[Antibacterial activity of apalcillin against 300 strains of enterobacteria]

The in vitro bacteriostatic activity of apalcillin was compared with those of piperacillin, mezlocillin and carbenicillin. The minimal inhibitory concentrations determined by a microtiter dilution method, show a bi-modal distribution: apalcillin, piperacillin: 1 mg/l - greater than 128 mg/l; mezlocillin: 2 mg/l - greater than 128 mg/l; carbenicillin: 4 mg/l - greater than 128 mg/l. Two thirds of the isolates are inhibited by 8 mg/l of any antibiotic, except carbenicillin (128 g/l). Two genus seem less susceptible: Klebsiella display modal MIC of apalcillin and piperacillin equal to 4 mg/l and above 128 mg/l: Serratia isolates resist to 128 mg/l, whatever antibiotic is considered. The in vitro bactericidal activity of apalcillin was evaluated by killing-curves method against 8 Enterobacteriaceae strains. Used at a concentration equal to the MIC or twice the MIC, apalcillin produces a 1,5-2 log10 reduction in viable count, 3 hours after the addition of antibiotic.