Typing of Staphylococcus aureus and Staphylococcus epidermidis strains by PCR analysis of Inter-IS256 spacer length polymorphisms

IS256 elements are present in multiple copies in the staphylococcal genome, either flanking the transposon Tn4001 or independent of it, PCR-based analysis of inter-IS256 spaces polymorphisms was developed for typing of methicillin-resistant Staphylococcus aureus (MRSA) and Staphylococcus epidermidis strains, Using SmaI macrorestriction analysis resolved by pulsed-field gel electrophoresis (PFGE) as the reference method for MRSA typing, excellent reproducibility (100%), discriminatory power (97%), and in vivo stability were observed, Good concordance of the results with those of other molecular typing methods rues found for two MRSA collections, Inter-IS256 PCR analysis of a U.S. collection of MRSA strains (n = 36), previously characterized by 15 typing methods, showed more limited discrimination, Agreement was 78% with PFGE analysis and 83% with ribotyping (HindIII), Analysis of a second set of Belgian MRSA strains (n = 17), categorized into two widespread epidemic clones by PFGE analysis, showed 65% agreement, Far typing of S. epidermidis strains (n = 26), inter-IS256 PCR showed complete typeability (100%) and good discriminately power (85%), Inter-IS256 PCR analysis is proposed as an efficient molecular typing assay for epidemiological studies of MRSA or S. epidermidis isolates.