Prevalence and Severity of Binary Toxin Producing Clostridium Difficile Isolates in ICU, Zagazig University Hospitals

Background: Clostridium difficile is an important pathogen that causes antibiotic-associated diarrhoea and pseudomembranous colitis with two virulence factors of toxins A (TcdA) and B (TcdB). A third toxin, called binary toxin (CDT), can be detected in some strains and has a role in Clostridium difficile associated disease (CDAD) pathogenesis. Objectives : To determine the prevalence of binary toxin producing isolates in C. difficile associated disease in ICU, Zagazig University Hospitals, Egypt. Also, to assess the risk factors and clinical characterizations among binary and non-binary toxin associated infections. Methodology: Stools samples were collected from 200 patients who were admitted to ICU, Zagazig University Hospitals, Egypt, during 2013-2015 and suspected of having CDAD. They were subjected to toxigenic culture and direct detection of toxin A-B by enzyme immunoassay (EIA) and 5plex PCR test. A 5-plex PCR was used for the detection of the C. difficile toxin genes, with 16S rDNA. Results: Out of the 200 stools samples obtained, 28 (14%) were positive by toxigenic culture, and 20 (10%)of them were positive by direct EIA of toxin A and B. Twenty –six isolates (13%) were PCR positive for toxin A and B genes, and 8 isolates were binary toxin positive. Regarding antibiotic use as a risk factors for infection, meropenem was a risk factor more frequently presented in binary toxin producing isolates, (OR (95% CI); 0.02 (0.0-0.27); P < 0.001), and the third generation cephalosporin was more frequently encountered in non-binary toxin isolates (P, 0.023). It was found that binary toxin producing isolates were associated with disease severity (P< 0.001). The evaluation of the direct  PCR in diagnosis of CDAD in comparison to toxigenic culture,  showed sensitivity of 92.9%, Specificity  of 100%, and Accuracy of 90%. Conclusion : Infection caused by binary toxin producing Cl difficile is an emerging medical problem and significantly associated with disease severity. The 5-plex PCR detection of C. difficile toxin genes is a sensitive screening method.