Abstract
An increase in resistance of Staphylococcus aureus to antibiotics; especially methicillin, vancomycin and linezolid; is a growing concern limiting the treatment modalities. The current study was conducted to find out the frequency and antibiotic resistant pattern of methicillin-sensitive and –resistant S. aureus. All the clinical samples received at Diagnostic Microbiological Laboratory PNS Shifa Hospital Karachi were processed. Staphylococci were identified by standard procedures. Methicillin-resistant S. aureus (MRSA) isolated were identified by a slide latex agglutination kit for the detection of penicillin binding protein 2 (PBP 2). Two hundred and fifty six Staphylococcus isolates were recovered from different samples of blood, pus, urine, ear swab, sputum, ascetic fluid, throat swab and pleural fluid. One hundred and forty eight (60.2%) were coagulase positive. Of these, 32 (21.8%) were found to be MRSA. Antibiogram of methicillin-sensitive S. aureus (MSSA) and MRSA was determined by standard Kirby-Bauer disc diffusion method. Co-existence of resistance to other antibiotics with methicillin was also noted in the present study. Vancomycin, linezolid and rifampicin were found to be the most effective drugs against both MRSA and MSSA. Highest resistance was found against penicillin i.e. 81.25% in MRSA and 75% in MSSA. It is concluded that due to the high and changing pattern of resistance of S. aureus, antimicrobial susceptibility testing is mandatory.
