Browsing by Author "García Cañete, Patricia Del Carmen"

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    A comparative study of two different methods for the detection of latent tuberculosis in HIV-positive individuals in Chile
    (Elsevier Ltd, 2008) Balcells Marty, María Elvira; Pérez Cortes, Carlos Miguel; Chanqueo Cornejo, Leonardo Andrés; Lasso Barreto, Martin Francisco; Villanueva, Marcela; Espinoza Concha, Mónica Ximena; Villarroel Del Pino, Luis Antonio; García Cañete, Patricia Del Carmen
    Objective: To compare the performance of two tests for diagnosing latent tuberculosis (TB) infection in the HIV-positive population in Chile, in order to better identify the subjects who might benefit from TB chemoprophylaxis. Design: This was a cross-sectional study among individuals attending three HIV outpatient clinics in Santiago, tested with a 2-TU purified protein derivative, QuantiFERON ® -TB Gold ‘in-tube’ (QFT-G), and a chest X-ray. Results: A total of 116 subjects were enrolled in the study, having a mean CD4 count of 393 cells/μl (range 100–977). The tuberculin skin text (TST; 5 mm cutoff) and QFT-G results were positive in 10.9% and 14.8% of the individuals, respectively, with moderate agreement between both tests (kappa = 0.59). A history of both known TB exposure (odds ratio (OR) 3.46, 95% confidence interval (CI) 1.02–11.22) and past TB (OR 4.31, 95% CI 1.13–15.5) were associated with a positive QFT-G result. Only past TB was significantly associated with a positive TST result (OR 6.63, 95% CI 1.62–26.3). Among the subjects with TST < 5 mm, 8.2% were positive by QFT-G test. These individuals had a lower mean CD4 cell count than those detected positive by both tests (328 cells/μl and 560 cells/μl, respectively, p = 0.03). Conclusions: In this population of HIV-infected individuals, QFT-G and TST showed an acceptable level of agreement, although QFT-G appears less affected by more advanced immunosuppression.
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    Endemic Scrub Typhus-like Illness, Chile
    (Centers for Disease Control an Prevention, 2011) Balcells Marty, María Elvira; Rabagliati Borie, Ricardo Miguel; García Cañete, Patricia Del Carmen; Poggi Mayorga, Helena Loreto; Oddo Benavides, Carlos David; Concha Rogazy, Marcela Andrea; Abarca Villaseca, Katia; Jiang, Ju; Kelly, Daryl J.; Richards, Allen L.; Fuerst, Paul A.
    We report a case of scrub typhus in a 54-year-old man who was bitten by several terrestrial leeches during a trip to Chiloe Island in southern Chile in 2006. A molecular sample, identified as related to Orientia tsutsugamushi based on the sequence of the 16S rRNA gene, was obtained from a biopsy specimen of the eschar on the patient's leg. Serologic analysis showed immunoglobulin G conversion against O. tsutsugamushi whole cell antigen. This case and its associated molecular analyses suggest that an Orientia-like agent is present in the Western Hemisphere that can produce scrub typhus-like illness. The molecular analysis suggests that the infectious agent is closely related, although not identical, to members of the Orientia sp. from Asia.
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    Evaluation of concordance of new QuantiFERON-TB Gold Plus platforms for Mycobacterium tuberculosis infection diagnosis in a prospective cohort of household contacts
    (2024) Ruiz-Tagle Seguel, Cinthya Grace; García Cañete, Patricia Del Carmen; Hernández, Mariluz; Balcells Marty, María Elvira
    Interferon-gamma (IFN-γ) release assays play a pivotal role in tuberculosis infection (TBI) diagnosis, with QuantiFERON-TB Gold Plus—an enzyme-linked immunosorbent assay (ELISA)—among the most widely utilized. Newer QuantiFERON-TB platforms with shorter turnaround times were recently released. We aimed to evaluate these platforms’ agreement in the diagnosis of TBI. Blood samples from a prospective cohort of tuberculosis household contacts were collected at baseline and after 12 weeks of follow-up, and tested with LIAISON, an automated chemiluminescence immunoassay (CLIA) system, QIAreach, a lateral flow (QFT-LF) semi-automated immunoassay, and the ELISA QuantiFERON-TB Gold Plus platform. Test concordances were analyzed. ELISA vs CLIA overall agreement was 83.3% for all tested samples (120/144) [Cohen’s kappa coefficient (κ): 0.66 (95% CI: 0.54–0.77)]. Samples positive with CLIA provided consistently higher IFN-γ levels than with ELISA (P < 0.001). Twenty-four (16.7%) discordant pairs were obtained, all CLIA-positive/ELISA-negative: 15 (62.5%) had CLIA IFN-γ levels within borderline values (0.35–0.99 IU/mL) and 9 (37.5%) >0.99 IU/mL. QFT-LF showed only 76.4% (68/89) overall agreement with ELISA [κ: 0.53 (95% CI: 0.37–0.68)] with 21 (23.6%) discordant results obtained, all QFT-LF-positive/ELISA-negative. Overall concordance between ELISA and CLIA platforms was substantial, and only moderate between ELISA and QFT-LF. The CLIA platform yielded higher IFN-γ levels than ELISA, leading to an almost 17% higher positivity rate. The techniques do not seem interchangeable, and validation against other gold standards, such as microbiologically-confirmed tuberculosis disease, is required to determine whether these cases represent true new infections or whether CLIA necessitates a higher cutoff.
