title: Sampling bias created by ampicillin in isolation media for Aeromonas.
abstract: Members of the bacterial genus Aeromonas are widely isolated from aquatic environments and studied in part for their ability to act as opportunistic pathogens in a variety of animals. All aeromonads, with the exception of Aeromonas trota, are generally thought to be resistant to ampicillin, so the antibiotic is frequently added to isolation medium as a selective agent. In this study, 282 aeromonads from environmental sources were isolated on a medium without ampicillin and their resistance to ampicillin determined. Of the 104 of these isolates that were judged to be independent (nonredundant), 18 (17.3%) were susceptible to ampicillin. A chi-square analysis was performed to determine the impact of ampicillin use on enumerating Aeromonas species from environmental samples. Our results indicate that, when ampicillin is used as a selective agent, a significant portion of the aeromonad population in at least some environments can be omitted from isolation.
authors.affiliation: Department of Biological Sciences, Texas Tech University, Lubbock 79409, USA. jennifer.huddleston@ttu.edu
authors.forename: Jennifer R
authors.initials: JR
authors.lastname: Huddleston
authors.forename: John C
authors.initials: JC
authors.lastname: Zak
authors.forename: Randall M
authors.initials: RM
authors.lastname: Jeter
mesh_terms: D000333:Aeromonas / Q000187:drug effects* / Q000302:isolation & purification*; D000667:Ampicillin / Q000494:pharmacology*; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D003470:Culture Media / Q000494:pharmacology; D008826:Microbial Sensitivity Tests / Q000379:methods; D015203:Reproducibility of Results; D013048:Specimen Handling / Q000379:methods / Q000706:statistics & numerical data*
chemical_list: D000900:Anti-Bacterial Agents; D003470:Culture Media; D000667:Ampicillin