L. monocytogenes strains were grown in aerated BHI cultures with various concentrations of ceftriaxone (Sigma; C5793), ampicillin (Sigma; A0166), bacitracin (Fisher Bioreagent; BP29501), daptomycin (Merck), lysozyme (Sigma; L6876), LL-37 (AnaSpec; AS61302), or hydrogen peroxide. MICs were determined as the median concentration of antimicrobial required to prevent replication over 12 h as determined by OD600 in a BioTek Eon or BioTek Synergy HT plate reader.