TY - CHAP M1 - Book, Section TI - Antibacterial Drugs: Resistance A1 - Levinson, Warren A1 - Chin-Hong, Peter A1 - Joyce, Elizabeth A. A1 - Nussbaum, Jesse A1 - Schwartz, Brian Y1 - 2020 N1 - T2 - Review of Medical Microbiology & Immunology: A Guide to Clinical Infectious Diseases, 16e AB - There are four major mechanisms that mediate bacterial resistance to drugs (Table 11–1). (1) Bacteria produce enzymes that inactivate the drug (e.g., β-lactamases can inactivate penicillins and cephalosporins by cleaving the β-lactam ring of the drug). (2) Bacteria synthesize modified targets against which the drug has a reduced effect (e.g., a mutant protein in the 30S ribosomal subunit can result in resistance to streptomycin, and a methylated 23S rRNA can result in resistance to erythromycin). (3) Bacteria reduce permeability to the drug such that an effective intracellular concentration of the drug is not achieved (e.g., changes in porins can reduce the amount of penicillin entering the bacterium). (4) Bacteria actively export drugs using a “multidrug-resistance pump” (MDR pump or “efflux” pump). The MDR pump imports protons and, in an exchange-type reaction, exports a variety of foreign molecules including certain antibiotics, such as tetracyclines. SN - PB - McGraw Hill CY - New York, NY Y2 - 2024/03/28 UR - accessmedicine.mhmedical.com/content.aspx?aid=1175824602 ER -