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Dolly Mehta 5-0236 dmehta@uic.edu. Beta Lactam Antibiotics. Non-beta Lactam Antibiotics. Penicilin. Vancomycin. Cephalosporins. Cycloserine. Bacitracin. Monobactum. Carbepenams Beta-lactam inhibitors. Tazobactum. Gram positive. Gram negative. Penta peptide
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Dolly Mehta 5-0236 dmehta@uic.edu
Beta Lactam Antibiotics Non-beta Lactam Antibiotics Penicilin Vancomycin Cephalosporins Cycloserine Bacitracin Monobactum Carbepenams Beta-lactam inhibitors Tazobactum
Gram positive Gram negative
Penta peptide (Glycine residues) Peptidoglycan NAG NAM L-Ala D-Glu L-Lys N acetylmuramic acid (NAM) N acetylglucosamine (NAG)
Bactoprenol (C55-carrier) P BP periplasm NAM NAG NAM NAG NAM NAM NAG NAM NAG NAM NAG NAM NAM NAM Glycosidic bond Peptide cross link Transglycolase (TG) Transpeptidase (TP)
D-ala D-ala alanine racemase cycloserine D-ala D-ala-D-ala-ligase D-ala D-ala UdP L-ala D-ala D-ala D-ala bacitracin D-ala NAM Bactoprenol (C55-carrier) P P BP Beta-lactams periplasm vancomycin NAM NAG NAM NAG NAM NAM NAG Inhibits TP NAM NAG NAM NAG NAM NAM NAM
Mechanism of Resistance Inability of agents to penetrate to site of action Production of b-lactamase Increased expression of efflux pumps Elaboration of normal penicillin binding proteins (PBPs)
Classification Cephalosporins Penicillins Natural Penicillins i.e. PenV Extended-Spectrum Penicillins i.e. (Ampicillin/Amoxycillin) Antistaphylococcal Penicillins i.e. Piperacillin Ist generation i.e. Ceftazolin IInd generation i.e. Cefactor IIIrd generation i.e. Cephaoxime IV generation i.e. Cefapime V generation i.e. Cefrazoline
Untoward Effects • Hypersensitivity ~(0.7%-4%) • Allergy to one penicillin risk to other penicillins/cephalosporins Haptens Penicilloic acid IgE Abs
Antibiotics Protein Synthesis Aminoglycosides Macrolides Teteracycline Chloramphenicol
Protein Synthesizing Machinery Ribosome mRNA tRNA bacteria has 50S and 30 S subunit which forms 70 S polysome that slides on mRNA has A, P and E sites for binding with tRNA forms template for protein synthesis transcribed from DNA attaches to 30s ribosomes brings amino acids attaches to A, P and E sites of ribosomes
Aminoglycosides MET Binds 30S uac P E A 50s uuu cca cau cca aug cca cau 30s
Pro Tetracycline uac Binds reversibly at 30 S ribosomal RNA Compete with tRNA P E A Met uac uuu cca cau cca aug cca cau
Macrolides, Lincosamide Binds 50S ribosomal RNA Blocks peptide translocation to P site P E A Met Pro uuu cca cau cca aug cca cau
Chloramphenicol Binds 50S ribosomal RNA Inhibit peptidyltransferase P E A Pro Met gga uuu cca cau cca aug cca cau
Oxazolidinones Inhibits ribosomal complex formation P E A 50s uuu cca cau cca aug cca cau 30s
Mechanisms of Resistance Low affinity of drug for bacterial ribosomes Efflux pumps (Tet, Mac) Intracellular penetration Modification of the ribosomal binding site (Tet) pH Anaerobic conditions (AG) acetylation, phosphorylation, adenylation of OH or NH2 gr (Macrolides, AG) Drug inactivation Metabolites can also compete with the drugs (Mac, AG)
Intracellular Penetration Macrolides, Tetracyclines, chloramphenicol Aminoglycosides a. Energy-Dependent Phase 1 (EDP1) b. Create fissure inducing bacterial damage (EDP2 phase)
Drug Interactions Erythromycin, Chloramphenicol Linezolid serotonin syndrome serotonins Cytochrome P450
Anti-tubercular and Anti-leprosy agents Mycobacteria Tuberculosis leprosy
Mycobacterial Cell Wall Mycolic acid Long fatty acids Allow the bacterium to grow dormantly Reside inside macrophages evading host's immune system
Drug Interactions of Rifampin induces Cytochrome P450 Increases elimination of several drugs i.e cyclosporineAnticonvulsants Protease inhibitors
Leprosy • Mycobacterium leprae • chronic ID skin, peripheral nerves and mucous membranes (eyes, respiratory tract). • also known as Hansen's disease as bacillus causing it was discovered by G.A. Hansen in 1873. • common in warm, wet areas in the tropics & subtropics.
Multidrug therapy Sulphones (Dapsones) inhibits the utilization of PABA folic acid metabolism Rifampin Clofazimine binds GC rich DNA; anti-inflammatory
Untoward Effects Dapsone • Sulphone syndrome: fever, jaundice, malaise • exacerbation of lepromatos leprosy Clofazimine skin discoloration ranging from red-brown to nearly black