In vitro antibacterial activities of erythromycin, clarithromycin, azithromycin and cephradine against methicillin-sensitive and methicillin-resistant Staphylococcus aureus strains
The in vitro antibacterial activities of erythromycin, clarithromycin, and azithromycin were evaluated against 75 methicillin-sensitive and methicillin-resistant Staphylococcus aureus strains isolated from the hospital and outpatient clinics by the broth microdilution method and these activities were compared with those of cephradine. Of these strains, 35 (47%) were isolated from in-patients and 40 (53%) from out-patients. A total of 19 (54.3%) of the hospital and 16 (40%) of the outpatient-clinic isolates were resistant to methicillin as determined by the disc diffusion method. Of the methicillin-sensitive hospital isolates, 75% were also susceptible to erythromycin, clarithromycin, and azithromycin (MIC range 0.25-64 μg/ ml), and 68.7% were susceptible to cephradine. For the strains (methicillin-resistant and methicillin-sensitive) that were isolated from outpatient clinics, the overall sensitivity rates were not statistically different, although the MIC values were lower for all the agents tested when compared with hospital isolates
