The Journal of Medical Microbiology, Vol 24, Issue 2 125-131, Copyright © 1987 by Society for General Microbiology
Difficulties in the serodiagnosis of infection with the fragilis group of Bacteroides
K. M. Elhag, A. M. Bahar and K. K. Mahajan
Department of Microbiology, University of Kuwait.
Bacteroides antibodies were studied in sera from 74 patients infected with
the fragilis group of Bacteroides and 74 healthy control persons, by
immunofluorescence of 26 different serotypes of the fragilis group.
Antibodies were present at titres of 10-320 in 65 (88%) patients and 50
(68%) controls (p less than 0.01). Titres of greater than or equal to 80
were demonstrated in sera of 38 (51%) patients and 5 (7%) controls (p less
than 0.01). Specific IgM antibodies were detected in sera of 42 (57%)
patients at a geometric mean titre (GMT) of 30, and 8 (11%) controls at a
GMT of 11 (p less than 0.01). High antibody titres as well as specific IgM
were found in 32 (43%) patients, while none of the controls showed such a
combination (p less than 0.01). The majority of positive patients' sera
(57%) reacted with five or more serotypes, whereas most positive control
sera (51%) reacted against only one or two serotypes (p less than 0.01). A
selected combination of serotypes not reacting with the control sera showed
positive reactions with 52 (70%) patients' sera. These findings may be
useful in devising schemes for the serodiagnosis of infection caused by the
fragilis group of Bacteroides. However, there are indications of geographic
variation in prevalence of serotypes, which may prevent the development of
a single universal scheme.
