[A nosocomial outbreak of diarrhea caused by toxin A-negative, toxin B-positive Clostridium difficile in a cancer center hospital].

Between February and July 2001, 15 patients were diagnosed as Clostridium difficile-associated diarrhea in a ward of hematological neoplasm and lung cancer in a cancer center hospital. Of these 15 patients, 10 had malignant lymphoma, and 12 and 11 had exposure to antimicrobial agents and cancer chemotherapy, respectively, before the onset of diarrhea. Toxin A-positive, toxin B-positive (A+ B+) C. difficile was recovered from five patients and the remaining 10 patients suffered from diarrhea caused by toxin A-negative, toxin B-positive (A- B+) strains. All of the 10A- B+ isolates represented an identical banding pattern by PCR ribotyping and classified into one type (two subtypes) by pulsed field gel electrophoresis typing, indicating that a nosocomial outbreak of diarrhea caused by A- B+ C. difficile occurred among the patients hospitalized on this ward. Detection of toxin A in stool specimens by a toxin A detection kit was performed on 14 patients. Although two patients who carried A+ B+ strains were positive for toxin A assay, toxin A detection test was negative in 12 patients including 10 patients with A- B+ C. difficile infection. Diagnosis of C. difficile-associated diarrhea by combination of toxin A assay in feces and culture of C. difficile could successfully lead to recognition of an outbreak caused by A- B+ C. difficile in a cancer center hospital.