441. Factors Associated with a Change of Antimicrobial Therapy in Patients with Cellulitis Who Started with Amoxicillin–Clavulanate (A/C) Monotherapy

BACKGROUND: Cellulitis is a frequent cause of admission of adult patients to medical wards and A/C monotherapy is commonly used as the initial regimen. Studies evaluating the factors associated with the change of this regimen are lacking. METHODS: Data were extracted from a prospective and observational study of 606 adult patients with cellulitis admitted to several Spanish hospitals. Comorbidities, microbiological, clinical, lab, diagnostic, and treatment data were analyzed and compared according to the continuation/change of A/C. Multiple logistic regression modeling was performed to determine the variables independently associated with A/C switching. RESULTS: Overall 259 (42.7%) patients started A/C monotherapy, 56 (21.6%) of which were switched to other antimicrobials. Patients switched from A/C developed sepsis (19.6% vs. 8.4%, P = 0.02) and underwent imaging methods (P < 0.01) more commonly than those kept on A/C. These A/C switched patients had higher serum glucose (P = 0.04), creatinine (P < 0.0001), leukocyte (P = 0.006) and neutrophil counts (P < 0.0001). Regarding microbiological data, patients switched from A/C had more frequently pus (P < 0.0001) and blood cultures (P = 0.002) available, a microorganism identified (P < 0.0001) and higher rates of Gram-negative bacilli infections (P = 0.003). Patients switched from initial A/C had also longer hospitalization stays (10.5 vs. 5.2 days, P < 0.00019, longer duration of IV (10.0 vs. 4.3 days, P < 0.0001), and overall antibiotic treatment (16.5 vs. 10.4 days, P < 0.0001) and needed more frequently surgical treatment (25.0 vs. 4.9%, P < 0.0001), specialized follow-up after discharge (36.4 vs. 17.3%, P = 0.0009) and combination therapy after discharge (35.9% vs. 1.1%, P < 0.0001).The variables independently asociated with A/C switch in the multivariate analysis were higher serum creatinine (P = 0.03), neutrophil counts (P = 0.003), days on IV antibiotics (P < 0.0001) and the needed for surgical treatment (P = 0.004) CONCLUSION: Patients switched from the initial A/C regimen do not have differences in the predisposing factors, but seem to have more serious cellulitis, characterized by higher neutrophil counts and serum creatinine, needing extended IV antibiotic therapy and additional surgical debridement. DISCLOSURES: All authors: No reported disclosures.