A two-hour antibiotic susceptibility test by ATP-bioluminescence / Antibiograma en dos horas mediante la medición de ATP por bioluminiscencia

The antibiotic susceptibility test (AST) in Clinical Microbiology laboratories is still time-consuming, and most procedures take 24 h to yield results. In this study, a rapid antimicrobial susceptibility test using ATP-bioluminescence has been developed. The design of method was performed using five ATCC collection strains of known susceptibility. This procedure was then validated against standard commercial methods on 10 strains of enterococci, 10 staphylococci, 10 non-fermenting gram negative bacilli, and 13 Enterobacteriaceae from patients. The agreement obtained in the sensitivity between the ATP-bioluminescence method and commercial methods (E-test, MicroScan and VITEK2) was 100%. In summary, the preliminary results obtained in this work show that the ATP-bioluminescence method could provide a fast and reliable AST in two hours

La mayoría de procedimientos diagnósticos para el estudio de la sensibilidad de las bacterias a los antibióticos en Microbiología Clínica requieren unas 24 horas para la obtención de resultados. En este estudio se propone una metodología para llevar a cabo un antibiograma rápido mediante la medición de ATP por bioluminiscencia. El diseño del antibiograma se realizó mediante el uso de cinco cepas de colección ATCC, las cuales presentan una sensibilidad conocida. Este diseño fue posteriormente validado frente a los métodos comerciales de antibiograma mediante el procesamiento de 10 cepas de enterococos, 10 de estafilococos, 10 de bacilos gramnegativos no fermentadores y 13 de Enterobacteriaceae aisladas de pacientes. El acuerdo obtenido entre la sensibilidad obtenida mediante bioluminiscencia y la obtenida mediante los métodos comerciales (E-test, MicroScan and VITEK2) fue del 100%. Por lo tanto, los resultados preliminares obtenidos en este trabajo indican que las medidas de ATP mediante bioluminiscencia podrían proporcionar, en dos horas, un antibiograma rápido y seguro

Evaluación del analizador de orinas Sysmex UF-1000i como método de cribado en el diagnóstico de la infección del tracto urinario / Evaluation of urine analyzer Sysmex UF-1000i as a screening method in the diagnosis of urinary tract infection

Introducción. Las muestras de orina son las más frecuentemente procesadas en los laboratorios de microbiología clínica. Teniendo en cuenta que del 60 al 80% de las muestras proporcionan resultados negativos, es recomendable realizar un cribado de las orinas para disminuir los gastos y la carga de trabajo, y adelantar los resultados negativos. El objetivo del trabajo fue evaluar el rendimiento del recuento de leucocitos y de bacterias en el analizador Sysmex UF-1000i para discriminar qué muestras debían ser procesadas para el cultivo convencional. Material y métodos. Mediante el procesamiento de una muestra representativa de la población de 922 muestras de orina, se calcularon, mediante curvas ROC, los puntos de corte óptimos de recuento bacteriano y de recuento de leucocitos con la finalidad de obtener la mejor sensibilidad para la mayor especificidad y, utilizando estos valores, se calcularon las características operacionales del cribado. Los cálculos estadísticos fueron realizados mediante los programas Analyze-it v.2.11 para Microsoft Excel y SPSS v.20.0. Resultados. La mejor sensibilidad para la mayor especificidad se obtuvo con los puntos de corte de 247.850 bacterias/ml o 31.800 leucocitos/ml. Utilizando estos puntos de corte, se obtuvo una sensibilidad del 90,6% (IC 95%: 86,7-94,6), una especificidad del 66,3% (IC 95%: 62,9-69,9), un valor predictivo de la prueba positiva del 47,8% (43,0%-52,1%) y un valor predictivo de la prueba negativa del 95,4% (IC 95%: 93,4-97,4). Conclusión. El Sysmex UF-1000i muestra unas características operacionales adecuadas para su incorporación en los laboratorios de microbiología clínica (AU)

