Isolation and characterization of Corynebacterium ulcerans from cephalic implants in macaques
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Published on: May 2, 2017
I L Bergin1, C C Chien, R P Marini
1Division of Comparative Medicine, Massachusetts Institute of Technology, Cambridge 02139, USA.
Abstract:
To determine the prevalence of colonization by Corynebacterium ulcerans, we cultured samples from the cephalic implant-skin margin and pharynx of 26 rhesus macaques and one pig-tailed macaque. All but one of the samples from the cephalic implants yielded a mixed population of bacteria. C. ulcerans grew from the cephalic implants in 56% and from the pharynx in 3% of the implanted animals. We screened nine of these isolates for diphtheria toxin (DT) and phospholipase D (PLD). Polymerase chain reactions (PCR) failed to identify DT in any of the tested isolates, which also lacked DT activity in Elek tests. However, all nine isolates tested had PLD toxin activity as determined by conjoint hemolysis on sheep blood agar plates in the presence of equi factor (Rhodococcus equi). In addition, PCR assays and Southern blot hybridization 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 relative clinical importance of this organism and the efficacy of various implant maintenance protocols in preventing infection.
Insights
Corynebacterium ulcerans frequently colonizes cephalic implants in macaques, producing phospholipase D (PLD) but not diphtheria toxin (DT). Further research is needed to understand the clinical significance of this common contaminant.
Area of Science:
- Microbiology
- Veterinary Medicine
- Infectious Diseases
Background:
- Corynebacterium ulcerans can colonize skin and mucous membranes.
- Cephalic implants may serve as a niche for bacterial colonization.
Purpose of the Study:
- To determine the prevalence of Corynebacterium ulcerans colonization on cephalic implants and in the pharynx of macaques.
- To investigate the presence of diphtheria toxin (DT) and phospholipase D (PLD) in C. ulcerans isolates.
Main Methods:
- Bacterial cultures from cephalic implant-skin margins and pharyngeal swabs of macaques.
- Screening of isolates for DT and PLD using PCR, Elek tests, and hemolysis assays.
- Southern blot hybridization to confirm the presence of the pld gene.
Main Results:
- Corynebacterium ulcerans was found in 56% of cephalic implant cultures and 3% of pharyngeal cultures.
- All tested isolates lacked diphtheria toxin but possessed phospholipase D (PLD) activity.
- PCR and Southern blot confirmed the presence of the pld gene in isolates.
Conclusions:
- Corynebacterium ulcerans is a frequent colonizer of cephalic implant sites in macaques.
- The role of PLD in C. ulcerans colonization of implants requires further investigation.
- Clinical significance and effective implant maintenance strategies warrant additional study.
