Ticagrelor alters the membrane of
Staphylococcus aureus
and enhances the activity of vancomycin and daptomycin without eliciting cross-resistance
Authors: Leeten Kirsten , Jacques Nicolas , Esquembre Lidia Alejo , Schneider Dana C. , Straetener Jan , Henriksen Camilla , Musumeci Lucia , Putters Florence , Melo Sofia , Sánchez-López Elena , Giera Martin , Penoy Noémie , Piel Géraldine , Verlaine Olivier , Amoroso Ana , Joris Bernard , Slavetinsky Christoph J. , Goffin Eric , Pirotte Bernard , Frees Dorte , Brötz-Oesterhelt Heike , Lancellotti Patrizio , Oury Cécile 
Published: September 2024

Infections with multidrug-resistant bacteria pose a major healthcare problem which urges the need for novel treatment options. Besides its potent antiplatelet properties, ticagrelor has antibacterial activity against Gram-positive bacteria, including methicillin- and vancomycin-resistant
Staphylococcus aureus
(MRSA and VRSA). Several retrospective studies in cardiovascular patients support an antibacterial effect of this drug which is not related to its antiplatelet activity. We investigated the mechanism of action of ticagrelor in
Staphylococcus aureus
and model
Bacillus subtilis,
and assessed cross-resistance with two conventional anti-MRSA antibiotics, vancomycin and daptomycin.
Bacillus subtilis
bioreporter strains revealed ticagrelor-induced cell envelope-related stress responses. Sub-inhibitory drug concentrations caused membrane depolarization, impaired positioning of both the peripheral membrane protein MinD and the peptidoglycan precursor lipid II, and it affected cell shape. At the MIC, ticagrelor destroyed membrane integrity, indicated by the influx of membrane impermeable dyes, and lipid aggregate formation. Whole-genome sequencing of
in vitro
-generated ticagrelor-resistant MRSA clones revealed mutations in genes encoding ClpP, ClpX, and YjbH. Lipidomic analysis of resistant clones displayed changes in levels of the most abundant lipids of the
Staphylococcus aureus
membrane, for example, cardiolipins, phosphatidylglycerols, and diacylglycerols. Exogeneous cardiolipin, phosphatidylglycerol, or diacylglycerol antagonized the antibacterial properties of ticagrelor. Ticagrelor enhanced MRSA growth inhibition and killing by vancomycin and daptomycin in both exponential and stationary phases. Finally, no cross-resistance was observed between ticagrelor and daptomycin, or vancomycin. Our study demonstrates that ticagrelor targets multiple lipids in the cytoplasmic membrane of Gram-positive bacteria, thereby retaining activity against multidrug-resistant
staphylococci
including daptomycin- and vancomycin-resistant strains.

IMPORTANCE

Infections with multidrug-resistant bacteria pose a major healthcare problem with an urgent need for novel treatment options. The antiplatelet drug ticagrelor possesses antibacterial activity against Gram-positive bacteria including methicillin-resistant and vancomycin-resistant
Staphylococcus aureus
strains. We report a unique, dose-dependent, antibacterial mechanism of action of ticagrelor, which alters the properties and integrity of the bacterial cytoplasmic membrane. Ticagrelor retains activity against multidrug-resistant staphylococci, including isolates carrying the most common
in vivo
selected daptomycin resistance mutations and vancomycin-intermediate
Staphylococcus aureus
. Our data support the use of ticagrelor as adjunct therapy against multidrug-resistant strains. Because of the presence of multiple non-protein targets of this drug within the bacterial membrane, resistance development is expected to be slow. All these findings corroborate the accumulating observational clinical evidence for a beneficial anti-bacterial effect of ticagrelor in cardiovascular patients in need of such treatment.