What is the recommended empirical antibiotic regimen for acute bacterial sexually transmitted infections in Australia?

Empirical STI Antibiotic Regimen in Australia

For empirical treatment of acute bacterial STIs in Australia, use ceftriaxone 500 mg IM as a single dose PLUS doxycycline 100 mg orally twice daily for 7 days to cover both gonorrhea and chlamydia. 1

Primary Treatment Algorithm

First-Line Regimen for Urogenital/Rectal Gonorrhea and Chlamydia

• Ceftriaxone 500 mg IM single dose is the recommended treatment for uncomplicated gonorrhea at all anatomic sites 1
• PLUS doxycycline 100 mg orally twice daily for 7 days if chlamydial infection has not been excluded 1
• This dual therapy approach ensures coverage of both N. gonorrhoeae and C. trachomatis, which commonly co-exist 2

Alternative Oral Regimen (When IM Not Feasible)

• Cefixime 400 mg orally single dose can be used as an alternative to ceftriaxone 2, 3
• PLUS doxycycline 100 mg orally twice daily for 7 days 2
• Note: Cefixime has slightly lower cure rates (97.4%) compared to ceftriaxone (99.1%) for urogenital infections 2, 3

Site-Specific Considerations

Pharyngeal Gonorrhea

• Ceftriaxone 500 mg IM is strongly preferred over oral cefixime for pharyngeal infections 2, 1
• Cefixime shows significantly reduced efficacy for pharyngeal gonorrhea, with treatment failures documented 4
• Pharyngeal infections require the higher bactericidal levels achieved only with IM ceftriaxone 2

Chlamydia-Only Treatment (If Gonorrhea Excluded)

• Azithromycin 1 g orally single dose OR doxycycline 100 mg orally twice daily for 7 days 2, 5
• Both regimens are equally effective for uncomplicated chlamydial urethritis/cervicitis 2, 6

Critical Pitfalls to Avoid

Quinolone Resistance

• Do NOT use fluoroquinolones (ciprofloxacin, ofloxacin) for gonorrhea treatment in Australia 2
• Quinolone-resistant N. gonorrhoeae (QRNG) is widespread in the Asia-Pacific region, making these agents unreliable 2
• Historical use of quinolones is no longer appropriate given resistance patterns 2

Azithromycin Monotherapy

• Never use azithromycin 1 g alone for gonorrhea - this is insufficient and promotes resistance 5
• While azithromycin 2 g single dose has some efficacy against gonorrhea, it causes significant gastrointestinal distress and is expensive 2, 6
• Azithromycin should only be used as part of dual therapy or for chlamydia-only infections 1

Inadequate Dosing

• Do NOT use ceftriaxone 125 mg - the updated recommendation is 500 mg to maintain therapeutic reserve against emerging resistance 1
• The dose was increased from 250 mg to 500 mg in 2020 specifically to address antimicrobial stewardship concerns 1

Partner Management and Follow-Up

Sexual Partner Notification

• All sexual partners within 60 days preceding symptom onset must be evaluated and treated empirically 2, 7
• Partners should receive the same dual therapy regimen even if asymptomatic 7

Abstinence Requirements

• Patients must abstain from sexual intercourse for 7 days after treatment initiation 2
• Both patient and partners must be asymptomatic before resuming sexual activity 7

Test-of-Cure

• Not routinely required for uncomplicated gonorrhea treated with recommended regimens 5
• However, patients with persistent symptoms after treatment require culture with antimicrobial susceptibility testing 5
• Pharyngeal infections may warrant test-of-cure given higher failure rates 4

Special Populations

Pregnancy

• Use ceftriaxone-based regimens only - avoid quinolones and tetracyclines 5, 7
• For chlamydia in pregnancy, use azithromycin 1 g single dose instead of doxycycline 5

Cephalosporin Allergy

• Spectinomycin 2 g IM single dose for patients who cannot tolerate cephalosporins 5
• Note: Spectinomycin is less effective for pharyngeal infections 5

HIV-Infected Patients

• Use the same antibiotic regimens as HIV-negative patients 7
• Consider alternative diagnoses (fungi, mycobacteria) in severely immunosuppressed states 7

Evidence Quality Assessment

The recommendation for ceftriaxone 500 mg represents the most recent high-quality guidance from CDC (2020), superseding older guidelines that recommended 250 mg 1. This update reflects ongoing surveillance data showing continued low ceftriaxone resistance but increasing azithromycin resistance, justifying the shift from dual therapy with azithromycin to doxycycline for chlamydia coverage 1. The European Urology Association guidelines align with this approach, confirming ceftriaxone as first-line with pathogen-specific adjustments 5.