Rapid antibiotic susceptibility testing (RAST) of blood cultures in enterobacteria with inducible chromosomal AmpC-type ß-lactamase.

INTRODUCTION: Early and adequate treatment of bloodstream infections decreases patient morbidity and mortality. The objective is to develop a preliminary method for rapid antibiotic susceptibility testing (RAST) in enterobacteria with inducible chromosomal AmpC. METHODS: RAST was performed directly on spiked blood cultures of 49 enterobacteria with inducible chromosomal AmpC. Results were read at 4, 6 and 8h of incubation. Commercial broth microdilution was considered the reference method. Disks of 10 antibiotics were evaluated. RESULTS: The proportion of readable tests at 4h was 85%. All RAST could be read at 6 and 8h. For most antibiotics, the S or R result at 4, 6 and 8h was greater than 80% after tentative breakpoints were established and Area of Technical Uncertainty was defined. CONCLUSIONS: This preliminary method seems to be of practical use, although it should be extended to adjust the breakpoints and differentiate them by species.

Rapid antibiotic susceptibility testing (RAST) of blood cultures in enterobacteria with inducible chromosomal AmpC-type B-lactamase / Pruebas rápidas de sensibilidad antibiótica de hemocultivos con enterobacterias portadoras de B-lactamasa tipo AmpC cromosómica inducible

Introduction: Early and adequate treatment of bloodstream infections decreases patient morbidity and mortality. The objective is to develop a preliminary method for rapid antibiotic susceptibility testing (RAST) in enterobacteria with inducible chromosomal AmpC. Methods: RAST was performed directly on spiked blood cultures of 49 enterobacteria with inducible chromosomal AmpC. Results were read at 4, 6 and 8h of incubation. Commercial broth microdilution was considered the reference method. Disks of 10 antibiotics were evaluated. Results: The proportion of readable tests at 4h was 85%. All RAST could be read at 6 and 8h. For most antibiotics, the S or R result at 4, 6 and 8h was greater than 80% after tentative breakpoints were established and Area of Technical Uncertainty was defined. Conclusions: This preliminary method seems to be of practical use, although it should be extended to adjust the breakpoints and differentiate them by species.(AU)

Introducción: El tratamiento precoz y adecuado de las bacteriemias disminuye la morbilidad y mortalidad de los pacientes. El objetivo es desarrollar un método preliminar de pruebas rápidas de sensibilidad antibiótica (PRSA) en enterobacterias con AmpC cromosómica inducible. Métodos: Las PRSA se realizaron directamente de hemocultivos simulados positivos para 49 enterobacterias con AmpC cromosómica inducible. Los resultados se leyeron a las 4, 6 y 8 horas de incubación. La microdilución en caldo comercial se consideró el método de referencia. Se evaluaron discos de 10 antibióticos. Resultados: La proporción de pruebas legibles a las 4 horas fue del 85%. Todas las PRSA pudieron leerse a las 6 y 8 horas. Para la mayoría de los antibióticos, el resultado S o R a las 4, 6 y 8 horas fue superior al 80%, después de que se establecieran puntos de corte provisionales y se definiera el área de incertidumbre técnica. Conclusiones: Este método preliminar parece ser de utilidad práctica, aunque debería ampliarse para ajustar los puntos de corte y diferenciar por especies.(AU)

Multicenter clinical evaluation of a novel transcription-mediated amplification assay for SARS-CoV-2 molecular testing / Evaluación clínica multicéntrica de un nuevo ensayo de amplificación mediada por transcripción para la detección molecular de SARS-CoV-2

