ABSTRACT
El éxito del tratamiento de las enfermedades infecciosas se ha visto comprometido en los últimos años debido a la diseminación de genes de resistencia a antibióticos entre las bacterias patógenas. Estos genes de resistencia a antibióticos son transportados por plásmidos, los cuáles son transferidos de una bacteria a otra mediante el proceso de conjugación. La reducción del uso inadecuado de los antibióticos y la búsqueda de inhibidores de la conjugación bacteriana son estrategias que podrían contribuir a la solución de este grave problema de salud pública. Basándose en la primera de esta estrategias, en enero de 2006 se regulo la dispensación de un grupo de antibióticos a fin de controlar su consumo. El análisis realizado en este trabajo seǹala que esta medida ha resultado ineficaz, puesto que el consumo y la resistencia bacteriana total a estos antimicrobianos se incrementó significativamente durante el periodo posterior a su promulgación. La resistencia bacteriana a muchas de las familias de antibióticos estudiadas esta solo parcialmente influenciada por su consumo, destacando la participación de otros factores, como la transferencia de genes de resistencia a antibióticos, en la prevalencia de cepas bacterianas resistentes. La identificación de proteínas del cito-cromo P450 de estructura y ligados conocidos, que tenían una similitud significativa en su secuencia de aminoácidos con la proteína de acoplamiento TRAG de los plásmidos R27 y R478, permitió identificar a los medicamentos diclofenac y ketoprofeno como potenciales inhibidores de la transferencia por conjugación de estos plásmidos. El modelado por homología de TRAG revelo que su dominio de solo hélices alfa podría ser el blanco de estos medicamentos. El ingreso de diclofenac o ketoprofeno a una cavidad en este dominio podría interferir en la interacción con el DNA portador de genes de resistencia a antibióticos que esta siendo transferido mediante el proceso de conjugación.
Subject(s)
Humans , Drug Resistance, Microbial/genetics , Anti-Inflammatory Agents, Non-Steroidal/pharmacology , Conjugation, Genetic/drug effects , Computational Biology/methods , Anti-Infective Agents/pharmacology , Diclofenac/therapeutic use , Diclofenac/pharmacology , Ketoprofen/therapeutic use , Ketoprofen/pharmacology , Communicable Diseases/drug therapy , Amino Acid Sequence/drug effects , Protein Conformation, alpha-Helical , Anti-Infective Agents/administration & dosage , Anti-Infective Agents/adverse effectsABSTRACT
We have attempted a new evaluation of the process of conjugation in bacteria, because of some basic dissimilarities observed between this and that of eukaryotes, or plants and animals. Reference donor and recipient strains, widely used to prove conjugation in bacteria, were chosen; addition of DNase during the conjugation process, led to an unexpected but highly reproducible increase in the transconjugant colony counts (TCC; ca. > or = 1 log), when compared with that of the controls without DNase. Transconjugants were also obtained when the same live donors were substituted with the UV-killed ones although the TCC was very low initially. Contrarily, donors treated with DNA-intercalating agents, e.g. acridine orange or ethidium bromide, resulted in a complete failure to produce transconjugants. There was a quantitative relationship between the DNase used on donors and levels of DNA sugars/nucleotides/DNA, which possibly resulted from interaction between the DNase and DNA being present/produced on the donor surface. This may be indicative of what may actually happen in the donor-recipient mixtures in the conjugation test proper, where the recipient DNase may activate a donor DNA production cycle. The evidences presented did not suggest that the donor DNA in the conjugation process is actually vestibuled through any intercellular conjugation passages, and is susceptible to the action of DNase or the intercalating dyes.
Subject(s)
Animals , Conjugation, Genetic/drug effects , DNA, Bacterial/metabolism , Deoxyribonucleases/pharmacology , Escherichia coli/drug effects , Fimbriae, Bacterial/genetics , Gene Transfer TechniquesABSTRACT
Fifteen independent E. coli strains of avian, bovine and porcine origin in Peninsular Malaysia were tested for antibiotic resistance and conjugative R plasmids. Eight (53%) isolates were found to be antibiotic resistant. Among them, 37.5% were mono-resistant and 62.5% were resistant to three or more antibiotics, i.e., multi-resistant. All of them were resistant to Tc and sensitive to Gm and Nx. Three of the eight antibiotic resistant strains were able to transfer all or part of their resistance to an E. coli K12 recipient by conjugation. The transfer frequencies of Km, Sm and Tc resistance of the three donors varied between 4.5 X 10(-8) to 6.8 X 10(-7). Analysis of the plasmid profiles of all the three donors and their respective transconjugants after agarose gel electrophoresis provided conclusive evidence that the transferable resistance traits were plasmid-mediated.