Comparación de tres procedimientos para la identificación rápida de microorganismos causantes de bacteriemias. Evaluación de su eficacia y aplicabilidad en el laboratorio de microbiología / Comparison of three procedures for the rapid identification of bacteraemia-causing microorganisms. Evaluation of their effectiveness and applicability to microbiology laboratories

RESUMEN

INTRODUCCIÓN: Evaluamos tres procedimientos de identificación rápida de microorganismos a partir de hemocultivos positivos. MÉTODOS: Aplicamos dos métodos basados en la extracción directa desde el frasco de hemocultivo Sepsityper(R) (Bruker Daltonics) (ST) y un método casero con saponina (MCS), y un tercer método basado en un subcultivo con incubación corta (SIC). Se comparan las identificaciones por espectrometría de masas Matrix-Assisted Laser Desorption Ionization-Time of Flight (EM-MALDI-TOF) aplicando los criterios de interpretación del fabricante y los puntos de corte corregidos (PCC). RESULTADOS: Aplicando los criterios del fabricante se identificaron a nivel de especie el 65,8%, el 45,8% y el 57,4% con ST, MCS y SIC, respectivamente. Aplicando los PCC, estos resultados fueron del 92,3%, del 80,6%, y del 85,2%, respectivamente. La identificación con ST fue significativamente mejor que el MCS. ST y SIC no mostraron diferencias significativas, excepto en levaduras. CONCLUSIONES: ST y SIC obtienen buenas tasas de identificación y pueden integrarse fácilmente en cualquier laboratorio

ABSTRACT

INTRODUCTION: Three procedures for rapid identification of microorganisms in positive blood cultures were evaluated. METHODS: We performed two methods based on direct extraction from a blood culture Sepsityper(R) (Bruker Daltonics) (ST) and a non-commercial saponin method (MCS), and another method consisting of a short incubation subculture (SIC). Identification values obtained by spectrometry Matrix-Assisted Laser Desorption Ionization-Time of Flight (EM MALDI-TOF) were compared by applying the manufacturer's interpretation criteria and corrected cut-off points. RESULTS: According to the manufacturer, 65.8%, 45.8% and 57.4% of microorganisms were identified at the species level by using ST, MCS and SIC, respectively. When applying corrected cut-off points, the values increased to 92.3%, 80.6% and 85.2%, respectively. ST offered significantly better results than MCS, and no significant differences were found between ST and SIC, except for with respect to yeast. Conclusions: Better identification rates were obtained by using ST and SIC, which are easily applicable in any laboratory