What antibiotic regimen is recommended for a urinary tract infection (UTI) with a negative nitrate test and prophylaxis against gonorrhea (GC) and chlamydia?

Antibiotic Regimen for UTI with Negative Nitrite and GC/Chlamydia Prophylaxis

For a UTI with negative nitrite requiring concurrent gonorrhea and chlamydia prophylaxis, use ceftriaxone 500 mg IM single dose PLUS doxycycline 100 mg orally twice daily for 7 days. This regimen provides comprehensive coverage for all three conditions simultaneously 1, 2.

Rationale for This Dual-Purpose Regimen

Gonorrhea and Chlamydia Coverage

• Ceftriaxone 500 mg IM is the gold standard for gonorrhea prophylaxis, achieving 99.1% cure rates for urogenital, anorectal, and pharyngeal infections 3, 4, 5.
• Doxycycline 100 mg twice daily for 7 days provides optimal chlamydia coverage and is the CDC's preferred agent when azithromycin single-dose therapy is not used 1, 6.
• Co-infection rates are extremely high (40-50% of gonorrhea patients also have chlamydia), making dual therapy essential for empiric treatment 1.

UTI Coverage

• Ceftriaxone provides excellent coverage for typical UTI pathogens including E. coli and other Enterobacterales, with sustained bactericidal levels 7.
• A negative nitrite test does not rule out UTI, as only 50% of UTI-causing organisms produce nitrite-reducing enzymes 7.
• Single-dose ceftriaxone has demonstrated 90% cure rates for uncomplicated UTIs 7.

Critical Advantages of This Single Regimen

• Eliminates the need for multiple antibiotics: One injection plus one oral medication covers all three conditions 1, 2.
• Superior pharyngeal gonorrhea coverage: Ceftriaxone is the only reliably effective treatment for pharyngeal infections, which are significantly more difficult to eradicate than urogenital infections 3, 5.
• Avoids fluoroquinolone resistance: Never use ciprofloxacin for gonorrhea prophylaxis due to widespread resistance 8, 9.

Alternative Regimen (If Ceftriaxone Unavailable)

• Cefixime 400 mg orally single dose PLUS doxycycline 100 mg twice daily for 7 days 10, 1.
• Mandatory test-of-cure at 1 week is required with cefixime due to inferior efficacy compared to ceftriaxone 1.
• Cefixime has only 97.1% cure rate for gonorrhea versus 99.1% for ceftriaxone 10.

Special Population Considerations

Pregnancy

• Use ceftriaxone 500 mg IM single dose PLUS azithromycin 1 g orally single dose 1.
• Never use doxycycline, quinolones, or tetracyclines in pregnancy 1, 6.

Severe Cephalosporin Allergy

• Azithromycin 2 g orally single dose for gonorrhea/chlamydia coverage 1.
• Add a separate UTI-specific antibiotic (nitrofurantoin or fosfomycin) as azithromycin has poor UTI coverage 10.
• Requires mandatory test-of-cure at 1 week due to lower efficacy (93% for gonorrhea) 1.

Critical Pitfalls to Avoid

• Never use azithromycin 1 g alone for gonorrhea: Only 93% efficacy, insufficient for prophylaxis 10, 3.
• Never use fluoroquinolones (ciprofloxacin) for gonorrhea: Widespread resistance makes them unreliable 8, 9.
• Never use spectinomycin if pharyngeal exposure suspected: Only 52% effectiveness for pharyngeal infections 3, 1.
• Do not assume negative nitrite excludes UTI: Many UTI pathogens don't produce nitrite 7.

Partner Management and Follow-Up

• All sexual partners from preceding 60 days require evaluation and treatment with the same dual therapy regimen 1.
• Patients should avoid sexual intercourse until therapy is completed and both patient and partners are asymptomatic 1.
• Retest approximately 3 months after treatment due to high reinfection risk for STIs 1, 9.
• Routine test-of-cure not needed for patients treated with recommended ceftriaxone-based regimens unless symptoms persist 1.

Dosing Summary

Recommended Regimen:

• Ceftriaxone 500 mg IM single dose 2
• PLUS Doxycycline 100 mg orally twice daily for 7 days 6, 2

This single regimen efficiently addresses the UTI, provides gonorrhea prophylaxis, and treats/prevents chlamydia infection without requiring multiple antibiotic courses 1, 2.