title: Analysis of the relationship between ampicillin resistance and beta-lactamase production in Branhamella catarrhalis.
abstract: 23 strains of Branhamella catarrhalis, mainly isolated from patients with acute exacerbations of chronic bronchitis, were studied. The strains were selected on the basis of a positive beta-lactamase reaction using the cefinase disc or the nitrocefin method. No bands were visible by isoelectric focusing of the crude enzyme extracts of strains showing a weak positive reaction with the cefinase method. In the 15 remaining strains, at least 6 different isoelectric focusing patterns could be detected. Four strains showed a pattern similar to that of the Ravasio strain, the most common type in a previous study. The most prevalent type in this study, present in 5 strains, demonstrated an isoelectric focusing pattern quite different from those described so far: a main band at pI 5.28 and 2 minor bands at pI 5.71 and 6.37. Two beta-lactamase-positive, but ampicillin-sensitive strains (MIC = 0.064 mg/L) showed different isoelectric focusing patterns, pI = 4.93 and 5.43, respectively, but similar substrate profiles.
mesh_terms: D000667:Ampicillin / Q000494:pharmacology*; D019818:Clavulanic Acid; D002969:Clavulanic Acids / Q000494:pharmacology; D007525:Isoelectric Focusing; D009346:Neisseriaceae / Q000187:drug effects* / Q000201:enzymology; D010403:Penicillin Resistance; D013379:Substrate Specificity; D001618:beta-Lactamases / Q000096:biosynthesis*
chemical_list: D002969:Clavulanic Acids; D019818:Clavulanic Acid; D000667:Ampicillin; D001618:beta-Lactamases