1209. Impact of Respiratory Staphylococcus aureus Abundance on Risk for Ventilator-Associated Pneumonia During Long-Term Care

Abstract Background Patients admitted to long-term acute care hospital (LTACH) for ventilator weaning are at high risk for ventilator-associated pneumonia, which may contribute to adverse ventilator-associated events (VAE). Staphylococcus aureus (Sa) is a common cause of VAP. We sought to evaluate the impact of respiratory Sa colonization and bacterial community dominance on subsequent Sa VAP and VAE during long-term acute care. Methods We enrolled 83 subjects dependent on mechanical ventilation at LTACH admission, collected endotracheal aspirates, performed 16S rRNA gene sequencing (Illumina HiSeq) and bacterial community profiling (QIIME2). Statistical analysis was performed with R and Stan; mixed effects models were fit to relate the abundance of respiratory Sa on admission to clinically-diagnosed VAP and VAE. Results Of the 83 subjects, 8 were diagnosed with Sa pneumonia during the 14 days prior to LTACH admission (“Known Sa”), and 17 additional subjects received anti- Sa antibiotics within 48 hours of admission (“Suspected Sa”); 58 subjects had no known or suspected Sa (“Unknown Sa”). Among the Known Sa group, all 8 had Sa detectable by 16S sequencing, with elevated admission Sa proportional abundance (median 0.36; range 0.0013 - 1). Among the Suspected Sa group, only 7 had Sa detectable by 16S sequencing, with a wide range of admission Sa proportional abundance (median 0; range 0 - 0.96). 25 of 58 subjects in the Unknown Sa group also had detectable respiratory Sa, and a wide range of Sa proportional abundance at admission (median 0; range 0 - 0.93). Incident Sa VAP was observed within 30 days among 2 (25%) of the Known Sa subjects, 0 (0%) of the Suspected Sa subjects, and 3 (5.17%) of the Unknown Sa subjects. VAE was observed within 30 days among 0 (0%) of the Known Sa subjects, 3 (18%) of the Suspected Sa subjects, and 1 (1.7%) of the Unknown Sa subjects. Admission Sa abundance was positively associated with 30-day VAP risk in the Suspected Sa (type S error < 0.001) and Unknown Sa (type S error < 0.001) groups. Conclusion Among patients admitted to LTACH for weaning for mechanical ventilation, we observed a high prevalence of respiratory Sa colonization. Respiratory Sa abundance was associated with risk of incident Sa VAP, particularly among subjects without recognized Sa colonization. Disclosures All Authors: No reported disclosures