title: Chromogenic plate assay distinguishing bacteriolytic from bacteriostatic activity of an antibiotic agent.
abstract: A solid agar plate assay was devised to discriminate bacteriolytic from bacteriostatic activity for a given antibacterial agent. The assay uses a bacterial culture harboring beta-galactosidase enzyme as reporter of cellular lysis. When a drop of bacteriolytic compound is placed on the agar, beta-galactosidase is released from the bacteria to the external solid medium where it hydrolyzes X-Gal substrate analogue, developing a blue halo at the edge of the inhibition growth zone. The assay was successfully evaluated against several antibiotics with well-known mechanism of action. It was found that bacteriostatic compounds consistently did not display blue halo at the inhibition zone.
authors.affiliation: Laboratorio de Bioquímica, Departamento de Genética Molecular y Microbiología, Pontificia Universidad Católica de Chile, Casilla 114-D, Santiago, Chile.
authors.forename: G
authors.initials: G
authors.lastname: Mardones
authors.forename: A
authors.initials: A
authors.lastname: Venegas
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D023181:Antimicrobial Cationic Peptides; D001433:Bacteriolysis / Q000187:drug effects*; D002863:Chromogenic Compounds / Q000378:metabolism; D004755:Enterobacteriaceae / Q000187:drug effects*; D004917:Erythromycin / Q000494:pharmacology; D005697:Galactosides / Q000378:metabolism; D006868:Hydrolysis; D007211:Indoles / Q000378:metabolism; D007544:Isopropyl Thiogalactoside / Q000494:pharmacology; D008826:Microbial Sensitivity Tests / Q000379:methods*; D010406:Penicillins / Q000494:pharmacology; D010455:Peptides / Q000494:pharmacology; D015203:Reproducibility of Results; D013752:Tetracycline / Q000494:pharmacology; D001616:beta-Galactosidase / Q000378:metabolism*
chemical_list: D000900:Anti-Bacterial Agents; D023181:Antimicrobial Cationic Peptides; D002863:Chromogenic Compounds; D005697:Galactosides; D007211:Indoles; D010406:Penicillins; D010455:Peptides; C061361:apidaecin; D007544:Isopropyl Thiogalactoside; D004917:Erythromycin; D001616:beta-Galactosidase; D013752:Tetracycline; C044888:5-bromo-4-chloro-3-indolyl beta-galactoside