Different molecular methods for typing of Staphylococcus aureus; A special focus on spatyping

Staphylococcus aureus, as leading cause of community-acquired and nosocomial infections, remains a major health problem around the world. Molecularcharacterization is used for the rapid identification of prevalent strains and will contribute to the control and prevention of S. aureusin healthcare settings. Pulsedfield gel electrophoresis (PFGE) is the most recent gold standard method for the typing of S. aureus isolates. However, due to its laborious character and difficulties in exchanging data between laboratories, and the requirement for inter-laboratory standardization, PFGE was replaced by multi-locus sequence typing (MLST) and staphylococcal protein A (spa) typing. MLST is a great tool for evolutionary investigations and differentiates isolates according to nucleotide variations in 7 housekeeping genes. Spa typing, which relies only on the assessment of the number of and sequence variation in repeats at the x region of the spa gene, exhibits excellent discriminatory power and has become a useful typing tool in terms of ease of performance, cheaper procedure, andstandardized nomenclature. According to the literature, the prevalence of spa types among S. aureus isolates varies in different areas worldwide. The most prevalent spa types are t032, t008 and t002 in Europe; t037 and t002 in Asia; t008, t002, and t242 in America; t037, t084, and t064 in Africa; andt020 in Australia. In Europe, all the isolates related to spa type t032 were MRSA. Inaddition, spa type t037 in Africa and t037and t437 in Australia also consisted exclusivelyof MRSA isolates.