Detection of Bacteroides fragilis, Bacteroides thetaiotaomicron, and Bacteroides ovatus in clinical specimens by immunofluorescence with a monoclonal antibody to B. fragilis lipopolysaccharide.
A total of 1,897 clinical specimens (1,019 aspirates and 876 swabs) were studied by indirect immunofluorescence (IF) with a mouse monoclonal antibody (MAb) against a D-galactose oligomer of Bacteroides fragilis lipopolysaccharide. The MAb has been shown to react with 96% of clinical B. fragilis isolates and with about 50% of Bacteroides ovatus and Bacteroides thetaiotaomicron isolates but not with other aerobic or anaerobic organisms tested. The sensitivity of IF in comparison with culturing was 78.9% for all three species. Of the 32 strains originating from culture-positive, IF-negative specimens, 13 lacked the target determinant for the MAb. Sensitivity was highest with specimens taken from the perineal area (87.1%) and lowest with those taken from undefined sites (56.6%). Sensitivity was better with aspirates (86.8%) than with swabs (72.6%). The specificity of IF was 95.6% for all of the material. Positive and negative predictive values were 51.1 and 98.0%, respectively. Neither long transportation times of specimens nor antimicrobial therapy seemed to correlate with the occurrence of IF-positive, culture-negative specimens. This study shows that a single MAb can be used to establish an IF assay that can complement isolation in the detection of these three members of the B. fragilis group.
Viljanen
M K
MK
Department of Medical Microbiology, University of Turku, Finland.
Linko
L
L
Lehtonen
O P
OP
D000907:Antibodies, Bacterial / Q000276:immunology; D000911:Antibodies, Monoclonal / Q000276:immunology; D001439:Bacteroides / Q000276:immunology / Q000302:isolation & purification*; D001441:Bacteroides fragilis / Q000276:immunology / Q000302:isolation & purification*; D005455:Fluorescent Antibody Technique; D006801:Humans; D008070:Lipopolysaccharides / Q000276:immunology*; D011237:Predictive Value of Tests
D000907:Antibodies, Bacterial; D000911:Antibodies, Monoclonal; D008070:Lipopolysaccharides