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Seminario Biología molecular
- 1. Valentina SánchezArbeláez Medicine Student Thirdsemester 2019-1 Universidad Pontificia Bolivariana
- 2. Large, heterogeneous group of gram negative rods natural habitat is the intestinal tract of humans and animals grow rapidly under aerobic or anaerobic conditions and are metabolically active. INTRODUCTIONENTEROBACTERIACEAE For example E. coli, is part of the normal microbiota and incidentally cause disease scherichia, Shigella, Salmonella, Enterobacter, Klebsiella, Serratia, Proteus, and others
- 3. uses a target site modification mechanism to protect bacteria from the action of colistin The presence phosphatidylethanolamine residue lowers the affinity of the lipid A to colistin and related polymyxins therefore rendering the antimicrobial inactive and making the bacteria resistant Multiresistance Is caused by mutations in bacterial chromosomal genes • Mutation in bacterial DNA replication • acquisition of new genes by DNA transfer from other bacteria or uptake of exogenous DNA. almost all the resistance-determinant genes on plasmids are present as transposons • R plasmids can encode and transfer multiresistance MCR- 1 Mobilized Colistin Resistance INTRODUCTION
- 4. mcr-1-mediated colistin resistance in bacteria is concerning, as colistin is used in treating multidrug-resistant bacterial infections. And mcr-1-producing bacteria have been multiple sources. Up to 248 million people use public transportation daily in China, however; public transportation hasn’t been studied as a potential source of community- transmission of mcr-1. Herein we investigated mcr-1- isolates from public transportation and explored the characteristics of them. OBJECTIVE
- 5. MATERIALES Y METODOS • Recolección de muestras en Guangzhou • Desde octubre de 2016 hasta abril de 2017 • Se evitó el tiempo de limpieza de rutina 8 52 PFGE Electroforesis de campo pulsado ¿Para qué? identificar polimorfismos genéticos en una población en este caso las enterobacterias Fundamento permite la separación de fragmentos de DNA de alto peso molecular empleando campos electricos multiples
- 6. MATERIALES Y METODOS MIC Concentración inhibitoria mínima Fundamento Uso de dilucion de agar de varias concentraciones e incubación anaerobica permiten reconocer la concentracion baja de antimicrobiano, capaz de inhibir el crecimiento de un aislado ¿Para qué? Reconocer la mínima concentración de antibiótico que en un período de tiempo predeterminado, es capaz de inhibir el crecimiento in vitro de un inóculo bacteriano previamente estandarizado
- 7. MATERIALES Y METODOS PCR reacción en cadena de la polimerasa ¿Para qué ? Amplifica millones de veces una secuencia especifica de ADN o ARN durante varios ciclos por medio de reacción enzimática in-vitro Fundamento Mediante el uso de una DNA polimerasa que tiene la capacidad de sintetizar naturalmente el DNA de las celulas
- 8. MATERIALES Y MÉTODOS Secuenciación del genoma completo ¿Para qué? para determinar qué segmentos de ADN contienen genes, mutaciones o que segmentos transportan instrucciones regulatorias, que activan o desactivan otros genes. Fundamento fragmentar el ADN para determinar el orden de las cuatro bases de nucleotidos y nuevamente volver a ensamblar en una secuencia consenso
- 9. RESULTADOS
- 10. RESULTADOS A
- 11. RESULTADOS B
- 12. RESULTADOS
- 13. DISCUSSION AUTHOR CONCEPT Falagas ME, et al Fosfomycin has generated renewed interest as a treatment option for multidrug-re- sistant gram-negative infections, including infections with produc- ers of ESBL Duriez P, et al Human commensal E. coli strains, however, are mostly grouped into the phylogroups A and B1 Poirel L , et al Wang Y, et al E. coli ST101 has been previously previously reported in water, sewage, and poultry and is regarded as an environmental lineage involved in spreading antibiotic resistance OR
- 14. CONCLUSIONS This study confirms the presence of MCR-1 in public transport, it shows a greater amount of this in E. Coli with respect to Kepsiella, despite this evidence a large variation of E. Coli in closer spaces. This would explain the great mutation that these cells have since they are permanently in contact and there is DNA passage generating multiresistance The areas where the research was done belong to highly trafficked places, as would be the example of group A, close to hospitals, the large number of bacterias near these places could explain the large multiresistance that the bacterias are generating to drugs and are causing opportunistic diseases in the same hospitals
- 15. MAPA
Editor's Notes
- MCR-1 uses a target site modification mechanism to protect bacteria from the action of colistin (polymyxin E). It is a gene which encodes an enzyme called phosphatidylethanolamine transferase which transfers the phosphatidylethanolamine residue to the lipid A of the Gram negative bacterial cell membrane. The lipid A of the bacterial outer membrane is the target binding site for colistin, which upon binding to it, it disrupts it by displacing magnesium and calcium, thus causing cell death. The presence of this residue lowers the affinity of the lipid A to colistin and related polymyxins therefore rendering the antimicrobial inactive and making the bacteria resistant. To date six different variants of mcr-1 have been found R plasmids can encode and transfer multiresistance R plasmids evolve rapidly and can easily acquire additional resistance-determining genes from fusion with other plasmids or acquisition of transposons. Most plasmids, and all R factors, contain many IS elements and transposons. In fact, almost all the resistance-determinant genes on plasmids are present as transposons. As a result, these genes can be amplified by tandem duplications on the plasmid and can hop to other plasmids (or to the bacterial chromosome) in the same cell. Combined with the natural properties of many plasmids to transfer themselves by conjugation (even between dissimilar bacterial species), the rapid evolutionary development of multiple drug resistance plasmids and their spread through populations of pathogenic bacteria is a predictable result of selection as a result of the widespread use of antimicrobials in our society.