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Tetracycline resistance is often due to the acquisition of new genes, which code for energy-dependent efflux of tetracyclines or for a protein that protects bacterial ribosomes from the action of tetracyclines. Furthermore, a limited number of bacteria acquire resistance to tetracyclines by mutations.
Tetracyclines have a broad spectrum of antibiotic action. Originally, they possessed some level of bacteriostatic activity against almost all medically relevant aerobic and anaerobic bacterial genera, both Gram-positive and Gram-negative, with a few exceptions, such as Pseudomonas aeruginosa and Proteus spp., which display intrinsic resistance.
Tetracycline-controlled transcriptional activation is a method of inducible gene expression where transcription is reversibly turned on or off in the presence of the antibiotic tetracycline or one of its derivatives (e.g. doxycycline).
TetR dimerizes by making hydrophobic contacts within the regulatory core. There is a binding cavity for tetracycline in the outer helices of the regulatory domain. When tetracycline binds this cavity, it causes a conformational change that affects the DNA-binding domain so that TetR is no longer able to bind DNA.
Other tetracycline antibiotics are contraindicated in pregnancy and up to eight years of age, due to the potential for disrupting bone and tooth development. [67] They include a class warning about staining of teeth and decreased development of dental enamel in children exposed to tetracyclines in utero, during breastfeeding or during young ...
However, potential harm from antibiotics extends beyond selection of antimicrobial resistance and their overuse is associated with adverse effects for patients themselves, seen most clearly in critically ill patients in Intensive care units. [105] Self-prescribing of antibiotics is an example of misuse. [106]
Narrow-spectrum antibiotics have low propensity to induce bacterial resistance and are less likely to disrupt the microbiome (normal microflora). [3] On the other hand, indiscriminate use of broad-spectrum antibiotics may not only induce the development of bacterial resistance and promote the emergency of multidrug-resistant organisms, but also cause off-target effects due to dysbiosis.
Eravacycline (TP-434, Xerava) is a synthetic halogenated tetracycline class antibiotic by Tetraphase Pharmaceuticals. It is closely related to tigecycline.It has a broad spectrum of activity including many multi-drug resistant strains of bacteria.