Resistance to tetracycline in Escherichia coli and Staphylococcus aureus: brief overview on mechanisms of resistance and epidemiology
2015
Velhner, Maja (Scientific Veterinary Institute Novi Sad, Novi Sad (Serbia)) | Milanov, Dubravka (Scientific Veterinary Institute Novi Sad, Novi Sad (Serbia))
In this work we briefl y present the mechanisms of resistance to te- tracyclines. Tetracycline’s were introduced in clinical practice in 1948, and are used for the therapy in human and veterinary medicine or as growth promoters in livestock industry. Th ere are three major mechanisms of resi- stance to tetracyclines. Gram negative bacteria utilize effl ux pump system of proteinaceous transporters in eliminating the drug from the cell. Th is mechanism of resistance is encoded by tet genes that belong to the group 1. Gram positive bacteria promote resistance to tetracyclines by producing soluble cytoplasmatic ribosomal protection proteins and the most frequent once are TetM and TetO proteins. Enzymatic inactivation is not widespread mechanism and the responsible gene is termed tetX. Epidemiological im- portance of tetracyclines is well documented in number of research papers. We described few works showing that tetracycline’s are provoking resistan- ce to other classes of antibiotics or vice versa. Th is phenomenon is probably due to the fact that resistance determinants are oſt en situated on mobile genetic elements. Withdrawal of the therapy does not exclude resistance in short time frame due to the various environmental factors and animal fee- ding habits. Most oſt en resistance to tetracycline is reported in Escherichia coli isolates from pigs, chickens and turkeys. Th e TetM and TetK proteins are most oſt en found in methicillin resistant Staphylococcus aureus.
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