Comparison of the in vitro activity of BL-P1654 with gentamicin and carbenicillin against Pseudomonas aeruginosa.
The in vitro activity of 6-[d-alpha-(3 guanylureido)-phenylacetamido]-penicillanic acid (BL-P1654) was evaluated against 117 clinical isolates of Pseudomonas aeruginosa, many of which were known to be resistant to both gentamicin and carbenicillin. BL-P1654 was two to eight times more active than carbenicillin against P. aeruginosa. However, all 28 highly carbenicillin-resistant isolates (minimal inhibitory concentration [MIC] > 500 mug/ml) were also highly resistant to BL-P1654. When an MIC of 32 mug/ml or less and a zone of inhibition of 12 mm or more by a 10-mug disk were used as criteria indicating susceptibility to BL-P1654, the false-resistance rate by the disk test was 10.6% and the false-susceptibility rate was 4.2%. The combination of BL-P1654 and gentamicin was synergistic against 45 of 70 isolates of P. aeruginosa tested, but synergism was demonstrated against only 4 of 24 highly gentamicin-resistant (MIC > 63 mug/ml), 1 of 12 highly BL-P1654-resistant (MIC > 250 mug/ml) isolates, and none of nine isolates highly resistant to both of these antibiotics.
D002228:Carbenicillin / Q000494:pharmacology*; D015169:Colony Count, Microbial; D004058:Diffusion; D004357:Drug Synergism; D005839:Gentamicins / Q000494:pharmacology*; D006801:Humans; D007231:Infant, Newborn; D008826:Microbial Sensitivity Tests; D010397:Penicillanic Acid / Q000031:analogs & derivatives* / Q000494:pharmacology; D011550:Pseudomonas aeruginosa / Q000187:drug effects*
D005839:Gentamicins; D010397:Penicillanic Acid; D002228:Carbenicillin