Browsing by Author "Vollrath, Valeska"

Now showing 1 - 7 of 7
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    Campylobacter spp. Prevalence in Santiago, Chile: A Study Based on Molecular Detection in Clinical Stool Samples from 2014 to 2019
    (2023) Porte, Lorena; Pérez, Caricia; Barbé, Mario; Varela, Carmen; Vollrath, Valeska; Legarraga, Paulette; Weitzel, Thomas
    Campylobacter spp. is an emerging cause of infectious diarrhea worldwide. In South American countries such as Chile, its prevalence is underestimated due to inadequate detection methods. Gastrointestinal multiplex PCR panels (GMP) permit rapid and sensitive detection of bacterial pathogens and provide important epidemiological information. This study aimed to analyze Campylobacter epidemiology using the results of molecular methods and to compare molecular detection results to those of culture methods. We performed a retrospective, descriptive analysis of Campylobacter spp. detected in clinical stool samples between 2014-2019 by GMP and culture. Within 16,582 specimens examined by GMP, Campylobacter was the most prevalent enteropathogenic bacteria (8.5%), followed by Salmonella spp. (3.9%), Shigella spp./enteroinvasive Escherichia coli (EIEC) (1.9%), and Yersinia enterocolitica (0.8%). The highest Campylobacter prevalence occurred in 2014/2015. Campylobacteriosis affected more males (57.2%) and adults from 19-65 years (47.9%) and showed a bimodal seasonality with summer and winter peaks. In 11,251 routine stool cultures, Campylobacter spp. was detected in 4.6%, mostly C. jejuni (89.6%). Among 4533 samples tested by GMP and culture in parallel, GMP showed a superior sensitivity (99.1% versus 50%, respectively). The study suggests that Campylobacter spp. is the most frequent bacterial enteropathogen in Chile.
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    Comparative evaluation of four rapid SARS-CoV-2 antigen detection tests using universal transport medium
    (2021) Weitzel, Thomas; Legarraga, Paulette; Iruretagoyena, Mirentxu; Pizarro, Gabriel; Vollrath, Valeska; Araos, Rafael; Munita, José; Porte, Lorena
    Correspondence
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    Effects of an Avocado-based Mediterranean Diet on Serum Lipids for Secondary Prevention after Ischemic Stroke Trial (ADD-SPISE)
    (2021) Olavarría, Verónica; Campodónico, Paola; Vollrath, Valeska; Von Geldern, Paula; Velásquez, Carolina; Pávez, Patricia; Valente, Bárbara; Donoso, Pamela; Ginesta, Alexandra; Cavada, Gabriel; Mazzon, Enrico; Navia, Víctor; Guzmán, Matías; Brinck, Pablo; Lavados, Pablo
    Background: A poor or unhealthy diet is responsible for an important fraction of ischemic stroke risk. Adherence to dietary patterns, such as the Mediterranean diet, rich in monounsaturated fatty acids mainly from olive oil, is associated with a lower stroke risk. Furthermore, lowering low-density cholesterol (LDL-C) levels decreases stroke recurrence. Interestingly, Avocado-substituted diets, which are also rich in monounsaturated fatty acids, significantly decrease LDL cholesterol levels. This study aims to evaluate whether a Mediterranean diet based on Avocados reduces LDL-C compared to a low-fat high-complex carbohydrate diet after 3 months of the intervention in patients who had a recent acute ischemic stroke. The trial will also assess safety and feasibility. Patients and methods: Prospective, randomized open-label, blinded outcome assessment clinical trial. Participants are patients within a month of being admitted with an ischemic stroke, who consent and fulfil the eligibility criteria. Patients are randomly assigned to either diet intervention in a 1:1 ratio on top of the usual secondary prevention treatment. The intervention diet is: A)Avocado-based Mediterranean diet with intake of 1/2 portion of Avocado per day and B)The control diet is a low-fat high-complex carbohydrate diet. The main efficacy outcome is a reduction in plasma LDL-C levels at 3 months of the dietary intervention. Secondary outcomes include changes in the levels of serum lipid profile and serum inflammation markers, safety, and feasibility. A sample size of 200 patients was estimated to provide 80% power and 5% level of significance (10% loss and 5% crossover) to detect a minimum difference of 4.6 mg/dL in LDL-C after 3 months of intervention. Conclusion: We hypothesize that an Avocado-based Mediterranean diet will further reduce the levels of LDL-cholesterol at 3 months compared to the control diet, and that the intervention is safe and feasible.
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    Enteric multiplex PCR panels: A new diagnostic tool for amoebic liver abscess?
    (Elsevier, 2017) Weitzel, Thomas; Cabrera, J; Rosas, R; Noriega, L.M.; Schiappacasse, Giancarlo; Vollrath, Valeska; Porte, Lorena
    Invasive amoebiasis is a life-threatening infection requiring immediate detection and treatment. However, diagnosis is challenging because conventional methods such as light microscopy and serology are unreliable. Molecular techniques are therefore considered the new diagnostic reference standard, but most of the developed assays are research tools and not widely available. Recently commercial multiplex PCR panels have been introduced which permit the simultaneous detection of multiple enteric pathogens including Entamoeba histolytica in stool samples. Our report demonstrates for the first time that these new assays might also serve as a rapid tool to diagnose amoebic liver abscess in patients with cystic focal liver lesions.
