RESUMEN
Burkholderia cepacia has recently been recognized as an important pathogen in chronic lung disease in patients with cystic fibrosis (CF). Because of the social, psychological, and medical implications of the isolation of B. cepacia from CF patients, accurate identification of this organism is essential. We compared the accuracies of four commercial systems developed for the identification of nonfermenting, gram-negative bacilli with that of conventional biochemical testing for 150 nonfermenters including 58 isolates of B. cepacia recovered from respiratory secretions from CF patients. The accuracies of the four systems for identifying all nonfermenters ranged from 57 to 80%, with the RapID NF Plus system being most accurate. The accuracies of these systems for identifying B. cepacia ranged from 43 to 86%, with the Remel system being most accurate. Depending on the commercial system, from two to seven isolates were misidentified as B. cepacia. The relatively poor performance of the commercial systems requires that identification of certain nonfermenters be confirmed by conventional biochemical testing. These organisms include B. cepacia, Burkholderia sp. other than B. cepacia, and infrequently encountered environmental species (Pseudomonas and Flavobacterium species). In addition, conventional biochemical testing should be done if a commercial system fails to assign an identification to an organism. Confirmatory testing should preferably be performed by a reference laboratory with experience in working organisms isolated from CF patients.
Asunto(s)
Técnicas Bacteriológicas , Burkholderia cepacia/aislamiento & purificación , Fibrosis Quística/microbiología , Bacterias Aerobias Gramnegativas/aislamiento & purificación , Burkholderia/aislamiento & purificación , Burkholderia/metabolismo , Burkholderia/patogenicidad , Infecciones por Burkholderia/complicaciones , Infecciones por Burkholderia/diagnóstico , Infecciones por Burkholderia/microbiología , Burkholderia cepacia/metabolismo , Burkholderia cepacia/patogenicidad , Enfermedad Crónica , Fibrosis Quística/complicaciones , Errores Diagnósticos , Fermentación , Flavobacterium/aislamiento & purificación , Flavobacterium/metabolismo , Flavobacterium/patogenicidad , Glucosa/metabolismo , Bacterias Aerobias Gramnegativas/metabolismo , Bacterias Aerobias Gramnegativas/patogenicidad , Infecciones por Bacterias Gramnegativas/complicaciones , Infecciones por Bacterias Gramnegativas/diagnóstico , Infecciones por Bacterias Gramnegativas/microbiología , Humanos , Enfermedades Pulmonares/complicaciones , Enfermedades Pulmonares/diagnóstico , Enfermedades Pulmonares/microbiología , Pseudomonas/aislamiento & purificación , Pseudomonas/metabolismo , Pseudomonas/patogenicidad , Infecciones por Pseudomonas/complicaciones , Infecciones por Pseudomonas/diagnóstico , Infecciones por Pseudomonas/microbiología , Sistema Respiratorio/microbiologíaRESUMEN
We sought to determine if commercially available susceptibility tests were accurate in detecting penicillin resistance and relative resistance in Streptococcus pneumoniae. We compared the reference MIC method with oxacillin disk screening and three commercial tests, E-test (AB Biodisk), JustOne (Radiometer America), and MicroScan Pos MIC Panel Type 6 (Baxter Diagnostics), with 80 selected clinical isolates. Thirty-three additional isolates were tested by the reference method and the E-test to further validate the latter method. Oxacillin screening was effective in detecting all penicillin-resistant and relatively resistant strains of S. pneumoniae. The MicroScan method was not effective in detecting penicillin resistance or relative resistance. The JustOne system classified only 6 (35%) of 17 resistant strains correctly, with 11 resistant strains classified as relatively resistant. The E-test correctly classified 30 (83%) of 36 resistant isolates, with 6 resistant isolates interpreted as relatively resistant. For determining penicillin MICs for S. pneumoniae, the E-test was the most accurate of the commercial systems that we studied.