title: Horizontal transfer of the tetracycline resistance gene tetM mediated by pCF10 among Enterococcus faecalis in the house fly (Musca domestica L.) alimentary canal.
abstract: The house fly (Musca domestica L.) alimentary canal was evaluated for the potential of horizontal transfer of tetM on plasmid pCF10 among Enterococcus faecalis. Two sets of experiments were conducted: (1) house flies without surface sterilization and (2) surface-sterilized flies. Both sets of flies were exposed to E. faecalis OG1RF:pCF10 as donor for 12 h and then E. faecalis OG1SSp as recipient for 1 h. Another group of flies received the recipient first for 12 h followed by exposure to the donor strain for 1 h. House flies were screened daily to determine the donor, recipient, and transconjugant bacterial load for up to 5 days. In addition, the sponge-like mouth parts used for food uptake (labellum) of surface-sterilized house flies were removed and analyzed for donors, recipients, and transconjugants, separately. In both groups of flies (n = 90 flies/group), transfer occurred within 24 h after exposure with a transconjugant/donor rate from 8.6 x 10(-5) to 4.5 x 10(1). Transconjugants were also isolated from the house fly labellum. Our data suggest that the house fly digestive tract provides a suitable environment for horizontal transfer of conjugative plasmids and antibiotic resistance genes among enterococci. Our results emphasize the importance of this insect as a potential vector of antibiotic-resistant bacterial strains.
authors.affiliation: Department of Entomology, Kansas State University, Manhattan, KS 66506, USA.
authors.forename: Mastura
authors.initials: M
authors.lastname: Akhtar
authors.forename: Helmut
authors.initials: H
authors.lastname: Hirt
authors.forename: Ludek
authors.initials: L
authors.lastname: Zurek
mesh_terms: D000818:Animals; D003227:Conjugation, Genetic; D013293:Enterococcus faecalis / Q000187:drug effects / Q000235:genetics*; D041981:Gastrointestinal Tract / Q000382:microbiology*; D022761:Gene Transfer, Horizontal; D005798:Genes, Bacterial; D006793:Houseflies / Q000382:microbiology*; D008826:Microbial Sensitivity Tests; D010957:Plasmids; D013753:Tetracycline Resistance / Q000187:drug effects / Q000235:genetics*