Molecular Typing of Methicillin Resistant Staphylococcus aureus Clinical Isolates on the Basis of Protein A and Coagulase Gene Polymorphisms

Abstract EN

Increased frequency of methicillin-resistant Staphylococcus aureus (MRSA) in hospitalized patients requires rapid and reliable characterization of isolates for control of MRSA spread in hospitals.

This study evaluated polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) as a molecular typing technique for MRSA strains on the basis of protein A (spa) and coagulase (coa) gene polymorphisms to verify their ability in assessing the relatedness of isolates.

Seventy-five MRSA isolates, from different ICUs of Alexandria University Main Hospital, were characterized using antibiotyping and PCR-RFLP analysis of coa and spa genes.

Thirty-two antibiotypes were identified.

coa gene PCR generated 3 types and 10 subtypes of band patterns.

HaeIII restriction digestion of amplified coa gene products produced 5 major banding patterns and 12 subtypes.

spa gene PCR products generated 4 major and 11 minor types, and their HaeII restriction digestion showed 5 major and 12 minor banding patterns.

The combined coa and spa RFLP patterns generated 22 combined R types.

Typing using coa PCR and PCR-RFLP had the same discriminatory index (DI) value (0.64), which was comparable to that of both spa PCR and PCR-RFLP techniques (0.68).

The combined grouping increased the DI value to 0.836.

The current study revealed that testing for multiple gene polymorphisms is more useful for local epidemiologic purposes.