Introduction. Urine samples are those most commonly processed in clinical microbiology laboratories. Given that around 60-80% of samples are negative, a screening urine samples is recommended for reducing costs of and technical staff workload, and for anticipating negative results. The aim of the work was to evaluate the Sysmex UF-1000i performance obtained from bacterial counts and leukocyte counts in order to discriminate samples must be cultured. Material and methods. By processing a representative sample of the population of 922 urines samples, an optimization of the screening was performed through calculating the optimal thresholds of the equipment through ROC curves in order to obtain the best sensitivity for the best specificity. Using these values, the operational characteristics of the screening were calculated. Statistical calculations were performed using the softwares Analyze-it v.2.11 for Microsoft Excel and SPSS v.20.0. Results. The best sensitivity for the best specificity was obtained with the cut-offs 247,850 bacteria/mL and 31,800 leukocytes/mL. By using these cutoffs, a 90,6% sensitivity (95% CI: 86.7-94.6), 66.3% specificity (95% CI: 62.9-69.9), 47.8% positive predictive value (95% CI: 43.0-52.1) and 95.4% negative predictive value (95% CI: 93.4-97.4) were obtained. Conclusion. The Sysmex UF-1000i shows suitable operational characteristics for its incorporation into clinical microbiology laboratories (AU)

A two-hour antibiotic susceptibility test by ATP-bioluminescence.

The antibiotic susceptibility test (AST) in Clinical Microbiology laboratories is still time-consuming, and most procedures take 24h to yield results. In this study, a rapid antimicrobial susceptibility test using ATP-bioluminescence has been developed. The design of method was performed using five ATCC collection strains of known susceptibility. This procedure was then validated against standard commercial methods on 10 strains of enterococci, 10 staphylococci, 10 non-fermenting gram negative bacilli, and 13 Enterobacteriaceae from patients. The agreement obtained in the sensitivity between the ATP-bioluminescence method and commercial methods (E-test, MicroScan and VITEK2) was 100%. In summary, the preliminary results obtained in this work show that the ATP-bioluminescence method could provide a fast and reliable AST in two hours.

A two-hour procedure for determining the susceptibility of enterococci and staphylococci to antibiotics by a colourimetric method.

INTRODUCTION: Rapid determination of the antibiotic susceptibility test in bacteria remains a challenge for Clinical Microbiology laboratories. METHODS: An improvement in the colorimetric antimicrobial susceptibility testing performed with resazurin in enterococci and staphylococci has been carried out. The design of method was performed using two collection strains, which have a known susceptibility. This procedure was then validated against standard commercial methods on 15 strains of staphylococci and 15 strains of enterococci from patients. RESULTS: The essential agreement between the colorimetric method and commercial methods (E-test, MicroScan and VITEK2) was 100%. CONCLUSION: Resazurin allows us to obtain a reliable antibiotic susceptibility test in staphylococci and enterococci in less than two hours.

A two-hour procedure for determining the susceptibility of enterococci and staphylococci to antibiotics by a colourimetric method / Un procedimiento de dos horas para determinar la sensibilidad de estaficolococos y enterococos a los antibióticos en dos horas mediante un método colorimétrico

Introduction. Rapid determination of the antibiotic susceptibility test in bacteria remains a challenge for Clinical Microbiology laboratories. Methods. An improvement in the colorimetric antimicrobial susceptibility testing performed with resazurin in enterococci and staphylococci has been carried out. The design of method was performed using two collection strains, which have a known susceptibility. This procedure was then validated against standard commercial methods on 15 strains of staphylococci and 15 strains of enterococci from patients. Results. The essential agreement between the colorimetric method and commercial methods (E-test, MicroScan and VITEK2) was 100%. Conclusion. Resazurin allows us to obtain a reliable antibiotic susceptibility test in staphylococci and enterococci in less than two hours (AU)

