Beta lactams that are not degraded by beta lactamases

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Beta-lactams that are not degraded by beta-lactamases o Beta-lactamase inhibitors Augmentin (amoxycillin + clavulanate ) SE: diarrhea Kiprocillin and tazobactam (zosin) Strategy to overcome altered penicillin binding proteins (MRSA and pen resistant pneumococci): o Develop new beta-lactams with markedly increased affinity for altered PBPs o New cephalosporins active against MRSA: ceftaroline, ceftobiprole Oral Beta-Lactams: (not effective against MRSA) o Keflex Suboptimal for MSSA, strep Well absorbed, well tolerated IV Beta Lactams (not used for MRSA) o Piperacillin/tazobactam (zosyn) for gram positive and gram negatives (pseudomonas, anearobes) o Cefazolin (ancef): 1 st gen ceph, MSSA, strep, E. coli, kleb
o Ceftazidime: 3 rd gen ceph, for nosocomial gram negative like pseudomonas, not really gram positive o Ceftriaxone: 3 rd gen ceph, for gram positives and some gram negatives but not pseudomonas o Cefepime: 4 th gen ceph, broad spectrum including pseudo o Meropenem: carbapenem very broad spectrum, many multi resistant nosocomoial bacteria, anaerobes Beta-lactam Antibiotic Side Effects: Nephritis o Acute interstitial nephritis o Eosinophils in the urine o Decreased renal function o Most common with methicillin (not used anymore) , oxacillin (used to treat staph infections that are methicillin sensitive) Hepatitis o Increased transaminases o Most common with oxacillin Hematologic o Hemolytic anemia o Thrombocytopenia o leukopenia Allergic: most common o Rash macular or maculopapular eruption o Immediate-type hypersensitivity reaction (anaphylaxis)
Lecture 11- Antibiotics: Protein Synthesis Inhibitors MOA of Protein Synthesis Inhibitors: Ribosomes are made of proteins and RNA. Bacterial have 70s ribosomes and eukaryotic ribosomes are 80s (except in mitochondria). There are large (50s) and small (30s) subunits. Target 50s o Chloramphenicol o Oxazolidines (linezolid) Target 30s o Aminoglycosides o Tetracyclines 50s subunit and interaction with 23s o Macrolides, Lincosamides, Streptogramins Chloramphenicol Very broad spectrum- o Aerobes, facultative anaerobes, and obligate anaerobes, Gram + cocci and bacilli o Gram negative cocci and bacilli except Pseudomonas and Stenotrophomonas. Practically never used in US Cheap and broad spectrum Well absorbed from gut (IV and oral equivalent F) o Crosses BBB very well Large Volume of distribution Gluceronidation by liver urine SE in newborns grey baby syndrome Resistance is wide-spread due to acetyl-transferase encoded on plasmids. Rare SE of aplastic anemia; not reversed w discontinuation Tetracyclines Broad spectrum Tetracycline Minocycline longer T1/2; much better absorbed o Not substrate for common S. aureus pumps o Used in most tet-resistant Staphs Tigecycline o Circumvents resistance; not a substrate for any common pumps o Does not extend tetracycline spectrum Not active against intrinsically resistant bacteria M. tuberculosis complex Not bactericidal so not used for S. aureus bacteremia if

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