RESUMEN
Introducción. La resistencia de Plasmodium falciparum a diferentes fármacos antipalúdicos es un obstáculo para eliminar la enfermedad. El genotipo resistente de P. falciparum a la artemisinina puede evaluarse examinando los polimorfismos en el dominio de la hélice del gen Pfk13. La Organización Mundial de la Salud recomienda utilizar estas mutaciones como marcadores moleculares para detectar la resistencia a la artemisinina en países donde la malaria por P. falciparum es endémica. Objetivo. Identificar mutaciones relacionadas con la resistencia a artemisinina presentes en el dominio de la hélice del gen k13 de P. falciparum. Materiales y métodos. Mediante la detección pasiva de casos, se recolectaron 51 muestras positivas por microscopía para Plasmodium, provenientes de seis comunidades del distrito de Río Santiago en Condorcanqui, Amazonas. Se realizó la confirmación molecular de la especie mediante PCR en tiempo real y el dominio de la hélice del gen Pfk13 se amplificó y secuenció por electroforesis capilar. Las secuencias obtenidas se compararon con la cepa de referencia 3D7 de fenotipo silvestre. Resultados. Se confirmó un total de 51 muestras positivas para P. falciparum, provenientes de las comunidades de Ayambis, Chapiza, Palometa, Muchinguis, Alianza Progreso y Caterpiza. Después del alineamiento de las secuencias de ADN, se determinó que las muestras no presentaron mutaciones asociadas con resistencia en el gen K13. Discusión. Los resultados obtenidos son coherentes con estudios similares realizados en otros países de Sudamérica, incluyendo Perú. Estos datos proporcionan una línea base para la vigilancia molecular de resistencia a artemisinina en la región Amazonas y refuerzan la eficacia de la terapia combinada con artemisinina en esta área.
Introduction. Resistance of Plasmodium falciparum to different antimalarial drugs is an obstacle to disease elimination. The artemisinin-resistant genotype of P. falciparum can be assessed by examining polymorphisms in the helix domain of the Pfk13 gene. The World Health Organization recommends these mutations as molecular markers to detect artemisinin-resistant in countries where P. falciparum malaria is endemic. Objective. To identify artemisinin resistance-related mutations present in the helix domain of the P. falciparum k13 gene. Materials and methods. We collected a total of 51 samples through passive case detection, positive for Plasmodium by microscopy, from six communities in the district of Río Santiago in Condorcanqui, Amazonas. Molecular species confirmation was performed by real-time PCR and Pfk13 helix domain was amplified and sequenced by capillary electrophoresis. The obtained sequences were compared with the wild type 3D7 reference strain. Results. A total of 51 positive samples were confirmed for P. falciparum from the communities of Ayambis, Chapiza, Palometa, Muchinguis, Alianza Progreso and Caterpiza. DNA sequences alignment showed the absence of resistance-associated mutations in the k13 gene of the collected samples. Discussion. The obtained results are consistent with similar studies conducted in other South American countries, including Perú, so these data provide a baseline for artemisinin- resistance molecular surveillance in the Amazon region and reinforce the efficacy of artemisinin-based combination therapy in this area.
Asunto(s)
Resistencia a Medicamentos , Malaria , Perú , Plasmodium falciparum , Ecosistema AmazónicoRESUMEN
BACKGROUND: Acanthamoeba spp. are the causative agents of a severe keratitis occurring mainly in contact lens wearers. The genus comprises more than 24 species that are currently divided into 20 different genotypes (T1-T20) according to sequence variations in the 18S rRNA gene. The objective of this study was to identify the genotypes and sub-genotypes of Acanthamoeba isolates collected at the Parasitology Laboratory of the Public Health Institute of Chile, the only laboratory in the country where Acanthamoeba screening is performed. This is the first report of genotypic identification of clinical isolates of Acanthamoeba in Chile and one of the few in South America. RESULTS: In this study, 114 Acanthamoeba isolates from 76 Acanthamoeba keratitis patients, obtained between 2005-2016, were genotyped. T4 was the predominant genotype; T2 and T11 genotypes, which are scarcely reported worldwide, were also identified in Chilean patients (one and two patients, respectively). This is the first report of T2 and T11 genotypes isolated from Acanthamoeba keratitis patients in South America. It is also the first report of the T2 genotype circulating in this continent. Analysis of the diagnostic fragment 3 region of the 18S rRNA gene showed 24 T4 variants, with a predominance of the sub-genotype T4/A, followed by T4/B, T4/G, T4/C and T4/D. Bayesian analysis revealed three groups among the T4 variants: two well supported groups that included 12 and 7 sub-genotypes, respectively, and a weakly supported group that included 5 sub-genotypes. Most of the predominant T4 sub-genotypes belonged to the same group, which included 71.3% of the patients, while some minority variants lied mainly in the other two clusters. CONCLUSIONS: T2, T4 and T11 genotypes were predominantly isolated from the Acanthamoeba keratitis patients in Chile. Chilean predominant T4 sub-genotypes, which have also been reported worldwide, formed a separate cluster of the minority T4 variants. This study provides useful information about the predominant genotypes and subgenotypes that would be useful in selecting suitable strains to develop immunological and/or molecular diagnostic assays in Chile.
