In-vitro disk diffusion sensitivity of meropenem against bacterial pathogens in Harare

Objective: To compare the in-vitro sensitivity of meropenem with imipenem and other antibiotics against clinically significant bacteria. Design: A longitudinal survey. Setting: Department of Medical Microbiology, in a tertiary care university hospital. Subjects: Specimens obtained from patients attending various clinics at tertiary care and teaching hospital in Harare. Those submitted to the Public Health Bacteriology Laboratory were analysed. Main outcome measures: Rates of resistance or susceptibility of the various bacteria to the antibiotics employed in the study. Results: There was excellent in-vitro bacterial activity of meropenem against virtually all clinically significant Gram positive and Gram negative isolates when compared with other antibiotics such as imipenem, ciprofloxacin, gentamicin, penicillin, ampicillin, fusidic acid, tetracyclines, erythromycin and clindamycin (p<0.5). All isolates of Streptococcus pyogenes, Pseudomonas aeruginosa, Enterobacteriaceae, Neisseria meningitidis were susceptible to meropenem. Meropenem showed 99% overall in-vitro sensitivity against Gram positive and Gram negative bacteria. About 80% of staphylococci were resistant to penicillin whereas at least 20-25% of S. aureus, coagulase negative staphylococci, S. pyogenes showed resistance to ampicillin, erythromycin, gentamicin, tetracycline and clindamycin. Conclusion: Meropenem is not included in the list of routinely tested antibiotics in our laboratory, a major tertiary laboratory in the country. As a result of the ultra-broad spectrum of activity, we recommend its inclusion in our routine antibiotic sensitivity testing and observe that there is a great potential for meropenem in the treatment of infections caused by several genera of bacteria in our environment. Request for reprints to: Professor C.L. Obi, Department of Microbiology and Biochemistry, University of Venda, Private Bag X5050, Thohoyandou 0950, South Africa.