Simple differentiation of Vibrio cholerae O139 from V. cholerae O1 and non-O1, non-O139 by modified CAMP test

Strong positive CAMP reactions were demonstrated by 121 Vibrio cholerae O139 and 504 El Tor isolates, and weak positive CAMP reactions were shown by 235 non-O1, non O139 isolates when these isolates were tested by a modified CAMP technique. Thirty-five classical biotype V. cholerae O1 isolates included in the tests were all CAMP negative.