Evaluation of a latex agglutination test for diagnosis of Clostridium difficile-associated colitis.
Current methods for diagnosis of Clostridium difficile-associated colitis (CAC) based on detection of cytotoxin B by a tissue culture assay (TCA) require technical expertise and up to 48 hours incubation. Recently, a latex agglutination (LA) test (Marion Laboratories) for rapid diagnosis of CAC has become available. Although early evaluations have been favorable, new evidence suggests that the LA reagent binds a soluble bacterial antigen that is not unique to toxigenic strains of C. difficile. The authors examined 201 stools received for CAC testing by LA and a reference TCA and investigated discrepant results. They obtained 29 LA(+)/TCA(+) and 155 LA(-)/TCA(-) results. Eleven patients had LA(+)/TCA(+) and 155 LA(-)/TCA(-) results. Eleven patients had LA(+)/TCA(-) results and 6 had LA(-)/TCA(+) results. The sensitivity and specificity of the LA were 83% and 93%, respectively, compared with TCA. The predictive values of positive and negative results obtained with the LA were 72% and 96%, respectively. Concentrated broth supernatants and live suspensions of three C. difficile isolates with LA(+)/TCA(-) results were tested in a rabbit ileal loop assay. All failed to demonstrate ability to produce an enterotoxin. The authors conclude that the LA method is suitable for rapid screening, but LA(+) results require confirmation by testing with other methods.
Sherman
M E
ME
Department of Pathology, New England Deaconess Hospital, Boston, Massachusetts 02215.
DeGirolami
P C
PC
Thorne
G M
GM
Kimber
J
J
Eichelberger
K
K
D000818:Animals; D001427:Bacterial Toxins / Q000032:analysis; D003013:Clostridium / Q000472:pathogenicity; D003015:Clostridium Infections / Q000175:diagnosis*; D003092:Colitis / Q000209:etiology*; D005243:Feces / Q000032:analysis; D006801:Humans; D007841:Latex Fixation Tests / Q000592:standards*; D008722:Methods; D011817:Rabbits
D001427:Bacterial Toxins