[The role of microbiological markers in the progression of Clostridioidesdifficile infection]

The main current diagnostic challenge in Clostridioides difficile infection (CDI) is to detect patients with the poorest prognoses. We have studied the association between the presence of toxin in the feces, the amplification of the toxin B gene at low cycles in PCR (Ct), and the detection of the binary toxin or ribotype with severity, recurrence, and poor prognosis. Toxigenic C. difficile has been investigated in adult diarrheal feces, regardless of the clinical request. Glutamate dehydrogenase (GDH), toxin A (TcdA) and toxin B (TcdB) have been assessed by immunoassay and the gene encoding toxin B (tcdB) and the binary toxin (cdtA) by PCR. The toxigenic strains recovered by toxigenic culture were typed by PCR-Ribotyping and subtyped by MLVA (multilocus-variable number tandem DNA repeat analysis). Eighty-two (82) cases of CDI were detected from 677 samples (12.1%). Patients with Ct ≤ 27.5 often presented criteria for severity, recurrence, and poor prognosis (59.3% versus 40.7%, P=.15; 80% versus 20%, P=.10; and 60.3% versus 39.7%, P=.055, respectively). The mean Ct was lower when recurrence was observed (25.48; SD=2.41; P=.058). By logistic regression, the variable most likely to indicate a poor prognosis was Ct ≤ 27.5 (OR=2.663; 95% CI=.983-7.636; P=.059). In summary, the cycle threshold of the PCR for toxin B is a possible marker of severity, recurrence, and poor prognosis in CDI. The diversity of ribotypes observed is remarkable, with no clonal relationship between isolates of the same ribotype.