Identification of the emerging skin pathogen Corynebacterium amycolatum using PCR-amplification of the essential divIVA gene as a target.

The actinomycete Corynebacterium amycolatum is a saprophytic bacterium usually associated with the human skin, but it is at present considered an emergent pathogen as it is isolated from nosocomial settings from samples of immunosuppressed patients. The conventional method to distinguish C. amycolatum from closely related species is mainly based on phenotypic or chemotaxonomic studies. We developed a molecular method to identify rapidly C. amycolatum based on the use of different primers for amplification of the cell division divIVA gene using conventional or real-time PCR. This technique was used for the first time to distinguish C. amycolatum from the closely related Corynebacterium striatum, Corynebacterium minutissimum and Corynebacterium xerosis, without the requirement of further molecular analysis. The suitability of the identification method was tested on 51 clinical isolates belonging to the nonlipophilic fermentative group of corynebacteria (cluster C. striatum/C. amycolatum), which were accurately characterized by sequencing a 0.8 kb fragment of the 16S rRNA gene.