2230. Analysis of the Microbiological Data from the Delafloxacin (DLX) Phase 3 Community-acquired Bacterial Pneumonia (CABP) Trial.

Background DLX is a novel fluoroquinolone (FQ) antibiotic with Gram-positive/MRSA, Gram-negative and atypical activity. It offers IV and oral treatment with no QT restrictions. In a Phase 3 study in CABP patients, DLX was non-inferior to moxifloxacin (MOX) in the primary endpoint, early clinical response at 96 ± 24 hours (88.9 vs. 89.0; 95% CI: −4.4, 4.1) in the intent-to-treat (ITT) population. A detailed microbiological analysis was conducted. Methods CABP pathogens were identified by culture/non-culture methods. Pathogens identified by non-culture methods included Streptococcus pneumoniae (Sp; culture, urinary antigen [UA], nasopharyngeal [NP] swab lytA PCR), Legionella pneumophila (Lp) (culture, UA, serology), Mycoplasma pneumoniae (Mp; culture, serology), and Chlamydia pneumoniae (Cp; serology). All other pathogens were identified using culture only. For Sp cultured from NP, a concomitant lytA PCR value of ≥ 1000 gene copies/mL was required. All isolates underwent susceptibility testing, and a subset of isolates underwent molecular or phenotypic characterization including whole-genome sequencing for FQ resistance mechanisms, PCR for PVL/ mecA genes (S. aureus), β-lactamases (Haemophilus / Moraxella spp), and serotyping (Sp). Results Included in submitted image. Conclusion DLX demonstrated potent in vitro and clinical activity against CABP pathogens, including Sp [MRSP, MDRSP, PRSP], MRSA , Haemophilus species, Enterobacteriaceae , P. aeruginosa, and the atypical pathogens Cp, Mp, and Lp. Disclosures All authors: No reported disclosures. [ABSTRACT FROM AUTHOR]