Browsing by Author "Ferrés, Marcela "

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    An Open One-Step RT-qPCR for SARS-CoV-2 detection
    (Public Library Science, 2024) Cerda Rojas, Ariel Patricio; Rivera, Maira; Armijo, Grace; Ibarra-Henríquez, Catalina; Reyes, Javiera; Blázquez Sánchez, Paula; Avilés, Javiera; Arce, Anibal; Seguel, Aldo; Brown, Alexander J.; Vásquez, Yesseny; Cortez-San Martín, Marcelo; Cubillos, Francisco A.; García, Patricia; Ferrés, Marcela; Ramírez Sarmiento, César Antonio; Federici, Fernan; Gutiérrez, Rodrigo A.
    The COVID-19 pandemic has resulted in millions of deaths globally, and while several diagnostic systems were proposed, real-time reverse transcription polymerase chain reaction (RT-PCR) remains the gold standard. However, diagnostic reagents, including enzymes used in RT-PCR, are subject to centralized production models and intellectual property restrictions, which present a challenge for less developed countries. With the aim of generating a standardized One-Step open RT-qPCR protocol to detect SARS-CoV-2 RNA in clinical samples, we purified and tested recombinant enzymes and a non-proprietary buffer. The protocol utilized M-MLV RT and Taq DNA pol enzymes to perform a Taqman probe-based assay. Synthetic RNA samples were used to validate the One-Step RT-qPCR components, demonstrating sensitivity comparable to a commercial kit routinely employed in clinical settings for patient diagnosis. Further evaluation on 40 clinical samples (20 positive and 20 negative) confirmed its comparable diagnostic accuracy. This study represents a proof of concept for an open approach to developing diagnostic kits for viral infections and diseases, which could provide a cost-effective and accessible solution for less developed countries.
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    Andes viral RNA load in chilean patients with Hantavirus Cardiopulmonary Syndrome
    (2008) Pablo, Vial A.; Mertz, G. J.; Ferrés, Marcela; Galeno, H.; Belmar, E.; Aldunate, R.; Castillo, C.; Noriega, L. M.; Tapia, M.; Donoso, S.; Ortega, C.; Navarro, E.; Arriagada, J. J.; Scholtz, L. A.; Ferrer, Pablo; Godoy, P.; Ibanez, R.; Hjelle, B.
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    Búsqueda de mutaciones en el gen UL 97 asociadas a resistencia a ganciclovir en citomegalovirus obtenidos desde muestras biológicas de pacientes chilenos
    (2010) Oyarzún Andrade, María Angélica; Bustos, Patricia; González Agüero, Marcela Margot; Domínguez Moreno, María Isabel; Aguayo González, Francisco Renan; Nervi Nattero, Bruno; Ferrés, Marcela
    Background: Long term use of ganciclovir (GCV) is associated with acquired resistance to it. Ninety percent of the responsible mutations occur in cytomegalovirus (CMV) UL97 gene. Aim: To search for these mutations, comparing nucleotide sequences of CMV-positive samples from post transplant and immunocompromised patients receiving GCV, with sequences of CMV isolates obtained from subjects not exposed to the drug. Patients and Methods: Codons 440 to 465 of gene UL97, including the most common mutations causing resistance to GCV, were amplified in 33 plasma samples from patients exposed to GCV and in 15 urine samples of newborns. Both populations and their nucleotide sequences were compared with the prototype strain CMV AD169. Results: Samples of exposed patients had multiple mutations but only one had a mutation associated with clinical resistance (M4601). Eight subjects had the D605E mutation, whose role in resistance is controversial. The remaining 150 mutations were silent mutations. Conclusions: A low frequency of mutations associated with CMV resistance to GCV was found in these exposed and unexposed samples. These mutations may reflect coexistence of multiple genetic variants of CMV. The absence of clinical expression of resistance, even with these mutations, can be explained by the use of GCV for a shorter lapse than that associated with the appearance of resistance. (Rev Med Chile 2010; 138: 421-427).
