Purpose: Interstitial cystitis is a chronic disease of unknown etiology characterized by bladder pain, urgency and frequency. Although a single microbe has not been implicated as a cause of interstitial cystitis, several groups noted various organisms in the urine of some women with interstitial cystitis and some patients reported that antibiotics decrease symptoms. Consequently we performed a prospective, randomized, double-blinded, placebo controlled pilot study of sequential oral antibiotics.
Materials and methods: We randomized 50 patients with interstitial cystitis to receive 18 weeks of placebo or antibiotics, including rifampin plus a sequence of doxycycline, erythromycin, metronidazole, clindamycin, amoxicillin and ciprofloxacin for 3 weeks each.
Results: Intent to treat analysis demonstrated that 12 of 25 patients (48%) in the antibiotic and 6 of 25 (24%) in the placebo group reported overall improvement (p = 0.14), while 10 and 5, respectively, noticed improvement in pain and urgency (p = 0.22). In the antibiotic group 20 participants (80%) had adverse effects compared with 10 (40%) in the placebo group (p = 0.009).
Conclusions: Our findings suggest that these antibiotics alone or in combination may sometimes be associated with decreased symptoms in some patients but they do not represent a major advance in therapy for interstitial cystitis.