451: MANAGEMENT OF STENOTROPHOMONAS MALTOPHILIA PNEUMONIA IN MECHANICALLY VENTILATED PATIENTS

Abstract

Introduction: Stenotrophomonas maltophilia is a gram negative opportunistic pathogen that most often causes infections in critically ill patients. S. maltophilia infections are associated with high morbidity and mortality. Common treatment options include sulfamethoxazole/trimethoprim (SMX/TMP), levofloxacin, and tetracyclines. SMX/TMP has been shown to have resistance rates up to 19%, and levofloxacin has shown minimal resistance rates (2%). Regardless of resistance rates, S. maltophilia is associated with a treatment failure rate of around 30%. The objective of this study is to evaluate the effectiveness of monotherapy treatment with SMX/TMP or levofloxacin in critically ill patients with S. maltophilia pneumonia on mechanical ventilation. Methods: Retrospective analysis of patients >/=18 years of age with a positive respiratory culture for S. maltophilia between January 1, 2018, to August 31, 2021. At the time of culture patients must have been on mechanical ventilation for at least 48 hours and treated with monotherapy SMX/TMP or levofloxacin for at least 48 hours. Patients were excluded if they received less than 48 hours of monotherapy, received concomitant treatment with an additional agent with activity agents S. maltophilia (minocycline, ceftazidime, cefiderocol), were pregnant, received combination therapy, had a diagnosis of cystic fibrosis, or had a history of S. maltophila positive culture within the previous 12 months. Results: A total of 105 patients were assessed for eligibility and 92 met inclusion criteria. Of these patients, 51 (55%) received SMX/TMP and 41 (45%) received levofloxacin. Treatment failure occurred more often in those treated with levofloxacin 20% compared to SMX/TMP 16%, p=0.045. Mortality was greater in the levofloxacin group 37% vs. 15%, p=0.011. Clinical cure, 30-day microbiological cure, ICU length of stay and hospital length of stay were similar between groups. Acute kidney injury occurred significantly more in patients treated with SMX/TMP. Conclusions: SMX/TMP was associated with less treatment failure and mortality compared to levofloxacin when treating S. maltophilia pneumonia in patients on mechanical ventilation. A large multicenter cohort study comparing SMX/TMP and levofloxacin is warranted to validate these findings.