Abstract
Thirty-five strains of verotoxin-producing Escherichia coli (VTEC) isolated mainly from diarrheal calves in Okinawa Prefecture between 1994 and 1997 were investigated for biological properties. The VTEC belonged to 6 serogroups-O111 (8 strains), O26 (4 strains), O157 (2 strains), O113 (1 strain), O119 (1 strain), O124 (1strain), rough (6 strains), and 12 untypable strains. Verotoxin typing by means of gene analysis using the polymerase chain reaction (PCR) showed that 26 strains (74.3%) carried VT1 genes and 8 (22.9%) carried VT2 genes. The eaeA gene was detected in 16 strains (45.7%) and the hlyA gene in 17 strains (48.6%), though negative results were obtained for both the bfpA gene and the aggR gene. Twenty-three strains (65.7%) were resistant to at least 1 of the 10 tested antibiotics, and 1 strain demonstrated multiple resistance to 7 antibiotics. All isolates possess from 1 to 6 plasmids. The 0157: H7 strain possessed the 90-kb virulence plasmid and several smaller plasmids.