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    Evaluation of a novel antigen-based rapid detection test for the diagnosis of SARS-CoV-2 in respiratory samples
    (2020) Porte, Lorena; Legarraga, Paulette; Vollrath, Valeska; Aguilera, Ximena; Munita, José; Araos, Rafael; Pizarro, Gabriel; Vial, Pablo; Iruretagoyena, Mirentxu; Dittrich, Sabine; Weitzel, Thomas
    Objectives: In the context of the coronavirus disease 2019 (COVID-19) pandemic, the development and validation of rapid and easy-to-perform diagnostic methods are of high priority. This study was performed to evaluate a novel rapid antigen detection test (RDT) for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in respiratory samples. Methods: The fluorescence immunochromatographic SARS-CoV-2 antigen test (Bioeasy Biotechnology Co., Shenzhen, China) was evaluated using universal transport medium with nasopharyngeal (NP) and oropharyngeal (OP) swabs from suspected COVID-19 cases. Diagnostic accuracy was determined in comparison to SARS-CoV-2 real-time (RT)-PCR. Results: A total of 127 samples were included; 82 were RT-PCR-positive. The median patient age was 38 years, 53.5% were male, and 93.7% were from the first week after symptom onset. Overall sensitivity and specificity were 93.9% (95% confidence interval 86.5-97.4%) and 100% (95% confidence interval 92.1-100%), respectively, with a diagnostic accuracy of 96.1% and Kappa coefficient of 0.9. Sensitivity was significantly higher in samples with high viral loads. Conclusions: The RDT evaluated in this study showed a high sensitivity and specificity in samples mainly obtained during the first week of symptoms and with high viral loads, despite the use of a non-validated sample material. The assay has the potential to become an important tool for early diagnosis of SARS-CoV-2, particularly in situations with limited access to molecular methods.
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    Evaluation of two fluorescence immunoassays for the rapid detection of SARS-CoV-2 antigen-new tool to detect infective COVID-19 patients
    (2021) Porte, Lorena; Legarraga, Paulette; Iruretagoyena, Mirentxu; Vollrath, Valeska; Pizarro, Gabriel; Munita, José; Araos, Rafael; Weitzel, Thomas
    Background Real-Time Reverse-Transcription Polymerase Chain Reaction (RT-PCR) is currently the only recommended diagnostic method for SARS-CoV-2. However, rapid immunoassays for SARS-CoV-2 antigen could significantly reduce the COVID-19 burden currently weighing on laboratories around the world. Methods We evaluated the performance of two rapid fluorescence immunoassays (FIAs), SOFIA SARS Antigen FIA (Quidel Corporation, San Diego, CA, USA) and STANDARD F COVID-19 Ag FIA (SD Biosensor Inc., Gyeonggi-do, Republic of Korea), which use an automated reader. The study used 64 RT-PCR characterized clinical samples (32 positive; 32 negative), which consisted of nasopharyngeal swabs in universal transport medium. Results Of the 32 positive specimens, all from patients within 5 days of symptom onset, the Quidel and SD Biosensor assays detected 30 (93.8%) and 29 (90.6%) samples, respectively. Among the 27 samples with high viral loads (Ct ≤ 25), the two tests had a sensitivity of 100%. Specificity was 96.9% for both kits. Conclusion The high performance of the evaluated FIAs indicates a potential use as rapid and PCR-independent tools for COVID-19 diagnosis in early stages of infection. The excellent sensitivity to detect cases with viral loads above ~106 copies/mL (Ct values ≤ 25), the estimated threshold of contagiousness, suggests that the assays might serve to rapidly identify infective individuals.
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    Modelo computacional interactivo, semi-automatizado y de código abierto aplicado a la vigilancia de virus respiratorios
    (2020) Reyes, Felipe; Ferrés, Marcela; Vial, Pablo; Vollrath, Valeska; Camponovo, Rossanna; Montecinos, Luisa; Hirsch, Tamara; Valenzuela, Patricia; Perret, Cecilia
    Las infecciones respiratorias agudas (IRA) causadas por virus son una importante causa de morbilidad y mortalidad en el mundo, afectando principalmente a niños y adultos mayores. Se asocian a un alto número de consultas y hospitalizaciones, a una significativa sobrecarga del sistema de salud y a un alto costo económico. La vigilancia de virus respiratorios tiene el potencial de ayudar a optimizar la respuesta sanitaria, garantizar la disponibilidad de recursos humanos, racionalizar los recursos y disminuir los costos asociados a la atención en salud. Con el objetivo de optimizar la recolección y visualización de los datos de nuestro actual sistema de vigilancia de virus respiratorios, se diseñó una plataforma basada en R y sus paquetes Shiny, que permite la creación de una interfase web interactiva y amigable para la recolección, análisis y publicación de los datos. Se ingresaron a esta plataforma los datos de la red de vigilancia metropolitana de virus respiratorios disponibles desde 2006. En esta plataforma, el investigador demora menos de un minuto en registrar los datos. El análisis y publicación es inmediato, llegando a cualquier usuario con un dispositivo conectado a Internet, quien puede elegir las variables a consultar. Con un costo muy bajo, en poco tiempo y utilizando el lenguaje de programación R, se logró crear un sistema simple e interactivo, disminuyendo el tiempo de carga y análisis de datos de forma considerable, posiblemente aumentando el impacto y la disponibilidad de esta vigilancia

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