What is a common mechanism of macrolide resistance?

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Multiple Choice

What is a common mechanism of macrolide resistance?

Macrolides bind to the 50S ribosomal subunit and block translocation during protein synthesis. The most common bacterial resistance mechanism is methylation of the 23S rRNA within that subunit, carried out by erm-encoded methyltransferases. This modification changes the antibiotic’s binding site, greatly reducing macrolide binding and rendering the drug ineffective. This also often leads to cross-resistance with lincosamides and streptogramin B (the MLS_B phenotype). Enzymatic degradation by beta-lactamases targets beta-lactam antibiotics, not macrolides. Altered DNA gyrase affects fluoroquinolones, not macrolides. P-glycoprotein is a human transporter, not the bacterial resistance mechanism (though bacteria can use efflux pumps to reduce drug levels, the classic bacterial mechanism described here is target modification by methylation).

Macrolides bind to the 50S ribosomal subunit and block translocation during protein synthesis. The most common bacterial resistance mechanism is methylation of the 23S rRNA within that subunit, carried out by erm-encoded methyltransferases. This modification changes the antibiotic’s binding site, greatly reducing macrolide binding and rendering the drug ineffective. This also often leads to cross-resistance with lincosamides and streptogramin B (the MLS_B phenotype).

Enzymatic degradation by beta-lactamases targets beta-lactam antibiotics, not macrolides. Altered DNA gyrase affects fluoroquinolones, not macrolides. P-glycoprotein is a human transporter, not the bacterial resistance mechanism (though bacteria can use efflux pumps to reduce drug levels, the classic bacterial mechanism described here is target modification by methylation).

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