title: Rapid detection of ampicillin-resistant Haemophilus influenzae and their susceptibility to sixteen antibiotics.
abstract: Ampicillin-resistant and -susceptible strains of Haemophilus influenzae were tested for susceptibility to 16 antibiotics. Chloramphenicol and a new cephalosporin, cefamandole, were most active with minimal inhibitory concentrations (MICs) for all bacteria tested between 0.5 to 2.0 mug/ml. All but two organisms were susceptible to tetracycline. Ampicillin-resistant strains of H. influenzae were less susceptible (MIC, 4 to 32 mug/ml) to carbenicillin and ticarcillin than ampicillin-susceptible organisms (MIC, 0.25 to 1.0 mug/ml). A rapid assay for beta-lactamase, utilizing a chromogenic cephalosporin substrate, detected enzyme production in all 17 ampicillin-resistant strains of H. influenzae.
mesh_terms: D000667:Ampicillin / Q000494:pharmacology*; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D002510:Cephalosporinase / Q000096:biosynthesis; D006193:Haemophilus influenzae / Q000187:drug effects* / Q000201:enzymology; D008826:Microbial Sensitivity Tests; D010403:Penicillin Resistance
chemical_list: D000900:Anti-Bacterial Agents; D000667:Ampicillin; D002510:Cephalosporinase