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14 Cards in this Set
- Front
- Back
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Penicillin V
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Beta Lactam Antibiotics
Mechanism: Competitive inhibitors of D-alanine in rxn with transpeptidases in the final step of bacterial cell wall synthesis, With no cell wall bacteria cannot maintain osmotic pressure and they burst Nucleophilic attack on carboxyl in penicillin by hydroxyl in PBP, The bond between nitrogen and carboxyl is broken, Penicillin is covalently bound to the enzyme blocking its action, cell wall synthesis Secondary mechanism: Activation of the enzyme muramyl synthase, Muramyl synthase separates daughter cells after cell division, Activation in the absence of cell division causes lysis of cell wall: a suicide mechanism Penicillins kill slowly- enzyme inactivation and then bacterial rupture Consistently high blood levels are needed for optimal success.– Not all bacteria divide at the same time Bactericidal Spectrum: Gram + Cocci, Gram + Rods, Most oral anaerobes Indications: soft tissue infections, cellulitis, pulpal origin infections Adverse: Antibiotic induced diarrhea: Amoxicillin is most common drug for this rxn Mild rash on trunk: pts mistake this for PCN allergy Allergy Dental: Pen V: most frequently prescribed for infections of dental origin Some patients may be receiving prophylactic therapy with PCN: require another antibiotic if they develop an infection Periodontal infections: Gram negative aerobic and anaerobic bacteria Broad spectrum with PCNase activity and metronidazole |
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Amoxicillin
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Beta Lactam Antibiotic
Mechanism: Competitive inhibitors of D-alanine in rxn with transpeptidases in the final step of bacterial cell wall synthesis, With no cell wall bacteria cannot maintain osmotic pressure and they burst Nucleophilic attack on carboxyl in penicillin by hydroxyl in PBP, The bond between nitrogen and carboxyl is broken, Penicillin is covalently bound to the enzyme blocking its action, cell wall synthesis Secondary mechanism: Activation of the enzyme muramyl synthase, Muramyl synthase separates daughter cells after cell division, Activation in the absence of cell division causes lysis of cell wall: a suicide mechanism Penicillins kill slowly- enzyme inactivation and then bacterial rupture Consistently high blood levels are needed for optimal success.– Not all bacteria divide at the same time Bactericidal Spectrum: Gram -/+ bacteria, Most oral anaerobes Drug of 1st choice for prevention of bacterial endocarditis 2 Grams po 1 hour prior to treatment Adverse: Antibiotic induced diarrhea: Amoxicillin is most common drug for this rxn Mild rash on trunk: pts mistake this for PCN allergy Allergy Dental: Amoxicillin has superior pharmacokinetics and a broader spectrum Some patients may be receiving prophylactic therapy with PCN: require another antibiotic if they develop an infection Periodontal infections: Gram negative aerobic andanaerobic bacteria Broad spectrum with PCNase activity and metronidazole |
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Bacterial Resistance to PCN
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3 Possible Mechanisms:
Reduce drug binding to PBP Hydrolysis of Penicillin by beta lactamase enzymes Development of tolerance by loss of autolysis mechanism Beta Lactamases cleave the bond between the nitrogen and the carboxyl This bond reacts with PBPs in the final step of bacterial cell wall synthesis |
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Augmentin
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Amoxicillin and Clavulanic Acid
It reacts with the lactamase and covalently binds to the active site, killing the enzyme activity Clavulanic acid is the only orally available inhibitor Clavulanic Acid is a beta-lactamase “suicide inhibitor” Not recommended for the treatment of routine oral infections Used only in infections caused by bacteria with beta lactamase activity Adverse: Antibiotic induced diarrhea: Amoxicillin is most common drug for this rxn Mild rash on trunk: pts mistake this for PCN allergy Allergy Dental: Some patients may be receiving prophylactic therapy with PCN: require another antibiotic if they develop an infection Periodontal infections: Gram negative aerobic and anaerobic bacteria Broad spectrum with PCNase activity and metronidazole |
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Dicloxacillin
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Penicillinase (Beta Lactamase)
