RESUMEN
Acinetobacter baumannii is an emerging multidrug-resistant pathogen and very little information is available regarding its imipenem resistance in Latin American countries such as Bolivia. This study investigated the antimicrobial resistance profile of 46 clinical strains from different hospitals in Cochabamba, Bolivia, from March 2008 to July 2009, and the presence of carbapenemases as a mechanism of resistance to imipenem. Isolates were obtained from 46 patients (one isolate per patient; 30 males,16 females) with an age range of 1 day to 84 years, and were collected from different sample types, the majority from respiratory tract infections (17) and wounds (13). Resistance to imipenem was detected in 15 isolates collected from different hospitals of the city. These isolates grouped into the same genotype, named A, and were resistant to all antibiotics tested including imipenem, with susceptibility only to colistin. Experiments to detect carbapenemases revealed the presence of the OXA-58 carbapenemase. Further analysis revealed the location of the bla(OXA-58) gene on a 40 kb plasmid. To our knowledge, this is the first report of carbapenem resistance in A. baumannii isolates from Bolivia that is conferred by the OXA-58 carbapenemase. The presence of this gene in a multidrug-resistant clone and its location within a plasmid is of great concern with regard to the spread of carbapenem-resistant A. baumannii in the hospital environment in Bolivia.
Asunto(s)
Infecciones por Acinetobacter/epidemiología , Acinetobacter baumannii/efectos de los fármacos , Antibacterianos/metabolismo , Carbapenémicos/metabolismo , Farmacorresistencia Bacteriana Múltiple/genética , Hospitales/estadística & datos numéricos , beta-Lactamasas/biosíntesis , Infecciones por Acinetobacter/microbiología , Acinetobacter baumannii/enzimología , Acinetobacter baumannii/genética , Adolescente , Anciano , Anciano de 80 o más Años , Antibacterianos/farmacología , Bolivia/epidemiología , Carbapenémicos/farmacología , Niño , Preescolar , Infección Hospitalaria/epidemiología , Infección Hospitalaria/microbiología , Femenino , Humanos , Imipenem/metabolismo , Imipenem/farmacología , Lactante , Recién Nacido , Masculino , Pruebas de Sensibilidad Microbiana , Persona de Mediana Edad , Plásmidos/genética , Adulto Joven , beta-Lactamasas/genéticaRESUMEN
Uptake and phosphorylation initiate the catabolism of gluconate in E. coli. Such activities conform two systems,GntI and GntII, encoded by two sets of genes differently located on the E. coli chromosome and under different regulation. gntT, gntU and gntK (minute 76) encode for high and low affinity gluconate transports and for a thermoresistant gluconokinase respectively, that conform GntI; the mentioned genes and those of the edd-eda operon (minute 41) are negatively regulated by the gntR gene product conforming the gntR regulon. idnT and gntV (minute 96), encode for another gluconate transport and a thermosensitive gluconokinase, conforming GntII. These genes are presumably positively controlled by IdnR. IdnT also functions as a permease for idonate; the corresponding gene is included in the idnDOTR operon, responsible for idonate metabolism, in which gluconate is an intermediary. Here we report a regulatory action of IdnR on the operons of the gntR regulon; i.e., gntT, gntKU and edd-eda. The expression of these operons, was diminished in a gntR mutant complemented with a clone of idnR and also in E. coli mutants in which the idnDOTR operon is expressed in a gluconate dependent inducibility. This is the first report of a regulatory effect of IdnR on edd-eda operon expression.
El transporte y la fosforilación inician el catabolismo del gluconato en E. coli. Estas actividades conforman dossistemas, GntI y GntII, codificados por dos grupos de genes, diferentemente regulados y ubicados en distintos sitios del cromosoma. Los genes gntT, gntU y gntK (minuto 76), codifican distintas proteínas para transportes de alta y baja afinidad para gluconato y una gluconoquinasa termoresistente respectivamente, que forman el sistema GntI; los genes respectivos junto con los del operón edd-eda (minuto 41), son regulados negativamente por el producto de gntR (minuto76) constituyendo el regulón gntR. Los genes IdnT y gntV (minuto 96), codifican otra permeasa para gluconato y una gluconoquinasa termosensible que forman GntII. IdnT funciona también como permeasa para idonato; el gen correspondiente es parte del operón idnDOTR, regulado positivamente por IdnR y responsable del metabolismo del idonato en el que gluconato es un intermediario. Se reporta un efecto regulatorio de IdnR sobre los operones del regulón gntR; i.e., gntT, gntKU and edd-eda. La expresión de estos operones resultó disminuida en una mutante gntR complementada con un clon de idnR y también en mutantes de E. coli en la que la expresión del operón idnDOTR se induce en presencia de gluconato. Este es el primer reporte de la acción regulatoria de IdnR sobre la expresión del operón eddeda.