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    Correlation between female sex, IL28B genotype, and the clinical severity of bronchiolitis in pediatric patients
    (2020) Astudillo, P.; Angulo, J.; Pino, K.; de Carvalho, J. B.; de Morais, G. L.; Perez, S.; de Vasconcelos, A. T. R.; Ferrés, Marcela; López Lastra, Marcelo Andrés
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    Detección del SARS-CoV-2 mediante RT-qPCR utilizando saliva en pacientes ambulatorios con estudio de COVID-19
    (2022) Perret Pérez, Cecilia; Abarca Villaseca, Katia; Solari Gajardo, Sandra; Aguilera, Pablo; García-Huidobro Munita, Diego Nicolas; Olivares, Felipe; Palma, Carlos; Contreras, Ana María; Martínez Valdebenito, Constanza Pamela; Ferrés, Marcela
    La pandemia de COVID-19 ha afectado a millones de personas en todo el mundo. La identificación de sujetos infectados ha sido importante para el control. Objetivo: Evaluar el rendimiento deuna reacción de polimerasa en cadena (RPC) cuantitativa en tiempo real (en inglés: RT-qPCR) para SARS-CoV-2, utilizando saliva como matriz en comparación con un hisopado nasofaríngeo (HNF). Metodología: Se reclutaron adultos en atención ambulatoria, la mayoría sintomáticos. Fueron estudiadas 530 muestras pareadas de saliva e HNF con RT-qPCR. Resultados: Fueron positivas 59 muestras de HNF y 54 de saliva. La sensibilidad con saliva fue 91%, especificidad 100%, el valor predictor positivo (VPP) 100%, valor predictor negativo (VPN) 98%. El índice Kappa fue de 0,95 y LR-0,08. En promedio, el umbral de ciclo (en inglés cycle threshold-CT) de la saliva fue 3,99 puntos más alto que los de HNF (p < 0,0001) mostrando que la carga viral (CV) es menor en saliva. La carga viral en ambas disminuyó con el tiempo después del inicio de los síntomas. El muestreo de saliva fue preferido por los sujetos en lugar de HNF. Conclusión: Este estudio demuestra que la RPC para SARS-CoV-2 utilizando saliva, es adecuada para el diagnóstico de COVID-19 en adultos ambulatorios,especialmente en la etapa temprana de los síntomas.
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    Early Anti-SARS-CoV-2 Convalescent Plasma in Patients Admitted for COVID-19: A Randomized Phase II Clinical Trial
    (2020) Balcells, María Elvira ; Rojas, Luis ; Le Corre, Nicole ; Martínez-Valdebenito, Constanza ; Ceballos, María Elena ; Ferrés, Marcela ; Chang, Mayling ; Vizcaya, Cecilia ; Mondaca, Sebastián ; Huete, Álvaro ; Castro, Ricardo ; Sarmiento, Mauricio ; Villarroel, Luis ; Pizarro, Alejandra; Ross, Patricio ; Santander, Jaime ; Lara, Barbara ; Ferrada, Marcela ; Vargas-Salas, Sergio ; Beltrán-Pavez, Carolina ; Soto-Rifo, Ricardo ; Valiente-Echeverría, Fernando ; Caglevic, Christian ; Mahave, Mauricio ; Selman, Carolina ; Gazitúa, Raimundo ; Briones, José Luis ; Villarroel-Espindola, Franz ; Balmaceda, Carlos ; Espinoza, Manuel A. ; Pereira, Jaime ; Nervi, Bruno
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    H1N1 pandemic influenza impact on hand hygiene and specific precautions compliance among healthcare workers
    (W B SAUNDERS CO LTD, 2011) Labarca L., Jaime; Zambrano González, Alejandra; Niklitschek, Sergio; Ferrés, Marcela; Pérez, Carlos; Rabagliati, Ricardo; Ajenjo Henríquez, María Cristina
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    Hantavirus in humans: a review of clinical aspects and management
    (2023) Vial Clavo, Pablo Agustín; Ferrés, Marcela; Vial, Cecilia; Klingstrom, Jonás; Ahlm, Clas; López, René; Le Corre Pérez, Monique Nicole; Mertz J., Gregory
    Hantavirus infections are part of the broad group of viral haemorrhagic fevers. They are also recognised as a distinct model of an emergent zoonotic infection with a global distribution. Many factors influence their epidemiology and transmission, such as climate, environment, social development, ecology of rodent hosts, and human behaviour in endemic regions. Transmission to humans occurs by exposure to infected rodents in endemic areas; however, Andes hantavirus is unique in that it can be transmitted from person to person. As hantaviruses target endothelial cells, they can affect diverse organ systems; increased vascular permeability is central to pathogenesis. The main clinical syndromes associated with hantaviruses are haemorrhagic fever with renal syndrome (HFRS), which is endemic in Europe and Asia, and hantavirus cardiopulmonary syndrome (HCPS), which is endemic in the Americas. HCPS and HFRS are separate clinical entities, but they share several features and have many overlapping symptoms, signs, and pathogenic alterations. For HCPS in particular, clinical outcomes are highly associated with early clinical suspicion, access to rapid diagnostic testing or algorithms for presumptive diagnosis, and prompt transfer to a facility with critical care units. No specific effective antiviral treatment is available.
