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.
Article
em En
| WPRIM
| ID: wpr-34960
Biblioteca responsável:
WPRO
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.
Palavras-chave
Texto completo:
1
Base de dados:
WPRIM
Assunto principal:
Kit de Reagentes para Diagnóstico
/
Saponinas
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Espectrometria de Massas por Ionização e Dessorção a Laser Assistida por Matriz
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Bactérias Gram-Negativas
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Bactérias Gram-Positivas
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Cloreto de Amônio
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Anti-Infecciosos
Tipo de estudo:
Diagnostic_studies
Limite:
Adult
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Child
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Humans
Idioma:
En
Revista:
Annals of Laboratory Medicine
Ano de publicação:
2016
Tipo de documento:
Article