MGY277H1 Lecture Notes - Lecture 8: Lactam, Microorganism, Enterobacteriaceae
30 Mar 2018
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Sources of resistance genes: spontaneous mutations, during replication, happen at low rate but can have great effect. Single base pair change can cause resistance: gene transfer, usually through conjugative transfers of r plasmids (usually have several genes, we are spreading them by misusing and overusing antimicrobials, travelling. Therapeutic index: lowest dose toxic/dose used for therapy: higher = less toxic. Beta lactam resistance: carbapenem: carbapenemases inactivate them, in enterobacteria, penicillin: inactivated by many beta lactamases, altered pbps, in s. pneumonia, methicillin: altered pbps (e. g. in s. aureus, carbapenemase enzymes, ndm. Frequently on conjugative plasmid that can transfer easily: class b (metallo beta lactamase, kpc, class a (serine based) Found ndm in k. penumoniae in wound swab of a: all patients in respiratory unit monitored, b and c also have ndm k. penumoniae, d also epidemiologically linked to a, b, c (in respiratory unit) E (roommate of a) also positive for ndm.
