title: Semisynthetic penicillin 6-(D(--)-alpha-carboxy-3-thienylacetamido) penicillanic acid active against Pseudomonas in vitro.
abstract: The activity of 6-[d(-)-alpha-carboxy-3-thienylacetamido] penicillanic acid, BRL2288, was determined against Pseudomonas aeruginosa and various gram-negative bacilli. The majority of Pseudomonas strains (89%) were inhibited by 100 mug of the antibiotic per ml. BRL2288 is twofold more active than carbenicillin against Pseudomonas at 100 mug/ml or less. Among Enterobacteriaceae tested, 87% Enterobacter and 87% of Proteus mirabilis strains were inhibited by 25 mug/ml or less. Indole-positive Proteus were inhibited by 10 mug/ml or less. Fifty-five per cent of ampicillin-resistant Escherichia coli were inhibited by 100 mug/ml. Klebsiella were uniformly resistant. BRL2288 is not hydrolyzed by most resistant Pseudomonas, but it is destroyed by the beta-lactamases of E. coli and P. mirabilis. The antibiotic shows synergy with gentamicin but not with penicillinase-resistant penicillins such as cloxacillin. Activity of BRL2288 against gram-positive organisms is two- to eightfold less than that of ampicillin or benzylpenicillin G.
mesh_terms: D004357:Drug Synergism; D004755:Enterobacteriaceae / Q000187:drug effects; D004926:Escherichia coli / Q000187:drug effects; D007709:Klebsiella / Q000187:drug effects; D008826:Microbial Sensitivity Tests; D010403:Penicillin Resistance; D010406:Penicillins / Q000494:pharmacology*; D011511:Proteus / Q000187:drug effects; D011549:Pseudomonas / Q000187:drug effects*; D011550:Pseudomonas aeruginosa / Q000187:drug effects
chemical_list: D010406:Penicillins