Antibiotic sensitivity pattern of Staphylococcus aureus in a tertiary care hospital of Sri Lanka.

The aim of this study was to determine the antibiotic sensitivity pattern of Staphylococcus aureus in a tertiary care hospital of Sri Lanka. S aureus isolated from patient samples received during the period April to December 2010 were identified by standard methods. The antimicrobial susceptibility testing was performed using the standard disc diffusion method recommended by the Clinical and Laboratory Standards Institute 2008. Of 431 S aureus isolates from all specimens received during this period, 203(47%) were methicillin resistant (MRSA), 45 of which were from screening swabs. Of the 210 methicillin sensitive S aureus (MSSA) isolates tested for penicillin sensitivity, 83% were resistant. Erythromycin and clindamycin sensitivity were tested in 149 isolates with 30.9% and 17.5% resistance respectively. Resistance to ciprofloxacin was 12% in 108 isolates tested. Erythromycin, clindamycin and ciprofloxacin were not tested for all the isolates due to non-availability of antibiotic discs. Erythromycin and clindamycin resistance in 164 MRSA isolates was 79% and 72% respectively. Ciprofloxacin resistance in 125 MRSA isolates tested was 54%. Gentamicin resistance of 44% (n=127 isolates) and cotrimoxazole resistance of 48% (n=158 isolates) was noted. All MRSA isolates were sensitive to vancomycin, teicoplanin and linezolid. There were 18 isolates of S aureus from blood cultures of 16 patients. Only 2 of 17 isolates tested were sensitive to penicillin. 7 of 18 (38.9%) isolates were MRSA. 50% of these isolates were resistant to erythromycin while 25% were resistant to clindamycin. 23.5% were resistant to ciprofloxacin. Of the 45 strains isolated from screening swabs, 18% were MRSA. As a high proportion of S aureus is MRSA in this hospital setting, it is important to do culture and sensitivity of relevant specimens when S aureus infection is suspected. The results of this study suggest that MRSA cover may need to be considered in empirical therapy of possible S aureus infections. DOI: http://dx.doi.org/10.4038/sljid.v2i2.4162 Sri Lankan Journal of Infectious Diseases Vol.2(2) 2012: 13-17