SUMMARY Eighteen isolates of enterotoxigenic Escherichia coli ( etec ) and 15 isolates of nonenterotoxigenic E coli ( netec ) obtained from calves with diarrheal disease were characterized biochemically. Of 64 biochemical tests employed, none allowed making differentiation of etec from netec . Eleven tests were used to separate etec isolates into 1 of 5 biotypes, although the ability to ferment dulcitol, salicin, sucrose, and sorbose gave sufficient information to identify the 5 biotypes of etec . The biotype data were confirmed upon testing 159 additional isolates of etec of bovine origin. All isolates of etec studied belong to serogroups 09:K35, O101:K30, O8:K85, O20:K?, O8:K25, and O101:K28. The etec in different serogroups were also different biotypically, with the exception that isolates in serogroups O101:K28 and O101:K30 were of the same biotype. The K99 antigen was detected in 172 of the 177 isolates of etec and in 1 of 15 isolates of netec . Marked biochemical differences were not found between K99+ and K99-isolates of E coli.
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Braaten et al. (1977) studied this question.