Clostridium innocuum is a vancomycin-resistant pathogen that may cause antibiotic-associated diarrhoea

摘要

ObjectivesClostridium innocuumcan cause extraintestinal infection in patients with underlying diseases. The role ofC.?innocuumin antibiotic-associated diarrhoea (AAD) remains unknown. MethodsClinical information of 103 patients from whomC.?innocuumwas isolated was reviewed. We carried out cellular and animal experiments to examine the pathogenic potential ofC.?innocuumin AAD. ResultsEighty-eight per cent (91/103) of the 103 patients received antibiotics within 2?weeks of diarrhoea onset. Patients were further classified into two groups, severe colitis and diarrhoea, according to clinical severity level. The mortality rate was 13.6% (14/103) among the patients from whomC.?innocuumwas isolated. The lowest concentrations at which 90% of the isolates were inhibited for metronidazole and vancomycin were 0.5 and 16 mg/L, respectively. All isolates tested were susceptible to metronidazole but resistant to vancomycin. Nineteen randomly selected isolates (ten from severe colitis group, nine from diarrhoea group) were subjected to furtherin?vitrocellular examinations. The level of cytotoxicity to Vero cells was significantly higher in isolates from the severe colitis group at both 24 and 48?hours after inoculation (24 and 48?hours, p 0.042 and 0.033, respectively). We observed apoptotic changes that subsequently led to cell death inC.?innocuum–infected Vero cells. Tissue damages, necrotic changes and oedema were observed in the mouse ileal loop infected byC.?innocuum. ConclusionsVancomycin-resistantC.?innocuummay play a potential role as a causative agent of AAD. The clinical manifestations of AAD caused byC.?innocuumwere diarrhoea or severe colitis, including pseudomembranous colitis.