Browsing by Author "O'Ryan, Miguel"

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    Antimicrobial Resistance of Helicobacter pylori Isolated From Latin American Children and Adolescents (2008–2023): A Systematic Review
    (2024) Cabrera, Camila; Torres, Joaquín; Serrano Honeyman, Carolina Andrea; Gallardo, Paulina; Orellana, Vicente; George, Sergio; O'Ryan, Miguel; Lucero, Yalda
    Background: Latin America has a high prevalence of Helicobacter pylori in children that may lead to peptic ulcer disease andeventually gastric cancer in adulthood. Successful eradication is hindered by rising antimicrobial resistance. We summarize H.pylori resistance rates in Latin American children from 2008 to 2023.Material and Methods: Systematic review following PRISMA guidelines and National Heart, Lung, and Blood Institute check-list to assess risk of bias (PROSPERO CRD42024517108) that included original cross-sectional observational studies reportingresistance to commonly used antibiotics in Latin American children and adolescents. We searched in PubMed, LILACS, andSciELO databases.Results: Of 51 studies, 45 were excluded. The quality of the six analyzed studies (297 H. pylori-positive samples) was satisfactory.Phenotypic methods (N = 3) reported higher resistance rates than genotypic studies (N = 3). Clarithromycin resistance rangedfrom 8.0% to 26.7% (6 studies; 297 samples), metronidazole from 1.9% to 40.2% (4 studies; 211 samples), amoxicillin from 0% to10.4% (3 studies; 158 samples), tetracycline resistance was not detected (3 studies; 158 samples), and levofloxacin resistance was2.8% (1 study; 36 samples).Conclusion: Scarce Latin American studies on H. pylori resistance, along with methodological heterogeneity, hinder conclusivefindings. Clarithromycin and metronidazole (first-line drugs) resistance is worrisome, likely impacting lower eradication rates.Urgent systematic surveillance or individual testing before treatment is necessary to enhance eradication.
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    Predominance of Rotavirus G8P[8] in a City in Chile, a Country Without Rotavirus Vaccination
    (2018) Lucero, Yalda; O'Ryan, Miguel; Liparoti, Giulia; Huerta, Nicole; Mamani, Nora; Ramani, Sasirekha; Lagomarcino, Anne J.; Del Canto, Felipe; Qüense, Jorge
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    Risk Factors Associated With Invasive Fungal Disease in Children With Cancer and Febrile Neutropenia A Prospective Multicenter Evaluation
    (LIPPINCOTT WILLIAMS & WILKINS, 2010) Villarroel, Milena; Aviles, Carmen L.; Silva, Pamela; Guzman, Ana M.; Poggi, Helena; Alvarez, Ana M.; Becker, Ana; O'Ryan, Miguel; Salgado, Carmen; Topelberg, Santiago; Tordecilla, Juan; Varas, Monica; Viviani, Tamara; Zubieta, Marcela; Santolaya, Maria E.
    Background: Empiric antifungal treatment has become standard of care in children with cancer and prolonged fever and febrile neutropenia (FN), with the downside that it leads to significant over treatment. We characterized epidemiologic, clinical, and laboratory features of invasive fungal disease (IFD) in children with cancer and FN with the aim to identify risk factors for IFD that can aid in better selecting children who require antifungal treatment.
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    Rotavirus genotypes in children with gastroenteritis assisted in two public hospitals from Chile: viral strains circulating in a country without a universal vaccination against rotavirus
    (SOC CHILENA INFECTOLOGIA, 2012) Lucero, Yalda; Mamani, Nora; Cortes, Hector; Pena, Alfredo; Vergara, Rodrigo; O'Ryan, Miguel
    Background: Rotavirus is the main cause of severe gastroenteritis (GE) in children. Two vaccines currently available have proven efficacy against the predominant genotypes. Rotavirus genotypes vary both geographically and/or temporally. Genotype surveillance is important to monitor trends associated or not with vaccine use. Aim: To update information on rotavirus genotypes circulating in two main cities of Chile. Methodology: Between May 2009-March 2010, children < 5y of age receiving medical care for GE in two large hospitals were recruited; none of these children had received rotavirus vaccine previously. Epidemiological information was recorded in an ad-hoc form and stool samples were collected for rotavinis detection by a commercial ELISA. Genotyping was performed by semi-nested RT-PCR. Results: A total of 296/967 samples (31%) were positive for rotavirus, with a peak in November/December mostly in children 7-24 months old (67%). G9P[8] was the predominant genotype (76%), followed for G1P[8] (6%) and G2P[4] (6%) in both cities. Conclusions: Rotavirus caused one third of GE requiring emergency room care and/or hospitalization, mostly in children within an age range susceptible to benefit from rotavirus vaccines. G9P[8], a genotype against which rotavirus vaccines have demonstrated high efficacy, was by far the most frequent rotavirus variant. Continued surveillance in Chile is crucial for providing background information on disease burden and strain diversity before the introduction of rotavirus vaccines.
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    SARS-CoV-2 Antibody Prevalence among 85,529 Healthcare Workers following the First Wave of COVID-19 in Chile
    (2021) Zuñiga, Marcela; O'Ryan, Miguel; Bertoglia, María Paz; Bravo Valenzuela, Paulina Fabiola; Lagomarcino, Anne J.; Muñoz, Sergio; Peña Alonso, Alfredo; Rodriguez, María Andrea; Vial, Pablo A.
    Background: Healthcare workers (HCWs) are at increased risk for SARS-CoV-2 infection, however not all face the same risk. We aimed to determine antibody prevalence and risk factors associated with seropositivity in the Chilean HCW community. Methods: This was a nationwide, cross-sectional study consisting of a questionnaire and COVID-19 antibody testing. All HCWs in the Chilean public health care system were invited to participate three to four months following the peak of the country's first wave. Findings: Overall SARS-Cov-2 blood antibody positivity by fingerstick or venipuncture in 85 529 HCWs was 7 · 2%, ranging from 1 · 6% to 12 · 4% between regions. SARS-Cov-2 positive PCR results were self-reported in 8 330 individuals (9 · 7%) of which 47% were seropositive. Overall 10 863 (12 · 7%) either reported prior PCR positive results and/or were seropositive. Several factors were independently associated with higher IRR for seropositivity, including working in hospital (IRR 1·484), medicine/surgery w ards (IRR 1·383), emergency room (IRR 1·266), and night shifts (IRR 1·616), as were history of contact with a confirmed case (IRR 1·462), and use of public transport (IRR 1·367). These variables remained significant when including self-reported PCR positive cases in the model. Interpretation: HCWs in the hospital were at highest risk for COVID-19, especially if working in medicine/surgery wards or emergency rooms, in night shifts, older age, exposed to confirmed cases and/or using public transport. Antibody results using lateral flow likely underestimated true infection rates by nearly 40-50%. Nevertheless, risk factors were sustained when adjusting for self-reported PCR positive cases.