Intramuscular Ceftriaxone with Oral Antibiotic Therapy in the Treatment of Outpatient Cellulitis

Purpose: Oral antibiotics are the treatment of choice for outpatient cellulitis; however, intramuscular (IM) antibiotics are frequently used in addition to oral antibiotics in the clinic setting. This study compared outcomes among patients with cellulitis who were administered IM ceftriaxone in addition to oral antibiotics versus those who received oral antibiotics alone. Methods: This study was a retrospective chart review of 982 adult primary care patients designed to evaluate rates of treatment failure of outpatient cellulitis among patients who received IM ceftriaxone and oral antibiotics versus oral antibiotics alone. Treatment failure was defined as: 1) hospital admission for intravenous (IV) antibiotics within 30 days of diagnosis, 2) prolonged antibiotic course, or 3) requiring a different antibiotic after initial antibiotic course. Results: Of the 982 patients in the study cohort, 104 (10.6%) received IM ceftriaxone in addition to oral antibiotics while 878 (89.4%) did not. In the IM ceftriaxone group, hospitalization within 30 days was seen in 10.6% vs. 4.2% of the oral treatment only group (p=0.004). Initial outpatient use of IM ceftriaxone was associated with a 3.031 (95% CI 1.928-4.765, p<0.001) increased adjusted odds ratio for treatment failure. Age, gender, race, the use of tobacco, and diagnosis of diabetes mellitus were not associated with adverse outcomes when controlling for all other variables. Conclusions: The patients who received an initial dose of IM ceftriaxone in addition to oral antibiotics were more likely to experience treatment failure than the non-ceftriaxone cohort. With increasing emergence of antibiotic resistant organisms, antibiotic prescribing practices must be reviewed to ensure efficacy and minimize risks associated with unnecessary antibiotic exposure.