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    Perfil clínico y epidemiológico de los casos de tuberculosis atendidos en una red de salud universitaria en Santiago de Chile entre los años 2000-2010
    (2012) Morgado Ahumada, Álvaro Esteban; Köhnenkampf, Ruth; Balcells Marty, María Elvira; Navarrete, Pablo; García Cañete, Patricia Del Carmen
    Background: The incidence and epidemiological profile of tuberculosis (TB) has changed significantly in the recent years in Chile. Aim: To evaluate the clinical and epidemiological characteristics of TB cases diagnosed in the last decade at a university hospital in Santiago. Material and Methods: The Mycobacterium tuberculosis culture registry of the microbiology laboratory was reviewed. Medical records of patients with a positive culture registered between 2000 and 2010 were retrieved and analyzed. Results: Two hundred forty positive Mycobacterium tuberculosis cultures were identified and the medical records of 158 of these patients were accessed for analysis. The median age was 53 years (range: 3 to 89), 55.1% were female and nearly 42% had extra-pulmonary TB. Among known risk factors, 32.9% of patients were older than 65 years, 4.4% were health care workers and 3.9% immigrants. Twenty eight percent (41/145) had some type of immunosuppression at diagnosis: 11.7% HIV infection and 16.6% were using immunosuppressive drugs. In this group, a previous tuberculin skin test was done in only 5 cases (12.2%). Adverse events related to TB treatment were reported in 21.3% of cases (17/80). No cases of fulminant hepatitis or death from this cause were identified. Four of 92 patients that had a complete follow up during treatment, died. Two of these patients were receiving steroids. Conclusions: Almost one third of TB cases occurred among immunosuppressed patients and 42% were extra-pulmonary forms. The prevention of TB reactivation in this group should be strengthened.
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    Window Prophylaxis for Mycobacterium tuberculosis Infection Prevention in Child and Adolescent Household Contacts: Study Protocol for a Cluster-Randomized Controlled Trial (the TB-WIN trial)
    (2025) Le Corre Pérez, Monique Nicole; Allel, Kasim; Hernández, Mariluz; Escobar, Nadia; Ruiz-tagle Seguel, Cinthya Grace; Valenzuela, Pablo; Bernales Silva, Margarita María; García Cañete, Patricia Del Carmen; Paredes Peñaloza, Fabio Ariel; Nathavitharana, Ruvandhi; Bronzic, Yasna; Bustamante, María Cecilia; Barra, Sofia De la; Kreft, Javiera; Madrid, Ricardo; Madrid, Rossana; Méndez, Mireya; Mery, Álvaro; Meyer, Matías; Oviedo, Valeria; Pérez, María Eugenia; Pérez de Arce, Juan; Ramírez, Ana María; Rivas, Mabel; Rojas, Gladys; Balcells Marty, María Elvira
    Abstract Trials guidance: The Abstract should not exceed 350 words. Please minimize the use of abbreviations and do not cite references in the abstract. The abstract must include the following separate sections: Background : Mycobacterium tuberculosis acquisition after exposure is common but difficult to diagnose and frequently requires serial testing given that immunological evidence of infection can take several weeks to develop. Even though tuberculosis infection (TBI) is asymptomatic, its long-term effects remain unclear due to poorly understood host-pathogen interactions and delayed disease development, and research has shown that active mycobacterial replication and inflammation occur during TBI. Although the main purpose of antituberculosis prophylaxis has been to prevent people with established TBI from progressing to active tuberculosis disease, a few studies have suggested that this prophylaxis, when administered during the window period after exposure, can prevent the acquisition of TBI in very young children. Considering that newer preventive regimens are shorter and safer, this study aims to assess whether tuberculosis prophylaxis —when given in the window period after exposure— can prevent new infections in older children and adolescents who have been recently exposed. Methods : A multicentre cluster-randomized controlled clinical trial will be performed in Chile. A total of 360 households (clusters) with children aged ≥5 to <18 years, who have been recently exposed to a new case of pulmonary tuberculosis will be randomized to intervention or control arm. In the intervention arm, contacts will receive immediate tuberculosis prophylaxis, regardless of the interferon-gamma release assay (IGRA) result. In the control arm, participants will receive tuberculosis prophylaxis only if the IGRA test results positive, as per standard of care. In both arms, the prophylaxis scheme will be the usual weekly isoniazid plus rifapentine for 12 weeks regimen. The primary outcome will be assessed at the individual level by IGRA conversions from negative at baseline to positive at the 12-week follow-up. Discussion : This trial will establish the effectiveness of a window prophylaxis strategy in reducing the risk of TBI acquisition after exposure in a community setting, a strategy that can potentially contribute to global tuberculosis elimination by reducing M. tuberculosis reservoirs. Trial registration : ClinicalTrials.gov, NCT07086820. Registered 17 July 2025, https://clinicaltrials.gov/study/NCT07086820.