Prevalence and Antibiogram Studies of Hospital Aquired Methicillin Resistant

Staphylococcus aureus

from Irrua Specialist Teaching Hospital, Irrua, Edo State, Nigeria

Methicillin-resistant

Staphylococcus aureus

(MRSA) is one of the main causative agents of nosocomial and environmental infections which pose a major threat to health-care delivery. The aim of this study was to determine the prevalence and antibiogram studies of Hospital acquired methicillin resistant

Staphylococcus aureus

(HA-MRSA) isolates from Irrua Specialist Teaching Hospital (ISTH). A total of 310 nasal, fomite and wound swabs were collected from different departments in ISTH. Swabs were cultured on Mannitol salt agar and incubated at 37°C for 24 hours for presumptive growth of

Staphylococcus aureus

. Gram staining and biochemical tests were conducted and the isolates were subcultured on Oxacillin Resistant Screening Agar Base for growth of MRSA. These were further screened for methicillin resistance by subjecting isolates through Oxacillin single disc and other classes of antibiotics. Molecular studies was done using the polymerase chain reaction to target some genes, using specific primers to detect,

nuc,

mecA, blaZ, pvl

and SCC

mec

. Isolates were assayed for some virulent factors comprising biofilm, haemolysin and DNase. Results from this study revealed that HA-MRSA had a prevalence of 27%. On the distribution of isolates within ISTH and according to specific source, the prevalence in decreasing order were fomites (32%), cleaners (24%), nurses (19%), patients (13%), and doctors (12%). The results revealed that 38% of HA-MRSA possessed the

nuc

gene. Of the three genes amplified on all isolates, 62% possessed the

mec

A gene, 43% had

blaZ,

gene while 10% had

pvl

gene. Findings from this study shows that 12% of the isolates had CA-MRSA associated SCC

mec

IV. From the distribution of the SCC

mec

and

pvl

, it is evident that there is a drift of genetic material influx from CA-MRSA to HA-MRSA strains. Inference from this study also shows that some MRSA isolates possessing the targeted genes correlates with HA-MRSA isolates with higher MAR index. Results revealed that 96% of the HA-MRSA were resistant to cloxacillin, while varying percent of the isolates were resistant to ciprofloxacin, gentamincin, tetracycline and erythromycin. Vancomycin and Linezolid were the best drug of choice. The multiple antibiotic resistant (MAR) index shows that some isolates had greater MAR index ranging between 0.2 - 0.4 and MAR index > 0.2 is a high risk source of antibiotic usage. In conclusion, most of the isolates recovered in this study had high MAR index, which is an indication of antibiotic overuse within the hospital sampled. Hence, the need for strict antibiotic stewardship.