Antimicrobial activity of lefamulin against pathogens most commonly causing community-acquired pneumonia: results from the China antimicrobial surveillance network in 2020-2022.

Objectives: Lefamulin is a novel pleuromutilin antibiotic used for the treatment of community-acquired pneumonia (CAP). This study aimed to evaluate the in vitro antimicrobial activity of lefamulin against clinical isolates obtained from China.

Methods: 1,052 non-duplicate isolates included the following isolates: Streptococcus pneumoniae (n = 529), Staphylococcus aureus (n = 306), Haemophilus influenzae (n = 121), Moraxella catarrhalis (n = 81), and Mycoplasma pneumoniae (n = 15), were collected from 70 hospitals participating in the China Antimicrobial Surveillance Network (CHINET) between October 1, 2020, and November 30, 2022. Minimum inhibitory concentrations were determined using the broth microdilution method in accordance with the standards set by the Clinical and Laboratory Standards Institute.

Results: In vitro, S. pneumoniae exhibited 100% sensitivity to lefamulin, with MIC₉₀ values of 0.125 µg/mL for penicillin-susceptible strains, 0.25 µg/mL for penicillin-intermediate strains, and 0.125 µg/mL for penicillin-resistant strains. Lefamulin remained effective against S. pneumoniae strains resistant to penicillin, erythromycin, and azithromycin. The susceptibility rate of S. aureus to lefamulin was 97.7%, with methicillin-sensitive S. aureus showing 98.4% sensitivity and methicillin-resistant S. aureus showing 96.6% sensitivity. Both strains had MIC₉₀ values of 0.125 µg/mL. H. influenzae and M. catarrhalis demonstrated 100% sensitivity to lefamulin. The MIC of lefamulin against M. pneumoniae was ≤ 0.03 µg/mL.

Conclusions: Lefamulin exhibited potent in vitro activity against prevalent and drug-resistant pathogens associated with CAP in China.