Delafloxacin Shows Good Activity Against Recent Community-Acquired Pneumonia Isolates

Of all the quinolones tested, delafloxacin had the highest susceptibility against methicillin-susceptible Staphylococcus aureus, according to a new study presented at IDWeek 2021.

Delafloxacin is a broad-spectrum fluoroquinolone approved in the United States for the treatment of community-acquired bacterial pneumonia. To determine the in-vitro susceptibilities of delafloxacin and the comparator quinolones levofloxacin, moxifloxacin, and ciprofloxacin, researchers from JMI Laboratories in North Liberty, Iowa, tested clinical isolates from patients with community-acquired pneumonia and lower respiratory tract infections at 67 US-based medical centers that participated in the SENTRY Surveillance Program from 2014 to 2020. 

Susceptibility testing was performed by using the Clinical and Laboratory Standards Institute (CLSI) broth microdilution method; CLSI 2021 interpretive criteria were applied, and US Food and Drug Administration criteria were used for delafloxacin susceptibility test interpretation. Because moxifloxacin has no CLSI breakpoint for Escherichia coli, Klebsiella pneumoniae, and Pseudomonas aeuruginosa, ciprofloxacin was tested for those species instead.

At 92%, delafloxacin had the highest susceptibility against methicillin-susceptible S aureus. Streptococcus pneumoniae and Haemophilus influenzae isolates were more than 97% susceptible and Haemophilus parainfluenzae was more than 91% susceptible to all 3 drugs tested. Moreover, quinolone-resistant S pneumoniae and H influenzae were uncommon.

The susceptibility of K pneumoniae ranged from 77% for delafloxacin to 86% for levofloxacin, and the susceptibilities of E coli and P aeuruginosa were similar for all 3 drugs.

“These in vitro results suggest that [delafloxacin] may be a useful therapeutic option for [community-acquired bacterial pneumonia] cased by Gram-positive, Gram-negative and fastidious pathogens,” concluded presenting author Dee Shortridge, PhD.

—Ellen Kurek

Reference:

Shortridge D, Streit JM, Huband MD, Castanheira M. In vitro evaluation of delafloxacin activity against contemporary US isolates from community-acquired pneumonia and community-acquired lower respiratory tract infections: results from the SENTRY Antimicrobial Surveillance Program (2014–2020). Paper presented at: IDWeek 2021; September 29-October 3, 2021; Virtual.