Positive camp-phenomenon elicited by coagulase-negative staphylococci

Abstract

Fifty out of sixty-five isolates of coagulase-negative staphylococci displayed a positive CAMP-reaction due to synergism of an extracellular toxin with S. aureus beta-toxin on sheep erythrocytes. Of the CAMP-positive isolates, 40 were identified as S. epidermidis, 8 as S. hemolyticus, and 2 each as S. hominis and S. saprophyticus. CAMP-positivity did not appear to be an indication of pathogenicity, and the incidence of CAMP-positive strains derived from wound infections did not differ from that found in clinically insignificant isolates. In five cases of mixed wound infection with S. aureus and a CAMP-positive S. epidermidis, no synergism between the toxins of the respective, paired isolates could be demonstrated since the S. aureus strains in these cases did not produce beta-toxin. The results show that most coagulase-negative staphylococci produce one or more toxins, possibly delta-toxin, detectable by the CAMP-reaction. The biological significance of toxin production remains to be elucidated.