title: Antibacterial activity of apalcillin (PC-904) against gram-negative bacilli, especially ampicillin-, carbenicillin-, and gentamicin-resistant clinical isolates.
abstract: Apalcillin (PC-904) is active against carbenicillin- and ampicillin-resistant strains of gram-negative bacilli. Among Pseudomonas aeruginosa strains highly resistant to carbenicillin (>/=3,200 mug/ml), half of them were susceptible to PC-904 at a concentration of 50 to 1,600 mug/ml. The minimal inhibitory concentration of PC-904 against P. aeruginosa strains resistant to carbenicillin (400 to 1,600 mug/ml) ranged from 3.1 to 25 mug/ml. Ampicillin- and carbenicillin-resistant Enterobacteriaceae strains were similarly susceptible to PC-904. However, drug resistance to PC-904 was already apparent among some strains of P. aeruginosa, Escherichia coli, Klebsiella pneumoniae, Proteus mirabilis, P. vulgaris, and P. morganii, recently isolated in Japan; i.e., 4, 35, 32, 4, 6, and 14% of strains isolated were resistant. PC-904 was more active, on the other hand, than ampicillin and carbenicillin against antibiotic-susceptible Enterobacteriaceae and also showed high activity against most species of Pseudomonadaceae, especially P. cepacia and P. aeruginosa. The minimum inhibitory concentrations of PC-904 were greatly affected by inoculum size when the organisms tested were strains producing large amounts of beta-lactamase.
mesh_terms: D000667:Ampicillin / Q000031:analogs & derivatives* / Q000494:pharmacology; D002228:Carbenicillin / Q000494:pharmacology; D004755:Enterobacteriaceae / Q000187:drug effects*; D005839:Gentamicins / Q000494:pharmacology; D008826:Microbial Sensitivity Tests; D009287:Naphthyridines / Q000494:pharmacology; D010403:Penicillin Resistance; D011549:Pseudomonas / Q000187:drug effects*
chemical_list: D005839:Gentamicins; D009287:Naphthyridines; D000667:Ampicillin; D002228:Carbenicillin
references.citation: Antimicrob Agents Chemother. 1974 Sep;6(3):253-62
references.pmid: 15830470
references.citation: Nature. 1954 Nov 27;174(4439):1012-3
references.pmid: 13214059
references.citation: J Biol Chem. 1951 Nov;193(1):265-75
references.pmid: 14907713
references.citation: Antimicrob Agents Chemother. 1977 Jun;11(6):936-40
references.pmid: 327924
references.citation: Antimicrob Agents Chemother. 1976 Oct;10(4):626-9
references.pmid: 825033
references.citation: Lancet. 1969 Aug 30;2(7618):448-52
references.pmid: 4183901
references.citation: Antimicrob Agents Chemother. 1975 Sep;8(3):344-9
references.pmid: 1167043
references.citation: J Infect Dis. 1972 Jun;125(6):613-8
references.pmid: 5037014
references.citation: Jpn J Microbiol. 1970 Mar;14(2):123-8
references.pmid: 4910534
references.citation: Antimicrob Agents Chemother. 1976 Jun;9(6):866-73
references.pmid: 820245
references.citation: Nature. 1975 Apr 10;254(5500):516-7
references.pmid: 1091862
references.citation: Antimicrob Agents Chemother. 1976 Feb;9(2):262-73
references.pmid: 1046355
references.citation: Antimicrob Agents Chemother. 1974 Jan;5(1):38-48
references.pmid: 4599124