Abstract

Staphylococcus aureus protein A coding gene (spa) is a proper gene for typing of S. aureus and used to trace in the epidemiological studies. The aim of this study was to explore the typing of S. aureus by polymerase chain reaction restriction fragment-length polymorphism (PCR-RFLP) spa gene. Hae II restriction enzyme (Fermentase Co, Germany) method was used to digest PCR product of spa gene of 178 S. aureus which was isolated from carrier and healthy subjects within Gorgan located in the northern Iran. 3 to 10 samples from each spa types were sequenced (ABI Big Dye Biosystems, CA, USA). The statistical comparison of findings was done by X², the p<0.05 was considered as significant. The S. aureus results were divided in 3 groups and 8 types by PCR-RFLP spa gene. The group 1 (3 bands), group 2 (2 band) and group 3 (4 band) with following ratios 69.7%, 26.4% and 3.9%, were detected respectively. Groups 1, 2 and 3 consist of 2, 3, 3 types, respectively. 20.8% of isolated S. aureus did not have either of A or B IgG binding region. The group 3 only was seen on the healthy carrier. The frequency of aforementioned groups among the patients and healthy carrier showed to have a significant difference (p<0.001). In conclusion, Hae II enzyme can be applied perfectly for typing of S. aureus. Due to deletion of either A or B IgG binding regions of spa in some isolated S. arueus, it is suggested to use spa PCR –RFLP HaeII enzyme for S. aureustyping simultaneously with spa Xr typing.

Key words: Staphylococcus aureus, protein A, spa, typing, polymerase chain reaction restriction fragment-length polymorphism (PCR-RFLP).