ANTIBIOTIC SUSCEPTIBILITY OF CLINICAL ISOLATES OF STREPTOCOCCUS-PNEUMONIAE

Ninety-three representative, recent clinical isolates of Streptococcus pneumoniae were examined for susceptibility to 9 antimicrobial drugs utilizing Mueller-Hinton agar (MHA) enriched with sheep blood and a hy percapnic atmosphere of incubation, One isolate was resistant to penic illin G (minimum inhibitory concentration, MIC = 2 mu g/ml) and 6 isol ates were of intermediate susceptibility to penicillin G (MICs = 0.125 -0.25 mu g/ml). The penicillin-G-resistant isolate was also resistant to cefuroxime (MIG = 4 mu g/ml) and of intermediate susceptibility tu cefotaxime (MIG = 1 mu g/ml). This isolate was resistant to chloramphe nicol (MIG = 16 mu g/ml) as well. All 93 isolates were susceptible to teicoplanin and vancomycin. Two isolates each were resistant (MICs = 1 6 mu g/ml) or moderately susceptible (MICs = 8 mu g/ml) to chloramphen icol. Eight isolates were resistant to doxycycline (MICs greater than or equal to 8 mu g/ml), whereas 2 isolates were of intermediate suscep tibility to this antibiotic (MICs = 4 mu g/ml). Three isolates were re sistant to erythromycin (MICs greater than or equal to 4 mu g/ml), and 2 isolates showed reduced susceptibility to erythromycin (MICs = 2 mu g/ml). Chocolatized MHA antagonized the activity of teicoplanin and v ancomycin against pneumococcal isolates. Haemophilus test and Wilkins- Chalgren media failed to support optimal growth of all pneumococcal is olates.