Genotypic and phenotypic relatedness of 80 strains ofBranhamella catarrhalisof worldwide origin

80 clinical Branhamella catarrhalis strains of worldwide origin were examined for genotypic relatedness and phenotypic characteristics. Using a quantitative bacterial dot method for DNA-DNA hybridization the strains were found to form a homogeneous group with delta Tm-values ranging from 0.0-2.3 degrees C, In Minibact-N, an identification kit for oxidase positive, Gram-negative diplococci using eight phenotypic characteristics, all isolates were correctly identified and also demonstrated complete homogeneity except for beta-lactamase production. Type strains representing the genera Branhamella, Moraxella and Neisseria were also examined for comparison. B. catarrhalis strain NCTC 4103-known to be atypical-had a delta Tm-value of 5.7 degrees C and produced gamma-glutamylaminopeptidase, in contrast to all other B. catarrhalis strains. In GN MicroPlate, a kit which tests utilizable carbon sources, B. catarrhalis strains were found to be able to utilize up to 16 to 95 carbon sources.