Chlamydia Urine Testing and Prostatic Infections
Urine testing for chlamydia primarily detects urethral infections and is not a reliable method for diagnosing prostatic chlamydial infections, as the organism is rarely recovered from prostatic tissue and urine specimens do not adequately sample the prostate gland. 1
Understanding What Urine Tests Detect
Urine-based nucleic acid amplification tests (NAATs) are highly sensitive and specific for detecting Chlamydia trachomatis in the urethra, with pooled sensitivities of 84-93% in men and specificities exceeding 97%. 2
However, urine specimens reflect urethral infection, not prostatic infection. The first-catch urine sample captures organisms shed from the urethral mucosa, not from deeper structures like the prostate. 3, 2
Evidence Regarding Prostatic Chlamydial Infection
Direct prostatic tissue sampling via transperineal biopsy has failed to demonstrate Chlamydia trachomatis in prostatic tissue from patients with chronic abacterial prostatitis, with 0% recovery rate in culture and immunofluorescence studies. 1
Expressed prostatic secretion (EPS) testing may be more informative than urine alone for suspected prostatic involvement, as it directly samples prostatic fluid. In one study, EPS was positive in 7 of 17 patients with prostatic complaints when urethral samples were negative. 4
For chronic bacterial prostatitis diagnosis, the CDC recommends microbiological culture from urine collected after prostatic massage (VB3) or expressed prostatic secretions (EPS) via the Meares-Stamey procedure, not standard urine testing. 5
Clinical Implications
If prostatic chlamydial infection is suspected, standard first-catch urine NAAT is insufficient. You need post-prostatic massage urine (VB3) or expressed prostatic secretions to adequately sample the prostate. 5, 4
Seminal fluid testing may improve detection of upper genital tract involvement, showing higher positivity rates (7.9%) compared to urethral samples (6.2%) in some studies, though this is not standard practice. 4
Common Pitfalls
Do not assume a negative urine NAAT rules out prostatic infection in men with clinical prostatitis symptoms, as the test was not designed to sample prostatic tissue. 1
False-positive urine results may occur in older men with non-chlamydial urinary tract infections, particularly with older EIA tests. 6, 7
Serum chlamydia serology has no value in diagnosing genital tract or prostatic infections, as it cannot distinguish current from past infection. 6
Recommended Approach for Suspected Prostatic Chlamydia
For symptomatic urethritis: standard first-catch urine NAAT is appropriate and highly sensitive. 7, 3
For suspected prostatic involvement: obtain post-prostatic massage urine (VB3) or expressed prostatic secretions using the Meares-Stamey procedure for culture and NAAT testing. 5
Consider empiric treatment for chronic bacterial prostatitis with fluoroquinolones (e.g., levofloxacin 500 mg daily for 28 days) if clinical suspicion is high, as microbiologic confirmation of prostatic chlamydia is challenging. 5