Chlamydia Frequently Coexists with Gonorrhea
The correct answer is C. Chlamydia - patients infected with N. gonorrhoeae are often coinfected with C. trachomatis, which is why dual therapy treating both infections simultaneously has become standard practice. 1
Evidence for Coinfection Rates
The coinfection rate between gonorrhea and chlamydia is substantial and clinically significant:
- Chlamydial infection accompanies 10-30% of gonococcal infections in most populations, making it the most common coinfection 1
- Some studies report even higher coinfection rates of 10-40% in the US and UK 2
- This high rate of coinfection led to the CDC recommendation that all patients treated for gonococcal infection should also be treated routinely with a regimen effective against uncomplicated genital C. trachomatis infection 1
Clinical Rationale for Dual Therapy
The CDC guidelines explicitly address why dual therapy became standard:
- Routine dual therapy without testing for chlamydia is cost-effective because the cost of chlamydia treatment (e.g., $0.50-$1.50 for doxycycline) is less than the cost of testing 1
- Presumptive treatment is indicated for patients who may not return for test results, ensuring they receive appropriate coverage for both infections 1
- The routine use of dual therapy has resulted in substantial decreases in the prevalence of chlamydial infection in many populations 1
Why Not the Other Options
Syphilis (Option A): While syphilis is another sexually transmitted infection, it does not have the same high rate of coinfection with gonorrhea that would warrant routine dual therapy 3
Herpes simplex virus (Option B): HSV is a viral infection with different transmission patterns and does not commonly coexist with gonorrhea at rates requiring routine cotreatment 3
Chancroid (Option D): This is a much less common STI caused by Haemophilus ducreyi and is not routinely associated with gonorrhea 3
Current Clinical Practice
- Ceftriaxone should routinely be accompanied by azithromycin or doxycycline to address the likelihood of coinfection with C. trachomatis 3
- In geographic areas where coinfection rates are lower, some clinicians may prefer highly sensitive testing for chlamydia rather than treating presumptively, though this approach requires reliable patient follow-up 1
- All patients diagnosed with gonorrhea should be tested for other sexually transmitted infections, including HIV, given the epidemiologic overlap 3