Tracking Clostridioides difficile in Germany: Active prospective surveillance progress and molecular epidemiological...

Clostridioides difficile infections pose significant healthcare challenges in Germany, driven by various ribotypes (RTs) and antimicrobial resistance. This study updates the molecular epidemiology through Germany's active and passive surveillance until the end of 2023, including changes during the COVID-19 pandemic.

As active surveillance, the first 10 stool samples tested positive for toxigenic C. difficile (one per patient) were collected biannually from 33 German microbiological laboratories. Passive surveillance included samples from severe cases and outbreaks. Isolates underwent genotypic characterization and antimicrobial susceptibility testing.

Regarding active surveillance, 1257 toxigenic C. difficile isolates were retrieved between October 2021 to October 2023. Previous surveillance data (n = 876) were added dating back to 2019. Among the 2133 strains, RT014 (18%), RT078 (7%) and RT001 (6%) were the most common RTs, while RT027 declined between 2019 and 2023 from 5% to 0.6%. Concerning the passive surveillance, from 509 isolates, RT027 was most prevalent (16%), followed by RT014 (13%), RT001 and RT002 (6% each). Emerging RTs, namely RT181 and RT955, were rarely detected or absent, respectively. No resistance to vancomycin or fidaxomicin was detected, and metronidazole resistance was low (0.5%). C. difficile RT027 isolates displayed high resistance for moxifloxacin, clarithromycin and rifampicin (~95%, ~95% and~70%, respectively). During the COVID-19 pandemic, no significant trends in RT diversity were observed while the reported number of cases decreased.

RT014 continues to be the most prevalent RT. Hypervirulent RTs remained rather constant, although numbers of RT027 declined over time. Ongoing surveillance remains crucial for monitoring emergent RTs.