Mouse Relapse Model of Clostridium difficile Infection

Abstract

Clostridium difficile is the causative agent of primary and recurrent antibiotic-associated diarrhea and colitis in hospitalized patients. The disease is caused mainly by two exotoxins, TcdA and TcdB, produced by the bacteria. Recurrent C. difficile infection (CDI) constitutes one of the most significant clinical issues of this disease, occurs in more than 20% of patients after the first episode, and may be increasing in frequency. However, there is no well-established animal model of CDI relapse currently available for studying disease pathogenesis, prevention, and therapy. Here we report the establishment of a conventional mouse model of recurrence/relapse CDI. We found that the primary episode of CDI induced little or no protective antibody response against C. difficile toxins and mice continued shedding C. difficile spores. Antibiotic treatment of surviving mice induced a second episode of diarrhea, while a simultaneous reexposure of animals to C. difficile bacteria or spores elicited a full spectrum of CDI similar to that of the primary infection. Moreover, mice treated with immunosuppressive agents were prone to more severe and fulminant recurrent disease. Finally, utilizing this model, we demonstrated that vancomycin only delayed disease recurrence, whereas neutralizing polysera against both TcdA and TcdB completely protected mice against CDI relapse. In conclusion, we have established a mouse relapse CDI model that allows for future investigations of the role of the host immune response in the disease's pathogenesis and permits critical testing of new therapeutics targeting recurrent disease.Clostridium difficile, a Gram-positive, anaerobic, and sporeforming bacterium, is an etiologic agent of pseudomembranous colitis and accounts for a quarter of all cases of antibioticassociated diarrhea (10). With the recent emergence of hypervirulent antibiotic-resistant strains, the incidence of C. difficile-associated diarrhea and intestinal inflammatory disease (collectively designated CDI) has increased significantly in both North America and Europe, causing lengthy hospitalizations and substantial morbidity and mortality (24,26). CDI is now considered an important reemerging disease.C. difficile produces metabolically dormant spores that are excreted from infected patients. The infectious spores persist in the environment and are highly resistant to commonly used disinfectants. Spores survive exposure to gastric acidity and germinate in the gut. The use of antibiotics that spare C. difficile but suppress the intestinal microbiota allows C. difficile to proliferate and produce two exotoxins, TcdA and TcdB, which cause intestinal tissue damage and inflammation. Therefore, antibiotic exposure is the most significant risk factor for the diseases (6). CDI ranges from mild diarrhea to life-threatening fulminant colitis (5,8,26). In addition to gastrointestinal disease, systemic complications of infection like ascites (15), pleural effusion (7, 38), hepatic abscess (30), and renal failure (11) have also been reported. ...

A Chimeric Toxin Vaccine Protects against Primary and Recurrent Clostridium difficile Infection

“…CDI has become increasingly difficult to manage due, in part, to the ineffectiveness of current antibiotic regimens which are associated with high relapse rates (24). We tested the efficacy of cTxAB immunization in preventing disease recurrence in a sporeinduced mouse CDI recurrence model (55). The immunization and challenge scheme is illustrated in Fig.…”

“…In some experiments, immunized mice were challenged with 10 6 spores of UK1 (027/B1/NAP1 strain kindly provided by D. Gerding, VA Chicago Health Care System). To induce CDI relapse, surviving mice were given antibiotic cocktail treatment followed by oral gavage of C. difficile spores (10 6 /mouse) 30 days after the primary infection (55).…”

Protection from Clostridium difficile Infection in CD4 T Cell- and Polymeric Immunoglobulin Receptor-Deficient Mice

“…The major protective Ab described for C. difficile is anti-toxin Ab (7-13, 17, 22-26). In both hamsters and mice, passive transfer of IgG anti-toxin mediates protection from CDI-associated mor- tality and disease, although protection is dependent on the amount of anti-toxin Ab administered (9,27). In humans, passive immunization of CDI patients with IgG anti-toxin A and B MAb resulted in decreased recurrent CDI (10), and IgG anti-toxin immunity actively acquired during CDI appears to decrease CDI recurrence (8,26), indicating that serum IgG anti-toxin Ab can be protective.…”

A chimeric protein comprising the glucosyltransferase and cysteine proteinase domains of toxin B and the receptor binding domain of toxin A induces protective immunity againstClostridium difficileinfection in mice and hamsters

“…Immunized or control mice were pretreated with an antibiotic cocktail followed by C. difficile spore infection via oral gavage as described previously. 51,52 Fourteen days after the third immunization, mice were challenged with 10 6 C. difficile UK6 spores.…”