Cellulitis Antimicrobial Selection
Doxycycline can be used for cellulitis when community-associated MRSA coverage is indicated. [1] For typical nonpurulent cellulitis without abscess or purulent drainage, doxycycline monotherapy is not recommended for streptococcal coverage, and β-lactam monotherapy is recommended. [1]
Role of Doxycycline for MRSA-Associated Cellulitis
MRSA is an uncommon cause of typical cellulitis, but MRSA-active therapy is recommended when cellulitis is associated with higher MRSA-risk features. [1] Oral doxycycline is listed as an option for MRSA coverage in cellulitis associated with penetrating trauma, illicit drug use, purulent drainage, nasal MRSA colonization, or concurrent evidence of MRSA infection elsewhere. [1]
Streptococcal Coverage Requirements
Doxycycline activity against β-hemolytic streptococci is not known. [1] In the absence of abscess, ulcer, or purulent drainage, β-lactam monotherapy is recommended rather than doxycycline monotherapy. [1]
Combination Therapy for Both MRSA and Streptococci
When both MRSA and streptococcal coverage are desired for oral therapy, doxycycline should be combined with a β-lactam (eg, penicillin, cephalexin, or amoxicillin). [1] Clindamycin alone is also listed as an oral option when coverage for both groups is desired. [1]
Initiation Thresholds for MRSA-Active Therapy
MRSA-active therapy is recommended when cellulitis is associated with penetrating trauma, especially from illicit drug use, purulent drainage, or evidence of MRSA infection elsewhere, or when nasal colonization with MRSA is present. [1] MRSA-active therapy is also considered for severe nonpurulent presentations associated with SIRS. [1]
Treatment Setting and Duration
A recommended duration of antimicrobial therapy is 5 days, with extension if clinical improvement has not occurred. [1] Outpatient therapy is recommended for patients without SIRS, altered mental status, or hemodynamic instability. [1]
Clinical Pitfalls
Doxycycline should not be used as sole therapy for pure nonpurulent cellulitis when streptococcal coverage is required. [1] Combination therapy is recommended when MRSA coverage is needed and streptococcal coverage must also be provided. [1]
Adjunctive Measures
Elevation of the affected area is recommended. [1] Predisposing conditions such as tinea pedis, trauma, or venous eczema should be treated. [1]