Is there a relationship between the presence of the binary toxin genes in Clostridium difficile strains and the severity of C. difficile infection (CDI)?

Abstract

Some strains of Clostridium difficile produce a binary toxin, in addition to the main C. difficile virulence factors (toxins A and B). There have been conflicting reports regarding the role of binary toxin and its relationship to the severity of C. difficile infection (CDI). Samples, isolates and clinical data were collected as part of a prospective multicentre diagnostic study. Clostridium difficile isolates (n = 1259) were tested by polymerase chain reaction (PCR) assay to detect binary toxin genes cdtA and cdtB. The PCR binary toxin gene results were compared with clinical severity and outcome data, including 30-day all-cause mortality. The 1259 isolates corresponded to 1083 different patients (October 2010 to September 2011). The prevalence of binary toxin positive strains was significantly higher in faecal samples with detectable toxin A/B than in those without toxin but that were positive by cytotoxigenic culture (26.3% vs. 10.3%, p < 0.001). The presence of binary toxin correlated moderately with markers of CDI severity (white cell count, serum albumin concentration and serum creatinine concentration). However, the risk ratio for all-cause mortality was 1.68 for binary toxin positive patients and patients were significantly less likely to survive if they had CDI caused by a binary toxin gene positive strain, even after adjusting for age (p < 0.001). The presence of binary toxin genes does not predict the clinical severity of CDI, but it is significantly associated with the risk of all-cause mortality.

The association of a reduced susceptibility to moxifloxacin in causative Clostridium (Clostridioides) difficile strain with the clinical outcome of patients

“…Several studies aimed to identify the strain specific characteristics, i.e. ribotype or the presence of binary toxin genes, linked adversely to patient outcomes [23][24][25] and the most common ribotype found to be associated with mortality was ribotype 027 [23,24]. Although RT176 is genetically related to the 'hypervirulent' RT027 [26], our data did not support the relationship between RT176 CDI and a poorer outcome for the patients.…”

Occurrence of Blastocystis in Patients with Clostridioides difficile Infection

“…Hence, the selection criteria used to determine positive samples (for CDI or Cd_tox) was when at least one positive result in any of the traditional molecular tests applied to DNA of the sample was obtained. Thus, in the case of toxigenic C. difficile, the presence of genes that encode for any of the toxins (toxins A or B, or binary toxin) determined a positive toxigenic C. difficile, since some studies show that binary toxins have cytopathic effects in vitro and exacerbate clinical outcomes in C. difficile patients [33,34]. Therefore, all toxigenic CDI samples had at least 2 molecular markers positive (16S-rRNA or gdh gene and at least 1 of the toxin genes).…”

The predictive value of quantitative nucleic acid amplification detection ofClostridium difficiletoxin gene for faecal sample toxin status and patient outcome

“…Indeed, in those patients with a low CT (≤25), mortality and longer LOS were also significantly associated with the presence of PCR-ribotype 027, compared with other PCR-ribotypes, highlighting a possible ‘at risk’ group. There is conflicting evidence regarding the role of binary toxin in CDI outcomes [12–13]. Our data show that the relative risk for mortality in patients with low CT increased from 1.45 to 1.72 when the presence of binary toxin gene was taken into account.…”