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Direct Identification and Antimicrobial Susceptibility Testing of Bacteria From Positive Blood Culture Bottles by Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry and the Vitek 2 System
Annals of Laboratory Medicine ; : 117-123, 2016.
Artigo em Inglês | WPRIM | ID: wpr-34960
ABSTRACT

BACKGROUND:

We evaluated the reliability and accuracy of the combined use of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) bacterial identification and Vitek 2 antimicrobial susceptibility testing (AST) for bacteria from positive blood culture bottles.

METHODS:

Direct identification and AST were performed in parallel to the standard methods in monomicrobial positive blood culture bottles. In total, 254 isolates grown on aerobic and/or anaerobic bottles were identified with MALDI-TOF Vitek MS (bioMerieux, France), and 1,978 microorganism/antimicrobial agent combinations were assessed. For isolates from anaerobic bottles, an aliquot of the culture broth was centrifuged, washed, and filtered through a nylon mesh. For isolates from aerobic/pediatric bottles, a lysis step using 9.26% ammonium chloride solution and 2% saponin solution was included.

RESULTS:

The overall correct identification rate was 81.8% (208/254) and that for gram-positive/gram-negative isolates was 73.9%/92.6%, respectively, and it was 81.8%, 87.6%, and 57.9% for isolates from aerobic, anaerobic, and pediatric bottles, respectively. Identification was not possible in 45 cases, and most of these isolates were streptococci (N=14) and coagulase-negative staphylococci (N=11). Misidentification occurred only in one case. Compared with standard methods, direct AST showed 97.9% (1,936/1,978) agreement with very major error of 0.25%, major error of 0.05%, and minor error of 1.8%.

CONCLUSIONS:

This simple and cost-effective sample preparation method gives reliable results for the direct identification and AST of bacteria. For the identification of streptococci and coagulase-negative staphylococci, the method should be further improved.
Assuntos

Texto completo: DisponíveL Índice: WPRIM (Pacífico Ocidental) Assunto principal: Kit de Reagentes para Diagnóstico / Saponinas / Espectrometria de Massas por Ionização e Dessorção a Laser Assistida por Matriz / Bactérias Gram-Negativas / Bactérias Gram-Positivas / Cloreto de Amônio / Anti-Infecciosos Tipo de estudo: Estudo diagnóstico Limite: Adulto / Criança / Humanos Idioma: Inglês Revista: Annals of Laboratory Medicine Ano de publicação: 2016 Tipo de documento: Artigo

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Texto completo: DisponíveL Índice: WPRIM (Pacífico Ocidental) Assunto principal: Kit de Reagentes para Diagnóstico / Saponinas / Espectrometria de Massas por Ionização e Dessorção a Laser Assistida por Matriz / Bactérias Gram-Negativas / Bactérias Gram-Positivas / Cloreto de Amônio / Anti-Infecciosos Tipo de estudo: Estudo diagnóstico Limite: Adulto / Criança / Humanos Idioma: Inglês Revista: Annals of Laboratory Medicine Ano de publicação: 2016 Tipo de documento: Artigo