Development of a Standardized Scoring System to Assess a Murine Model of Colitis.

infection is the most common cause of antimicrobial-associated diarrhea. Our aim was to introduce a novel and efficient clinical sickness score (CSS), and to define a detailed histologic injury score (HIS) in a murine model of colitis. Mice received an antibiotic cocktail (kanamycin, gentamicin, colistin, metronidazole, and vancomycin) for 96 h. After 48 h, mice received an intraperitoneal injection of clindamycin, followed by oral (1.5 × 10 CFU). Signs of sickness were scored using a novel CSS (range 0-12) with scores ≥6 consistent with colitis. Intestinal tissue was analyzed utilizing an adapted HIS (range 0-9) with scores ≥4 consistent with colitis. Stool was analyzed for and survival evaluated. No control mice showed signs of sickness, whereas 23% of mice receiving antibiotics alone and 65% of mice exposed to antibiotics and subsequently demonstrated signs of sickness ( = 0.0134). No control mice had histologic injury, whereas 8% of mice receiving antibiotics alone and 75% of mice exposed to antibiotics followed by had evidence of histologic injury ( = 0.0001). Mice exposed to lost more weight, although not significant ( = 0.070). Mice that received had decreased survival compared to control mice and mice receiving antibiotics only ( = 0.03). We have developed a novel clinical scoring system, and detailed histological grading system, that enables the objective evaluation of a murine colitis model. This model allows the study of this disease in a host that demonstrates clinical and histologic signs comparable to human infection. This will allow for improved study of therapeutics for this disease in the future.