Identification of Flavobacterium strains by gas liquid chromatographic analysis of volatile fatty acids produced in culture.

The classification previously established for 74 Flavobacterium strains by gas liquid chromatographic (GLC) analysis of volatile fatty acids (VFA) produced in culture allowed the recovery of 9 groups (J. gen. Microbiol., 1986, 132, 2723-2732). Since graphic representation of the strains based on the first 3 factors obtained by principal component analysis (PCA) clearly separated these groups, we tried to identify 80 new strains by comparing their positions with those of the 9 groups, on the basis of both hierarchical classification and PCA methods. Of the 153 strains studied, only 12 were not allocated to a group corresponding to their original biochemical identification. Thus, on the whole, this characterization method by GLC analysis seemed satisfactory, although it could not be established whether the method was adequate for routine identification, or would serve merely as a complement.

Classification and identification of Flavobacterium species by carbon source utilization.

Carbon substrates used as the sole source of carbon and energy were tested for the classification and identification of species of Flavobacterium: Flavobacterium meningosepticum, F. breve, F. odoratum, F. multivorum, F. thalpophilum, and Flavobacterium sp. group IIb. Hierarchical classification and stepwise discriminant analysis revealed three F. meningosepticum, two F. breve, two F. odoratum, and two Flavobacterium sp. group IIb subgroups. Glucose, histidine, asparagine, tryptophan, maltose, citric acid, and glycine were selected as the most useful substrates to differentiate between the groups and subgroups.

Characterization of Flavobacterium species by analysis of volatile fatty acid production.

Seventy-four Flavobacterium strains were characterized by gas-liquid chromatographic analysis of volatile fatty acids produced in the culture medium. Principal components analysis permitted the graphic representation of the relative positions of the different strains, and aggregation according to the variance enabled a hierarchical classification to be established. The study revealed three subgroups each for F. meningosepticum and F. odoratum. Our F. breve, Flavobacterium sp. group IIb and F. multivorum strains appeared to be homogeneous. These results tallied with those of previous studies on DNA base composition and reassociation, electrophoretic protein profiles and cellular fatty acid composition.

[Evaluation of the sensitivity to antibiotics of Bacteroides and Fusobacterium using the ATB ANA system]. / Evaluation de la sensibilité aux antibiotiques de Bacteroides et Fusobacterium à l'aide de la galerie ATB ANA.

The susceptibility to antibiotics of 100 Gram negative obligate anaerobes of the Bacteroides and Fusobacterium species was tested using the ATB ANA method. Results were compared to those obtained by addition of the tested antibiotics to Wilkins-Chalgren medium in the critical concentrations. Agreement between the two methods was satisfactory (80 to 100%) for the low cutoff concentrations, except for doxycycline. When the pathogens are divided into susceptible, intermediate and resistant strains, results are more difficult to interpret because of the existence of the intermediate category: however, major discrepancies (R/S) did not exceed 3.2% except for cefotaxime (15%). Our results show that use of ATB ANA microplates in an anaerobic enclosure is a valuable method in clinical practice.

Epidemiological investigation of exfoliative toxin-producing Staphylococcus aureus strains in hospitalized patients.

The incidence of exfoliative toxin-producing strains of Staphylococcus aureus was studied. Samples from hospitalized patients of all ages and samples from infants less than 6 weeks old were screened; out of 2,632 coagulase-positive S. aureus strains tested, 6.2% synthesized exfoliative toxin. The clinical features could be assessed in 86 patients harboring exfoliative toxin-producing staphylococci. Skin lesions (pustules, blisters, and bullous impetigo) could be observed only when the exfoliative toxin-positive strains were isolated from the skin. Phage nongroup II strains seemed less skin pathogenic than phage group II strains. Outbreaks and sporadic cases were observed.