Clostridioides difficile: Relevance, ribotypes, and endoscope reprocessing

  • Clostridioides difficile is one of the most common nosocomial pathogens and is also present outpatient settings.

  • The hypervirulent ribotype 027 results in serious disease outcomes and increased mortality in numerous countries worldwide.

  • If flexible endoscopes are cleaned and disinfected thoroughly after each patient use, based on current evidence, endoscopic procedures pose no risk in terms of the transmission of Clostridioides difficile.

Clostridioides (formerly Clostridium) difficile (C. difficile) is considered one of the most common pathogens of nosocomial and antibiotic-associated diarrhea. The number of C. difficile infections (CDIs) occurring globally has increased substantially since 2000. For example, according to one study from 2014, the pathogen caused 12.1% of all reported nosocomial infections in US hospitals 9. CDIs prolong hospitalization in the United States by 2.8 to 10.4 days and cause costs in the amount of 42,000 US dollars per case. Elderly patients and individuals with serious underlying illnesses and comorbidities are at particular risk. However, C. difficile is also a growing problem outpatient settings. Thus, an increased incidence of CDIs has also been observed in outpatient settings for some years.

Spread of hypervirulent ribotype 027

At the same time, an increased number of severe cases and outbreaks has been observed. This development can be attributed in particular to the spread of a hypervirulent strain of the C. difficile pathogen, ribotype 027 (RT 027). Originating in North America, RT 027 has spread along two distinct epidemic lines to regions that include Europe, Australia, and South Korea, as has been shown in genetic analyses. RT 027 exhibits an increased production of the toxins that trigger disease. For example, this strain releases 16 times more enterotoxin and 23 times more cytotoxin B. RT 027 also produces the binary toxin CDT. Infections with the strain result in a substantially higher mortality rate. RT 027 is, furthermore, resistant to several antibiotics, especially the fluoroquinolones.

Ribotypes 001, 014, 017, 078, and 176 are other C. difficile strains for which severe cases and complications have also been described. The pathogenic strains also include ribotype 106. First identified in the UK, the strain has now spread worldwide and superseded RT027 as the most prevalent strain in the USA. Studies have concluded that RT 106 causes less severe illness than RT 027 1. However, patients infected with the RT 106 strain are significantly more likely to suffer multiple CDI relapses.

C. difficile in endoscopy

Despite the high contagiousness of C. difficile, there has to date been only one documented cases of possible transmission after a colonoscopy 8. The risk of developing C. difficile-associated diarrhea (CDAD) after a gastrointestinal endoscopy procedure is therefore considered to be low. However, another study showed that 10 out of 15 colonoscopes were contaminated with C. difficile immediately after being used for CDAD patients 7.

In terms of patient safety, thorough manual cleaning followed by automated washing and disinfection in endoscope washer-disinfectors (EWD/AER) play a key role. Validated automated processes are used to safely reprocess endoscopes, and the processes used for EWD/AER must be proven to be effective against bacterial spores in accordance with ISO 15883-4. In addition, with EN 17126, a new testing method has been available since 2018 for demonstrating the sporicidal efficacy of chemical disinfectants, including spores from C. difficile ribotype 027 used as test microorganism. According to this standard, the disinfectant must reduce the number of spores by at least 4 log10 within 60 minutes.