Leading Causative Organisms of Epididymitis in Men Under 35
In men under 35 years of age, Chlamydia trachomatis is the leading causative organism of epididymitis, followed closely by Neisseria gonorrhoeae. 1, 2
Primary Pathogens by Age
Men Under 35 Years (Sexually Active)
- Chlamydia trachomatis is the most common pathogen in this age group 1, 3, 4
- Neisseria gonorrhoeae is the second most common causative organism 1, 3, 4
- Both organisms cause sexually transmitted epididymitis that is typically accompanied by urethritis, which is often asymptomatic 1
- Among men who practice insertive anal intercourse, sexually transmitted Escherichia coli infection also occurs 1
Men Over 35 Years
- Gram-negative enteric organisms (particularly E. coli and other Enterobacteriaceae) predominate in this older age group 1, 5, 6
- These infections are typically associated with urinary tract abnormalities, bladder outlet obstruction, or recent urinary tract instrumentation 1, 3
Clinical Context and Diagnostic Implications
The age cutoff of 35 years is critical for determining empiric treatment, as the microbiology shifts dramatically at this threshold 1, 3:
- In sexually active men aged 14-35 years, urethritis is frequently present (even if asymptomatic), and diagnostic evaluation should include urethral swab testing for C. trachomatis and N. gonorrhoeae rather than relying solely on urinalysis 2, 7
- Current tests for C. trachomatis are not sufficiently sensitive to exclude infection even when negative, so empiric treatment is warranted based on clinical presentation 1, 2
Treatment Implications
Because C. trachomatis and N. gonorrhoeae are the leading organisms in men under 35, the CDC recommends dual therapy:
- Ceftriaxone 250 mg IM single dose PLUS doxycycline 100 mg orally twice daily for 10 days 1, 2, 7, 8
- This regimen covers both organisms effectively, as C. trachomatis requires prolonged doxycycline therapy while N. gonorrhoeae is treated with the single-dose ceftriaxone 1, 3, 4
Important Caveats
- Sex partners should be evaluated and treated empirically regardless of their symptoms, as male partners are frequently asymptomatic carriers 1
- Partners who had sexual contact within 60 days preceding symptom onset require treatment 1, 7, 8
- Failure to improve within 3 days of appropriate treatment requires reevaluation of both diagnosis and therapy, including consideration of testicular torsion, abscess, or other diagnoses 2, 7