Introduction The onset and spread of COVID-19 pandemic has forced clinical laboratories to rapidly expand testing capacity for SARS-CoV-2. This study evaluates the clinical performance of the TMA Procleix SARS-CoV-2 assay in comparison to the RT-PCR assay Allplex™ SARS-CoV-2 for the qualitative detection of SARS-CoV-2 RNA. Methods Between November 2020 and February 2021, 610 upper-respiratory specimens received for routine SARS-CoV-2 molecular testing were prospectively collected and selected at the Hospital Universitari Vall d’Hebron and the Hospital Universitari Bellvitge in Barcelona, Spain. All samples were processed in parallel with the TMA and the RT-PCR assays, and results were compared. Discrepancies were retested by an additional RT-PCR method and the clinical history of these patients was reviewed. Results Overall, the level of concordance between both assays was 92.0% (κ, 0.772). Most discordant results (36/38, 94.7%) corresponded to samples testing positive with the TMA assay and negative with the RT-PCR method. Of these discrepant cases, most (28/36, 77.8%) were finally classified as confirmed or probable SARS-CoV-2 cases according to the discrepant analysis. Conclusion In conclusion, the TMA Procleix SARS-CoV-2 assay performed well for the qualitative detection of SARS-CoV-2 RNA in a multisite clinical setting. This novel TMA assay demonstrated a greater sensitivity in comparison to RT-PCR methods for the molecular detection of SARS-CoV-2. This higher sensitivity but also the qualitative feature of this detection of SARS-CoV-2 should be considered when making testing algorithm decisions (AU)

Introducción El inicio y la expansión de la pandemia por COVID-19 han forzado a los laboratorios clínicos a ampliar rápidamente la capacidad de detección de SARS-CoV-2. Evaluamos el rendimiento clínico del ensayo de TMA Procleix SARS-CoV-2 en comparación con el ensayo de RT-PCR Allplex™ SARS-CoV-2 para la detección cualitativa de ARN de SARS-CoV-2. Métodos Entre noviembre de 2020 y febrero de 2021 se seleccionaron prospectivamente 610 muestras del tracto respiratorio superior recibidas de rutina en el Hospital Universitario Vall d’Hebron y el Hospital Universitario de Bellvitge en Barcelona, España, para el diagnóstico molecular de SARS-CoV-2. Todas las muestras fueron procesadas en paralelo con los ensayos de TMA y RT-PCR, y se compararon los resultados. Las discrepancias se estudiaron por un método adicional de RT-PCR y se revisaron las historias clínicas de los pacientes. Resultados En general, la concordancia entre ambos ensayos fue del 92,0% (κ, 0,772). La mayoría de los casos discrepantes (36/38, 94,7%) correspondían a muestras positivas con el ensayo de TMA y negativas con el método de RT-PCR. De estos, la mayoría (28/36, 77,8%) fueron finalmente clasificados como casos confirmados o probables de SARS-CoV-2 de acuerdo al análisis de discrepantes. Conclusión El ensayo de TMA Procleix SARS-CoV-2 funcionó bien para la detección cualitativa de ARN de SARS-CoV-2 en un entorno clínico multicéntrico. Este ensayo TMA demostró una mayor sensibilidad en comparación con métodos de RT-PCR para la detección molecular de SARS-CoV-2. Esta mayor sensibilidad, pero también el carácter cualitativo de esta detección de SARS-CoV-2, se deben considerar en el diagnóstico de la infección (AU)

Multicenter clinical evaluation of a novel transcription-mediated amplification assay for SARS-CoV-2 molecular testing.

INTRODUCTION: The onset and spread of COVID-19 pandemic has forced clinical laboratories to rapidly expand testing capacity for SARS-CoV-2. This study evaluates the clinical performance of the TMA Procleix SARS-CoV-2 assay in comparison to the RT-PCR assay Allplex™ SARS-CoV-2 for the qualitative detection of SARS-CoV-2 RNA. METHODS: Between November 2020 and February 2021, 610 upper-respiratory specimens received for routine SARS-CoV-2 molecular testing were prospectively collected and selected at the Hospital Universitari Vall d'Hebron and the Hospital Universitari Bellvitge in Barcelona, Spain. All samples were processed in parallel with the TMA and the RT-PCR assays, and results were compared. Discrepancies were retested by an additional RT-PCR method and the clinical history of these patients was reviewed. RESULTS: Overall, the level of concordance between both assays was 92.0% (κ, 0.772). Most discordant results (36/38, 94.7%) corresponded to samples testing positive with the TMA assay and negative with the RT-PCR method. Of these discrepant cases, most (28/36, 77.8%) were finally classified as confirmed or probable SARS-CoV-2 cases according to the discrepant analysis. CONCLUSION: In conclusion, the TMA Procleix SARS-CoV-2 assay performed well for the qualitative detection of SARS-CoV-2 RNA in a multisite clinical setting. This novel TMA assay demonstrated a greater sensitivity in comparison to RT-PCR methods for the molecular detection of SARS-CoV-2. This higher sensitivity but also the qualitative feature of this detection of SARS-CoV-2 should be considered when making testing algorithm decisions.

