Abstract
Citrobacter freundii possessing the common O antigen of Escherichia coli O157 was isolated from 5 (16.7%) of 30 raw fishes, 6 (4.1%) of 148 vegetables, 3 (3.4%) of 89 pieces of raw meat and 1 (0.9%) of 111 other foods during a survey of Shiga toxin-producing E. coli O157. Of 15 C. freundii strains, 13 (including one H2S-negative strain) were atypical because of positivity for both malonate and dulcitol. The results of cross-agglutination and agglutininabsorption tests indicated that the O antigen of C. freundii (both typical and atypical) was almost serologically identical to that of E. coli O157. In addition to a Salmonella O301 strain, isolated C. freundii strains hybridized to the rfbE (encoded E. coli O157 antigen) probe at low hybridization temperature, but did not hybridize at high hybridization temperature.
