A CAMP phenomenon between Vibrio cholerae biotype El Tor and staphylococcal B-hemolysin

A CAMP phenomenon was demonstrated by Vibrio cholerae biotype El Tor and B-lysin producing Staphylococcus aureus in 5% sheep red blood cells-tryptic soy agar medium. All 394 El Tor vibrio strains tested, all showed a crescent-shaped hemolysis (positive CAMP) when the cultures were incubated in a candle jar whereas 67% were CAMP positive when incubated aerobically. Only 9% of the isolates produced detectable hemolysin in a standard tube test using heart infusion broth and 72% in a tube test using heart infusion broth containing 1% glycerol. Seven classical V. cholerae tested were CAMP negative. The CAMP reaction is easy to perform and may be useful for routine use in the differentiation of V. cholerae biotype El Tor from classical V. cholerae.