title: Haemophilus influenzae clinical isolates with plasmid pB1000 bearing blaROB-1: fitness cost and interspecies dissemination.
abstract: Plasmid pB1000 is a mobilizable replicon bearing the bla(ROB-1) beta-lactamase gene that we have recently described in Haemophilus parasuis and Pasteurella multocida animal isolates. Here we report the presence of pB1000 and a derivative plasmid, pB1000', in four Haemophilus influenzae clinical isolates of human origin. Pulsed-field gel electrophoresis showed unrelated patterns in all strains, indicating that the existence of pB1000 in H. influenzae isolates is not the consequence of clonal dissemination. The replicon can be transferred both by transformation and by conjugation into H. influenzae, giving rise to recipients resistant to ampicillin and cefaclor (MICs, > or =64 microg/ml). Stability experiments showed that pB1000 is stable in H. influenzae without antimicrobial pressure for at least 60 generations. Competition experiments between isogenic H. influenzae strains with and without pB1000 revealed a competitive disadvantage of 9% per 10 generations for the transformant versus the recipient. The complete nucleotide sequences of nine pB1000 plasmids from human and animal isolates, as well as the epidemiological data, suggest that animal isolates belonging to the Pasteurellaceae act as an antimicrobial resistance reservoir for H. influenzae. Further, since P. multocida is the only member of this family that can colonize both humans and animals, we propose that P. multocida is the vehicle for the transport of pB1000 between animal- and human-adapted members of the Pasteurellaceae.
authors.affiliation: Departamento de Sanidad Animal, Universidad Complutense de Madrid, 28040 Madrid, Spain.
authors.forename: Alvaro
authors.initials: A
authors.lastname: San Millan
authors.forename: Silvia
authors.initials: S
authors.lastname: Garcia-Cobos
authors.forename: Jose Antonio
authors.initials: JA
authors.lastname: Escudero
authors.forename: Laura
authors.initials: L
authors.lastname: Hidalgo
authors.forename: Belen
authors.initials: B
authors.lastname: Gutierrez
authors.forename: Laura
authors.initials: L
authors.lastname: Carrilero
authors.forename: Jose
authors.initials: J
authors.lastname: Campos
authors.forename: Bruno
authors.initials: B
authors.lastname: Gonzalez-Zorn
mesh_terms: D000818:Animals; D002433:Cefaclor / Q000494:pharmacology; D003227:Conjugation, Genetic; D024881:Drug Resistance, Bacterial / Q000235:genetics; D006192:Haemophilus Infections / Q000188:drug therapy / Q000453:epidemiology / Q000382:microbiology*; D006193:Haemophilus influenzae / Q000187:drug effects / Q000201:enzymology / Q000235:genetics* / Q000302:isolation & purification*; D006801:Humans; D017720:Molecular Epidemiology; D008969:Molecular Sequence Data; D016979:Pasteurella multocida / Q000235:genetics; D010957:Plasmids / Q000235:genetics*; D012093:Replicon; D013030:Spain / Q000453:epidemiology; D013045:Species Specificity; D014170:Transformation, Genetic; D001618:beta-Lactamases / Q000235:genetics
chemical_list: D002433:Cefaclor; D001618:beta-Lactamases