In vitro activity of iclaprim and comparator agents against Listeria monocytogenes clinical isolates from 2012 to 2018

•Iclaprim is a novel diaminopyrimidine that inhibits bacterial dihydrofolate reductase (DHFR).•Iclaprim is active against Gram-positive pathogens including emerging drug-resistant pathogens.•In vitro activity of iclaprim was tested against 40 Listeria monocytogenes clinical isolates collected between 2012–2018.•The iclaprim MIC90 value for all L. monocytogenes was 0.015 μg/mL.•Iclaprim MIC50/90 values were 4-fold lower than trimethoprim, the only FDA-approved DHFR inhibitor, against all isolates.