Molecular Identification of mecA gene in Methicillin-Resistant Staphylococcus aureus Isolated from the Hospitalized Patients in Teaching Hospitals of Ahvaz, Iran

Aims: Staphylococcus aureus is a causative agent of nosocomial infections. Methicillin is one of the most important antibiotics that is used in treatment of S. aureus infections; however, resistance to this antibiotic has occured in recent years. The aim of this study was detection of mecA gene in methicillin-resistant S. aureus (MRSA) strains which were isolated from the hospitalized patients.
Methodology: In this study, 255 Staphylococci isolates were collected from the patients with infection in three teaching hospitals. These strains were isolated from different specimens and identified using microscopic and standard biochemical tests. S. aureus strains phenotypically resistant to oxacillin, were screened after determination of drug resistance patterns against 9 antibiotics by disk diffusion method based on CLSI guidelines. Then, DNA was extracted from phenotypic MRSA strains and finally mecA gene was amplified by PCR.
Results: Out of 255 Staphylococci isolates collected from the patients with infection, 180 isolates were confirmed as S. aureus. The results of the antibiogram test revealed the highest and lowest rate of resistance against gentamicin and nitrofurantoin, respectively. These results also showed that out of 180 isolates of S. aureus, 59 isolates (32.7%) were identified phenotypically as MRSA and mecA gene was confirmed in 58 of them by PCR method.
Conclusion: The results of our study showed high prevalence of HA-MRSA isolates among of the examined patients, as nearly one third of these isolates were resistant to methicillin. So, for prevention of the spread of Health care- associated MRSA infection, it is necessary to augument control measures of hospitals and it is recommended that the patients with staphylococcal infection be treated only after verification of drug sensitivity of isolates by clinical laboratories.