Epidemiology of Clostridioides difficile PCR ribotype 181 after the COVID-19 pandemic in Northern Greece.

Clostridioides difficile infection (CDI) is one of the most significant causes of diarrhea in hospitalized patients. The aim of this study was to investigate the incidence and epidemiology of CDI after the COVID-19 pandemic in hospitalized patients in a rehabilitation center in Thessaloniki, Greece. Α retrospective observational cohort study was performed in inpatients diagnosed with diarrhea of all ages (January 2023 - December 2023) who were initially screened for CDI. From the total cohort of patients with proven CDI, some patients were randomly selected based on their monthly isolation incidence throughout the study period, to investigate their epidemiological data and clinical characteristics. Laboratory diagnosis of CDI was performed by enzyme immunoassay, followed by specific anaerobic culture and molecular testing for detection of toxigenic C. difficile. The isolated C. difficile strains were further characterized by PCR ribotyping. The annual incidence of CDI during the study period was 27.1% (130/480). The linear trend of CDI incidence decreased from 32.5% to 18.2% (P = 0.024). The all-cause mortality rate was 5.0% (3/60). A positive correlation was observed between the length of hospital stay and the number of recurrences (r = 0.546, P < 0.001), while 28 patients (46.7%) experienced recurrence of the infection. Seven different PCR ribotypes were identified in this study. C. difficile tcdA+, tcdB+, cdtA+, cdtB+ PCR ribotype 181 (RT181) was the predominant (76.6%, 46/60), followed by toxin A-negative PCR RT017 (11.6%, 7/60). The annual incidence of CDI decreased after the COVID-19 pandemic. Our study demonstrates predominance of C. difficile RT181 with tcdA+, tcdB+, cdtA+, cdtB+ toxin gene profile after COVID-19 pandemic in Northern Greece.