What are the treatment options for cellulitis and the corresponding pathogens they cover?

From the Guidelines

Treatment options for cellulitis include several antibiotics that target the most common causative pathogens, with first-line therapy typically involving beta-lactam antibiotics like cephalexin or dicloxacillin, which effectively cover Streptococcus species and methicillin-sensitive Staphylococcus aureus (MSSA) 1. The choice of antibiotic depends on the severity of the infection and the suspected causative pathogens. For patients with penicillin allergies, clindamycin is an alternative that covers streptococci and staphylococci. If methicillin-resistant Staphylococcus aureus (MRSA) is suspected, trimethoprim-sulfamethoxazole or doxycycline may be used. Some key treatment options for cellulitis include:

• Cephalexin (500 mg orally four times daily for 5-10 days) or dicloxacillin (500 mg orally four times daily for 5-10 days) for Streptococcus species and MSSA
• Clindamycin (300-450 mg orally three times daily for 5-10 days) for patients with penicillin allergies, covering streptococci and staphylococci
• Trimethoprim-sulfamethoxazole (1-2 double-strength tablets twice daily for 5-10 days) or doxycycline (100 mg twice daily for 5-10 days) for suspected MRSA
• Cefazolin (1-2 g every 8 hours) for streptococci and MSSA, vancomycin (15-20 mg/kg every 12 hours) for MRSA and streptococci, or piperacillin-tazobactam (3.375 g every 6 hours) for broader coverage including gram-negative organisms in complicated cases 1. Treatment duration should be individualized based on clinical response, with most uncomplicated cases resolving within 5-10 days of appropriate therapy, as recommended by the 2014 IDSA guideline and the 2019 National Institute for Health and Care Excellence (NICE) guideline 1. Elevation of the affected area, pain management, and monitoring for improvement are important adjunctive measures.

From the FDA Drug Label

Clindamycin is indicated in the treatment of serious infections caused by susceptible anaerobic bacteria. Clindamycin is also indicated in the treatment of serious infections due to susceptible strains of streptococci, pneumococci, and staphylococci Levofloxacin tablets are indicated for the treatment of uncomplicated skin and skin structure infections (mild to moderate) including abscesses, cellulitis, furuncles, impetigo, pyoderma, wound infections, due to methicillin-susceptible Staphylococcus aureus, or Streptococcus pyogenes.

The treatment options for cellulitis and the pathogens they cover are:

• Clindamycin:
  • Anaerobic bacteria
  • Streptococci
  • Staphylococci
• Levofloxacin:
  • Methicillin-susceptible Staphylococcus aureus
  • Streptococcus pyogenes 2 3

From the Research

Treatment Options for Cellulitis

The following are treatment options for cellulitis and the pathogens they cover:

• Penicillin: covers Streptococcus and methicillin-sensitive Staphylococcus aureus 4, 5
• Amoxicillin: covers Streptococcus and methicillin-sensitive Staphylococcus aureus 4, 5
• Cephalexin: covers Streptococcus and methicillin-sensitive Staphylococcus aureus 4, 5, 6
• Cefazolin: covers methicillin-susceptible Staphylococcus aureus, and has been shown to have a lower risk of mortality compared to nafcillin or oxacillin 7
• Clindamycin: covers methicillin-resistant Staphylococcus aureus (MRSA), but is not generally recommended for non-purulent cellulitis 5, 6
• Ceftriaxone: covers a wide range of bacteria, including Streptococcus and Staphylococcus aureus, and has been shown to have a low risk of gastrointestinal side effects 6
• Azithromycin: covers a wide range of bacteria, including Streptococcus and Staphylococcus aureus 6
• Pristinamycin: covers a wide range of bacteria, including Streptococcus and Staphylococcus aureus, and has been shown to have a high cure rate for erysipelas, but with a higher risk of rash 6

Pathogens Covered

The following pathogens are commonly covered by these treatment options:

• β-hemolytic Streptococcus
• Methicillin-sensitive Staphylococcus aureus
• Methicillin-resistant Staphylococcus aureus (MRSA) (in cases with specific risk factors) 4

Duration of Treatment

The recommended duration of treatment for cellulitis is typically 5 days, with extension if symptoms are not improved 4, 8