Penicillin-resistant Streptococcus pneumoniae isolates in Harare, Zimbabwe

OBJECTIVE: To determine the susceptibility of Streptococcus pneumoniae isolates to penicillin and other antimicrobial drugs. DESIGN: This was a laboratory based study. SETTING: Department of Medical Laboratory Sciences, University of Zimbabwe and the Bacteriology Unit, Public Health Laboratories, Harare. SUBJECTS: 71 S. pneumoniae isolates from Parirenyatwa and Harare hospitals. MAIN OUTCOME MEASURES: Penicillin resistance, MIC of penicillin to S. pneumoniae, multi-drug resistance. RESULTS: 71 S. pneumoniae isolates were tested for their susceptibilities to penicillin G, erythromycin, tetracycline, ampicillin, ciprofloxacin and clindamycin. Five (7%) of the isolates were resistant to penicillin G and were also all resistant to erythromycin. Isolates resistant to other antibiotics were; tetracycline (4), ampicillin (3) and ciprofloxacin (2). The five isolates that were resistant to penicillin G showed resistance to two or more antibiotics. Four S. pneumoniae isolates were designated highly resistant to penicillin (MIC > or = 2 micrograms/ml) and one isolate was designated intermediate in resistance to penicillin (MIC between 0.1 and 1.0 microgram/ml). CONCLUSIONS: A low percentage of S. pneumoniae isolates were resistant to penicillin and were also resistant to erythromycin. The penicillin resistant strains showed multi-drug resistance.