Both Fidaxomicin and Vancomycin Inhibit Outgrowth of Clostridium difficile Spores

Abstract

b Fidaxomicin (FDX) is approved to treat Clostridium difficile-associated diarrhea and is superior to vancomycin in providing a sustained clinical response (cure without recurrence in the subsequent 25 days). The mechanism(s) behind the low recurrence rate of FDX-treated patients could be multifactorial. Here, we tested effects of FDX, its metabolite OP-1118, and vancomycin on spore germination and determined that none affected the initiation of spore germination but all inhibited outgrowth of vegetative cells from germinated spores.C lostridium difficile, a Gram-positive, spore-forming, obligate anaerobe, causes intestinal infections, usually in people who have recently completed antibiotic therapies for unrelated conditions (1). Antibiotics cause alterations in the normally protective colonic microbiota, creating a niche for C. difficile to colonize (2, 3). To cause disease, C. difficile spores, which are unaffected by inciting antibiotics, must germinate to vegetative, or actively growing, bacteria in the anaerobic environment of the colon in order to produce the toxins that are responsible for the primary disease symptoms (4-6). Therefore, C. difficile spores, which are highly resistant to chemical disinfectants and antibiotics, are the source of infection. Although the exact mechanism and receptors involved in C. difficile spore germination are not clearly defined, both taurocholic acid and glycine have been identified as factors that synergistically stimulate germination of spores into virulent vegetative cells that secrete potent toxins (7,8).Vancomycin and metronidazole are commonly prescribed to treat C. difficile infections (CDI) (1). However, patients treated with vancomycin or metronidazole frequently relapse with C. difficile disease (1). Recently, fidaxomicin (FDX) was approved in the United States, Europe, and Canada as an alternative for the treatment of CDI. During phase 3 clinical trials, FDX was shown to be superior to vancomycin in sustaining clinical response without recurrence for up to 25 days following treatment (9, 10).Multiple factors may lie behind the reduced rate of relapsing CDI in FDX-treated patients. Both FDX and its main metabolite OP-1118 have been shown to strongly inhibit C. difficile spore formation (11). FDX also has a reduced impact on the normally protective colonic microbiota (12,13). In this study, we evaluated whether FDX might block germination of C. difficile spores.To test the effect of FDX on C. difficile spore germination, we purified spores from C. difficile strains CD196 (14) and UK1 (15), as described previously (16). To provide a quantitative measure of the effects of FDX, OP-1118, and vancomycin on C. difficile spore germination, we analyzed the kinetics of the initiation of spore germination. By measuring the maximum rate of spore germination under different conditions, we are able to determine an apparent K m , defined as the concentration that provides a half-max- difficile CD196. Purified C. difficile UK1 spores (A) and C. difficile CD196 spores (B) were ...

Bile Acid Recognition by the Clostridium difficile Germinant Receptor, CspC, Is Important for Establishing Infection

“…The relative affinities of bile acids for the C. difficile spore were determined using kinetics of germination [18], [19], [37], [38], [39]. While these studies were important milestones in determining which bile acids affect C. difficile germination and what features are important for triggering or inhibiting germination, the precise interaction of the bile acid with the germinant receptor has not been analyzed.…”

Muricholic Acids Inhibit Clostridium difficile Spore Germination and Growth

“…C. difficile strain UK1 [34], [38], [41], [42] and strain M68 [13], [43] were grown in BHIS medium (Brain Heart Infusion supplemented with 5 g/L yeast extract and 0.1% L-cysteine) at 37°C in an anaerobic environment (85% nitrogen, 10% hydrogen and 5% carbon dioxide).…”

Esporas de Clostridium difficile y su relevancia en la persistencia y transmisión de la infección

“…Ninguno de estos tres antibacterianos afecta la viabilidad de las esporas latentes de C. difficile. Solamente vancomicina y fidaxomicina logran disminuir la eficiencia con la cual las esporas de C. difficile forman colonias (i.e., eficiencia de germinación) 91 .…”