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Terminologies on anti infective agents


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Undergraduate level presentation on Terminologies on anti-infective agents.

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Terminologies on anti infective agents

  1. 1. Terminologies on Anti-infective Agents Kyaw San Lin (RN. 22) Khin Kant Kaw Gyi (RN. 47) Terminologies on Anti-infective Agents 1
  2. 2. Terminologies Antibiotic antimicrobials Spectrum Resistance Bactericidal Bacteriostatic Post-antibiotic effect (PAE) Time-dependent killing Dose-dependent killing Terminologies on Anti-infective Agents 2
  3. 3. Anti-microbial chemotherapy  the drug treatment of parasitic infections in which parasites (bacteria, viruses, protozoa, fungi, helminths) are destroyed or inhibited without injuring the host, by a process known as “selective toxicity” Terminologies on Anti-infective Agents 3
  4. 4. Selective Toxicity  interfering with some metabolic processes that exist only in the infectious organisms (not in the cells of the host) by the anti-infective agents at concentrations tolerated by the host (may be complete or relative) Terminologies on Anti-infective Agents 4
  5. 5. Antibiotics  chemical substances originally produced by various species of mi- cro-organisms (bacteria, fungi, actinomycetes), that in high dilution suppress the growth or cause death of other microorganisms. Terminologies on Anti-infective Agents 5
  6. 6. Antibacterial spectrum  List of bacteria which are normally susceptible to antibacterial action of particular agents. Terminologies on Anti-infective Agents 6
  7. 7. Narrow-spectrum antibiotics  Antibiotics that act only on a single or a limited group of microorganisms.  E.g., isoniazid is active only against mycobacteria. Terminologies on Anti-infective Agents 7 Mycobacteria Other Chlamydia Mycoplasma Spirochetes G (-) rods G (+) bacilli Anaerobic organisms G (+) cocci G (-) cocci
  8. 8. Extended-spectrum antibiotics Terminologies on Anti-infective Agents 8  Antibiotics that are effective against G (+) & also against a significant number of G (-) bacteria.  E.g. Ampicillin Other Chlamydia Mycoplasma Spirochetes G (-) rods G (+) bacilli Anaerobic organisms G (+) cocci G (-) cocci G (+) bacilli Listeria monocytogenes G (-) rods E. coli H. influenzae Proteus Salmonella typhi
  9. 9. Broad-spectrum antibiotics  Antibiotics that are effective against G (+), G(-), aerobic & anaerobic bacteria.  E.g., tetracycline Terminologies on Anti-infective Agents 9 Other Chlamydia Mycoplasma Spirochetes G (-) rods G (+) bacilli Anaerobic organisms G (+) cocci G (-) cocci Actinomyces Rickettsiae Amoebae Chlamydia Mycoplasma Spirochetes Anaerobic organisms G (-) rods
  10. 10. Superinfection  Drug therapy, particularly with broad- spectrum antimicrobials or combination of agents, can lead to alteration of normal flora of respiratory, GI & GU tracts, permitting the overgrowth of opportunistic organisms. Terminologies on Anti-infective Agents 10
  11. 11. Resistance to anti-microbial drugs Microorganisms produce enzymes which destroy the active drugs. Microorganisms change their permeability to the drug. Microorganisms develop an altered structural target for drug. Microorganisms development an altered metabolic pathway that bypasses the reaction inhibited by drug. Microorganisms develop an altered enzyme that can still perform its metabolic function but is much less affected by drug than the enzyme in susceptible organisms. Terminologies on Anti-infective Agents 11
  12. 12. Cross-resistance  Microorganisms resistant to certain drug may also be resistant to other drugs that share mechanism of action or attachment.  Such relationships exist mainly between agents that are closely related chemically (Erythromycin – Oleandomycin, Neomycin – Kanamycin), but they may also exist between unrelated chemicals (Erythromycin – Lincomycin). Terminologies on Anti-infective Agents 12
  13. 13. Bactericidal Vs Bacteriostatic Terminologies on Anti-infective Agents 13
  14. 14. Terminologies on Anti-infective Agents 14 Bacteriostatic Bactericidal No antimicrobial agent
  15. 15. Bacteriostatic  Inhibiting the growth or multiplication of bacteria  Number of bacteria remains relatively constant.  Immunologic mechanisms are required to eliminate organisms.  Examples:  drugs that usually inhibit a metabolic reaction that is needed for bacterial growth but is not necessary for survival (e.g., sulfonamides block the synthesis of folic acid)  Drugs that reversibly inhibit bacterial protein synthesis (e.g., tetracyclines) Terminologies on Anti-infective Agents 15
  16. 16. Bactericidal  Lethal effect on mature bacteria (kill the bacteria)  Number of organisms falls rapidly after exposure to the drug.  Induce lethal changes in microbial metabolism or block activities that are essential for microbial viability.  Examples: • drugs that inhibit the synthesis of the bacterial cell wall (e.g., penicillins) • drugs that irreversibly inhibit protein synthesis (e.g., streptomycin) Terminologies on Anti-infective Agents 16
  17. 17. Pharmacodynamic interactions  Bacteriostatic + Bacteriostatic  Different binding site → Synergism  Same binding site → Indifference  Bactericidal + Bactericidal → Synergism  Bactericidal + Bacteriostatic → Antagonism  Bactericidal drugs are usually more effective against rapidly dividing bacteria.  Their effect may be reduced if bacterial growth is slowed by a bacteriostatic drug. Terminologies on Anti-infective Agents 17
  18. 18. Minimum inhibitory concentration (MIC)  minimum concentration that will inhibit growth of a pathogen. Terminologies on Anti-infective Agents 18
  19. 19. Dose-dependent Killing  Some drugs kill better when the maximum concentration of the drug is very high compared with MIC. Terminologies on Anti-infective Agents 19 1 x MIC 2 x MIC 3 x MIC 4 x MIC
  20. 20. Examples  Vancomycin  Fluoroquinolones  Aminoglycosides Terminologies on Anti-infective Agents 20
  21. 21. Time-dependent Killing  Killing effect of some drugs depend on the percentage of time that blood concentrations of a drug remain above the MIC. Terminologies on Anti-infective Agents 21 1 x MIC 4 x MIC
  22. 22. Examples  Penicillins  Cephalosporins Terminologies on Anti-infective Agents 22
  23. 23. Post-antibiotic effect (PAE)  Persistent suppression of microbial growth that occurs after levels of antibiotic have fallen below the MIC.  Antimicrobial drugs exhibiting a long PAE (several hours) often require only one dose per day.  For example, aminoglycosides and fluoroquinolones, exhibit a long PAE.  Proposed mechanisms by which the PAE occurs include both nonlethal damage induced by the antimicrobial agent & a limited persistence of the antimicrobial agent at the bacterial binding site. Terminologies on Anti-infective Agents 23
  24. 24. References  Department of Pharmacology: Lecture notes on Pharmacology Volume 2, 4th ed. Universities of Medicine 1 & 2 (Yangon), Mandalay, Magway, Defense Services Medical Academy, 2013.  Clark MA, Finkel R, Rey JA, Whalen K: Lippincott’s Illustrated Reviews of Pharmacology, 5th ed. Lippincott Williams & Wilkins, 2012.  Bennett PN, Brown MJ, Sharma P: Clinical pharmacology, 11th ed. Churchill Livingstone, 2012.  Brenner GM, Stevens CW: Pharmacology, 4th ed. Saunders, 2012. Terminologies on Anti-infective Agents 24
  25. 25. Thank you! ^_^ Terminologies on Anti-infective Agents 25