A simple double differential centrifugation-wash procedure to rapidly obtain bacterial identification and direct antimicrobial susceptibility testing from positive blood cultures / Método sencillo basado en una doble centrifugación diferencial para obtener una identificación bacteriana y sensibilidad a antibióticos rápida a partir de hemocultivos positivos

Introduction: This study proposes a simple and rapid method for both bacterial identification and direct antimicrobial susceptibility testing (AST) by using MALDI-TOF and a double differential centrifugation-wash procedure from positive blood cultures. Methods: Fifty-two positive blood cultures (37 gramnegative bacilli and 15 grampositive cocci) were studied by two methods for identification and AST: a reference method, and the rapid MALDI-TOF method obtaining a purified pellet by using a double differential centrifugation procedure. Results : A total of 1101 MIC values (mg/l) were interpreted according to EUCAST clinical breakpoints and compared using the two methods simultaneously. Discrepancies in 81 MIC values (7.35%) were detected. By analyzing standard parameters, we obtained 98.28% essential agreement and 92.65% categorical agreement considering all isolates tested. Conclusion: This method provides rapid bacterial identification and AST, offering definitive results 24–48h earlier than the conventional method (p<0.001) and improving the turnaround time in blood culture diagnostics, especially in laboratories without 24-h on-call.(AU)

Introducción: Este trabajo propone un método sencillo, rápido y barato de identificación bacteriana y sensibilidad antibiótica utilizando MALDI-TOF y una doble centrifugación diferencial a partir de hemocultivo positivo. Métodos: Se estudiaron 52 hemocultivos positivos (37 bacilos gramnegativos y 15 cocos grampositivos). Se compararon 2 métodos: un método convencional de identificación y determinación de sensibilidad a antibióticos automatizada partiendo de colonia crecida, y un método rápido utilizando MALDI-TOF, caracterizado por la obtención de un pellet purificado procedente de un hemocultivo positivo, mediante un procedimiento basado en una doble centrifugación diferencial. Resultados: Se analizaron y compararon 1.101 valores de CMI (mg/l) de acuerdo con los criterios establecidos por EUCAST y obtenidos por ambos métodos. Se detectaron discrepancias en 81 valores de CMI (7,35%). Considerando todos los aislados, la concordancia esencial fue del 98,28% y la concordancia categórica del 92,65%. Conclusión: Este método proporciona resultados de identificación y sensibilidad a antibióticos definitivos 24-48h antes que un método convencional (p<0,001), mejorando el tiempo de respuesta en el diagnóstico microbiológico de bacteriemias, especialmente en laboratorios sin servicio de guardias de 24h.(AU)

A simple double differential centrifugation-wash procedure to rapidly obtain bacterial identification and direct antimicrobial susceptibility testing from positive blood cultures.

INTRODUCTION: This study proposes a simple and rapid method for both bacterial identification and direct antimicrobial susceptibility testing (AST) by using MALDI-TOF and a double differential centrifugation-wash procedure from positive blood cultures. METHODS: Fifty-two positive blood cultures (37 gramnegative bacilli and 15 grampositive cocci) were studied by two methods for identification and AST: a reference method, and the rapid MALDI-TOF method obtaining a purified pellet by using a double differential centrifugation procedure. RESULTS: A total of 1101 MIC values (mg/l) were interpreted according to EUCAST clinical breakpoints and compared using the two methods simultaneously. Discrepancies in 81 MIC values (7.35%) were detected. By analyzing standard parameters, we obtained 98.28% essential agreement and 92.65% categorical agreement considering all isolates tested. CONCLUSION: This method provides rapid bacterial identification and AST, offering definitive results 24-48h earlier than the conventional method (p<0.001) and improving the turnaround time in blood culture diagnostics, especially in laboratories without 24-h on-call.

