Duration of Clindamycin for MRSA Abscess
For a simple MRSA abscess treated with incision and drainage, clindamycin should be given for 5–7 days if antibiotics are used at all; however, incision and drainage alone without antibiotics is adequate for uncomplicated abscesses smaller than 5 cm in immunocompetent patients. 1, 2
When Antibiotics Are Actually Needed After Drainage
The decision to add antibiotics after drainage depends on specific high-risk features. Antibiotics are recommended only when one or more of the following conditions exist: 1
- Severe or extensive disease involving multiple infection sites 1
- Rapid progression despite drainage or associated cellulitis extending beyond the abscess 1
- Systemic illness with fever, tachycardia, or signs of sepsis 1
- Immunosuppression or comorbidities such as diabetes, HIV/AIDS, or malignancy 1
- Extremes of age (very young infants or elderly patients) 1
- Difficult-to-drain locations including face, hand, or genitalia 1
- Abscess diameter >5 cm 2
- Lack of response to drainage alone within 48–72 hours 1
Evidence Supporting Short-Course Therapy
A landmark placebo-controlled trial demonstrated that clindamycin for 10 days after drainage achieved an 83.1% cure rate versus 68.9% with drainage alone, but this benefit was restricted to patients with confirmed S. aureus infection. 3 However, the IDSA guidelines now recommend 5–10 days for uncomplicated infections, reflecting more recent evidence that shorter courses are equally effective. 4
For simple abscesses <5 cm in immunocompetent children, incision and drainage without antibiotics was effective in 93% of cases, even when the organism was MRSA. 2 This underscores that drainage is the primary treatment and antibiotics play a subsidiary role in uncomplicated cases.
Specific Clindamycin Dosing Regimen
When antibiotics are indicated:
- Adults: clindamycin 300–450 mg orally every 6–8 hours (three to four times daily) 1
- Children: clindamycin 10–13 mg/kg/dose orally every 6–8 hours, not to exceed 40 mg/kg/day 1
- Duration: 5–7 days for uncomplicated abscess with adequate drainage 1, 4; extend to 7–14 days only for complicated infections involving deeper tissues or multiple sites 4
Critical Caveat: Local Resistance Patterns
Clindamycin should only be used if local MRSA clindamycin resistance rates are <10%. 1, 4 Canadian pooled data show clindamycin resistance exceeding 40%, making it inappropriate in many regions. 5 If local resistance is high, use trimethoprim-sulfamethoxazole (TMP-SMX) 1–2 double-strength tablets twice daily or doxycycline 100 mg twice daily instead. 1, 4
Alternative Oral Regimens for MRSA Coverage
If clindamycin cannot be used:
- TMP-SMX: 1–2 double-strength tablets (160–320/800–1600 mg) orally twice daily 1, 4
- Doxycycline or minocycline: 100 mg orally twice daily (avoid in children <8 years and pregnancy category D) 1, 4
- Linezolid: 600 mg orally twice daily (expensive; reserve for complicated cases) 1, 4
TMP-SMX demonstrated an 81.7% cure rate in the same trial, statistically equivalent to clindamycin, but was associated with a higher recurrence rate at 1 month (13.5% vs. 6.8%). 3
Common Pitfalls to Avoid
- Do not prescribe antibiotics reflexively for every drained abscess. Drainage alone is adequate for simple cases <5 cm without systemic features. 1, 2
- Do not use beta-lactams (cephalexin, amoxicillin, dicloxacillin) for MRSA coverage. These are ineffective due to the mecA gene encoding altered penicillin-binding protein. 4
- Do not extend treatment to 10–14 days based on tradition. Five to seven days is sufficient for uncomplicated infections with adequate drainage. 1, 4
- Do not ignore local resistance data. Clindamycin resistance exceeding 10% makes it unreliable for empiric MRSA therapy. 1, 5
Reassessment and Treatment Failure
Reassess clinically at 48–72 hours to ensure appropriate response. 4 If no improvement occurs, consider: