DETECTION OF METHICILLIN RESISTANT STAPHYLOCOCCUS AUREUS IN WOUND INFECTION SAMPLES, ANTIBIOTIC SENSITIVITY PATTERN AND MINIMUM INHIBITORY CONCENTRATION (MIC) FOR DAPTOMYCIN

The carriage of Methicillin-resistant Staphylococcus aureus (MRSA) among persons in hospitals, health care settings even without exposure to healthcare in the community is a growing public health challenge. This study aims at finding out the occurrence of Methicillin resistant Staphylococcus aureus isolates from wound infection samples at a tertiary care hospital from January 2013 to June 2013. The samples from wound infection were processed following standard laboratory protocol. Overall 490 Staphylococcus aureus isolates were identified based on colony morphology, Gram stain and coagulase test. Antibiotic susceptibility test was performed by Kirby- Bauer disc diffusion method. The following antibiotics were used. Erythromycin (15mcg), Gentamicin (10mcg), Amikacin (30mcg),Cephalexin(30mcg),Ofloxacin (5mcg), Cefotaxime (30mcg), ciprofloxacin (5mcg), Vancomycin(30mcg) and Linezolid(30mcg).All isolates were tested for Methicillin resistance using Cefoxitin disc diffusion (30mcg) and Oxacillin disc diffusion (1mcg) method according to CLSI guidelines. Cefoxitin zone diameter less than or equal to 21mm was resistant and greater than or equal to 22mm taken as sensitive. Oxacillin zone diameter greater than or equal to13 mm is considered as Methicillin Sensitive Staphylococcus aureus (MSSA), 11to 12 mm as Intermediate, less than or equal to 10 mm as MRSA. Minimum Inhibitory Concentration (MIC) for Daptomycin was tested by E test for 30 MRSA isolates. The observations were recorded and analyzed. Among 490 isolates of Staphylococcus aureus 171(34.89 percent) were detected as MRSA. All the isolates were 100 percent sensitive to Vancomycin and Linezolid. Among 30 isolates of MRSA tested 29(96.66 percent) were sensitive to Daptomycin with MIC of less than or equal to 1mcg per ml. The mecA gene appears to render the cell wall of MRSA more stable which results in the high level of drug resistance. MRSA infections are difficult to treat. So early diagnosis is very useful to treat MRSA. Hand hygiene practices, early diagnosis and effective treatment may help to reduce Methicillin resistant Staphylococcus aureus in Hospitals and Health care facilities and prevent their spread.