Management of Cellulitis from Bug Bites

Microbiology and Treatment Principles

Cellulitis is most commonly caused by streptococci and Staphylococcus aureus, with bug bites potentially introducing normal skin flora, including S. aureus, as common pathogens 3, 2
The Infectious Diseases Society of America recommends beta-lactam antibiotics as first-line therapy for typical non-purulent cellulitis, targeting streptococci effectively 2, 6
A 5-day course of antimicrobial therapy can be as effective as a 10-day course if clinical improvement occurs, according to the Infectious Diseases Society of America 2, 7

Doxycycline is recommended for empiric coverage of CA-MRSA, for outpatients with purulent cellulitis, and when there's concern for both streptococcal and staphylococcal infection, including MRSA, as suggested by the Infectious Diseases Society of America 1, 2
Combination therapy with doxycycline and a beta-lactam (e.g., amoxicillin, cephalexin) is an option for coverage of both beta-hemolytic streptococci and CA-MRSA, as per the Infectious Diseases Society of America guidelines 1, 2

Bug bites represent a form of penetrating trauma, increasing the risk of S. aureus infection, including MRSA, as noted by the Infectious Diseases Society of America 2, 5
In cases of cellulitis associated with water exposure after a bug bite, consider coverage for water-associated pathogens (Aeromonas, Vibrio) with doxycycline, as recommended by the Infectious Diseases Society of America 5

The Infectious Diseases Society of America recommends 5-10 days of therapy for uncomplicated cellulitis, with duration based on clinical response 1, 2
Elevation of the affected area is an important adjunct to antibiotic therapy to promote drainage of edema and inflammatory substances, as suggested by the Infectious Diseases Society of America 5
Consider local resistance patterns when selecting empiric therapy, as advised by the European Society of Clinical Microbiology and Infectious Diseases 3, 8