RESUMEN
A series of colistin-resistant Klebsiella pneumoniae isolates recovered from different countries was investigated in order to evaluate the involvement of the PmrA/PmrB two-component system in this resistance. Six isolates possessed a mutated PmrB protein, which is encoded by the pmrB gene, part of the pmrCAB operon involved in lipopolysaccharide modification. The same amino acid substitution (Thr157Pro) in PmrB was identified in the six isolates. The six isolates belonged to four distinct clonal groups, recovered in South Africa (sequence type 14 [ST14]), Turkey (ST101), and Colombia (ST258 and ST15). Three out of the four clones produced a carbapenemase, OXA-181, OXA-48, or KPC-3, while a single isolate did not produce any carbapenemase. Expression assays revealed an overexpression of the pmrA (70-fold), pmrB (70-fold), pmrC (170-fold), and pmrK (40-fold) genes in the pmrB-mutated isolate compared to expression of the pmrB wild-type isogenic K. pneumoniae isolate, confirming that the PmrB substitution was responsible for increased expression levels of those genes. Complementation assays leading to the expression of a wild-type PmrB protein restored the susceptibility to colistin in all isolates, confirming that the substitution in PmrB was responsible for the resistance phenotype. This study identified a key amino acid located in the PmrB protein as being responsible for the overexpression of pmrCAB and pmrHFIJKLM operons, leading to resistance to colistin.
Asunto(s)
Sustitución de Aminoácidos , Proteínas Bacterianas/genética , Farmacorresistencia Bacteriana/genética , Regulación Bacteriana de la Expresión Génica , Klebsiella pneumoniae/genética , Factores de Transcripción/genética , beta-Lactamasas/genética , Antibacterianos/farmacología , Proteínas Bacterianas/metabolismo , Colistina/farmacología , Colombia , Prueba de Complementación Genética , Humanos , Infecciones por Klebsiella/tratamiento farmacológico , Infecciones por Klebsiella/microbiología , Klebsiella pneumoniae/efectos de los fármacos , Klebsiella pneumoniae/aislamiento & purificación , Klebsiella pneumoniae/metabolismo , Pruebas de Sensibilidad Microbiana , Familia de Multigenes , Mutación , Operón , Sudáfrica , Factores de Transcripción/metabolismo , Turquía , beta-Lactamasas/metabolismoRESUMEN
Corynebacterium species other than Corynebacterium diphtheriae rarely cause infections in human but rather reside in flora, however they have been reported to cause opportunistic infections in both immunocompromised and immunecompetent patients. Here we report for the first time a case of an elderly female patient presenting with a fatal urosepsis caused by a recently defined pathogen, Corynebacterium riegelii, identified on second day after patient hospitalization leading to a progressive worsening and death of the patient on 6th day.
Asunto(s)
Infecciones por Corynebacterium/diagnóstico , Corynebacterium/aislamiento & purificación , Infecciones Urinarias/diagnóstico , Anciano , Antibacterianos/uso terapéutico , Corynebacterium/clasificación , Corynebacterium/genética , Infecciones por Corynebacterium/tratamiento farmacológico , Infecciones por Corynebacterium/microbiología , ADN Bacteriano/química , ADN Bacteriano/genética , Resultado Fatal , Femenino , Humanos , Datos de Secuencia Molecular , Análisis de Secuencia de ADN , Infecciones Urinarias/tratamiento farmacológico , Infecciones Urinarias/microbiologíaRESUMEN
Corynebacterium species other than Corynebacterium diphtheriae rarely cause infections in human but rather reside in flora, however they have been reported to cause opportunistic infections in both immunocompromised and immunecompetent patients. Here we report for the first time a case of an elderly female patient presenting with a fatal urosepsis caused by a recently defined pathogen, Corynebacterium riegelii, identified on second day after patient hospitalization leading to a progressive worsening and death of the patient on 6th day.(AU)
Asunto(s)
Corynebacterium , Corynebacterium diphtheriae , Infecciones por Corynebacterium , Humanos , BacteriasRESUMEN
Corynebacterium species other than Corynebacterium diphtheriae rarely cause infections in human but rather reside in flora, however they have been reported to cause opportunistic infections in both immunocompromised and immunecompetent patients. Here we report for the first time a case of an elderly female patient presenting with a fatal urosepsis caused by a recently defined pathogen, Corynebacterium riegelii, identified on second day after patient hospitalization leading to a progressive worsening and death of the patient on 6th day.