ANTIBIOTIC-PROPHYLAXIS AND TREATMENT OF REACTIVE ARTHRITIS - LESSONS FROM AN ANIMAL-MODEL

Objective. To study the effect of antibiotic prophylaxis and treatment of reactive arthritis (ReA), using an experimental model. Methods. Ye rsinia enterocolitica O:8, when injected intravenously into Lewis rats , causes a sterile arthritis closely resembling human ReA in 70% of th e animals, Arthritis develops in 1-2 weeks; in some of the animals it remains chronic, and exacerbations occur, This model was applied to st udy the effect of a 7-day treatment with ciprofloxacin, using 2 differ ent dosages (20 or 100 mg/kg/day) and 4 different schedules for initia tion of treatment, The effects were evaluated by determining the daily arthritis score, the number of rats developing arthritis, and fecal e xcretion of Yersinia, In addition, weight gain was monitored, At autop sy (35 or 60 days after inoculation with bacteria), samples were obtai ned for determination of Yersinia-specific antibodies in the serum, At the same time, samples were collected from mesenteric lymph nodes, lu ng, spleen, and liver for bacterial cultures, and from the ankle joint s for histologic evaluation, In a separate experiment, ciprofloxacin c oncentrations in samples from serum and mesenteric lymph nodes were an alyzed by high performance liquid chromatography. Results. A 7-day cou rse,vith 100 mg/kg/day of ciprofloxacin, started on day 3 after bacter ial inocula-tion, completely prevented the development of ReA and elim inated Yersinia during the 60-day experiment. If a dosage of 20 mg/kg/ day was used, development of acute arthritis was prevented, but some o f the animals had positive fecal cultures at the end of experiment, If antibiotic treatment was started on day 5, the preventive effect was still observed, but was less pronounced, If the treatment was started at the peak of the development of arthritis, no effect on arthritis wa s observed. Conclusion. These results indicate that if any effect of a ntibiotic treatment in Yersinia-triggered ReA is to be expected, the t reatment must be started early and given in sufficient dosage, However , antibiotic treatment has no effect on fully developed arthritis.