Comparative in vitro study of temocillin (BRL 17421), a new penicillin.

The activity of temocillin (BRL 17421), a new penicillin, was tested in vitro against 653 isolates of gram-negative bacilli and gram-positive cocci. The drug was compared with other beta-lactam antibiotics and tobramycin. It inhibited the majority of gram-negative bacilli tested except for Pseudomonas aeruginosa and Acinetobacter calcoaceticus, which were highly resistant. It was active against more than 50% of the multiresistant strains tested. Temocillin was more active than mezlocillin against most gram-negative bacilli and more active than moxalactam, ceftriaxone, and ceftazidime against Enterobacter spp. In general, it was slightly less active than the other drugs tested and had no activity against the gram-positive cocci. There was no significant change in drug activity when pH and medium were varied, and the effect of serum binding was minimal. There was no significant inoculum effect when the size of the inoculum was increased from 10(4) to 10(6) organisms per ml.