Analysis of genetic relationships and antimicrobial susceptibility of verotoxin-producing Escherichia coli strains isolated in Nagasaki Prefecture, Japan in 1996.

A total of 19 Escherichia coli O157 isolates were obtained in Nagasaki Prefecture, in the southwestern part of Japan, between 1990 and 1996, Pulsed-field gel electrophoresis (PFGE) and computer-assisted analysis were applied to determine genetic relationships among these strains. Fragment patterns of the isolates in Nagasaki, as determined by PFGE, were compared with those of isolates in other areas where large outbreaks and sporadic cases of E. coli O157 infection occurred. Similarity values of all the strains isolated in Nagasaki Prefecture were over 0.65 except for E, coli O26, Some strains were identical to the strains isolated from the areas where large outbreaks occurred. All strains were susceptible to ampicillin, fosfomycin, minocycline, amikacin, ofloxacin and sulfamethoxazole-trimethoprim.