RESUMO
Antimicrobial resistance is rapidly expanding, in a large part due to mobile genetic elements. We screened 94 fecal fluoroquinolone-resistant Escherichia coli isolates from Nigeria for six plasmid-mediated quinolone resistance (PMQR) genes. Sixteen isolates harbored at least one of the PMQR genes and four were positive for aac-6-Ib-cr. In one strain, aac-6-Ib-cr was mapped to a 125 Kb self-transmissible IncFII plasmid, pMB2, which also bears blaCTX-M-15, seven other functional resistance genes and multiple resistance pseudogenes. Laboratory strains carrying pMB2 grew faster than isogenic strains lacking the plasmid in both rich and minimal media. We excised a 32 Kb fragment containing transporter genes and several open-reading frames of unknown function. The resulting 93 Kb mini-plasmid conferred slower growth rates and lower fitness than wildtype pMB2. Trans-complementing the deletion with the cloned sitABCD genes confirmed that they accounted for the growth advantage conferred by pMB2 in iron-depleted media. pMB2 is a large plasmid with a flexible resistance region that contains loci that can account for evolutionary success in the absence of antimicrobials. Ancillary functions conferred by resistance plasmids can mediate their retention and transmissibility, worsening the trajectory for antimicrobial resistance and potentially circumventing efforts to contain resistance through restricted use.
Assuntos
Conjugação Genética , Farmacorresistência Bacteriana/genética , Infecções por Escherichia coli , Proteínas de Escherichia coli , Escherichia coli , Plasmídeos/genética , Farmacorresistência Bacteriana/efeitos dos fármacos , Escherichia coli/genética , Escherichia coli/isolamento & purificação , Escherichia coli/metabolismo , Infecções por Escherichia coli/genética , Infecções por Escherichia coli/metabolismo , Proteínas de Escherichia coli/genética , Proteínas de Escherichia coli/metabolismo , Fluoroquinolonas/farmacologia , Humanos , Testes de Sensibilidade Microbiana , Nigéria , Plasmídeos/metabolismoRESUMO
In many infection studies and approaches in breeding research it is of high importance to know the genetic predisposition of pigs for the susceptibility to the Escherichia coli (E. coli). Therefore, we developed a gene test to determine the status of the F18 receptor, as indicated by the FUT1 gene. A SNP in the FUT1 gene was first described by Vogeli et al. (1996) and a gene test was patented by Meijerink et al. (1997). Up until now, the gene test of Meijerink has been used in research. However, faster and cheaper genotyping techniques are now available, which led us to develop an easily applicable, fast and cost effective genetic test to determine the status of the F18 receptor. To check the accuracy of the new test, we genotyped 32 pigs with the established test as well as with our new test. All in all, we genotyped 430 German Landrace pigs. The test was successful. We suggest this allele specific test as a new standard genetic tool to determine the ETEC F18 receptor status in pigs.
Assuntos
Infecções por Escherichia coli/genética , Fucosiltransferases/genética , Predisposição Genética para Doença , Técnicas Genéticas/veterinária , Doenças dos Suínos/genética , Suínos/genética , Animais , Cruzamento , Escherichia coli Enterotoxigênica , Escherichia coli , Proteínas de Escherichia coli , Técnicas Genéticas/economia , Técnicas Genéticas/normas , Genótipo , Polimorfismo de Nucleotídeo Único/genéticaAssuntos
Resistência à Doença/genética , Edematose Suína/microbiologia , Escherichia coli Enterotoxigênica , Infecções por Escherichia coli/veterinária , Fucosiltransferases/genética , Suínos/genética , Adiposidade/genética , Animais , Pesos e Medidas Corporais , Edematose Suína/economia , Edematose Suína/genética , Infecções por Escherichia coli/economia , Infecções por Escherichia coli/genética , Feminino , Estudos de Associação Genética , Aptidão Genética , Genótipo , Paridade , Polimorfismo de Fragmento de Restrição , Gravidez , Suínos/crescimento & desenvolvimento , Galactosídeo 2-alfa-L-FucosiltransferaseRESUMO
A mixed hidden Markov model (HMM) was developed for predicting breeding values of a biomarker (here, somatic cell score) and the individual probabilities of health and disease (here, mastitis) based upon the measurements of the biomarker. At a first level, the unobserved disease process (Markov model) was introduced and at a second level, the measurement process was modeled, making the link between the unobserved disease states and the observed biomarker values. This hierarchical formulation allows joint estimation of the parameters of both processes. The flexibility of this approach is illustrated on the simulated data. Firstly, lactation curves for the biomarker were generated based upon published parameters (mean, variance, and probabilities of infection) for cows with known clinical conditions (health or mastitis due to Escherichia coli or Staphylococcus aureus). Next, estimation of the parameters was performed via Gibbs sampling, assuming the health status was unknown. Results from the simulations and mathematics show that the mixed HMM is appropriate to estimate the quantities of interest although the accuracy of the estimates is moderate when the prevalence of the disease is low. The paper ends with some indications for further developments of the methodology.