Inclusion Criteria:

• pre-menopausal woman aged 18-40 years
• current symptomatic uncomplicated cystitis
• cystitis is treated with trimethoprim-sulfamethoxazole (TMP-SMX)
• completion of screening procedures
• negative screening monolayer Pap smear or hysterectomy
• history of at least two prior symptomatic UTI's treated within the past 12 months or one pior symptomatic UTI treated in the past six months
• agree to return for the Randomization Visit (Visit 2)
• regular menstrual cycles or amenorrheic due to use of a long acting progestin, continuous use of oral contraceptives or hysterectomy
• willing to insert vaginal capsules without an applicator
• capable of providing informed consent
• able to read and understand English
• agree to abstain from self-medication with antibiotics for UTI symptoms
• agree to abstain from antibiotic prophylaxis for recurrent UTI
• agree to abstain from the use of any other intra-vaginal product
• agree to abstain from sexual intercourse for 24 hours after capsule insertion
• agree to not use tampons for 24 hours after capsule insertion
• agree to use an adequate method of birth control

Exclusion Criteria:

• complicated cystitis or uncomplicated pyelonephritis.
• cystitis at Visit 1 not treated with TMP-SMX
• uropathogen resistant to TMP-SMX isolated at Visit 1 and persistent symptoms at Visit 2 or failure to achieve a significant reduction in urine wbc count at Visit 2
• vaginal or cervical infection, currently or within the past 21 days, with bacterial vaginosis (treated, symptomatic infection), Trichomonas vaginalis, Neisseria gonorrhoeae, Chlamydia trachomatis or Herpes Simplex
• symptomatic bacterial vaginosis at Visit 1

• high risk for sexually transmitted diseases and/or HIV, including:

  1. diagnosis of N. gonorrhoeae, C. trachomatis or T. vaginalis on two or more occasions during the previous six months;
  2. sexual intercourse with a homosexual/bisexual male in the last 10 years;
  3. sexual intercourse with an injection drug user or sex worker in the last 10 years; or
  4. shared needles for injected drugs in the last 10 years.
• chronic vaginal, urinary or pelvic symptoms not attributable to UTI
• recurrent bacterial vaginosis (three or more symptomatic, treated infections in the prior 12 months)
• pregnancy or within two months of last pregnancy
• lactation
• antibiotic therapy fewer than three days prior to Randomization Visit
• antifungal therapy fewer than seven days prior to the Randomization Visit
• Antibiotics planned within four months
• abnormal Pap smear requiring a procedure for diagnosis or treatment in the past 12 months
• use of CTV-05 within one year of the Randomization Visit
• menopause
• use of a NuvaRing planned during the course of the study
• any significant disease or acute illness that in the Investigator's assessment could complicate the evaluation
• known HIV infection
• immunosuppressive drug within 60 days
• known allergy to any component of LACTIN-V or the placebo capsule
• unavailable for follow-up visits
• drug or alcohol abuse within past two years
• any social or medical condition that, in the opinion of the Investigator, would preclude provision of informed consent, make participation in the study unsafe, complicate interpretation of study outcome data, or otherwise interfere with achieving the study objectives