ABSTRACT
Growth properties of coagulase-negative staphylococci in the presence and in the absence of human and rabbit serum in soft-agar prepared in modified Staphylococcus 110 broth were studied. The adherent growth was examined in modified Staphylococcus 110 broth and 1% glucose-meat broth. Of 100 strains examined 69% exhibited diffuse, 18% compact, 7% transient and 6% mixed growth. Compact type colonies were mainly characteristic of Staphylococcus haemolyticus strains. The presence of serum failed to influence the types of colony morphology in any of the strains. Sixty-three percent of the strains showed adherent growth; none of the S. haemolyticus strains produced adherent growth. The glucose-meat broth, unlike modified Staphylococcus 110 broth, was suitable to study adherence. The coincidence of the compact colony morphology in soft-agar and the absence of adherent growth seems to be a taxonomic sign for the species S. haemolyticus and differentiate it from the species Staphylococcus epidermidis.
Subject(s)
Staphylococcus/growth & development , Agar , Bacterial Adhesion , Coagulase/metabolism , Culture Media , Glass , Hemolysis , Humans , Species Specificity , Staphylococcus/classification , Staphylococcus/physiology , Staphylococcus epidermidis/classification , Staphylococcus epidermidis/growth & development , Staphylococcus epidermidis/physiologyABSTRACT
The bacteriostatic and bactericidal activities of cefetamet (Ro 15-8074) were compared with those of cefadroxil, cefaclor, ampicillin, doxycycline, chloramphenicol and erythromycin against a total of 400 bacterial strains isolated from nosocomial respiratory tract and auditory canal infections. The broth macrodilution method was used to determine antimicrobial susceptibility. None of the compounds was effective against Pseudomonas aeruginosa and methicillin-resistant Staphylococcus aureus strains. Cefetamet was very active against ampicillin-resistant Klebsiella pneumoniae. Proteus mirabilis and Escherichia coli strains with the minimal inhibitory concentrations for 90% of the strains tested ranging from 0.25 to 1 mg/l. Cefetamet at a concentration of 8 mg/l inhibited 90% of Enterobacter aerogenes and 60% of S. epidermidis strains. In biophotometric studies, subinhibitory concentrations of cefetamet greatly lengthened the lag-phase and flattened the log-phase, the extent varying with the concentrations and species tested. It did not cause detectable lysis in the stationary-phase of the cultures. Adding two to 32 times inhibitory concentrations of cefetamet to middle-log cultures, no or moderate lysis occurred., except with Esch. coli. This observation suggests that cefetamet is primarily bacteriostatic for some of the strains tested.
