Legionnaire’s disease is a severe form of pneumonia caused by Legionella. These bacteria are transmitted by inhaling aerosols from contaminated water. In Europe, incidence of the condition increased by 44% between 2018 and 2023 from 2.42 infections per 100,000 to 3.5.
Why exactly rates of the disease have increased so much remains unknown. Possible explanations, however, may include greater awareness within healthcare systems, an increase in proportion of population at greatest risk of infection, and rising global temperatures.
Delafloxacin is a fourth-generation fluoroquinolone that has been approved in Europe and the US for treating various bacterial infections. Research has shown that it is more effective and produces fewer adverse effects than other quinolones like levofloxacin, a current first-line treatment against Legionnaire’s disease, against a broad spectrum of bacteria.
In the present study, researchers compared the efficacy of delafloxacin with levofloxacin. They used an in vitro model of intracellular infection in human macrophages, and analyzed ten representative strains of Legionella.
Ultimately, delafloxacin decreased the intracellular multiplication of Legionella 5- 10 times more than levofloxacin. Using viability PCR techniques, the researchers found that both antibiotics resulted in a genuine reduction of bacterial viability. Delafloxacin showed greater intracellular activity in all but one species- Legionella longbeachae- in which case the two antibiotics had similar effects.
"As an intracellular pathogen, Legionella requires antibiotics that effectively penetrate host cells, and delafloxacin has demonstrated promising intracellular activity that supports further clinical investigation as a potential improvement over current treatments," first author of the study, Roger Cortès-Tarragó of Institut de Recerca Germans Trias i Pujol (IGTP), Spain, said in a press release.
Sources: EurekAlert, International Journal of Infectious Diseases