Typing of coagulase-negative staphylococci by Southern hybridization of chromosomal DNA fingerprints using a ribosomal RNA probe.

Ribotyping consists of restriction endonuclease fingerprinting of ribosomal RNA (rRNA) genes visualized by Southern hybridization with an rRNA probe. This method was developed and compared with restriction endonuclease fingerprinting of chromosomal DNA for typing coagulase-negative staphylococci. Twenty-five American Type Culture Collection reference type strains and 53 clinical isolates were typed. Both methods clearly distinguished all 15 species of coagulase-negative staphylococci and most individual strains within each species. Except in the case of Staphylococcus warneri, ribotyping was most discriminating with the use of ClaI, one of eight endonucleases tested. HpaI and AvaI were more specific than ClaI for discrimination between strains of Staphylococcus warneri. The patterns produced by ribotyping were much simpler and thus easier to interpret than corresponding chromosomal fingerprints. However, ribotyping was slightly less discriminating. It is concluded that ribotyping offers an alternative method for molecular typing of coagulase-negative staphylococci. The application of both methods needs to be further evaluated in the clinical setting.