LEGARRAGA RADDATZ, PAULETTE
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LEGARRAGA RADDATZ, PAULETTE
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plegarraga@udd.cl
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36898830800

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Chromosome-Mediated Colistin Resistance in Clinical Isolates of Klebsiella pneumoniae and Escherichia coli: Mutation Analysis in the Light of Genetic Background

2023 , María Paz Riquelme , Jose Rodrigo W Martínez , Bárbara Brito , Patricia García , Paulette Legarraga , Aniela Wozniak

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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 TORRE, LORENA ISABEL , LEGARRAGA RADDATZ, PAULETTE , Sabine Dittrich , Valeska Vollrath , AGUILERA SANHUEZA, XIMENA PAZ , MUNITA SEPULVEDA, JOSE MANUEL , ARAOS BRALIC, RAFAEL IGNACIO , Gabriel Pizarro , VIAL CLARO, PABLO AGUSTIN , IRURETAGOYENA BRUCE, MIRENTXU INES , WEITZEL, THOMAS

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SARS-CoV-2 rapid antigen detection tests

2021 , WEITZEL, THOMAS , Caricia Pérez , Danixa Tapia , LEGARRAGA RADDATZ, PAULETTE , PORTE TORRE, LORENA ISABEL

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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 TORRE, LORENA ISABEL , LEGARRAGA RADDATZ, PAULETTE , IRURETAGOYENA BRUCE, MIRENTXU INES , Valeska Vollrath , Gabriel Pizarro , MUNITA SEPULVEDA, JOSE MANUEL , ARAOS BRALIC, RAFAEL IGNACIO , 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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Longitudinal assessment of SARS-CoV-2 IgG seroconversionamong front-line healthcare workers during the first wave of the Covid-19 pandemic at a tertiary-care hospital in Chile

2021 , IRURETAGOYENA BRUCE, MIRENTXU INES , Macarena R. Vial , Maria Spencer-Sandino , Pablo Gaete , Anne Peters , DELGADO BECERRA, OROZIMBA IRIS , Inia Perez , Claudia Calderon , PORTE TORRE, LORENA ISABEL , Alicia Anderson , MUNITA SEPULVEDA, JOSE MANUEL , LEGARRAGA RADDATZ, PAULETTE , AGUILERA SANHUEZA, XIMENA PAZ , VIAL CLARO, PABLO AGUSTIN , WEITZEL, THOMAS

Abstract Background Healthcare workers (HCWs) are at high risk of exposure to SARS-CoV-2. Cross-sectional studies have provided variable rates of seroprevalence in HCWs. Longitudinal assessments of the serological response to Covid-19 among HCWs are crucial to understanding the risk of infection and changes in antibody titers over time. We aimed to investigate seroprevalence and risk factors associated with seroconversion in a prospective cohort of HCWs during the peak of the first wave of the Covid-19 pandemic. Methods We conducted a longitudinal study among 446 front-line HCWsin a tertiary-care hospital in Chile from April to July 2020. IgG was determined monthly using two different ELISAs in serum samples of HCWs, during the three-month period. In each visit, demographic data, symptoms, risk factors, and exposure risks were also assessed. Results The overall seroprevalence at the end of the study period was 24% (95% CI20.2–28.3), with 43% of seropositive HCWs reporting no prior symptoms. Seroconversion rates significantly differed over the study period, from 2.1% to as high as 8.8% at the peak of the epidemic. There were no statistically significant differences observed between HCWs in direct clinical care of patients with Covid-19 and those working in low risk areas. Antibody titers appeared to wane over time. Conclusions HCWs were severely affected with a high rate of seroconversion that appeared to mirror the local epidemiological situation. A significant amount of participants underwent an asymptomatic infection, highlighting the need for improved surveillance policies. Antibody titers appear to wane over time; further studies to understand this finding’s impact on the risk of reinfection are warranted.

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A prospective, multi-center study of Candida bloodstream infections in Chile

2019 , Maria E. Santolaya , THOMPSON MOYA, LUIS ADALBERTO , Dona Benadof , Cecilia Tapia , Claudia Cortés , LEGARRAGA RADDATZ, PAULETTE , Marcela Rabello , Romina Valenzuela , Pamela Rojas , Ricardo Rabagliati

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Comparative evaluation of four rapid SARS-CoV-2 antigen detection tests using universal transport medium

2021 , WEITZEL, THOMAS , LEGARRAGA RADDATZ, PAULETTE , IRURETAGOYENA BRUCE, MIRENTXU INES , Gabriel Pizarro , Valeska Vollrath , ARAOS BRALIC, RAFAEL IGNACIO , MUNITA SEPULVEDA, JOSE MANUEL , PORTE TORRE, LORENA ISABEL

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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 TORRE, LORENA ISABEL , Caricia Pérez , Mario Barbé , Carmen Varela , Valeska Vollrath , LEGARRAGA RADDATZ, 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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