Mutations that inactivate the nonessential glycerophosphate transporter render bacteria resistant to fosfomycin.Prescribing fosfomycin together with at least another active drug reduces the risk of developing bacterial resistance. Fosfomycin acts synergistically with many other antibiotics, including aminoglycosides, carbapenems, cephalosporins, daptomycin and oritavancin. Enzymes conferring resistance to fosfomycin have also been identified and are encoded both chromosomally and on plasmids.Three related fosfomycin resistance enzymes (named FosA, FosB, and FosX) are members of the glyoxalase superfamily. These enzymes function by nucleophilic attack on carbon 1 of fosfomycin, which opens the epoxide ring and renders the drug ineffective. The enzymes differ by the identity of the nucleophile used in the reaction: glutathione for FosA, bacillithiol for FosB, and water for FosX.In general, FosA and FosX enzymes are produced by Gram-negative bacteria, whereas FosB is produced by Gram-positive bacteria.FosC uses ATP and adds a phosphate group to fosfomycin, thus altering its properties and making the drug ineffective. Side effects
The drug is well tolerated and has a low incidence of harmful side effects. Mechanism of action
Despite its name (ending in -omycin) Fosfomycin is not a macrolide, but a member of a novel class of phosphonic antibiotics. Fosfomycin is bactericidal and inhibits bacterial cell wall biogenesis by inactivating the enzyme UDP-N-acetylglucosamine-3-enolpyruvyltransferase, also known as MurA. This enzyme catalyzes the committed step in peptidoglycan biosynthesis, namely the ligation of phosphoenolpyruvate (PEP) to the 3-hydroxyl group of UDP-N-acetylglucosamine. This pyruvate moiety provides the linker that bridges the glycan and peptide portion of peptidoglycan.
Other radium-223-based compounds
Although radium does not easily form stable molecular complexes, data has been presented on methods to increase and customize its specificity for particular cancers by linking it to monoclonal antibodies, by enclosing the 223Ra in liposomes bearing the antibodies on their surface. See also
Actinium-225
Actinium series
Bismuth-213
Isotopes of radium
Radium chloride

References
External links
"Radium-223". Drug Information Portal. U.S. National Library of Medicine. "FDA approves new drug for advanced prostate cancer" (Press release). US FDA. Archived from the original on 4 June 2013. Retrieved 16 December 2019.