What are the first-line antibiotic treatments for cellulitis?

From the Guidelines

The first-line antibiotic treatment for cellulitis is typically a cephalosporin, penicillin, or clindamycin, with a recommended course of 5 to 7 days. According to the most recent guidelines, patients with uncomplicated cellulitis should receive antibiotics, but the duration of treatment may vary depending on the clinical response 1. For patients with cellulitis associated with penetrating trauma, evidence of MRSA infection elsewhere, nasal colonization with MRSA, injection drug use, or systemic inflammatory response syndrome, the inclusion of another antimicrobial effective against both MRSA and streptococci is recommended 1.

Some key points to consider when treating cellulitis include:

• The use of oral beta-lactam antibiotics, such as cephalexin, as the preferred option for uncomplicated cases
• The consideration of alternatives, such as dicloxacillin or clindamycin, for patients with penicillin allergies
• The use of intravenous therapy, such as cefazolin, for more severe cases
• The importance of elevating the affected area to reduce swelling, keeping the area clean and dry, and monitoring for signs of worsening infection
• The consideration of adding coverage with trimethoprim-sulfamethoxazole or doxycycline if MRSA is suspected based on risk factors or local prevalence 1.

It's essential to note that the optimal duration of antibiotic therapy for cellulitis is still a topic of debate, and further study is needed to evaluate the best approach 1. However, based on the current evidence, a course of 5 to 7 days is generally recommended.

From the FDA Drug Label

The cure rates in clinically evaluable patients were 90% in linezolid-treated patients and 85% in oxacillin-treated patients The cure rates by pathogen for microbiologically evaluable patients are presented in Table 18. The cure rates in microbiologically evaluable patients with MRSA skin and skin structure infection were 26/33 (79%) for linezolid-treated patients and 24/33 (73%) for vancomycin-treated patients

The first-line antibiotic treatments for cellulitis include:

• Linezolid: 600 mg IV or oral every 12 hours for 10 to 14 days
• Oxacillin: 2 g every 6 hours IV
• Vancomycin: 1 g every 12 hours IV
• Ampicillin/sulbactam: 1.5 to 3 g IV
• Amoxicillin/clavulanate: 500 to 875 mg every 8 to 12 hours orally These treatments are based on the cure rates of clinically evaluable patients with complicated skin and skin structure infections, including MRSA infections 2.

From the Research

First-Line Antibiotic Treatments for Cellulitis

The first-line antibiotic treatments for cellulitis typically cover Streptococcus and methicillin-sensitive Staphylococcus aureus (S. aureus) 3. The choice of antibiotic may be expanded to cover methicillin-resistant S. aureus (MRSA) in cases with specific risk factors, such as athletes, children, men who have sex with men, prisoners, military recruits, residents of long-term care facilities, those with prior MRSA exposure, and intravenous drug users.

Antibiotic Options

• Cephalexin is a commonly used antibiotic for the treatment of uncomplicated cellulitis 4, 5.
• Trimethoprim-sulfamethoxazole is an alternative option that has been shown to have a higher treatment success rate than cephalexin in some studies 6, 5.
• Clindamycin is another option that may be considered, particularly in cases with suspected MRSA infection 6.
• Penicillin or cephalosporin may also be used to treat cellulitis 7.

Treatment Duration

The typical treatment duration for cellulitis is 5 days, with extension of treatment if symptoms are not improved 3. It is essential to note that the treatment should be directed against the suspected causative organisms, and failure to improve with first-line antibiotics should prompt consideration of resistant organisms or underlying complicating conditions.

Special Considerations

• The role of CA-MRSA in nonpurulent cellulitis is less clear, and some studies suggest that empirical coverage of CA-MRSA may not be necessary in all cases 4, 5.
• Point-of-care ultrasound can be a useful tool in differentiating cellulitis and abscess in unclear cases 7.
• Loop drainage is preferred over traditional incision and drainage technique for abscesses, and adjunctive antibiotics can be considered 7.