Molecular analysis of the coagulase gene in clinical and nasal carrier isolates of methicillin-resistant Staphylococcus aureus by restriction fragment length polymorphism.

Abstract

The coagulase enzyme, encoded by the coa gene, is an important virulence factor of Staphylococcus aureus and can be used for typing of S. aureus isolates. In this study, coa gene typing was used to study the epidemiology of S. aureus at a university hospital in Hamadān (Iran). A total of 200 S. aureus strains were analysed, among which 150 were isolated from clinical samples and 50 were from nasal swab specimens of carriers. Methicillin resistance was confirmed by presence of the mecA gene by PCR. For polymorphism analysis, the coa gene was amplified by PCR and the products were subjected to restriction digestion using the enzyme AluI. Amplification of the coa gene produced five classes of bands based on size, ranging from 300bp to 800bp. The 600-bp amplicon included coa 3 genotype predominated in S. aureus isolated from clinical and carrier specimens (150/200; 75.0%). AluI digestion of the PCR products produced eight distinct restriction fragment length polymorphism (RFLP) patterns, designated coa 1-8. The results showed that the 700-bp and 800-bp amplicons formed two (coa 4a and 4b) and three (coa 5a, 5b and 5c) patterns following AluI digestion, respectively, whereas the 300-, 500- and 600-bp fragments generated unique patterns designated coa 1, coa 2 and coa 3, respectively. This study performed coagulase typing, a technique used to determine the molecular epidemiology of S. aureus clinical isolates. coa gene amplification has been considered a simple and accurate method for typing of S. aureus.