Should Bactrim Be Prescribed for a Drained 2 cm x 2 cm Neck Abscess?
Yes, Bactrim (trimethoprim-sulfamethoxazole) should be prescribed at 1-2 double-strength tablets (160/800 mg) orally twice daily for 5-6 days following incision and drainage of this abscess, as antibiotic therapy after drainage significantly improves cure rates and reduces subsequent infections compared to drainage alone. 1, 2, 3
Evidence Supporting Antibiotic Use After Drainage
The most definitive evidence comes from high-quality randomized controlled trials demonstrating clear benefit:
For abscesses ≤5 cm (which includes your 2 cm lesion), trimethoprim-sulfamethoxazole after incision and drainage resulted in an 80.5% cure rate versus 73.6% with drainage alone (absolute benefit of 7%, P=0.005) 3
In the per-protocol analysis, TMP-SMX achieved 92.9% cure versus 85.7% with placebo (P<0.001), demonstrating robust efficacy when patients complete therapy 3
A separate multicenter trial confirmed that both clindamycin and TMP-SMX were superior to placebo (83.1% and 81.7% cure rates respectively versus 68.9% with placebo, P<0.001 for both) 2
Recommended Dosing Regimen
Adult dosing: 1-2 double-strength tablets (160/800 mg) orally twice daily for 5-6 days 1
This dosing is specifically recommended by the Infectious Diseases Society of America for purulent cellulitis and skin abscesses with suspected MRSA, which is the predominant pathogen in community-acquired skin abscesses 1
Additional Benefits Beyond Primary Cure
Antibiotic therapy provides important secondary benefits:
Reduces need for repeat surgical drainage: 3.4% with TMP-SMX versus 8.6% with placebo (absolute reduction of 5.2%, P<0.001) 3
Prevents new skin infections at other sites: 3.1% with TMP-SMX versus 10.3% with placebo (absolute reduction of 7.2%, P<0.001) 3
Decreases household member infections: 1.7% with TMP-SMX versus 4.1% with placebo 3
Reduces new lesion formation at 30 days: 9% with TMP-SMX versus 28% with placebo (P=0.02) 4
Microbiologic Context
The benefit of antibiotics is particularly relevant given current epidemiology:
MRSA prevalence is high: In contemporary studies, 49-77% of cultured skin abscesses yielded MRSA 5, 2
The benefit is specific to S. aureus infections: The therapeutic advantage of antibiotics was restricted to participants with documented S. aureus infection 2
TMP-SMX provides excellent MRSA coverage and is the preferred agent for this indication 1
Alternative Agents (If TMP-SMX Cannot Be Used)
If Bactrim is contraindicated or not tolerated:
Clindamycin 300-450 mg orally three times daily is equally effective (cure rate 83.1% versus 81.7% for TMP-SMX, P=0.73) but carries higher risk of C. difficile infection and more adverse events (21.9% versus 11.1% with TMP-SMX) 5, 2
Doxycycline 100 mg orally twice daily is an alternative but not recommended for children under 8 years or during pregnancy 1
Important Contraindications
Do not prescribe Bactrim if:
- Patient is pregnant, especially third trimester (Category C/D) 1
- Patient is an infant under 2 months of age 1
- Patient has documented sulfa allergy
Common Pitfalls to Avoid
Do not skip antibiotics assuming drainage alone is sufficient: Multiple high-quality trials demonstrate that drainage alone has significantly lower cure rates (69-86%) compared to drainage plus antibiotics (81-93%) 2, 3
Do not prescribe longer courses: The evidence supports 5-7 day courses; longer duration increases adverse events without additional benefit 1, 3
Monitor for gastrointestinal side effects: TMP-SMX causes mild GI symptoms more frequently than placebo, though these are generally well-tolerated 3
Consider drug interactions: If patient is on methotrexate, TMP-SMX increases risk of severe cytopenia and should be used with caution 6