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Strictly aerobic Gram negative bacteria are found more and more often in human pathological specimens and in the environment. Amongst these bacteria, Flavobacterium poses problems of bacteriological diagnosis as their precise taxonomy is still recent. In this study, conducted on 321 strains of Flavobacterium from various sources, but essentially from patients in the intensive care unit, the authors define the methods and features of identification and the clinical significance of the species of the Flavobacterium genus. One species is particularly important in medical bacteriology, Flavobacterium meningosepticum which can cause septicaemia and neonatal meningitis which are difficult to treat.

Six new serotypes (G to L) of Flavobacterium meningosepticum are described herein. Cross-reactions between the 12 serotypes, A to L (including the 6 serotypes A to F of Owen and Lapage, 1974) are described. Sixty-six strains isolated in France (61 from Strasbourg) belong to the following serotypes (with number of strains): A (1), F (4), G (51), H (1), I (1), J (6), K (1) and L (1). Use of meningosepticum serotyping is recommended as an epidemiological tool.

Profiles of enzymatic activities were studied using 19 chromogenic substrates for 22 species (211 strains) belonging to the genera Agrobacterium, Alcaligenes, Alteromonas, Flavobacterium and Pseudomonas. The observed patterns of reactions may be useful as an aid in identification of these species and for epidemiological studies.

Twenty encapsulated strains of Flavobacterium multivorum were isolated from soil by elective culture in minimal medium containing inulin as the sole source of carbon and energy. These strains were compared with the type strain and with 5 other strains (including 4 clinical strains) of F. multivorum. Of 168 substrates tested, 18 carbohydrates were used as the sole carbon and energy source by all 26 strains. A few amino acids were used by some strains. The yellow pigment produced was found to be a carotene and its production was photo-inducible. The presence of a cytochrome c oxidase of the aa3 type was suggested by absorption spectra. The major cell lipids were phosphatidylethanolamine and sphingolipids; the major fatty acids were 13-methyltetradecanoic and 2-hydroxy-13-methyltetradecanoic acids. Soil and clinical strains of F. multivorum showed roughly similar patterns of antibiotic multiresistance. The average G + C content of the DNA of 11 strains was 40.8 +/- 1.5 mol%.