In-vitro activity of piperacillin and tazobactam combination against clinically significant bacteria

The in-vitro activity of piperacillin/tazobactum which is not among the routinely tested antibiotic at the Public Health Bacteriology Laboratory, Parirenyatwa Hospital, Harare, Zimbabwe was evaluated for its activity against bacterial pathogens using the Kirby-Bauer disk diffusion method. Piperacillin/tazobactum showed superior in-vitro activity against both gram positive and gram negative bacteria when compared with routinely tested antibiotics such as gentamicin, erythromycin, tetracycline, penicillin, chloramphenicol, fusidic acid and clindamycin and the difference was statistically significant (p < 0.05). Ciprofloxacin showed in-vitro activity comparable to that of tazobactam/piperacillin. Specifically, 96% of gram positive isolates (comprising Streptococcus pyogenes, Staphylococcus aureus, coagulase negative staphylococci and Streptococcus pneumoniae were sensitive to piperacillin/tazobactam. For gram negative organisms, 98% of Haemophilus influenzae Shigella spp, Klebsiella spp were also sensitive to the combination. The broad spectrum of activity of piperacillin/tazobactam shows that the potential of the drug combination for the treatment of infections caused by diverse microorganisms should not be underestimated. We recommend its inclusion in routine antibiotic sensitivity testing in our hospital.