Can I use Bactrim DS (sulfamethoxazole and trimethoprim) to treat hidradenitis suppurativa?

Can Bactrim DS Be Used to Treat Hidradenitis Suppurativa?

Bactrim DS (trimethoprim/sulfamethoxazole, also called co-trimoxazole) can be used to treat hidradenitis suppurativa in specific clinical contexts, but it is not a first-line or second-line therapy according to current North American guidelines. The 2025 guidelines provide conditional recommendations for its use only in special populations, particularly HIV-positive patients, while explicitly recommending against its use in pregnancy due to safety concerns 1.

Guideline-Based Recommendations for Co-trimoxazole

Special Population: HIV-Positive Patients

• In HIV-positive patients with HS requiring systemic antibiotics, co-trimoxazole is conditionally recommended due to its added benefit of lowering mortality and infection rates in this population 1.
• The dual benefit of treating HS while providing prophylaxis against opportunistic infections makes co-trimoxazole particularly valuable in this specific context 1.

Contraindication: Pregnancy

• Co-trimoxazole should be avoided in pregnant patients with HS due to increased risk of preterm birth, low birthweight, and kernicterus 1.
• This represents a conditional recommendation with low-quality evidence, but the potential fetal risks outweigh benefits 1.

Special Population: Hepatitis B or C with Cirrhosis

• In patients with chronic hepatitis B or C and evidence of cirrhosis, co-trimoxazole is conditionally suggested as it appears safe and may reduce risk of spontaneous bacterial peritonitis 1.
• This recommendation carries conditional strength with low-quality evidence 1.

Why Co-trimoxazole Is Not First-Line Therapy

Standard Treatment Algorithm

The 2019 and 2025 North American guidelines establish a clear hierarchy that does not include co-trimoxazole as a primary option 1, 2:

For mild disease (Hurley Stage I):

• First-line: Topical clindamycin 1% twice daily for 12 weeks 1, 2

For moderate disease (Hurley Stage II):

• First-line: Tetracyclines (doxycycline 100 mg once or twice daily for 12 weeks) 1, 2
• Second-line: Clindamycin 300 mg twice daily PLUS rifampicin 300-600 mg daily for 10-12 weeks, achieving response rates of 71-93% 1, 2

For severe disease (Hurley Stage III):

• First-line biologic: Adalimumab (160 mg week 0,80 mg week 2, then 40 mg weekly) 1, 2

Evidence from Bacterial Culture Studies

Recent research reveals important considerations about antibiotic resistance patterns in HS 3, 4, 5:

• Bacterial cultures from HS lesions show 100% sensitivity to ciprofloxacin and high sensitivity to trimethoprim/sulfamethoxazole 3.
• However, patients previously treated with trimethoprim/sulfamethoxazole were significantly more likely to grow trimethoprim/sulfamethoxazole-resistant Proteus species (88% vs 0% in untreated patients, P < 0.001) 4.
• One study found 74% resistance to ciprofloxacin and variable resistance patterns to other antibiotics 5.

These findings suggest that while co-trimoxazole may have initial activity, its use can induce resistance, particularly in Proteus species, which are common in HS lesions 3, 4.

Clinical Decision Algorithm

If considering co-trimoxazole for HS, use this approach:

1. First, determine if the patient fits a special population where co-trimoxazole has specific benefits:

   • HIV-positive patient? → Co-trimoxazole is conditionally recommended 1
   • Pregnant? → Avoid co-trimoxazole; use cephalexin or azithromycin instead 1
   • Hepatitis B/C with cirrhosis? → Co-trimoxazole may be considered 1

2. If not a special population, follow standard treatment algorithm:

   • Hurley Stage I: Start topical clindamycin 1, 2
   • Hurley Stage II: Start doxycycline 100 mg once or twice daily for 12 weeks 1, 2
   • If doxycycline fails at 12 weeks: Escalate to clindamycin 300 mg + rifampicin 300-600 mg twice daily for 10-12 weeks 1, 2
   • If clindamycin-rifampicin fails: Escalate to adalimumab 1, 2

3. If bacterial culture data are available showing sensitivity to trimethoprim/sulfamethoxazole and resistance to standard agents:

   • Co-trimoxazole may be considered as a culture-directed therapy 3
   • However, this represents off-guideline use and should be coordinated with dermatology

Critical Pitfalls to Avoid

• Do not use co-trimoxazole as empiric first-line therapy for HS – it is not supported by guidelines and may induce resistance 1.
• Do not use co-trimoxazole in pregnant patients with HS – the risks of preterm birth, low birthweight, and kernicterus outweigh potential benefits 1.
• Do not assume sensitivity based on older culture data – resistance patterns evolve with antibiotic exposure, and trimethoprim/sulfamethoxazole resistance in Proteus species increases from 0% to 88% after prior use 4.
• Do not use co-trimoxazole monotherapy for Hurley Stage II disease with abscesses – combination therapy with clindamycin-rifampicin achieves far superior response rates (71-93%) 1, 2.

When Co-trimoxazole May Be Reasonable

Despite not being guideline-recommended as first-line therapy, co-trimoxazole may be considered in these specific scenarios:

• HIV-positive patients where dual benefit (HS treatment + opportunistic infection prophylaxis) is valuable 1
• Patients with documented bacterial cultures showing sensitivity to trimethoprim/sulfamethoxazole and resistance to tetracyclines and clindamycin-rifampicin 3
• Patients with hepatitis B or C and cirrhosis where spontaneous bacterial peritonitis prophylaxis is needed 1
• As part of a culture-directed approach after multiple antibiotic failures 3

Adjunctive Measures Regardless of Antibiotic Choice

All patients with HS should receive 1, 2:

• Smoking cessation referral (tobacco worsens outcomes)
• Weight management referral if BMI elevated
• Pain management with NSAIDs for symptomatic relief
• Appropriate wound dressings for draining lesions
• Screening for depression/anxiety
• Screening for cardiovascular risk factors (BP, lipids, HbA1c)