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    Historia natural de la infección por virus de inmunodeficiencia humano en una cohorte de pacientes chilenos
    (1996) Vial Claro, Pablo Agustín; Ferreccio Readi, Catterina; Abarca Villaseca, Katia; Ortiz Neira, Marisol Edith; Noriega Ricalde, Miguel Luis; Pérez Cortés, Carlos; Labarca L., Jaime; Torres H. M.; Ferrés, Marcela; González Wiedmaier, Claudia; Acuña L., Guillermo
    We characterized clinical manifestations and the risk to develop AIDS in a cohort of 32 patients infected with human immunodeficiency virus without AIDS. A multivariate analysis was performed to determine association between the progression of infection and control variables (socioeconomic level, age, sex and sexual preferences) and causal variables (psycho-social changes, significant clinical events, stress scoring and sexual activity). The cumulative AIDS incidence, defined as a CD4 lymphocyte count below 200 cells/cm3 was 50% at 6.5 years and 82% at 8 years. Using clinical criteria to define AIDS, 50% developed the disease at 8 years of follow up. Among studied factors, only age (faster progression at higher age) and time of evolution were associated with progression. In stages before AIDS, the most frequent diseases were acute diarrhea, sexual transmission diseases, oral candidiasis, sinusitis and varicella zoster infections. The reduction of CD4 lymphocytes below 200 cells/cm3 always preceded the symptoms of the disease. Two patients have remained more than eight years without clinical or immunological deterioration.
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    Influenza pandémica A (H1N1) 2009: epidemiología, características clínicas y diferencias con influenza estacional en Chile
    (Sociedad Chilena de Infectología, 2011) Rabagliati Borie, Ricardo Miguel; Siri Zunino, Leonardo; Pérez Cortés, Carlos Miguel; Labarca L., Jaime; Ferrés, Marcela
    La pandemia de inluenza A (H1N1) 2009 generó preguntas sobre sus diferencias con influenza estacional. Objetivos: Describir las características de influenza pandémica y comparar con influenza estacional. Pacientes y Métodos: Estudio descriptivo de casos confirmados de influenza pandémica en adultos internados en el Hospital Clínico de la Pontificia Universidad Católica entre mayo y julio de 2009, comparado con 95 casos históricos de influenza estacional. Resultados: 54 pacientes con influenza pandémica, 51,9% género masculino, edad 52,8 ± 19,5 años; 79,6% presentaban co-morbilidades; 16,7% inmunocomprometidos, 7,4% mujeres embarazadas, 25,9% de adquisición nosocomial, 31,5% requirió cuidados intensivos/intermedios. Se diagnosticó neumonía en 37% y la mortalidad global fue 3,7%. En la comparación con inluenza estacional, la pandémica afectó menos pacientes > de 65 años (31,5 vs 68%, p < 0,0001), dobló los casos con adquisición nosocomial y hubo más casos de neumonía y muertes. Conclusiones: La infección por inluenza pandémica afectó a un grupo de menor edad y generó mayor transmisión nosocomial, neumonía y muerte que la inluenza estacional.
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    Microbiome disturbance and resilience dynamics of the upper respiratory tract during influenza A virus infection
    (2020) Kau, Drishti; Rathnasinghe, Raveen Shevantha; Ferrés, Marcela; Tan, Gene S.; Barrera Vásquez, Aldo Vincent; Pickett, Brett E.; Methe, Barbara A.; Das, Suman; Budnik Ojeda, Isolda Cecilia; Halpin, Rebecca A.; Wentworth, David; Schmolke, Mirco; Mena, Ignacio; Albrecht, Randy A.; Singh, Indresh; Nelson, Karen E.; Garcia Sastre, Adolfo; Dupont, Chris L.; Medina, Rafael
    Infection with influenza can be aggravated by bacterial co-infections, which often results in disease exacerbation. The effects of influenza infection on the upper respiratory tract (URT) microbiome are largely unknown. Here, we report a longitudinal study to assess the temporal dynamics of the URT microbiomes of uninfected and influenza virus-infected humans and ferrets. Uninfected human patients and ferret URT microbiomes have stable healthy ecostate communities both within and between individuals. In contrast, infected patients and ferrets exhibit large changes in bacterial community composition over time and between individuals. The unhealthy ecostates of infected individuals progress towards the healthy ecostate, coinciding with viral clearance and recovery. Pseudomonadales associate statistically with the disturbed microbiomes of infected individuals. The dynamic and resilient microbiome during influenza virus infection in multiple hosts provides a compelling rationale for the maintenance of the microbiome homeostasis as a potential therapeutic target to prevent IAV associated bacterial co-infections. Influenza A virus (IAV) infection can be exacerbated by bacterial co-infections but the effect of IAV on the upper respiratory tract (URT) microbiome remains unclear. Here, the authors compare the dynamics of the UTR microbiome in IAV-infected ferrets and humans, finding similar trends at the ecosystem and individual taxon level in both hosts.
