523. Dual vs. Triple Antibiotic Therapy for Carbapenem-Resistant Acinetobacter baumannii Infections

Abstract

BackgroundInfections caused by carbapenem-resistant Acinetobacter baumannii (CRAB) remain some of the most difficult to treat due to extremely high rates of resistance. The purpose of this study was to compare the efficacy of dual vs. triple targeted antibiotic regimens for CRAB infections.MethodsThis was an IRB approved retrospective cohort study performed at a 607-bed community health system between January 2016 and December 2018. Patients were included in the analysis if they were ≥18 years old and received antibiotics for CRAB for ≥72 hours. Patients were excluded if they were pregnant and had CRAB isolated solely from the urine. The primary endpoints of the study were differences in all-cause in-hospital mortality (ACIM) and clinical cure (CC) rates for patients treated with dual vs. triple antibiotic therapy. The secondary endpoint result focused on the difference in length of stay (LOS) between treatment groups. A sub-group analysis was performed for patients treated with tigecycline vs. minocycline combination therapy to determine differences ACIM and CC, and LOS. A multi-logistic regression analysis (MLRA) was performed to determine patient factors that were associated with ACIM and CC.ResultsA total of 32 patients were included in the primary analysis. No difference was seen in ACIM between dual vs. triple antibiotic groups (9.5% vs. 18.2%, P = 0.59). CC (63.6% vs. 57.1%, P = 1.0) and LOS (12 vs. 11 days, P = 1.0) was similar amongst patients treated with dual vs. triple antibiotic group. No differences were seen in ACIM (15.4% vs. 16.7% P = 1.0), CC (83.3% vs. 69.2%, P = 1.0) and LOS (15 vs. 14 days, P = 1.0) between tigecycline and minocycline combination therapy groups. The MLRA revealed a positive association with increased serum creatinine and ACIM (OR 3.29, 95% CI 1.35–8.04; P = 0.009) as well as shorter time to appropriate antibiotic therapy and clinical cure (OR 1.49, 95% CI 1.02–2.20; P = 0.04). CRAB isolates were more likely to be susceptible to minocycline vs. tigecycline (83% vs. 18%, P = 0.003).ConclusionNo differences were seen in ACIM, CC and LOS between dual vs. triple antibiotic groups. Minocycline tends to sustain better susceptibility toward CRAB vs. tigecycline. Elevated serum creatinine was found to be a predictor for ACIM while shorter time to appropriate antibiotic therapy was associated with CC. Disclosures All authors: No reported disclosures.