Activity of the Fluoroketolide, Solithromycin Tested against Bacterial Species Associated with Significant Community-Acquired Bacterial Pneumonia and Other Gram-positive Organisms

Results: Against S. aureus (SA), SOL (MIC 50/90 , 0.06/>4 µg/mL) displayed similar activity to telithromycin (TEL; MIC 50/90 , ≤0.06/>8 µg/mL) and four-fold greater than erythromycin (ERY; MIC 50 , 0.5 µg/mL). SOL (MIC 50/90 , ≤0.03/>4 µg/mL) showed comparable activity to TEL against CoNS (78.2% S). Methicillin (M) R SA (40.2%) and CoNS (68.4%) displayed higher SOL MICs compared to MS strains. SOL was moderately active against enterococci (ENT; MIC 50/90 , 0.5/2 µg/mL), but was two-fold more potent than TEL (MIC 50/90 , 1/4 µg/mL). SOL exhibited greater potency against E. faecalis (MIC 50 , 0.06 µg/mL) compared to E. faecium (MIC 50 , 1 µg/mL). SOL was very active against S. pneumoniae (SPN; MIC 90 , 0.12 µg/mL), Viridans group streptococci (MIC 90 , 0.06 µg/mL) and β-haemolytic streptococci (VGS and BHS; MIC 90 , 0.06 and ≤0.03 µg/mL). SPN isolates were only 88.9, 59.2 and 77.2% S to penicillin (PEN), ERY and clindamycin (CLI), respectively. SOL was very active against M. catarrhalis (MCAT; MIC 90 , ≤0.12 µg/mL) with lower activity against H. influenzae (HI; MIC 50/90 , 2/2 µg/mL); however, SOL displayed four-fold greater activity than ERY against HI.