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    Modelo computacional interactivo, semi-automatizado y de código abierto aplicado a la vigilancia de virus respiratorios
    (Sociedad Chilena de Infectología, 2020) Reyes Zaldivar, Felipe Tomás; Ferrés, Marcela; Vial, Pablo; Vollrath Reyes, Valeska; Camponovo, Rossanna; Montecinos, Luisa; Hirsch Birn, Tamara; Valenzuela Contreras, Patricia; Perret Pérez, 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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    Mother-to-child transmission of Andes virus through breast milk, Chile
    (2020) Ferrés, Marcela; Martínez Valdebenito, Constanza; Angulo, J.; Henríquez, C.; Vera Otarola, Jorge Andrés; Vergara, M. J.; Vial Cox, María Cecilia; Vial Claro, Pablo; Pérez, J.; Le Corre Pérez, Monique Nicole; Fernández, J.; Sotomayor, V.; Valdés, M. F.; González-Candia, D.; Tischler, N. D.; Mertz, G.
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    Pandemic (H1N1) 2009 Reinfection, Chile
    (CENTERS DISEASE CONTROL & PREVENTION, 2010) Pérez, Carlos; Ferrés, Marcela; Labarca L., Jaime
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    Parte I. Requerimientos básicos de infectología para hospitales que atienden pacientes hemato-oncológicos: ambiente hospitalario, protocolos diagnósticos y arsenal terapéutico. Fundamentación
    (Sociedad Chilena de Infectología, 2019) Rabagliati Borie, Ricardo Miguel; Santolaya, María Elena; Ferrés, Marcela; Rabello, Marcela; Catalán, Paula
    La atención de pacientes con cáncer, incluyendo los receptores de trasplantes de precursores hematopoyéticos, plantea numerosos desafíos para los hospitales que deben proveer ambientes seguros, en que se logre aminorar al máximo posible la exposición a patógenos que generan morbilidad y mortalidad. Al mismo tiempo deben contar con protocolos establecidos que permitan realizar un estudio racional de las posibles etiologías infecciosas que pueden presentar estos pacientes. A su vez, deben asegurar la existencia de un arsenal terapéutico adecuado, junto a algoritmos de tratamiento oportuno, actualizado según guías consensuadas y efectivo según la infección sospechada o confirmada. En este artículo se introducen algunos de los argumentos que sustentan estos requerimientos que luego se desarrollan en tres artículos sucesivos dedicados al ambiente hospitalario, protocolos diagnósticos y arsenal terapéutico.
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    Reconocimiento de influenza-A como etiología de síndrome febril e insuficiencia respiratoria en adultos hospitalizados durante brote en la comunidad
    (2004) Rabagliati Borie, Ricardo Miguel; Benítez Gómez, Rosana; Fernández Montenegro, María Alicia; Gaete Gutiérrez, Pablo Antonio; Guzmán Durán, Ana María; García Cañete, Patricia; Ferrés, Marcela; Pérez Cortés, Carlos Miguel; Labarca L., Jaime
    Background: Influenza-A (IA) occurs every winter, is mostly observed among outpatients. Aim: To describe the clinical and epidemiological characteristics of cases that required hospital admission during an outbreak in Chile in 1999. Patients and methods: Adults subjects, with Influenza A confirmed by antigen detection test, hospitalized in the clinical hospital of the «Hospital Clínico de la Universidad Católica de Chile» between May and June, with fever or respiratory symptoms were studied. A special record was designed to register clinical, microbiological and therapeutic data. Results: Fifty five cases, 26 males, aged 15 to 91 years, were studied. Eighty four percent had chronic concomitant diseases and 9.1% were immunosuppressed. Clinical findings were fever in 87.3%, asthenia in 83.6%, cough in 93.6%, abnormal pulmonary signs in 69%, an elevated C-reactive protein (mean value of 11.6 ± 7.1 mg/dL) and acute respiratory insufficiency in 54.5%. Cases were isolated in cohort or individual rooms and 38.2% were admitted to intensive or intermediate care units. Amantadine was prescribed to 52 patients and was well tolerated. Thirty three percent of cases developed pneumonia. These subjects were older, had more dyspnea and respiratory insufficiency than patients without pneumonia. Conclusions: IA should be borne in mind when dealing with hospitalized adults, during epidemic outbreaks in the community. The clinical picture can resemble a serious bacterial infection. An early diagnosis allows the use of specific treatments, to decrease the risk of nosocomial spread and to avoid unnecessary use of antibiotics.
