What is the treatment for acute bacterial paronychia, possibly with an abscess, in a patient who may have a history of penicillin allergy?

Treatment of Acute Bacterial Paronychia with Possible Abscess

For acute bacterial paronychia with possible abscess, incision and drainage is the primary treatment, with oral antibiotics reserved for cases with surrounding cellulitis, systemic signs of infection, or immunocompromised patients. 1, 2

Immediate Management: Drainage First

Incision and drainage is the definitive treatment for acute paronychia with abscess formation. 1, 2 The presence of fluctuance or visible pus mandates drainage, as antibiotics alone will not adequately treat a localized abscess. 1, 2

Drainage Techniques

• Simple needle drainage: For early or small abscesses, lift the nail fold with a 21G or 23G needle to allow pus drainage without anesthesia. 3 This technique provides immediate pain relief and allows normal finger use within 2 days when combined with antibiotics. 3
• Scalpel incision: For larger abscesses or when needle drainage is inadequate, make a longitudinal incision along the lateral nail fold to ensure complete drainage. 2
• Partial nail avulsion: Consider this for abscesses extending under the nail plate or when simple drainage fails. 1, 2

After drainage, cover the site with a dry dressing—packing the wound offers no advantage and causes more pain. 1

Antibiotic Selection

When to Use Antibiotics

Antibiotics are indicated when: 1, 2

• Surrounding cellulitis extends beyond the immediate paronychial area
• Systemic signs present (fever >38°C, tachycardia >90 bpm, or elevated WBC >12,000/µL)
• Immunocompromised state
• Inadequate drainage achieved

If adequate drainage is accomplished in an immunocompetent patient without systemic signs, antibiotics are often unnecessary. 1, 2

First-Line Antibiotic Choice

For patients requiring antibiotics, use an oral penicillinase-resistant penicillin or first-generation cephalosporin, as most paronychia isolates are methicillin-susceptible Staphylococcus aureus. 1, 4

Specific regimens:

• Dicloxacillin 250-500 mg orally every 6 hours for 7-10 days (take on empty stomach, 1 hour before or 2 hours after meals with at least 4 oz water). 5
• Cephalexin 500 mg orally every 6 hours for 7-10 days (alternative for mild penicillin allergy). 1, 6

For Penicillin-Allergic Patients

For documented penicillin allergy (non-Type I hypersensitivity), cephalexin remains safe with <10% cross-reactivity risk. 6 However, exercise caution and monitor for allergic reactions. 6

For severe penicillin allergy (Type I/anaphylaxis) or cephalosporin intolerance, use: 1

• Doxycycline 100 mg orally twice daily for 7-10 days (avoid in children <8 years due to tooth discoloration risk)
• Clindamycin 300-450 mg orally three times daily for 7-10 days
• Trimethoprim-sulfamethoxazole (TMP-SMX) DS orally twice daily for 7-10 days

Critical caveat: TMP-SMX should not be used as monotherapy if group A Streptococcus is suspected, as this organism has intrinsic resistance. 1

MRSA Coverage

If MRSA is suspected (prior MRSA infection, local prevalence >10%, or treatment failure after 48-72 hours), switch to: 1

• TMP-SMX DS orally twice daily for 7-10 days
• Doxycycline 100 mg orally twice daily for 7-10 days
• Clindamycin 300-450 mg orally three times daily for 7-10 days (only if local susceptibility confirmed)

Culture and Sensitivity Testing

Obtain Gram stain and culture of purulent drainage from the abscess to guide antibiotic therapy, especially if MRSA is suspected or the patient fails initial treatment. 1 However, treatment without cultures is reasonable in typical cases. 1

Adjunctive Measures

• Warm water soaks or Burow solution soaks 3-4 times daily for 15-20 minutes to promote drainage and reduce inflammation. 4, 2
• Topical antibiotics (mupirocin) with or without topical corticosteroids for mild cases without abscess formation. 1, 2
• Avoid nail manipulation, biting, or trauma during healing. 1, 4

Treatment Duration and Monitoring

Continue antibiotics for at least 7-10 days or until 48 hours after the patient becomes afebrile and asymptomatic. 5 Severe infections may require 14 days of therapy. 5

Reassess at 48-72 hours: 1

• If worsening or no improvement, obtain cultures (if not already done) and switch to MRSA-active antibiotics
• Consider inadequate drainage and repeat incision/drainage if needed
• Rule out viral (herpetic whitlow), fungal, or non-infectious causes if antibiotic-resistant 7, 8

Critical Pitfalls to Avoid

• Never rely on antibiotics alone when an abscess is present—drainage is mandatory for cure. 1, 2
• Do not use systemic antibiotics routinely for simple paronychia without abscess or cellulitis, as warm soaks and topical therapy suffice. 7, 2
• Avoid first-generation cephalosporins in patients with documented Type I penicillin hypersensitivity (anaphylaxis), as cross-reactivity risk increases. 6
• Consider non-bacterial causes (viral, fungal, drug-induced, pemphigus) if the paronychia fails to respond to appropriate antibiotics and drainage. 7, 8
• Evaluate for chronic paronychia (symptoms >6 weeks) if recurrent, which requires different management focused on irritant avoidance and topical steroids/antifungals rather than antibiotics. 4, 7, 2