title: Gram-positive bacteria are a major reservoir of Class 1 antibiotic resistance integrons in poultry litter.
abstract: Reversing the spread of antibiotic multiresistant bacteria is hampered by ignorance of the natural history of resistance genes, the mobile elements carrying them, and the bacterial hosts harboring them. Using traditional cultivation and cultivation-independent molecular techniques, we quantified antibiotic resistance genes and mobile elements called integrons in poultry house litter from commercial poultry farms. Unexpectedly, the major reservoir for Class 1 integrons in poultry litter is not their previously identified hosts, Gram-negative Enterobacteriaceae such as Escherichia coli. Rather, integrons and associated resistance genes abound in several genera of Gram-positive bacteria that constitute >85% of the litter community compared with Enterobacteriaceae that comprise <2% of this ecosystem. This finding warrants reexamination of our assumptions about the persistence and spread of antibiotic resistance genes.
authors.affiliation: Department of Microbiology, University of Georgia, Athens, GA 30602, USA.
authors.forename: Sobhan
authors.initials: S
authors.lastname: Nandi
authors.forename: John J
authors.initials: JJ
authors.lastname: Maurer
authors.forename: Charles
authors.initials: C
authors.lastname: Hofacre
authors.forename: Anne O
authors.initials: AO
authors.lastname: Summers
mesh_terms: D000818:Animals; D002645:Chickens / Q000382:microbiology*; D004197:Disease Reservoirs; D024881:Drug Resistance, Bacterial / Q000235:genetics* / Q000502:physiology; D006094:Gram-Positive Bacteria / Q000235:genetics* / Q000378:metabolism; D019426:Integrases / Q000235:genetics* / Q000378:metabolism; D032023:Integrons
chemical_list: D019426:Integrases; C115006:integron integrase IntI1