NGU: Doxycycline (Plus or Minus Tinidazole) Versus Azithromycin (Plus or Minus Tinidazole)

This study represents a clinical evaluation of the use of combination therapy for the initial treatment of non-gonococcal urethritis (NGU). This study will provide more current data on the comparison of cure rates between the 2 currently recommended therapies for NGU, doxycycline and azithromycin. Emerging clinical data has suggested that the latter may have become more efficacious for NGU as it is more effective in eradicating Mycoplasma (M.) genitalium from the genital tract than the former. Only in vitro data, limited as it is, suggests that doxycycline should be active against M. genitalium. The researchers hypothesize that cure rates for NGU will be significantly improved for both doxycycline and azithromycin using combination therapy with tinidazole. Important safety and tolerability data will be collected with regards to the use of combination therapy. Additionally, the study will provide data on the prevalence of the targeted pathogens in 4 geographic areas and on characteristics of men with NGU that may help to target populations who would benefit the most from combination therapy. The researchers hypothesize that currently recommended initial therapies for NGU are inadequate in at least certain populations due to lack of coverage for Trichomonas (T.) vaginalis. The researchers further hypothesize that between the 2 currently recommended regimens, azithromycin will result in a greater number of cures than doxycycline due to its greater efficacy in M. genitalium infected men. The primary study objectives are to: compare the clinical cure rates of doxycycline versus doxycycline with tinidazole; and azithromycin versus azithromycin with tinidazole for the treatment of NGU; and to evaluate the safety and tolerability of doxycycline/tinidazole and azithromycin/tinidazole in the treatment of NGU. Secondary study objectives are to: evaluate microbiological cure of Chlamydia (C.) trachomatis, T. vaginalis, M. genitalium in men treated with doxycycline versus doxycycline with tinidazole; and azithromycin versus azithromycin with tinidazole. Analysis will also include: (doxycycline plus doxycycline/tinidazole) versus (azithromycin plus azithromycin/tinidazole); for the clinical cure rates, analysis will also include: (doxycycline plus doxycycline/tinidazole) versus (azithromycin plus azithromycin/tinidazole); determine the prevalence of C. trachomatis, T. vaginalis, and M. genitalium in the study population of men with non-gonococcal urethritis; determine clinical, behavioral, and demographic predictors of the above organisms in men with non-gonococcal urethritis; and collect specimens for future studies to determine the role of unique and novel pathogens in the etiology of non-gonococcal urethritis. Outcome measures include clinical failure, clinical cure, microbiological cure, and unevaluable cure assessed at the first and second follow-up visits. Study participants will include 300 men ages 16-45 years with NGU attending sexually transmitted disease clinics in Birmingham, AL; New Orleans, LA; Durham, NC; and Baltimore, MD. Subjects will be randomly assigned to 1 of 4 active treatment arms: 75 subjects doxycycline; 75 subjects doxycycline plus tinidazole; 75 subjects azithromycin; and 75 subjects azithromycin plus tinidazole.

Inclusion criteria

• Male, 16 to 45 years old.
• Symptoms of non-gonococcal urethritis (NGU), including urethral discharge and/or dysuria for less than or equal to 14 days, or urethral discharge on exam.
• Urethral smear with greater than or equal to 5 polymorphonuclear leukocytes (PMNs) per 3-5 oil immersion fields.
• Willing to abstain from sexual intercourse or use condoms during the study.
• Willingness to provide written consent.

Exclusion criteria

• Presence of gonorrhea at baseline visit.
• History of recurrent non-gonococcal urethritis (NGU) (3 or more episodes in the prior year) or history of recent NGU (within past 30 days).
• Signs or symptoms of epididymitis or prostatitis.
• Known allergy to or intolerance of tinidazole, tetracyclines, macrolides or metronidazole.
• History of photosensitivity related to doxycycline use.
• Received systemic antibiotics within 30 days of study enrollment.
• Unwillingness to abstain from alcohol for 24 hours after enrollment.
• Serious underlying infection, including known HIV or other primary or secondary immunosuppression.
• Concomitant infection, which requires antimicrobial therapy.
• History of mental illness, which would preclude responsible participation in the study.
• Current drug abuse that might affect ability to follow the protocol.
• Previously enrolled in this study.
• Men who have sex with men, due to different microbiology of NGU.
• Voided within the previous hour.
• Ingested alcohol within the past 8 hours.
• Subject requires concurrent lithium, anticoagulation therapy, or antabuse.