The first step is to determine if the recurrent infection is due to relapse or reinfection. Most cases of cystitis are reinfections, with episodes separated by weeks or months.
Features of relapse:
(1) Relapse usually involves a recurrent infection with same organism within 2 weeks after completion of therapy for an initial episode.
(2) Often associated with some cause such as an organism with antibiotic resistance, incorrect antibiotic selection, defect in host defense, abscess, or structural defect in the urinary tract. Patients with relapse may benefit from culture with susceptibility testing and from a more complete urologic examination.
If the woman uses a diaphragm with spermicide, then an alternative contraceptive method should be tried.
If the woman is sexually active and episodes of cystitis are temporally related to intercourse, then postcoital antibiotic prophylaxis may be tried.
Postmenopausal women with recurrent infections may benefit from prophylactic vaginal estrogens which alter the vaginal flora.
The number of recurrence per year may help guide therapy.
(1) If there are 1-2 infections per year, then consider patient initiated therapy for symptomatic episodes.
(2) If there are 3 or more infections per year, then daily or intermittent prophylaxis may be indicated.
