[Microbiological studies with the new penicillin BRL 17421 (temocillin)].

In vitro Evaluation of BRL 17421 (Temocillin), a New Penicillin. The in vitro antibacterial activity of BRL 17421 (temocillin), a new penicillin, was determined in quantitative serial broth dilution tests and was compared to that of mezlocillin, piperacillin, cefazolin and cefotaxime against 751 clinical isolates of the Enterobacteriaceae family. In addition, the sensitivity of 211 mezlocillin-resistant gram-negative rods to BRL 17421 was also determined. Temocillin exhibited a high level of antibacterial activity against various bacterial species of the Enterobacteriaceae family, including isolates resistant to mezlocillin. The 90% MICs against Escherichia coli, Klebsiella pneumoniae, Citrobacter freundii, Enterobacter cloacae, Salmonella spp., Yersinia spp. and indole-negative and indole-positive Proteus strains ranged from 0.5 mg/l to 16 mg/l. Concentrations of 16 mg/l were required to inhibit 80% of the Serratia marcescens strains; some isolates were resistant. No significant difference between MIC and MBC values was observed.