title: Synergistic effect of human lysozyme plus ampicillin or beta-lysin on the killing of Listeria monocytogenes.
abstract: Although ampicillin is often only bacteriostatic for Listeria monocytogenes in vitro, serum from ampicillin-treated patients was bactericidal. The bactericidal effect of serum was partly removed by bentonite, Seitz-filtration, and addition of FeCl3, suggesting it is mediated by lysozyme and beta-lysin. Partly purified human beta-lysin plus purified human lysozyme or either protein plus ampicillin were bactericidal for L. monocytogenes. Hen egg white lysozyme was not active. Lysozyme and beta-lysin were not synergistic with tetracycline, trimethoprim/sulfamethoxazole, or chloramphenicol. Thus, lysozyme and beta-lysin may play a role in the natural resistance to L. monocytogenes, and these serum proteins could contribute to the effectiveness of ampicillin in vivo.
authors.affiliation: Department of Medicine, Veterans Administration Medical Center, San Diego, CA 92161.
authors.forename: V
authors.initials: V
authors.lastname: Asensi
authors.forename: J
authors.initials: J
authors.lastname: Fierer
mesh_terms: D000667:Ampicillin / Q000494:pharmacology*; D023181:Antimicrobial Cationic Peptides; D001798:Blood Proteins; D004357:Drug Synergism; D008089:Listeria monocytogenes / Q000187:drug effects*; D008826:Microbial Sensitivity Tests; D009113:Muramidase / Q000494:pharmacology*; D011506:Proteins / Q000302:isolation & purification / Q000494:pharmacology*
chemical_list: D023181:Antimicrobial Cationic Peptides; D001798:Blood Proteins; D011506:Proteins; C011679:beta lysin, human; D000667:Ampicillin; D009113:Muramidase