The comparison of Staphylococcus aureus types 5 and 8 with respect to methicillin resistance in patients admitted to Al-Zahra Hospital by PCR.

BACKGROUND

Staphylococcus aureus is a common human pathogen in community- and hospital-acquired infection, and its capsule is involved in pathogenesis. The predominance of 2 capsular polysaccharides types 5 and 8, on the surface of clinical isolates, led to the development of conjugate vaccine (Staph VAX) based on capsular polysacchrides types 5 and 8 conjugated to a carrier protein. The aim of this study was to determine the prevalence of capsular polysaccharides types 5 and 8 Staphylococcus aureus strains among isolates and their comparison with respect to methicillin resistance.

MATERIALS AND METHODS

We studied the capsular genotypes of 193 isolates that encompassed both hospital- and community-acquired infection in Al-Zahra Hospital of Isfahan city from 2008 to 2009. Cap5 and 8 genes were detected by PCR method. Methicillin resistance was determined by PCR (mecA) and disk diffusion methods as well.

RESULT

In this population (193 cases), most of the clinical isolates (73%) expressed capsular polysaccharide type 5 (24%) and 8 (49%), whereas 27% were non-typeable. The prevalence of MRSA in type 8 was 67.9%, whereas MRSA isolates in the capsular genotype 5 were 22.2%.

CONCLUSION

This study Staphylococcus aureus confirms that the prevalence of capsular polysaccharide types (5 and 8) are predominant, and Staphylococcus aureus type 8 is more resistant to methicillin compared to type 5.