Evaluation of a mass spectrometry and Vitek 2 combined protocol for rapid identification and susceptibility testing of Enterobacterales directly from positive blood cultures / Evaluación de la combinación de espectrometría de masas y el sistema Vitek 2 para la identificación rápida y el estudio de sensibilidad de Enterobacterales directamente desde frascos de hemocultivo positivos

OBJECTIVE: The aim was to evaluate a rapid method which would combine identification and susceptibility testing directly from positive blood cultures for Gram-negative bacilli of the Enterobacterales. MATERIAL AND METHODS: Gram-negative rods from blood cultures were directly identified by MALDI-TOF. Samples with Enterobacterales were selected for direct antimicrobial susceptibility testing by Vitek 2. The results were compared to those obtained with our laboratory's standard method. RESULTS: MALDI-TOF directly from blood cultures identified correctly 83% of the samples. Enterobacterales (n = 68) were identified at gender and species level in 85% of blood cultures with a score >1.7. In general, MICs were obtained after 7 h. MICs of amoxicillin-clavulanate, amikacin and ciprofloxacin showed in almost 50% of the cases after 5 h. CONCLUSIONS: A simple procedure with low cost and reduced working time makes it possible to integrate both identification and susceptibility testing directly from blood cultures. Thus, this protocol could offer advantages when it comes to selection and cost of treatment and patients' clinical outcomes

OBJETIVO: Evaluar un método rápido de identificación y estudio de sensibilidad directamente desde hemocultivos positivos para bacilos gramnegativos del orden Enterobacterales. MATERIAL Y MÉTODOS: Los hemocultivos con bacilos gramnegativos fueron utilizados para identificación mediante MALDI-TOF, seleccionándose aquellos con Enterobacterales para estudio de sensibilidad con Vitek 2. Los resultados fueron comparados con el método estándar del laboratorio. RESULTADOS: MALDI-TOF identificó correctamente el 83% de las muestras obtenidas directamente de hemocultivos. En caso de Enterobacterales (n = 68), el 85% se identificaron a nivel de género y especie con un score > 1,7. El tiempo necesario para la obtención de CMIs fue de 7 horas, reduciéndose a 5 en amoxicilina-clavulánico, amicacina y ciprofloxacino, casi en el 50% de los casos. CONCLUSIONES: Un protocolo simplificado, con bajo coste y reducido tiempo de trabajo, combinando identificación y estudio de sensibilidad directamente desde hemocultivos, podría proporcionar beneficios en la elección y coste del tratamiento, y mejora clínica del paciente

Evaluation of a mass spectrometry and Vitek 2 combined protocol for rapid identification and susceptibility testing of Enterobacterales directly from positive blood cultures.

OBJECTIVE: The aim was to evaluate a rapid method which would combine identification and susceptibility testing directly from positive blood cultures for Gram-negative bacilli of the Enterobacterales. MATERIAL AND METHODS: Gram-negative rods from blood cultures were directly identified by MALDI-TOF. Samples with Enterobacterales were selected for direct antimicrobial susceptibility testing by Vitek 2. The results were compared to those obtained with our laboratory's standard method. RESULTS: MALDI-TOF directly from blood cultures identified correctly 83% of the samples. Enterobacterales (n=68) were identified at gender and species level in 85% of blood cultures with a score >1.7. In general, MICs were obtained after 7h. MICs of amoxicillin-clavulanate, amikacin and ciprofloxacin showed in almost 50% of the cases after 5h. CONCLUSIONS: A simple procedure with low cost and reduced working time makes it possible to integrate both identification and susceptibility testing directly from blood cultures. Thus, this protocol could offer advantages when it comes to selection and cost of treatment and patients' clinical outcomes.