Validation of MALDI-TOF for the early detection of the ST175 high-risk clone of Pseudomonas aeruginosa in clinical isolates belonging to a Spanish nationwide multicenter study.

INTRODUCTION: Pseudomonas aeruginosa causes severe infections, particularly in healthcare settings and immunocompromised patients in whom MDR and XDR isolates are more prevalent. The aim of this study is to validate a method based on MALDI-TOF spectra analysis for early detection of the ST175 high-risk clone (HRC). METHODS: The MALDI-TOF spectra of the first 10 P. aeruginosa clinical isolates from each of the 51 participating Spanish hospitals were analyzed (n=506). Resistance profiles were determined by broth microdilution, and clonal epidemiology was assessed by PFGE analysis and multilocus sequence typing (MLST) in a previous study. RESULTS: Among all the isolates, 14.2% were XDR and 26.9% were non-susceptible to meropenem, while rates of resistance to ceftolozane/tazobactam (3.6%) and colistin (5.7%) were low. Up to 41.7% of all XDR isolates belonged to the ST175 clone, and most of them were only susceptible to ceftolozane/tazobactam and colistin. However, most of the resistance to ceftolozane/tazobactam among isolates belonging to this HRC was observed in carbapenemase-producing isolates. A model based on the presence of two MALDI-TOF biomarker peaks at m/z 6911 and 7359 yielded a negative predictive value (NPV) and a positive predictive value (PPV) of 99.8% and 91.9%, respectively, and sensitivity and specificity values of 97.1% and 99.4%, respectively. CONCLUSIONS: MALDI-TOF spectra analysis using a model based on the presence of two biomarker peaks proved to maintain high sensitivity and specificity for early detection of the ST175 HRC in a large collection of isolates from all Spanish regions. These data support the use of this model in a clinical setting; however, the consequences of detection of the ST175 HRC, such as choice of empirical antibiotic therapy, must be consistent with local epidemiology and the prevalence of certain resistance patterns of this HRC, such as carbapenemase production, in a given geographical area.

Validation of MALDI-TOF for the early detection of the ST175 high-risk clone of Pseudomonas aeruginosa in clinical isolates belonging to a Spanish nationwide multicenter study / Validación del MALDI-TOF para la detección precoz del clon de alto riesgo ST175 de Pseudomonas aeruginosa en aislados clínicos pertenecientes a un estudio multicéntrico nacional

Introduction: Pseudomonas aeruginosa causes severe infections, particularly in healthcare settings and immunocompromised patients in whom MDR and XDR isolates are more prevalent. The aim of this study is to validate a method based on MALDI-TOF spectra analysis for early detection of the ST175 high-risk clone (HRC). Methods: The MALDI-TOF spectra of the first 10 P. aeruginosa clinical isolates from each of the 51 participating Spanish hospitals were analyzed (n=506). Resistance profiles were determined by broth microdilution, and clonal epidemiology was assessed by PFGE analysis and multilocus sequence typing (MLST) in a previous study. Results: Among all the isolates, 14.2% were XDR and 26.9% were non-susceptible to meropenem, while rates of resistance to ceftolozane/tazobactam (3.6%) and colistin (5.7%) were low. Up to 41.7% of all XDR isolates belonged to the ST175 clone, and most of them were only susceptible to ceftolozane/tazobactam and colistin. However, most of the resistance to ceftolozane/tazobactam among isolates belonging to this HRC was observed in carbapenemase-producing isolates. A model based on the presence of two MALDI-TOF biomarker peaks at m/z 6911 and 7359 yielded a negative predictive value (NPV) and a positive predictive value (PPV) of 99.8% and 91.9%, respectively, and sensitivity and specificity values of 97.1% and 99.4%, respectively. Conclusions: MALDI-TOF spectra analysis using a model based on the presence of two biomarker peaks proved to maintain high sensitivity and specificity for early detection of the ST175 HRC in a large collection of isolates from all Spanish regions. These data support the use of this model in a clinical setting; however, the consequences of detection of the ST175 HRC, such as choice of empirical antibiotic therapy, must be consistent with local epidemiology and the prevalence of certain resistance patterns of this HRC, such as carbapenemase production, in a given geographical area.(AU)

Introducción: P. aeruginosa causa infecciones graves, particularmente asociadas a cuidados sanitarios y en pacientes inmunodeprimidos, donde los aislamientos MDR o XDR son más frecuentes. El objetivo de este estudio es validar el método basado en el análisis de espectros MALDI-TOF para la detección precoz del clon de alto riesgo ST175. Métodos: Se analizaron los espectros de MALDI-TOF de los primeros 10 aislados clínicos de P. aeruginosa pertenecientes a cada uno de los 51 hospitales españoles participantes (n=506). En un trabajo previo se determinaron los perfiles de resistencia mediante microdilución en caldo y se estableció su relación clonal mediante electroforesis en campo pulsante (PFGE) y multilocus sequence typing (MLST). Resultados: Del total de los aislamientos el 14,2% fueron XDR y el 26,9% resultaron ser no sensibles a meropenem, mientras que la resistencia al ceftolozano-tazobactam (3,6%) y la colistina (5,7%) fue baja. Hasta el 41,7% de todos los aislamientos XDR pertenecieron al clon ST175 y la mayoría de ellos solo resultaron ser sensibles a ceftolozano-tazobactam y a colistina. No obstante, la mayor parte de la resistencia a ceftolozano-tazobactam observada entre los aislados pertenecientes a este clon de alto riesgo se debió a la producción de carbapenemasas. El modelo basado en la presencia de dos picos de biomarcadores MALDI-TOF en m/z 6911 y 7359 obtuvo un valor predictivo negativo y positivo (VPN/VPP) del 99,8/91,9% y valores de sensibilidad y especificidad del 97,1/99,4%, respectivamente. Conclusiones: El análisis de los espectros de MALDI-TOF utilizando el modelo basado en la presencia de dos picos de biomarcadores ha demostrado poseer una alta sensibilidad y especificidad para la detección precoz del clon de alto riesgo ST175 en una gran colección de aislados clínicos representando todo el territorio español.(AU)

