Abstract

A retrospective eight-year study (January 1998 to December 1999 and January 2008 to December 2009) was under taken in a Government Hospital in Islamabad, Pakistan to evaluate bactericidal activity of various brands of cephradine against Staphylococcus aureus. The maximum resistance of the bacterium was observed for ampicillin, penicillin and cotrimaxazole. Where as, the minimum resistance was exhibited against vancomycin. One hundred and fifty five clinical isolates were further tested for minimum inhibitory concentration against various brands of cephradine. The high level of bacterial resistance to different cephradine brands was observed for these isolates after incubation of 18 to 24 h. Majority of the isolates had MIC 50 to 90 in response to 64 to 512 mg/ mL of various brands of cephradine. While, 512 and above 1024 mg/mL of antibiotic had shown the maximum bactericidal activity. The study suggested that the presence or absence of antibiotic-resistant subpopulations among S. aureus isolates and their selection during treatment should be considered when therapy is advised.

Key words: Staphylococcus aureus, cephradine, minimum inhibitory concentration, minimum bactericidal concentration.