Isolation and characterization of Corynebacterium ulcerans from cephalic implants in macaques

To determine the prevalence of colonization by Corynebacterium ulcerans, we cultured samples from the cephalic implant-skin margin and pharynx of 26 r hesus macaques and one pig-tailed macaque. All but one of the samples from the cephalic implants yielded a mixed population of bacteria. C, ulcerans g rew from the cephalic implants in 56% and from the pharynx in 3% of the imp lanted animals. We screened nine of these isolates for diphtheria toxin (DT ) and phospholipase D (PLD), Polymerase chain reactions (PCR) failed to ide ntify DT in any of the tested isolates, which also lacked DT activity in El ek tests. However, all nine isolates tested had PLD toxin activity as deter mined by conjoint hemolysis on sheep blood agar plates in the presence of e qui factor (Rhodococcus equi). In addition, PCR assays and Southern blot hy bridization confirmed the presence of pld in the isolates. The role of the PLD toxin in promoting colonization of cephalic implants by C. ulcerans is unknown. We found C, ulcerans to be a frequent contaminant of the cephalic implant-skin margin. Further studies are necessary to investigate the relat ive clinical importance of this organism and the efficacy of various implan t maintenance protocols in preventing infection.