A comparative evaluation of Wadsworth Anaerobic Manual and Bailey & Scott Stool pretreatment method for culture isolation of Clostridioides difficile in suspected C. difficile Infection.

BACKGROUND

Accurate detection of Clostridioides difficile (C. difficile) is essential for diagnosing and monitoring C. difficile infection (CDI). Culture remains important for epidemiological investigations and strain characterization, but its success depends on effective stool pretreatment to enhance spore survival and suppress competing flora. This study aimed to compare the diagnostic yield, specifically culture isolation rates of C. difficile, between two stool pretreatment techniques: the Wadsworth Anaerobic Method (WAM) and the Bailey & Scott Method (BSM), using samples from clinically suspected CDI cases.

METHODS

A total of 337 stool samples from suspected CDI patients were processed. All samples were screened using glutamate dehydrogenase (GDH) and Toxin A/B immunoassays. Each specimen underwent both WAM and BSM pretreatment, followed by anaerobic culture for C. difficile isolation. Culture positivity rates were compared between methods and correlated with GDH/toxin results.

RESULTS

Of the 337 samples, 34 (10.08%) were Toxin A/B ± GDH positive, while 19 (5.63%) were GDH positive but toxin negative. Overall, C. difficile was isolated from 21 samples (6.23%). C. difficile isolation rate was approximately 9.5-fold higher with WAM pretreatment than with BSM pretreatment (19 vs 2 isolates). Culture positivity was higher among GDH/toxin-positive samples than toxin-negative ones. Notably, five isolates were recovered from GDH- and toxin-negative samples, indicating that culture can detect organisms missed by immunoassays.

CONCLUSION

Stool pretreatment significantly impacts C. difficile culture recovery. WAM showed superior performance over BSM, suggesting its utility for improving culture-based diagnosis and epidemiological studies. Higher isolation rates in GDH/toxin-positive samples indicate that toxin detection correlates with increased bacterial burden and improved likelihood of culture recovery.