Multicenter clinical evaluation of a novel transcription-mediated amplification assay for SARS-CoV-2 molecular testing.

INTRODUCTION: The onset and spread of COVID-19 pandemic has forced clinical laboratories to rapidly expand testing capacity for SARS-CoV-2. This study evaluates the clinical performance of the TMA Procleix SARS-CoV-2 assay in comparison to the RT-PCR assay AllplexTM SARS-CoV-2 for the qualitative detection of SARS-CoV-2 RNA. METHODS: Between November 2020 and February 2021, 610 upper-respiratory specimens received for routine SARS-CoV-2 molecular testing were prospectively collected and selected at the Hospital Universitari Vall d'Hebron and the Hospital Universitari Bellvitge in Barcelona, Spain. All samples were processed in parallel with the TMA and the RT-PCR assays, and results were compared. Discrepancies were retested by an additional RT-PCR method and the clinical history of these patients was reviewed. RESULTS: Overall, the level of concordance between both assays was 92.0% (κ, 0.772). Most discordant results (36/38, 94.7%) corresponded to samples testing positive with the TMA assay and negative with the RT-PCR method. Of these discrepant cases, most (28/36, 77.8%) were finally classified as confirmed or probable SARS-CoV-2 cases according to the discrepant analysis. CONCLUSION: In conclusion, the TMA Procleix SARS-CoV-2 assay performed well for the qualitative detection of SARS-CoV-2 RNA in a multisite clinical setting. This novel TMA assay demonstrated a greater sensitivity in comparison to RT-PCR methods for the molecular detection of SARS-CoV-2. This higher sensitivity but also the qualitative feature of this detection of SARS-CoV-2 should be considered when making testing algorithm decisions.

¿Es útil la estratificación de la sensibilidad antibiótica de los patógenos urinarios en el Servicio de Urgencias? / Is stratification of antibiotic susceptibility of urinary pathogens useful in the Emergency Department?

OBJETIVO: Determinar la sensibilidad antibiótica de los patógenos causantes de infección del tracto urinario (ITU) estratificándola en función de datos clínicos y demográficos de los pacientes. MATERIAL Y MÉTODOS: Se analizó sensibilidad antibiótica de las bacterias aisladas en orina de 144 pacientes con ITU escogidos al azar y se estratificó en función del sexo, la edad, el tipo de ITU, el haber padecido o no ITU previa y del tratamiento antibiótico previo. RESULTADOS: Se analizó la sensibilidad global de todas las cepas y de las cepas de E. coli observándose diferencias significativas en función del sexo (fluoroquinolonas), la edad (cefuroxima, ertapenem, gentamicina), el tipo de ITU (cefuroxima, cefotaxima, ertapenem, fluoroquinolonas), el haber tenido ITU previa y antibioterapia previa (cefotaxima, fluoroquinolonas, fosfomicina). CONCLUSIONES: El empleo de datos clínicos y demográficos adaptados a la población y a la epidemiología local de resistencia de los uropatógenos, podría ayudar a la elección del tratamiento empírico de la ITU

OBJECTIVE: The aim of the study wat to analyze the antibiotic susceptibility of the pathogens causing urinary tract infection (UTI) and to stratify the results in function of patient's clinical and demographic dates. MATERIAL AND METHODS: The susceptibility of the pathogens isolated in the urine of 144 patients with UTI randomly chosen was analyzed. The results were stratified in function of sex, age, type of UTI, previous UTI and previous antibiotic treatment. RESULTS: The susceptibility of the all isolates and of the Escherichia coli isolates was analyzed. There were significant differences between groups in function of sex (fluoroquinolones), age (cefuroxime, ertapenem and gentamicin), type of UTI (cefuroxime, cefotaxime, ertapenem and fluoroquinolones), previous UTI and previous antibiotic treatment (cefotaxime, fluoroquinolones and fosfomycin). CONCLUSIONS: The use of clinical and demographic data according to population and local resistance epidemiology of the pathogen causing UTI may help to select an adequate empirical treatment for UTI