Browsing by Author "Legarraga, Paulette"
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Item A prospective, multi-center study of Candida bloodstream infections in Chile(2019) Santolaya, Maria E.; Thompson, Luis; Tapia, Cecilia; Legarraga, Paulette; Cortés, Claudia; Rabello, Marcela; Valenzuela, Romina; Rojas, Pamela; Rabagliati, RicardoBackground Active surveillance is necessary for improving the management and outcome of patients with candidemia. The aim of this study was to describe epidemiologic and clinical features of candidemia in children and adults in tertiary level hospitals in Chile. Methods We conducted a prospective, multicenter, laboratory-based survey study of candidemia in 26 tertiary care hospitals in Chile, from January 2013 to October 2017. Results A total of 780 episodes of candidemia were included, with a median incidence of 0.47/1,000 admissions. Demographic, clinical and microbiological information of 384 cases of candidemia, from 18 hospitals (7,416 beds), was included in this report. One hundred and thirty-four episodes (35%) occurred in pediatric patients and 250 (65%) in adult population. Candida albicans (39%), Candida parapsilosis (30%) and Candida glabrata (10%) were the leading species, with a significant difference in the distribution of species between ages. The use of central venous catheter and antibiotics were the most frequent risk factors in all age groups (> 70%). Three hundred and fifteen strains were studied for antifungal susceptibility; 21 strains (6.6%) were resistant to fluconazole, itraconazole, voriconazole, anidulafungin or micafungin. The most commonly used antifungal therapies were fluconazole (39%) and echinocandins (36%). The overall 30-day survival was 74.2%, significantly higher in infants (82%) and children (86%) compared with neonates (72%), adults (71%) and elderly (70%). Conclusions Our prospective, multicenter surveillance study showed a low incidence of candidemia in Chile, with high 30-day survival, a large proportion of elderly patients, C. glabrata as the third most commonly identified strain, a 6.6% resistance to antifungal agents and a frequent use of echinocandins.Publication 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, ThomasCampylobacter 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.Publication Chromosome-Mediated Colistin Resistance in Clinical Isolates of Klebsiella pneumoniae and Escherichia coli: Mutation Analysis in the Light of Genetic Background(2023) Riquelme, María; Martinez, Rodrigo; Brito, Bárbara; García, Patricia; Legarraga, Paulette; Wozniak, AnielaPurpose: Colistin resistance mechanisms involving mutations in chromosomal genes associated with LPS modification are not completely understood. Mutations in genes coding for the MgrB regulator frequently account for colistin resistance in Klebsiella pneumoniae, whereas mutations in genes coding for PhoPQ and PmrAB are frequent in E. coli. Our aim was to perform a genetic analysis of chromosomal mutations in colistin-resistant (MIC ≥4 µg/mL) clinical isolates of K. pneumoniae (n = 8) and E. coli (n = 7) of different STs. Methods: Isolates were obtained in a 3-year period in a university hospital in Santiago, Chile. Susceptibility to colistin, aminoglycosides, cephalosporins, carbapenems and ciprofloxacin was determined through broth microdilution. Whole genome sequencing was performed for all isolates and chromosomal gene sequences were compared with sequences of colistin-susceptible isolates of the same sequence types. Results: None of the isolates carried mcr genes. Most of the isolates were susceptible to all the antibiotics analyzed. E. coli isolates were ST69, ST127, ST59, ST131 and ST14, and K. pneumoniae isolates were ST454, ST45, ST6293, ST380 and ST25. All the isolates had mutations in chromosomal genes analyzed. K. pneumoniae had mutations mainly in mgrB gene, whereas E. coli had mutations in pmrA, pmrB and pmrE genes. Most of the amino acid changes in LPS-modifying enzymes of colistin-resistant isolates were found in colistin-susceptible isolates of the same and/or different ST. Eleven of them were found only in colistin-resistant isolates. Conclusion: Colistin resistance mechanisms depend on genetic background, and are due to chromosomal mutations, which implies a lower risk of transmission than plasmid-mediated genes. Colistin resistance is not associated with multidrug-resistance, nor to high-risk sequence types.Item 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, LorenaCorrespondenceItem 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, ThomasObjectives: 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.Item 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, ThomasBackground 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.Item 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, Mirentxu; Vial, Macarena; Spencer-Sandino, Maria; Gaete, Pablo; Peters, Anne; Delgado, Iris; Perez, Inia; Calderón, Claudia; Porte, Lorena; Legarraga, Paulette; Anderson, Alicia; Aguilera, Ximena; Vial, Pablo; Weitzel, Thomas; Munita, JoséBackground: 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 warrantedItem SARS-CoV-2 rapid antigen detection tests(2021) Weitzel, Thomas; Pérez, Caricia; Tapia, Danixa; Legarraga, Paulette; Porte, LorenaPapers who discuss the benefits and limitations of SARS-CoV-2 antigen rapid detection tests (AgRDTs) for scaling up diagnostic capacities in different settings. As recent evaluations suggest, Ag-RDTs can reliably detect patients during the initial infective phase of COVID-19 (when patients have high viral loads). As the authors emphasise, the screening of asymptomatic individuals in low-prevalence settings is hampered by imperfect specificity. The dilemma that most detected cases represent false positives rather than true infections might require a twotier approach with molecular confirmation, affecting the practicality and acceptance of such a strategy. Here we suggest alternative strategies to optimise the use of AgRDTs in asymptomatic populations with low positivity likelihood.