Clostridium difficile cytotoxin B in adults with diarrhea: a comparison of patients treated or not treated with antibiotics prior to infection.

OBJECTIVE: To study the detection rate of Clostridium difficile cytotoxin B in stool specimens from adults with diarrhea as related to previous antimicrobial treatment.
METHODS: Stool specimens from 802 adult patients with diarrhea and 203 healthy controls were tested for C. difficile cytotoxin B using a cell cytotoxicity assay. Antibiotic susceptibility testing of C. difficile was performed with the E test.
RESULTS: Of 173 patients treated with antimicrobial medication within 5 weeks of onset of diarrhea, 60 (35%) were positive for C. difficile cytotoxin B (group A) compared to only 41 (7%) of 629 untreated patients (group B) and two of the 203 (1%) healthy controls. Compared to patients in group A, patients in group B possessed characteristics not usually connected with C. difficile disease. They were generally younger (median age 40 years vs. 73 years), had been hospitalized less frequently (10% vs. 67%), had more often travelled abroad within the previous 2 weeks (46% vs. 1%), and more often had multiple enteropathogens (41% vs. 3%). Minimal inhibitory concentrations for vancomycin, metronidazole and fucidic acid to C. difficile isolates ranged from 0.5 to 4 mg/L, from 0.125 to 256 mg/L and 0.25 to 4 mg/L, respectively.
CONCLUSIONS: The detection rate of C. difficile cytotoxin B in patients with diarrhea, not associated with antibiotic treatment, is comparable to that in healthy control subjects. It probably merely reflects a carrier state without clinical significance.