Introducción. La realización de un antibiograma rápido sigue siendo un reto para los laboratorios de Microbiología Clínica. Métodos. Se ha realizado una mejora en el antibiograma colorimétrico realizado mediante resazurina en estafilococos y enterococos. El diseño del método se realizó mediante el uso de dos cepas de colección que presentan una sensibilidad conocida. Este procedimiento se validó posteriormente frente a los métodos comerciales mediante el procesamiento de 15 cepas de estafilococos y 15 de enterococos aisladas de pacientes. Resultados. Se ha obtenido un 100% de concordancia entre la sensibilidad obtenida mediante resazurina y la obtenida mediante los métodos comerciales (E-test, MicroScan and VITEK2). Conclusión. Mediante el uso de resazurina es posible obtener un antibiograma en estafilococos y enterococos en menos de dos horas de forma fiable (AU)

New procedure for rapid identification of microorganisms causing urinary tract infection from urine samples by mass spectrometry (MALDI-TOF)

INTRODUCTION: Matrix assisted laser desorption/ionization-time of flight (MALDI-TOF) mass spectrometry is widely established as a technique in clinical microbiology laboratories for the identification of microorganisms. Using this technique, it is also possible to obtain the identification of microorganisms from untreated urine samples. METHODS: In this study, a differential centrifugation protocol and a criterion for validation of the results in order to achieve microbial identification from untreated urine samples are proposed. Additionally, the sensitivity of the analytical procedure in monobacterial urine samples has beenevaluated. RESULTS: A 90% sensitivity (confidence interval of 81.96%-94.84%) was obtained in urine samples with bacterial counts of ≥ 1×105 CFU/ml, and it was possible to improve the percentages of direct identifications from urine samples with bacterial counts of < 1 × 105 CFU/ml. CONCLUSIÓN: It is concluded that the MALDI-TOF system is both fast and reliable in the identification of individual microorganisms from untreated urine samples with counts of ≥ 1 × 105 CFU/mll

INTRODUCCIÓN: El uso de la espectrometría de masas Matrix Assisted Laser Desorption/Ionization-Time of Flight (MALDI-TOF) es una técnica implantada en los laboratorios de Microbiología Clínica que permite llevar a cabo la identificación de microorganismos. Una de las aplicaciones de esta técnica es la identificación a partir de muestra directa de orina. MÉTODOS: En este estudio se propone un protocolo de centrifugación diferencial y un criterio de validación de los resultados para alcanzar la identificación microbiana a partir de muestra directa de orina. Adicionalmente se estudia la sensibilidad del procedimiento analítico en muestras de orina monomicrobianas. RESULTADOS: Las orinas con recuentos ≥ 1×105 UFC/ml mostraron un 90% de sensibilidad (Intervalo de Confianza de 81.96%-94.84%) y se logró mejorar los porcentajes de identificación directa a partir de orinas con recuentas bacterianos < 1×105 UFC/ml. CONCLUSIONES: La espectrometría de masas MALDI-TOF es un sistema rápido y fiable para la identificación de microorganismos a partir de orinas monomicrobianas con recuentos ≥ 1 × 105 UFC/ml

New procedure for rapid identification of microorganisms causing urinary tract infection from urine samples by mass spectrometry (MALDI-TOF).

INTRODUCTION: Matrix assisted laser desorption/ionization-time of flight (MALDI-TOF) mass spectrometry is widely established as a technique in clinical microbiology laboratories for the identification of microorganisms. Using this technique, it is also possible to obtain the identification of microorganisms from untreated urine samples. METHODS: In this study, a differential centrifugation protocol and a criterion for validation of the results in order to achieve microbial identification from untreated urine samples are proposed. Additionally, the sensitivity of the analytical procedure in monobacterial urine samples has been evaluated. RESULTS: A 90% sensitivity (confidence interval of 81.96%-94.84%) was obtained in urine samples with bacterial counts of ≥1×10(5)CFU/ml, and it was possible to improve the percentages of direct identifications from urine samples with bacterial counts of <1×10(5)CFU/ml. CONCLUSION: It is concluded that the MALDI-TOF system is both fast and reliable in the identification of individual microorganisms from untreated urine samples with counts of ≥1×10(5)CFU/ml.