Sorbitol negative E. coli strains were selected. Serogrouping of the E. coli isolates was done by agglutination test. Verocytotoxin productivity was investigated by polymerase chain reaction (PCR) and reversed passive latex agglutination (RPLA). Human infection risk was estimated in comparison with EHEC strains isolated from cow, pig and food materials in Korea.
RESULTS
Twenty-five E. coli strains were isolated from the diarrheal patients who were suspected to be infected with EHEC. However, none of these E. coli strains produced verocytotoxin. Out of 25 E. coli isolates, 16 serogroups of E. coli O1, O6, O8, O15, O20, O25, O26, O28, O29, O44, O86a, O119, O126, O128, O152 and 157:H- were found. In each of the E. coli O157:H- and O25 serogrorps 3 strains were found.
CONCLUSION
None of 25 E. coli isolated from diarrheal patients who were suspected of EHEC infection produced verocytotoxin producing E. coli have been reported recently in Korea.