title: Malthusian Parameters as Estimators of the Fitness of Microbes: A Cautionary Tale about the Low Side of High Throughput.
abstract: The maximum exponential growth rate, the Malthusian parameter (MP), is commonly used as a measure of fitness in experimental studies of adaptive evolution and of the effects of antibiotic resistance and other genes on the fitness of planktonic microbes. Thanks to automated, multi-well optical density plate readers and computers, with little hands-on effort investigators can readily obtain hundreds of estimates of MPs in less than a day. Here we compare estimates of the relative fitness of antibiotic susceptible and resistant strains of E. coli, Pseudomonas aeruginosa and Staphylococcus aureus based on MP data obtained with automated multi-well plate readers with the results from pairwise competition experiments. This leads us to question the reliability of estimates of MP obtained with these high throughput devices and the utility of these estimates of the maximum growth rates to detect fitness differences.
authors.affiliation: Department of Biology, Emory University, Atlanta, Georgia, United States of America.
authors.forename: Jeniffer
authors.initials: J
authors.lastname: Concepción-Acevedo
authors.affiliation: Department of Mathematics, Georgia Institute of Technology, Atlanta, Georgia, United States of America.
authors.forename: Howard N
authors.initials: HN
authors.lastname: Weiss
authors.affiliation: Department of Biology, Emory University, Atlanta, Georgia, United States of America; National University of Sciences and Technology, Islamabad, Pakistan.
authors.forename: Waqas Nasir
authors.initials: WN
authors.lastname: Chaudhry
authors.affiliation: Department of Biology, Emory University, Atlanta, Georgia, United States of America.
authors.forename: Bruce R
authors.initials: BR
authors.lastname: Levin
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001419:Bacteria / Q000187:drug effects / Q000254:growth & development*; D018407:Bacterial Physiological Phenomena; D003227:Conjugation, Genetic; D024881:Drug Resistance, Bacterial; D005947:Glucose / Q000378:metabolism; D009154:Mutation
chemical_list: D000900:Anti-Bacterial Agents; D005947:Glucose