Comparison of the Prevalence and Characteristic of Clostridioides difficile Infection in Hospital- associated and Community-associated Diarrhea

Background and Objectives: Clostridioides difficile infection (CDI) used to be considered almost exclusively a health-care associated infection. However, patients in the community have recently come to be considered at risk of the infection, as severe cases of community associated CDI have been reported among populations without any known risk factors. This study aimed to determine the prevalence of C. difficile in community- and hospital-associated diarrhea, and to compare, over a one-year period, the two settings in terms of isolates’ antibiotic resistance phenotypes and their toxin production ability. Materials and Methods: To make the comparison, stool samples collected from patients with diarrhea were divided into two different categories. The first (n=290) included those taken from patients referred to hospital due to diarrhea and were thus, considered as the community-associated type. The second samples (n=110), however, belonged to those afflicted with diarrhea after 72 hours following their admission to hospital, hence categorized as the hospital-associated type. After an initial alcohol-shock, all the samples underwent bacterial culture using C. difficile agar medium in anaerobic condition. C.difficile was initially identified by colony morphology and horse barn odor, and then confirmed by PCR for gdh gene. Minimum inhibitory concentration (MIC) of six antibiotics (fidaxomicin, tigecycline, vancomycin, metronidazole, ciprofloxacin and erythromycin) was determined for C.difficile isolates, using the agar dilution method. In addition, multiplex PCR was performed through the use of specific primers to detect tcdA (encoding toxin A), tcdB (encoding toxin B) and Binary toxin ( cdtA , cdtB ) genes. Results: Out of the 290 community-associated diarrhea samples, 17 (5.9%) were positive for C.difficile, while in the case of hospital-associated diarrhea, figures for the isolation rate of C.difficile reached 24%. Although no evidence of resistance to metronidazole and vancomycin was observed in the isolates of the community cases, resistance to erythromycin and ciprofloxacin was observed in 93.8% and 56.3% of the isolates, respectively. In the hospital category, similar to the community-associated samples, no evidence of resistance to metronidazole was found. However, resistance to erythromycin, ciprofloxacin and vancomycin were observed (76.2%, 66.6%, and 4.8%, respectively). No evidence of a decrease in susceptibility to fidaxomicin and tigecycline was observed in C.difficile strains irrespective of their isolation setting. The number of C.difficile strains positive for toxin genes was higher in the hospital setting (57.8%) than in the community one (43.8%). Conclusion: The results of this study lend support to the suggestion that patients in the community are also at the risk of CDI, and that significant numbers of C.difficile strains from community were toxigenic with high levels of resistance to erythromycin and ciprofloxacin. Ribotyping of the isolates from two settings are suggested to further investigate the presence of highly pathogenic strains.