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)

SAP couples Fyn to SLAM immune receptors.

SAP (SLAM-associated protein) is a small lymphocyte-specific signalling molecule that is defective or absent in patients with X-linked lymphoproliferative syndrome (XLP). Consistent with its single src homology 2 (SH2) domain architecture and unusually high affinity for SLAM (also called CD150), SAP has been suggested to function by blocking binding of SHP-2 or other SH2-containing signalling proteins to SLAM receptors. Additionally, SAP has recently been shown to be required for recruitment and activation of the Src-family kinase FynT after SLAM ligation. This signalling 'adaptor' function has been difficult to conceptualize, because unlike typical SH2-adaptor proteins, SAP contains only a single SH2 domain and lacks other recognized protein interaction domains or motifs. Here, we show that the SAP SH2 domain binds to the SH3 domain of FynT and directly couples FynT to SLAM. The crystal structure of a ternary SLAM-SAP-Fyn-SH3 complex reveals that SAP binds the FynT SH3 domain through a surface-surface interaction that does not involve canonical SH3 or SH2 binding interactions. The observed mode of binding to the Fyn-SH3 domain is expected to preclude the auto-inhibited conformation of Fyn, thereby promoting activation of the kinase after recruitment. These findings broaden our understanding of the functional repertoire of SH3 and SH2 domains.