Detección de betalactamasas, diversidad y localización genética de sus genes en bacterias aisladas de intestino de peces del Lago Chungará, Chile.
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Date
2025
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Universidad de Concepción
Abstract
La resistencia a antibióticos (RA) es una creciente problemática para la salud global, en especial la resistencia a antibióticos betalactámicos, ampliamente usados en clínica humana. El principal mecanismo de resistencia a estos compuestos es la producción de betalactamasas. Bajo el enfoque “Una Salud”, se reconoce la necesidad de estudiar la RA en diversos entornos. El Lago Chungará (4500 m.s.n.m.), hábitat de la especie invasora Onchorhynchus mykiss y los peces endémicos Orestias chungarensis y Trichomycterus chungaraensis, representa un entorno extremo único para investigar este fenómeno. Se estudió la producción de betalactamasas en cepas bacterianas aisladas del intestino de estos peces y se determinaron los niveles de resistencia a 8 antibióticos betalactámicos. Veinte cepas fueron sometidas a secuenciación de genoma completo para identificar genes codificantes de betalactamasas. Se detectó actividad de betalactamasas en más del 90% de las cepas y se identificaron 8 géneros bacterianos. Se detectaron betalactamasas de clases A, B, C y/o D. Los análisis estadísticos demostraron diferencias significativas según géneros bacterianos (p=0,000999), pero no entre especie de peces (p=0,985). Las cepas analizadas presentaron baja susceptibilidad a antibióticos betalactámicos, que podría estar asociada a la producción de betalactamasas. La diversidad de estas enzimas depende del género bacteriano y no de la especie hospedera, lo que sugiere una baja presión de selección ambiental en este ecosistema extremo.
Antibiotic resistance (AR) is an emerging global health concern, particularly resistance to betalactam antibiotics, which are widely used in human clinical settings. The primary mechanism of resistance to these compounds is the production of betalactamases. Within the One Health approach, there is a recognized need to study AR across diverse environments. Lake Chungará (4,500 m.a.s.l.), habitat of the invasive species Oncorhynchus mykiss and the endemic fishes Orestias chungarensis and Trichomycterus chungaraensis, represents a unique extreme environment to investigate this phenomenon. The study examined betalactamase production in bacterial strains isolated from the intestines of these fishes and determined resistance levels to eight betalactam antibiotics. 20 strains underwent whole-genome sequencing to identify betalactamase-encoding genes. betalactamase activity was detected in over 90% of the strains, and eight bacterial genera were identified. Betalactamases from classes A, B, C, and/or D were detected. Statistical analyses revealed significant differences among bacterial genera (p = 0.000999), but not between fish species (p = 0.985). The analyzed strains exhibited low susceptibility to betalactam antibiotics, potentially associated with betalactamase production. The diversity of these enzymes was dependent on bacterial genus rather than host species, suggesting a low environmental selection pressure in this extreme ecosystem.
Antibiotic resistance (AR) is an emerging global health concern, particularly resistance to betalactam antibiotics, which are widely used in human clinical settings. The primary mechanism of resistance to these compounds is the production of betalactamases. Within the One Health approach, there is a recognized need to study AR across diverse environments. Lake Chungará (4,500 m.a.s.l.), habitat of the invasive species Oncorhynchus mykiss and the endemic fishes Orestias chungarensis and Trichomycterus chungaraensis, represents a unique extreme environment to investigate this phenomenon. The study examined betalactamase production in bacterial strains isolated from the intestines of these fishes and determined resistance levels to eight betalactam antibiotics. 20 strains underwent whole-genome sequencing to identify betalactamase-encoding genes. betalactamase activity was detected in over 90% of the strains, and eight bacterial genera were identified. Betalactamases from classes A, B, C, and/or D were detected. Statistical analyses revealed significant differences among bacterial genera (p = 0.000999), but not between fish species (p = 0.985). The analyzed strains exhibited low susceptibility to betalactam antibiotics, potentially associated with betalactamase production. The diversity of these enzymes was dependent on bacterial genus rather than host species, suggesting a low environmental selection pressure in this extreme ecosystem.
Description
Tesis presentada para optar al grado de Magíster en Ciencias, mención en Microbiología.
Keywords
Beta-Lactamasas, Genética bacteriana, Peces Investigaciones