The in vitro evaluation of solithromycin (CEM-101) against pathogens isolated in the United States and Europe (2009)

Abstract

Objectives: Solithromycin (formerly CEM-101) is a novel fluoroketolide with potent activity against bacterial pathogens that are susceptible or resistant to other MLS(B)-ketolide agents. The objective of this study was to assess the activity of solithromycin and comparator antimicrobials against a large number and variety of contemporary clinical bacterial pathogens collected in the United States (USA) and Europe during 2009.

Method: During 2009, a total of 10,670 non-duplicated clinical isolates were collected from 52 medical centers located in the USA (27 centers; 6228 isolates) and Europe (25 centers; 4442 isolates). Susceptibility testing and interpretation were performed using CLSI reference methods.

Results: Among 1363 Streptococcus pneumoniae isolates, 99.9% of the strains displayed solithromycin MIC values at ≤0.5 mg/L, and 100% were inhibited at an MIC of 1 mg/L. Solithromycin demonstrated activity and potency against Haemophilus influenzae comparable to azithromycin (MIC(50), 1 mg/L and MIC(90), 2 mg/L) and was very potent against all 313 Moraxella catarrhalis isolated (MIC(50), 0.06 mg/L and MIC(90), 0.12 mg/L). Against 4729 Staphylococcus aureus isolates, solithromycin (MIC(50), 0.06 mg/L and MIC(90), >4 mg/L) activity was greater against methicillin-susceptible isolates (MIC(50), 0.06 mg/L and MIC(90), 0.06 mg/L) compared to methicillin-resistant isolates (MIC(50), 0.06 mg/L and MIC(90), >4 mg/L). Solithromycin was very active against all 757 β-haemolytic streptococci (MIC(50), ≤0.03 mg/L and MIC(90), 0.06 mg/L) and 310 viridans group streptococci (MIC(50), ≤0.03 mg/L and MIC(90), 0.06 mg/L) evaluated.

Conclusion: This contemporary surveillance study utilizing clinical isolates shows that solithromycin exhibits favorable in vitro potency and spectrum of activity against bacterial pathogens most frequently isolated in community-acquired respiratory tract (CA-RTI) and skin and skin structure infections (SSSI).