Clinical Significance of Toxigenic Clostridioides difficile Growth in Stool Cultures during the Era of Nonculture Methods for the Diagnosis of C. difficile Infection

The importance of the detection of relevant toxins or toxin genes to diagnose Clostridioides difficile infection (CDI) or the prediction of clinical outcomes of CDI has been emphasized in recent years. Although stool culture of C. difficile is not routinely recommended in the era of nonculture methods as the preferred tools for CDI diagnosis, the clinical significance of toxigenic C. difficile growth (tCdG) in stool cultures was analyzed. A clinical study was conducted in medical wards of Tainan Hospital, Ministry of Health and Welfare, in southern Taiwan. Diarrheal adults with fecal glutamate dehydrogenase and C. difficile toxin between January 2013 and April 2020 were included. Of the 209 patients with CDI, 158 (75.6%) had tCdG found in stool cultures, and the rest (51, 24.4%) had no tCdG in stool. Only prior ceftazidime or ceftriaxone therapy was independently associated with no tCdG in stool (odds ratio [OR] 2.17, P = 0.02). Compared to the patients with tCDG in stool, those without tCdG in stool experienced treatment success more often (97.1% versus 67.0%, P < 0.001) if treated with metronidazole or vancomycin but had a similar in-hospital mortality or recurrence rate. In the multivariate analysis among 114 patients with CDI treated with metronidazole or vancomycin, treatment success was independently associated with no tCdG in stool (OR 12.7, P = 0.02). Despite the limited utility of stool cultures in CDI diagnoses, no tCdG in stool culture heralds a favorable therapeutic outcome among adults with CDI treated with metronidazole or vancomycin. IMPORTANCE The importance of detecting toxins or toxin genes when diagnosing Clostridioides difficile infections (CDIs) or predicting the severity and outcomes of CDI has been emphasized in recent years. Although the yielding of C. difficile from stool cultures might implicate higher bacterial loads in fecal samples, in an era of nonculture methods for the standard diagnosis of CDIs, clinical significance of positive stool cultures of toxigenic C. difficile was analyzed in this study. Despite the limited ability of stool cultures in CDI diagnoses, no yielding of C. difficile growth might predict the successful CDI therapy.