2425. Clinical and Microbiologic Outcomes Among Patients With Monomicrobial Stenotrophomonas maltophilia Infections

BACKGROUND: Stenotrophomonas maltophilia is an opportunistic pathogen observed in nosocomial infections. Due to biofilm production and intrinsic resistance to numerous antimicrobials, organism eradication is difficult and morbidity and mortality remain high. Unfortunately, study outcomes are often confounded by co-infecting organisms. Therefore, clinical and microbiologic outcome data for monomicrobial infections is warranted. METHODS: Single-center, retrospective chart review of adult patients receiving treatment for S. maltophilia between January 2012 and October 2016. Polymicrobial infections and cystic fibrosis patients were excluded. Primary endpoint was clinical cure (CC) at end of therapy. Secondary endpoints included microbiological eradication (ME), 28-day mortality, and resistance selection. An exploratory analysis was performed in patients receiving trimethoprim-sulfamethoxazole (TMP/SMX) or levofloxacin (LVX). RESULTS: Seventy-six patients were included in the analysis. The population was 60 years of age, predominantly female (62%) with median APACHE score of 16. Infection onset occurred 6 days after admission with 71% located in the ICU. Approximately 2/third of ICU patients were intubated. Primary site of infection was the lung (92%). Treatment strategies included TMP/SMX (45 patients) or LVX (31 patients). Overall, CC, ME, and 28-day mortality was observed in 79%, 82%, and 14%, respectively. Adverse events were uncommon with three patients receiving TMP/SMX requiring alternate therapy. Comparative analysis revealed similar baseline characteristics except higher APACHE scores (18 vs. 14; P = 0.03) and frequency of mechanical ventilation in the TMP/SMX group (64% vs. 30%; P = 0.007). CC was similar between TMP/SMX and LVX (82% vs. 74%, respectively (P = 0.4)). ME was observed in 84% and 77%, respectively (P = 0.5). Resistance selection to primary treatment was observed in 29% (2/7) and 86% (6/7), respectively (P = 0.1). CONCLUSION: Use of TMP/SMX or LVX for S. maltophilia infections resulted in high CC rates. No differences in primary or secondary outcomes were observed; however, a trend toward resistance selection with LVX was identified. Larger studies assessing outcomes and resistance selection are warranted to further delineate treatment. DISCLOSURES: K. Klinker, Melinta Therapeutics: Consultant, Speaker honorarium. Nabriva Therapeutics: Scientific Advisor, Consulting fee.