Evaluation of the in vitro Activity of Cefprozil Relative to Other Oral Antimicrobial Agents Against Bacteria in Clinical Specimens from Patients in São Paulo With Respiratory Tract Infections.

Cefprozil is a new oral second generation cephalosporin. Its in vitro antimicrobial activity was evaluated against 371 recent clinical isolates from patients with respiratory infections. We tested the susceptibility of 244 streptococci (96 Streptococcus pneumoniae, 105 group viridans streptococci, 32 Streptococcus agalactiae, and 11 group A beta-hemolitic streptococci) 107 Haemophilus influenzae, and 20 oxacillin-susceptible S.aureus (OSSA). The isolates were susceptibility tested against cefprozil, cefaclor and amoxicillin/clavulanic acid by the E-test method; and against cefadroxil, cefuroxime, cefetamet, erythromycin, and azythromycin by disk diffusion. The methods and the susceptibility categorization followed the National Committee for Clinical Laboratory Standards (NCCLS) procedures. Amoxicillin/clavulanic acid was slightly more active againstH.influenzae (MICs(90) 0.5µg/mL) than cefprozil or cefaclor (MICs(90) 4 and 2µg/mL respectively). Cefprozil demonstrated potent activity against streptococci. Against S.pneumoniae, cefprozil was 2-4 fold more active than cefaclor (MICs(90)0.125 and 0.38µg/mL, respectively). S. pneumoniae susceptibility was 84% to penicillin, 95% to erythromycin and 97% to azithromycin by disk diffusion. Viridans streptococci showed higher MICs for cefprozil and cefaclor (MICs(90) 4µg/mL and 8µg/mL, respectively) and only 50% susceptibility to the macrolides. Cefprozil was four times more active than cefaclor and as active as amoxieillin/clavulanic acid against group A beta-hemolytic streptococci and S.agalactiae. These three compounds showed similar activity against OSSA. In conclusion, cefprozil demonstrated excellent in vitro activity against bacterial species responsible for respiratory infections in São Paulo.