Comparative in vitro appraisal of piperacillin, including its activity against Salmonella typhi

Piperacillin was evaluated in vitro against 711 clinical isolates of aerobic and anerobic gram-positive and gram-negative bacteria, including 76 isolates of Salmonella typhi. Piperacillin minimum inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBCs) were compared with those of a range of beta-lactam, aminoglycoside, and other antimicrobial agents, and inoculum size effects were considered. The relationship between dilution and disk diffusion tests was studied by regression analysis. In addition, piperacillin was assessed in combination with aminoglycoside and other beta-lactam drugs. This investigation has confirmed the activity of piperacillin against a broad range of bacteria, including Pseudomonas, Enterobacteriaceae, Neisseria, beta-lactamase-negative Haemophilus influenzae, and Staphylococcus aureus as well as enterococci, Bacteroides fragilis, and other anaerobes. All strains of Pseudomonas aeruginosa were inhibited by