MELS223 Lecture Notes - Lecture 6: Plasmid, Vancomycin-Resistant Staphylococcus Aureus, Disinfectant
6 Sep 2013
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Document Summary
To discuss mechanisms of antibiotic resistance and the selective pressures that promote resistance. To understand the nature of methicillin resistance in. Staphylococcus aureus and the importance of mrsa in nz and world-wide. Route of excretion of penicillin antibiotics through kidneys. Exerts a selective pressure, resistant bacteria will remain. A particular bacterium can acquire resistance gene from another bacterium- usually through mutation. Bacterial transformation release of dna to recipient cell. Bacterial conjugation via conjugation plasmid. Disk diffusion test lawn of bacteria, disk on. Epsilon test (etest) antibiotic gradient in strip. These tests depend on diffusion of antibiotic in the agar concentration gradient. Mrsa resistant to all beta-lactam antibiotics (penicillins and cephalosporins. ) Mrsa frequently carry the panton-valentine leucocidin (pvl) gene. Infect rabbit lungs with and without pvl gene. Multiplies inside neutrophils, lyse neutrophils and cytotoxic elements inside neutrophils leaks out, surrounds tissues are killed. Msra more likely to be resistant to other antibiotics. Only small increase in msra over time in nz.
