Lecture 13 - Antibiotics - Use and Abuse

Lecture 13 - Antibiotics - Use and Abuse - Lecture 13 -...

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Lecture 13 - Antibiotics Use and Abuse and Antibiotic Sensitivity Testing. MI-30a. Explain the difference between intrinsic and acquired resistance Intrinsic resistance-inherent to the organism based on chromosomally encoded genes and their related phenotype o Gram negative rods/chromosomal beta- lactamase o Anaerobes/ aminoglycoside antibiotics Acquired resistance-transferred via plasmid/transposon from one bacteria to another o Enterococcus/Vancomycin o Enteric Gram negative rods/cephalosporins MI-30b. List the principal mechanisms of resistance to b-lactams, carbepenems, glycopeptides (vancomycin), and each class of protein synthesis inhibitors MOA of Antibiotic resistance Enzymatic destruction of antibiotic (e.g. Staph. aureus/beta-lactamases) Decrease the penetration of the antibiotic to its target (Pseudomonas porin mutations/beta-lactams; aminoglycosides/anaerobes) Alter the target of the antibiotic (penicillin binding protein changes/Pneumococcus, MRSA) B-lactams Inactivate antibiotic with beta- lactamases (many bacteria) Staph aureus [Gram (+) à inactive penicillin] Enteric Gram negative rods à wide array Decrease penetration through porin mutations Pseudomonas Alter the target Pneuococcus and altered penicillin binding proteins Beta lactam you can use all three of the strategies Methicillin à alteration of penicillin binding proteins Carbepenems Glycopeptides (Vancomycin) Protein Synthesis inhibitors: Staph Aureus treatment options: Cephalexin- ?resistance Go to drug à easy to administer because it tastes good Dicloxacillin- ?resistance, tastes bad **both of these first one, resistance Vancomycin- parenteral Babies need to be in hospital Clindamycin- tastes bad TMP/SMX- drug reactions; lack of experience Newer quinolones (Levofloxacin, Trovafloxacin, Gatifloxacin)-”contraindicated” Staph aureus has become resistant to this during different mechanisms Linezolid- expensive, lack experience Antibiotic of last resort Daptomycin-expensive, parenteral, can’t use for pneumonia there is a lot of drugs you can use! Treatment options MSSA cephalexin dicloxacillin MRSA Clindamycin TMP/SMX Vancomycin Daptomycin Linezolid Resistance problem organisms Strep. pneumoniae Primiary because it can cause so many diseases Ear infections, sinus infections As it become resistance to penicillin
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This note was uploaded on 09/14/2011 for the course PHARM mb taught by Professor Staff during the Spring '11 term at UCSD.

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Lecture 13 - Antibiotics - Use and Abuse - Lecture 13 -...

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