N-terminal sequence polymorphism in the coagulase gene of Staphylococcus aureus and its potential use as an epidemiological marker

N-terminal DNA sequences of the coagulase gene were amplified from Staphylococcus aureus strain ISP8 (NCTC 8325-4) DNA using the polymerase chain reaction. The amplified DNA product (984 bp) was used to probe SmaI and DraI digested total DNA of methicillin- and multiresistant S. aureus (MRSA) type strains, methicillin-sensitive S. aureus (MSSA) clinical isolates, and community (commensal) isolates. A SmaI fragment of a similar size in all the isolates examined hybridized with the coagulase gene fragment probe. All MRSA isolates, representing closely related (clonal) types, revealed identical coagulase hybridization patterns with DraI digested DNA. MSSA and community isolates closely related to ISP8 by SmaI fragment analysis shared closely related DraI/coagulase hybridization patterns, differing from that identified for the MRSAs. In contrast, the community and MSSA isolates not related to ISP8 as judged by total SmaI fragment polymorphisms, were also diverse in their DraI/coagulase hybridization patterns. In addition, the intensity of the hybridization signal obtained with the MRSA isolates varied significantly (less than) from the other isolates, indicating the presence of multiple and probably different coagulase genes between the isolates. The findings reported here indicate that hybridization analysis using single genes as DNA probes is less discriminant than restriction fragment length polymorphism analysis of the total genome of different isolates.