["Second look" at cytotoxin B of Clostridium difficile in the course of diarrhea associated with antibiotic therapy].
Clostridium difficile is a sporulated obligate anaerobe responsible for most cases of antibiotic-associated colitis, for 15 to 25% of cases of antibiotic-related diarrhea, and for a substantial proportion of nosocomial infections. The most important laboratory test for the diagnosis of C. difficile infection is examination of the stool for C. difficile toxins A and/or B. Detection of cytotoxin B using the direct cytotoxicity assay (D-CA) is the gold standard test. Whether routine isolation of the organism from stool is warranted remains controversial.


OBJECTIVE
To evaluate second-look CA done on C. difficile culture-positive filtrates from stool samples negative by the D-CA.


METHODS
300 consecutive stool samples sent to the Alfred Fournier Institute from April through October 1998 for a CA were routinely cultured on modified Cefoxitin Cycloserine Fructose Agar medium (CCFA). All CA-negative samples that grew C. difficile were examined by second-look CA.


RESULTS
245 stool specimens (81.7%) were negative by both CA and culture. The remaining 55 specimens all yielded C. difficile by culture; 32 (58.2%) had a positive D-CA and nine (16.4%) a negative D-CA with a positive second-look CA done on culture filtrates.


CONCLUSIONS
Our data suggest that stool specimens sent for a direct CA should be routinely cultured to provide material for a second-look CA on culture-positive filtrates if the first CA prove negative. Culturing also allows to study antimicrobial drug resistance phenotypes and epidemiological markers.
Service de Bactériologie, Institut Alfred Fournier, Paris, France.
P
P
Sednaoui
B
B
el Mantih
M
M
Cauwell
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000900:Anti-Bacterial Agents / Q000009:adverse effects*; D001426:Bacterial Proteins; D001427:Bacterial Toxins / Q000032:analysis*; D002648:Child; D002675:Child, Preschool; D016360:Clostridioides difficile / Q000302:isolation & purification; D003967:Diarrhea / Q000139:chemically induced*; D004761:Enterocolitis, Pseudomembranous / Q000175:diagnosis / Q000503:physiopathology*; D005243:Feces / Q000382:microbiology; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies
D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D001427:Bacterial Toxins; C031815:toxB protein, Clostridium difficile
"Seconde détection" de la cytotoxine B de Clostridium difficile au cours des diarrhées associées à l'antibiothérapie.