Antibiotic selection for cellulitis in immunocompetent adults (no abscess present)

ESBL: extended-spectrum beta-lactamase; IDU: intravenous drug use; IV: intravenous; MRSA: methicillin-resistant Staphylococcus aureus; MSSA: methicillin-sensitive Staphylococcus aureus.

* Patients with cellulitis and sustained refractory hypotension (ie, septic shock) are typically treated as toxic shock syndrome if no other red-flag conditions or causes of shock are identified. Refer to UpToDate content on toxic shock syndrome.

¶ For patients with severe sepsis who cannot take any beta-lactam agents, we suggest IV vancomycin plus either levofloxacin (750 mg IV once daily) or aztreonam (2 g IV every 8 hours; dosing up to 2 g every six hours may be reasonable for weight >120 kg).

Δ If a causative organism is identified, narrow antibiotics to target the pathogen as appropriate.

◊ For patients with lymphangitis, some UpToDate contributors would require additional criteria to warrant parenteral antibiotics.

§ Other risk factors may not be as strongly associated with MRSA infection, so we individualize the decision for MRSA coverage in such cases. A complete list of MRSA risk factors can be found in UpToDate content.

¥ Five to six days of antibiotic therapy is generally adequate; extension up to 14 days may be warranted for severe infection or slow clinical response.

‡ The majority of patients with reported beta-lactam allergies can take a cephalosporin (refer to UpToDate content for details).

† We generally avoid clindamycin, if possible, due to risk of Clostridium difficile infection and the possibility of streptococcal and staphylococcal resistance (refer to UpToDate content for details).