title: Identification and Characterization of Imipenem-Resistant Klebsiella pneumoniae and Susceptible Klebsiella variicola Isolates Obtained from the Same Patient.
abstract: Klebsiella variicola, a bacterium closely genetically related to Klebsiella pneumoniae, is commonly misidentified as K. pneumoniae by biochemical tests. To distinguish between the two bacteria, phylogenetic analysis of the rpoB gene and the identification of unique genes in both bacterial species by multiplex-polymerase chain reaction (PCR) provide the means to reliably identify and genotype K. variicola. In recent years, K. variicola has been described both as the cause of an intrahospital outbreak in a pediatric hospital, which resulted in sepsis in inpatients, and as a frequent cause of bloodstream infections. In the present study, K. pneumoniae and K. variicola were isolated from a unique patient displaying different antimicrobial susceptibility phenotypes and different genotypes of virulence determinants. Eight clinical isolates were obtained at different time intervals; all during a 5-month period. The isolates were identified as K. pneumoniae by an automated identification system. The clinical (biochemical test) and molecular (multiplex-PCR and rpoB gene) characterization identified imipenem resistance in the first six K. pneumoniae ST258 isolates, which encode the SHV-12 cephalosporinase and KPC-3 carbapenemase genes. The two last remaining isolates corresponded to susceptible K. variicola. The bacterial species showed a specific profile of virulence-associated determinants, specifically the fimA, fimH, and ecpRAB fimbrial-encoding genes identified only in K. pneumoniae isolates. However, the entb (enterobactin), mrkD (fimbrial adhesin), uge (epimerase), ureA (urease), and wabG (transferase) genes were shared between both bacterial species. Recent studies attribute a higher mortality rate to K. variicola than to K. pneumonia. This work highlights the identification of K. pneumoniae and the closely related K. variicola isolated from the same patient. The value of distinguishing between these two bacterial species is in their clinical significance, their different phenotypes and genotypes, and the fact that they can be isolated from the same patient.
authors.affiliation: 1 Departamento de Diagnóstico Epidemiológico, Centro de Investigación Sobre Enfermedades Infecciosas (CISEI) , Instituto Nacional de Salud Pública (INSP), Cuernavaca, México.
authors.forename: Ulises
authors.initials: U
authors.lastname: Garza-Ramos
authors.affiliation: 1 Departamento de Diagnóstico Epidemiológico, Centro de Investigación Sobre Enfermedades Infecciosas (CISEI) , Instituto Nacional de Salud Pública (INSP), Cuernavaca, México.
authors.forename: Stephania
authors.initials: S
authors.lastname: Moreno-Dominguez
authors.affiliation: 2 Departamento Ecología de Agentes Patógenos, Hospital General "Dr. Manuel Gea González," México, México.
authors.forename: Rigoberto
authors.initials: R
authors.lastname: Hernández-Castro
authors.affiliation: 1 Departamento de Diagnóstico Epidemiológico, Centro de Investigación Sobre Enfermedades Infecciosas (CISEI) , Instituto Nacional de Salud Pública (INSP), Cuernavaca, México.
authors.forename: Jesús
authors.initials: J
authors.lastname: Silva-Sanchez
authors.affiliation: 1 Departamento de Diagnóstico Epidemiológico, Centro de Investigación Sobre Enfermedades Infecciosas (CISEI) , Instituto Nacional de Salud Pública (INSP), Cuernavaca, México.
authors.forename: Humberto
authors.initials: H
authors.lastname: Barrios
authors.affiliation: 1 Departamento de Diagnóstico Epidemiológico, Centro de Investigación Sobre Enfermedades Infecciosas (CISEI) , Instituto Nacional de Salud Pública (INSP), Cuernavaca, México.
authors.forename: Fernando
authors.initials: F
authors.lastname: Reyna-Flores
authors.affiliation: 1 Departamento de Diagnóstico Epidemiológico, Centro de Investigación Sobre Enfermedades Infecciosas (CISEI) , Instituto Nacional de Salud Pública (INSP), Cuernavaca, México.
authors.forename: Alejandro
authors.initials: A
authors.lastname: Sanchez-Perez
authors.affiliation: 3 Departamento Biología Molecular e Histocompatibilidad, Hospital General "Dr. Manuel Gea González," México, México.
authors.forename: Erika M
authors.initials: EM
authors.lastname: Carrillo-Casas
authors.affiliation: 2 Departamento Ecología de Agentes Patógenos, Hospital General "Dr. Manuel Gea González," México, México.
authors.forename: María Carmen
authors.initials: MC
authors.lastname: Sanchez-León
authors.affiliation: 4 Laboratorio Clínico, Hospital General "Dr. Manuel Gea González," México, México.
authors.forename: David
authors.initials: D
authors.lastname: Moncada-Barron
mesh_terms: D000368:Aged; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001426:Bacterial Proteins / Q000378:metabolism; D024901:Drug Resistance, Multiple, Bacterial / Q000235:genetics*; D005260:Female; D005838:Genotype; D006801:Humans; D015378:Imipenem / Q000494:pharmacology*; D007710:Klebsiella Infections / Q000188:drug therapy* / Q000382:microbiology*; D007711:Klebsiella pneumoniae / Q000187:drug effects / Q000235:genetics* / Q000302:isolation & purification*; D008826:Microbial Sensitivity Tests; D010802:Phylogeny; D037521:Virulence Factors / Q000235:genetics; D001618:beta-Lactamases / Q000378:metabolism
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D037521:Virulence Factors; D015378:Imipenem; D001618:beta-Lactamases; C063912:carbapenemase