In a prospective cohort of 598 ED patients, 5 risk factors were independently associated with uncomplicated cellulitis patients who fail initial antibiotic therapy as outpatients and require a change of antibiotics or admission to hospital: 

1. Fever (temperature > 38°C) at triage (OR = 4.3, 95% CI = 1.6 to 11.7)
2. Chronic leg ulcers (OR = 2.5, 95% CI = 1.1 to 5.2)
3. Chronic edema or lymphedema (OR = 2.5, 95% CI = 1.5 to 4.2)
4. Prior cellulitis in the same area (OR = 2.1, 95% CI = 1.3 to 3.5)
5. Cellulitis at a wound site (OR = 1.9, 95% CI = 1.2 to 3.0)

Patients presenting with uncomplicated cellulitis and any of these risk factors may need to be considered for observation +/- IV antibiotics.

References

Peterson D, et al. Predictors of Failure of Empiric Outpatient Antibiotic Therapy in Emergency Department Patients with Uncomplicated Cellulitis. Acad Emerg Med 2014; 21(5):526-31. [PMID 24842503]

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