Increasing Prevalence of Toxin A-Negative, Toxin B-Positive Isolates of Clostridium difficile in Korea: Impact on Laboratory Diagnosis

Of 462 Korean Clostridium difficile isolates, 77.5% were toxin B positive but 21.4% were toxin A negative (A(-) B(+)). The binary toxin gene was detected in nine isolates. A higher fluoroquinolone resistance of A(-) B(+) strains may contribute to the increase of these strains. Toxin A detection alone may underdiagnose C. difficile-associated disease.