Utilidad del valor Ct en las infecciones respiratorias agudas causadas por el virus respiratorio sincitial A y B y los virus gripales A (H1N1)pdm09, A (H3N2) y B / Usefulness of Ct value in acute respiratory infections caused by respiratory syncytial virus A and B and influenza virus A (H1N1)pdm09, A (H3N2) and B

INTRODUCCIÓN: Las infecciones respiratorias agudas de causa viral son unas entidades muy frecuentes. La dificultad para valorar la detección de un determinado virus en estas entidades podría solucionarse con la determinación de la carga viral. MÉTODOS: Se ha realizado un estudio prospectivo sobre el valor medio de los Ct (cycle threshold value) detectados frente al VRS-A, VRS-B y los virus gripales A (H1N1)pdm09, A(H3N2) y B en pacientes de diferente procedencia y edad. La detección se ha realizado mediante una técnica de amplificación molecular (RT-PCR) comercial. RESULTADOS: Se han detectado valores medios de Ct distintos para cada virus. En las infecciones por VRS, no se han observado diferencias entre las causadas por el VRS-A o VRS-B en pediatría. De acuerdo con la edad de los pacientes solo se ha observado significación estadística en los incluidos en los grupos de 0-4 meses para el VRS-A y este grupo y el de 5-12 meses para el VRS-B (valores más elevados). En los pacientes adultos se ha detectado una carga viral menor que en los pediátricos. En las infecciones gripales no se ha observado significación estadística en los valores medios detectados en los pacientes procedentes de la Red Centinela, en los diagnosticados en las urgencias de adultos ni en los ingresados hospitalarios. En los pacientes adultos ingresados en la UCI solo se ha observado un valor medio algo más bajo en los infectados por el virus gripal A (H1N1)pdm09 pero sin significación estadística. No hubo ningún paciente ingresado en la UCI con infección por gripe B. CONCLUSIÓN: La detección de la carga viral podría ser una buena herramienta para la evaluación, seguimiento y pronóstico de las infecciones respiratorias agudas víricas. A excepción de las causadas por el VRS, no se han observado diferencias significativas en las infecciones gripales, salvo en los pacientes pediátricos de menor edad

INTRODUCTION: Acute respiratory infections of viral cause are very frequent entities. The difficulty in evaluating the detection of a virus in these entities could be solved by determining the viral load. METHODS: A prospective study on the mean Ct value (cycle threshold value) detected against RSV-A, RSV-B and influenza A (H1N1)pdm09, A (H3N2) and B viruses in patients of different origin and age was performed. Detection was performed using a commercial molecular amplification (RT-PCR) technique. RESULTS: Different mean Ct values were detected for each virus. In RSV infections, no differences were observed between those caused by RSV-A or RSV-B in children. Depending on the patient's age, the only statistical significance was observed in those included in the 0-4 month groups for RSV-A and this group and the 5-12 months group for RSV-B (higher values). A lower viral load was detected in adult patients than in paediatric patients. In influenza infections, no statistical significance was observed in the mean values detected in patients from the Red Centinela ("sentinel network", a Spanish network of doctors aimed at research and surveillance of diseases), those diagnosed in the adult emergency room or in hospital admissions. In the adult patients admitted to the ICU, only a slightly lower mean value was observed in those infected with influenza A (H1N1)pdm09, but without statistical significance. There were no patients admitted to the ICU with influenza B infection. CONCLUSION: The detection of viral load could be a good tool for the evaluation, monitoring and prognosis of acute viral respiratory infections. With the exception of those caused by RSV, no significant differences were observed in influenza infections except in younger paediatric patients

Usefulness of Ct value in acute respiratory infections caused by respiratory syncytial virus A and B and influenza virus A (H1N1)pdm09, A (H3N2) and B. / Utilidad del valor Ct en las infecciones respiratorias agudas causadas por el virus respiratorio sincitial A y B y los virus gripales A (H1N1)pdm09, A (H3N2) y B.

INTRODUCTION: Acute respiratory infections of viral cause are very frequent entities. The difficulty in evaluating the detection of a virus in these entities could be solved by determining the viral load. METHODS: A prospective study on the mean Ct value (cycle threshold value) detected against RSV-A, RSV-B and influenza A (H1N1)pdm09, A (H3N2) and B viruses in patients of different origin and age was performed. Detection was performed using a commercial molecular amplification (RT-PCR) technique. RESULTS: Different mean Ct values were detected for each virus. In RSV infections, no differences were observed between those caused by RSV-A or RSV-B in children. Depending on the patient's age, the only statistical significance was observed in those included in the 0-4 month groups for RSV-A and this group and the 5-12 months group for RSV-B (higher values). A lower viral load was detected in adult patients than in paediatric patients. In influenza infections, no statistical significance was observed in the mean values detected in patients from the Red Centinela («sentinel network¼, a Spanish network of doctors aimed at research and surveillance of diseases), those diagnosed in the adult emergency room or in hospital admissions. In the adult patients admitted to the ICU, only a slightly lower mean value was observed in those infected with influenza A (H1N1)pdm09, but without statistical significance. There were no patients admitted to the ICU with influenza B infection. CONCLUSION: The detection of viral load could be a good tool for the evaluation, monitoring and prognosis of acute viral respiratory infections. With the exception of those caused by RSV, no significant differences were observed in influenza infections except in younger paediatric patients.