Resistant Penicillin Semi synthetic penicillins that are resistant to beta lactamase Culture and sensitivity tests should be performed before prescribing these medications There are species of staphylococci that are resistant to these drugs Ineffective against chromosomally mediated beta lactamases found in Enterobacter, Pseudomonas aeruginosa And organisms producing inducible extended spectrum beta lactamases Adverse: Antibiotic induced diarrhea: Amoxicillin is most common drug for this rxn Mild rash on trunk: pts mistake this for PCN allergy Allergy Dental: Some patients may be receiving prophylactic therapy with PCN: require another antibiotic if they develop an infection Periodontal infections: Gram negative aerobic and anaerobic bacteria Broad spectrum with PCNase activity and metronidazole |
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Cephalosporins
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1st generation: gram positive aerobes, facultative cocci, MSSA
Example Cephalexin (Keflex) 2nd generation: anti-staphylococcal activity, gram -, anaerobes Example Cefaclor (Ceclor) 3rd generation: gram -, PCN resistant S. pneumoniae, Pseudomonas 4th generation: Pseudomonas, MRSA, hyper beta lactamase organisms |
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Cephalexin (Keflex)
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Cephalosporin
1st generation: gram positive aerobes, facultative cocci, MSSA Identical to PCNs Side chain modifications -Differences in spectrum -Susceptibility to various beta lactamases -Affinity for different PBPs Cephalosporinase: like PCNases 1st generation most sensitive Most concern: High level resistance in E. Coli, Klebsiella, Enterobacter to ceftazidime About 1 % of population is allergic to cephalosporin The issue of cross sensitivity to cephalosporin and PCNs is unresolved. PCN allergic individuals have a 4-fold greater risk of allergy to cephalosporin But they have a 3-4 times risk of being allergic to any drug Interactions: Antacids decrease absorption of cefaclor Nephrotoxic Bacteriostatic antibiotics -tetracycline, erythromycin, clindamycin interfere with the bactericidal effects of cephalosporin |
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Cefaclor (Ceclor)
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Cephalosporin
2nd generation: anti-staphylococcal activity, gram -, anaerobes Identical to PCNs Side chain modifications -Differences in spectrum -Susceptibility to various beta lactamases -Affinity for different PBPs Cephalosporinase: like PCNases 1st generation most sensitive Most concern: High level resistance in E. Coli, Klebsiella, Enterobacter to ceftazidime About 1 % of population is allergic to cephalosporin The issue of cross sensitivity to cephalosporin and PCNs is unresolved. PCN allergic individuals have a 4-fold greater risk of allergy to cephalosporin But they have a 3-4 times risk of being allergic to any drug Interactions: Antacids decrease absorption of cefaclor Nephrotoxic Bacteriostatic antibiotics -tetracycline, erythromycin, clindamycin interfere with the bactericidal effects of cephalosporin |
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Cipro
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Fluoroquinolone
2nd generation Mechanism: Prevent DNA supercoiling Topoisomerase nicks double stranded DNA and seals the nicked DNA DNA gyrase guides the passage of DNA through the enzyme complex Stabilization of DNA enzyme complex after nicking and before resealing Use in dentistry: culture and sensitivity test Management of refractory or rapidly progressive periodontitis Adverse: N+V Heartburn Headache, dizziness Rash, sunburn Arthralgia, joint swelling Increase CNS toxicity with NSAIDS Reduces the hepatic clearance of warfarin Cimetidine increases blood levels of Cipro Antacids and sucralfate decreases absorption Resistance: Mutations in DNA gyrase and topoisomerase Drug efflux pumps Reduction in outer membrane permeability |
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Erythromycin
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Macrolide
MOA: Reversibly bind to the P site of the 50S ribosomal subunit and inhibits translocation of ribosome along mRNA Inhibit RNA-dependent protein synthesis Stimulate the dissociation of peptidyl t-RNA from the ribosome Bacteriostatic Fat soluble: Selective uptake by phagocytic cells These cells are drug delivery vehicles of the drug to sites of inflammation and infection Post antibiotic effects: Tissue concentration exceeds MIC for days after plasma levels have dropped. Spectrum: aerobic and anaerobic gram + cocci, pneumococci, staphylococci Also active against: Mycoplasma, Legionella, Chlamydia, Helicobacter, and some mycobacteria Interactions: Inhibit p450 enzymes, many drug interactions -Carbamazepine -Theophylline -Benzodiazepines -Cyclosporin and tacrolimus -HMG-CoA Inhibitors -Methylprednisolone Resistance: Transport from the cell Phosphorylation and glycosylation of the drugs Reduced macrolide binding by demethylation of a residue on the 23S ribosomal RNA transferase region |
