The Journal of Medical Microbiology, Vol 13, Issue 2 231-245, Copyright © 1980 by Society for General Microbiology
A scheme for the identification of clinical isolates of Gram-negative anaerobic bacilli by conventional bacteriological tests
B. I. Duerden, J. G. Collee, R. Brown, A. G. Deacon and W. P. Holbrook
More than 1000 strains of gram-negative anaerobic bacilli, including
reference strains, clinical isolates, and members of the normal flora of
the mouth, lower gastro-intestinal tract and vagina of healthy human
subjects, were studied by conventional bacteriological methods and by
gas-liquid chromatographic analysis of metabolic products in a series of
investigations. A short combined set of tests with particular discriminant
value was selected, and a scheme for the identification of the species and
subspecies encountered in the diagnostic bacteriological laboratory was
based upon our composite results. The tests are: antibiotic-disk resistance
tests with neomycin 1000 micrograms, kanamycin 1000 micrograms, penicillin
2 units and rifampicin 15 micrograms per disk; tolerance tests with sodium
taurocholate, Victoria blue 4R and gentian violet; and tests for pigment
production, indole production, aesculin hydrolysis and the fermentation of
glucose, lactose, sucrose, rhamnose, trehalose, mannitol and xylose.
Gram-negative anaerobic bacilli are divided into four groups: (1) the
fragilis group with nine species, which include the five subgroups
previously classified as subspecies of B. fragilis; (2) the
melaninogenicus-oralis group, which includes the three saccharolytic
subspecies (ss.) of B. melaninogenicus--ss. melaninogenicus, ss.
intermedius and ss. levii--and four non-pigmented species; (3) the
asaccharolytic group, which comprises B. asaccharolyticus (formerly B.
melaninogenicus ss. asaccharolyticus), B. corrodens and other non-pigmented
non-saccharolytic strains, and (4) the fusobacteria.