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    SARS-CoV-2 vaccine booster in solid organ transplant recipients previously immunised with inactivated versus mRNA vaccines: A prospective cohort study
    (2022) Dib Marambio, Martín Javier; Le Corre Pérez, Monique Nicole; Ortiz Koh, Catalina Alejandra; García, Daniel; Ferrés, Marcela; Martínez Valdebenito, Constanza; Ruiz-Tagle, Cinthya; Ojeda Valenzuela, María José; Espinoza Sepúlveda, Manuel Antonio; Jara Contreras, Aquiles; Arab Verdugo, Juan Pablo; Rabagliati B., Ricardo; Vizcaya Altamirano, Cecilia; Ceballos, María Elena; Sarmiento Maldonado, Mauricio; Mondaca Contreras, Sebastián Patricio; Viñuela Morales, Macarena Rocío; Pastore Thomson, Antonia; Szwarcfiter Neiman, Vania; Galdames Lavín, Elizabeth Alejandra; Barrera Vásquez, Aldo Vincent; Castro Gálvez, Pablo Federico; Gálvez Arriagada, Nicolás Marcelo Salvador; Soto Ramírez, Jorge Andrés; Bueno Ramírez, Susan; Kalergis Parra, Alexis Mikes; Nervi Nattero, Bruno; Balcells Marty, María Elvira
    Solid-organ transplant (SOT) recipients have worse COVID-19 outcomes than general population and effective immunisation in these patients is essential but more difficult to reach. We aimed to determine the immunogenicity of an mRNA SARS-CoV-2 vaccine booster in SOT recipients previously immunised with either inactivated or homologous SARS-CoV-2 mRNA vaccine. Methods: Prospective cohort study of SOT recipients under medical care at Red de Salud UC-CHRISTUS, Chile, previously vaccinated with either CoronaVac or BNT162b2. All participants received a BNT162b2 vaccine booster. The primary study end point was anti-SARS-CoV-2 total IgG antibodies (TAb) seropositivity at 8-12 weeks (56-84 days) post booster. Secondary end points included neutralising antibodies (NAb) and specific T-cell responses. Findings: A total of 140 (50% kidney, 38% liver, 6% heart) SOT recipients (mean age 54 [13.6] years; 64 [46%] women) were included. Of them, 62 had homologous (three doses of BNT162b2) and 78 heterologous vaccine schedules (two doses of CoronaVac followed by BNT162b2 booster). Boosters were received at a median of 21.3 weeks after primary vaccination. The proportion achieving TAb seropositivity (82.3% vs 65.4%, P = 0.035) and NAb positivity (77.4% vs 55.1%, P = 0.007) were higher for the homologous versus the heterologous group. On the other hand, the number of IFN-γ and IL-2 secreting SARS-CoV-2-specific T-cells did not differ significantly between groups. Interpretation: This cohort study shows that homologous mRNA vaccine priming plus boosting in SOT recipients, reaches a significantly higher humoral immune response than inactivated SARS-CoV-2 vaccine priming followed by heterologous mRNA booster.
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    Symptom Profiles and Risk Factors for Hospitalization in Patients With SARS-CoV-2 and COVID-19 : A Large Cohort From South America
    (2020) Díaz Piga, Luis Antonio; García-Salum, T.; Fuentes López, Eduardo; Ferrés, Marcela; Medina, Rafael; Riquelme Pérez, Arnoldo
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    The humoral immune response during the acute and convalescent phase of hantavirus infection in children
    (2006) Vigil, J. R.; Ferrés, Marcela; Nofchissey, R. A.; Pierce, A. A.; Goade, D. E.