ROM Chap. 10

Mupirocin- used as topical antibiotic to eliminate antibiotic resistant S. aureus from the noses of hospital workers.

Aminoglycosides- widely used antibiotic. (Streptomycin) It binds to a small subunit of the ribosome and freezes the ribosome on the mRNA so that it does not proceed to synthesize the protein.This family seems to prevent later steps in protein
synthesis, despite the fact that they have similar structures.
-one way bacteria can become resistant is to mutate the ribosomal protein that provides the binding site for the antibiotic. The antibiotic no longer binds to the ribosome and tus no longer inhibits growth of the bacteria. Also
bacteria can fail to take them up. They are charged molecules that do not diffuse readily through the cytoplasmic membrane of a bacterium. So they can enter the bacterial cell only if they are actively transported through the
-can have toxic effects; kidney damage and damage to inner ear

Tetracyclines- binds to the small subunit of the bacterial ribosome. It does not freeze the ribosome on the mRNA, rather it distorts the structure of the small ribosomal subunit so that the incoming amino acid bearing tRNA molecues can no longer
interact properly with the mRNA.
-they diffuse readily through membranes so bacteria cannot become resistant to tetracycline by failing to take up the antibiotic.Can become resistant by modifiying it by rendering it inactive, by using a protein located in the bacterial
cytoplasmic membrane that actively pumps tetracycline out of the bacterial cell, and by a bacterial protein that
protects the ribosome by modifying it so that it no longer binds tetracycline but it still is able to synthesize proteins.
- still inaffective against anthrax and Lyme disease.

Macrolides- treats a varitety of bacterial infection including respiratory infections and wound infections. It acts by binding to the
large subunit of bacterial ribosomes and preventing the elongation of bacterial proteins
-A bacterial enzyme that methyltes a key residue of this rRNA molecule simultaneously confers resistance to the
classes of antibiotics by reducing their binding to the ribosome

Lincosamides- Antibiotic that bind the large subunit of bacterial ribosome. A lincosamide that has been extensively used in the therapy of human diseases caused by anaerobic bacteria is clindamycin.

Streptomyces- New antibiotic. It is effective against many of the same gram-positive bacteria that were once susceptible to vancomycin. They act by binding to an RNA component of the large subunit of the ribosome.

Oxazolidones- they inhibit the formation of the intact ribosome. Act at an earlier stage of protein synthesis than any other
antibiotics. Have a different ribosomal target because these are not likely to be targets for the development of
cross resistance selected by other classes of antibiotics binding to the same site of the ribosome.
-primarily used to treat infections caused by gram-positive bacteria that are resistant to other antibiotics.

Aminoglycosides: Streptomycin, Amikacin, Neomycin
Tetracyclines: Doxycycline, Oxytetracycline, Demeclocycline, Minocycline
Macrolides: Erythromycin, Azithromycin
Lincosamides: Clindamycin
Streptogramin: Quinupristin, dalfopristin
Oxazolidone: Linezolid
Mupirocin: Mupirocin

-Erica Luetje

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