Predicting recurrence of C. difficile colitis using bacterial virulence factors: binary toxin is the key.

BACKGROUND

Recurrent Clostridium difficile colitis is common, yet the ability to predict recurrence is poorly developed.

METHODS

Patients ≥18 years of age treated at our institution for C. difficile of any severity were consecutively enrolled. C. difficile colitis was defined as symptoms of colitis with a positive PCR stool test. Each bacterial isolate was studied for virulence factors: tcdC mutations via PCR; the presence of genes for toxins A, B, and binary toxin using restriction fragment length polymorphism; and identification of ribotype 027 by PCR. Chi-squared tests, t tests, and logistic and linear regression were used to determine which virulence factors predicted recurrence.

RESULTS

Sixty-nine patients (male, 57 %) were studied, with a mean age of 64 ± 13 years. Twenty-one (30 %) patients were initially diagnosed as outpatients. There was no difference (p > 0.05) between virulence factors among inpatients and outpatients. The presence of a binary toxin gene was the single virulence factor independently associated with recurrence (p = 0.02). The combination of a tcdC mutation with binary toxin gene resulted in the highest odds of recurrence (OR, 5.3; 95 % CI, 3.52-6.09).

CONCLUSION

Binary toxin gene is a predictor of recurrent infection. Its presence may require longer antibiotic regimens in an effort to lower already elevated recurrence rates.