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Clarithromycin
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Macrolide
MOA: Reversibly bind to the P site of the 50S ribosomal subunit and inhibits translocation of ribosome along mRNA Inhibit RNA-dependent protein synthesis Stimulate the dissociation of peptidyl t-RNA from the ribosome Bacteriostatic Fat soluble: Selective uptake by phagocytic cells These cells are drug delivery vehicles of the drug to sites of inflammation and infection Post antibiotic effects: Tissue concentration exceeds MIC for days after plasma levels have dropped. Spectrum: aerobic and anaerobic gram + cocci, pneumococci, staphylococci Also active against: Mycoplasma, Legionella, Chlamydia, Helicobacter, and some mycobacteria Clarithromycin dose: 250-500 mg q12h for 7-10 days Causes less GI upset than erythromycin Interactions: Inhibit p450 enzymes, many drug interactions -Carbamazepine -Theophylline -Benzodiazepines -Cyclosporin and tacrolimus -HMG-CoA Inhibitors -Methylprednisolone Resistance: Transport from the cell Phosphorylation and glycosylation of the drugs Reduced macrolide binding by demethylation of a residue on the 23S ribosomal RNA transferase region |
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Azithromycin (Zithromax)
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Macrolide
MOA: Reversibly bind to the P site of the 50S ribosomal subunit and inhibits translocation of ribosome along mRNA Inhibit RNA-dependent protein synthesis Stimulate the dissociation of peptidyl t-RNA from the ribosome Bacteriostatic Fat soluble: Selective uptake by phagocytic cells These cells are drug delivery vehicles of the drug to sites of inflammation and infection Tissue concentrations of Azithromycin may reach 100 times that of serum. Post antibiotic effects: Tissue concentration exceeds MIC for days after plasma levels have dropped. Spectrum: aerobic and anaerobic gram + cocci, pneumococci, staphylococci Also active against: Mycoplasma, Legionella, Chlamydia, Helicobacter, and some mycobacteria Azithromycin dose: 500 mg on day 1, 250 mg qd days 2-5 Causes less GI upset than erythromycin Resistance: Transport from the cell Phosphorylation and glycosylation of the drugs Reduced macrolide binding by demethylation of a residue on the 23S ribosomal RNA transferase region |
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Clindamycin
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Lincosamide
Mechanism: Similar to macrolides, binds to the 50 S subunit of the ribosome Spectrum: aerobic gram + cocci, some anaerobic gram -/+ organisms, pneumococci, staphylococci Good penetration into bone and soft tissue Indications: Prevention of bacterial endocarditis in patients allergic to PCN -orofacial infections that can’t be eradicated by PCN Fat soluble: Selective uptake by phagocytic cells These cells are drug delivery vehicles of the drug to sites of inflammation and infection Post antibiotic effects: Tissue concentration exceeds MIC for days after plasma levels have dropped. Also active against: Mycoplasma, Legionella, Chlamydia, Helicobacter, and some mycobacteria Adverse: GI upset and diarrhea Most serious: Pseudomembranous Colitis Drug Interaction: Absorption inhibited by kaolin-pectin (Kaopectate) antidiarrheal drugs |
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Metronidazole (Flagyl)
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Mechanism: In sensitive anaerobes, the nitro group is reduced to metabolites that inhibit DNA polymerase
Bactericidal Uses: Highly effective against gram – anaerobes and parasites Serious acute orofacial infections Management of refractory/rapidly progressive periodontitis Resistance: Reduction in activity or expression of genes that control nitroreductase activity Reduces concentration of active metabolites of metronidazole Most commonly seen in H. pylori Interactions: Metronidazole increases the levels of: -Lithium -Warfarin -Phenytoin Cimetidine decreases the liver metabolism of metronidazole Phenobarbital may reduce its effectiveness Adverse: N+V Disulfiram rxn with EtOH: flushing, tachycardia, N+V, psychosis Metallic taste Dark red or brown urine |
