Laboratory evaluation of pirbenicillin a new penicillin with anti pseudomonal activity

Greenwood, D.; Pearson, N. J.; Olivant, J.; O&apos; grady, F.

The new penicillin, pirbenicillin, was 8-16 times more active than carbenicillin against many strains of Pseudomonas aeruginosa, but was uniformly less active against indole-positive Proteus spp. The intrinsic activity of the new antibiotic against ampicillin-sensitive Escherichia coli was intermediate between those of ampicillin and carbenicillin. No unusual activity of pirbenicillin was detected among a group of enterobacteria previously shown to exhibit distinct patterns of resistance to .beta.-lactam antibiotics.