RESUMEN
The objective of this study was to evaluate molecular and epidemiologic factors associated with Escherichia coli sequence type 131 (ST131) among long-term care facility (LTCF) residents who acquired gastrointestinal tract colonization with fluoroquinolone-resistant E. coli (FQREC). Colonizing isolates from 37 residents who newly developed FQREC colonization at three LTCFs from 2006 to 2008 were evaluated. Twenty-nine (78%) of 37 total FQREC colonizing isolates were ST131. Most ST131 isolates had a distinctive combination of gyrA and parC replacement mutations. The ST131 and non-ST131 isolates differed significantly for the prevalence of many individual virulence factors but not for the proportion that qualified molecularly as extraintestinal pathogenic E. coli (ExPEC) or aggregate virulence factor scores. E. coli ST131 was highly prevalent among LTCF residents with FQREC colonization. Future studies should determine the risk factors for infection among ST131-colonized residents, and assess the potential for increased transmissibility of ST131 in the long-term care setting.
Asunto(s)
Antibacterianos/farmacología , Infecciones Asintomáticas/epidemiología , Farmacorresistencia Bacteriana Múltiple/genética , Infecciones por Escherichia coli/epidemiología , Escherichia coli/efectos de los fármacos , Fluoroquinolonas/farmacología , Tracto Gastrointestinal/microbiología , Cuidados a Largo Plazo , Anciano , Girasa de ADN/genética , Topoisomerasa de ADN IV/genética , ADN Bacteriano/genética , Escherichia coli/genética , Escherichia coli/aislamiento & purificación , Infecciones por Escherichia coli/microbiología , Femenino , Humanos , Masculino , Pruebas de Sensibilidad Microbiana , Factores de Virulencia/genéticaRESUMEN
The specific mechanisms underlying general anesthesia are primarily unknown. The intravenous general anesthetic etomidate acts by potentiating GABA(A) receptors, with selectivity for beta2 and beta3 subunit-containing receptors determined by a single asparagine residue. We generated a genetically modified mouse containing an etomidate-insensitive beta2 subunit (beta2 N265S) to determine the role of beta2 and beta3 subunits in etomidate-induced anesthesia. Loss of pedal withdrawal reflex and burst suppression in the electroencephalogram were still observed in the mutant mouse, indicating that loss of consciousness can be mediated purely through beta3-containing receptors. The sedation produced by subanesthetic doses of etomidate and during recovery from anesthesia was present only in wild-type mice, indicating that the beta2 subunit mediates the sedative properties of anesthetics. These findings show that anesthesia and sedation are mediated by distinct GABA(A) receptor subtypes.
