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Antimicrobials

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Antimicrobials overview

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Antimicrobials

  1. 1. ANTIMICROBIALS MECHANISM OF ACTION Dr.Elza Joy Munjely JR-I Depmt. Of Pharmacology Govt. Medical College,Kottayam.
  2. 2.  CHEMOTHERAPY – treatment of systemic or topical infection with drugs that have selective toxicity for an invading pathogen without harming the host cells.  Takes advantage of the biochemical & physiological differences that exist between microorganism & human beings.
  3. 3. Antimicrobials  Drugs that inhibit microbial growth & multiplication  Antibacterial  Antiviral  Antifungal  Antiprotozoal  Antihelminthics  Cidal/static  Narrow/Extended/Broad spectrum
  4. 4.  BACTERIOSTATICArrest the growth & replication & limit the spread of infection.  Macrolides -Oxazolidones  Chloramphinicol -Tetracyclines  Sulphonamides -Trimethoprim  Clindamycin -Nitrofurantoin  Ethambutol -Linezolid  Erythromycin 
  5. 5.  BACTERICIDALKill or irreversibly damage the multiplying bacteria.  Betalactam -Vancomycin  Polymixin -Bacitracin  Isoniazid -Pyrazinamide  Rifampicin -Aminoglycosides  Nalidixic acid -Ciprofloxacin  Metronidazole -Cotrimoxazole  Chloramphenicol - static against gram –ve rods & cidal against pneumococci  Sulphonamides/trimethoprim-static when used alone ,cidal when used in combination.  Cidal is preferred when host defences are impaired & for complicated infections.
  6. 6.  BROAD SPECTRUM  effective against a wide range of infectious microorganisms which includes gram positive, gram negative & atypical bacteria  Can be used emperically in case of serious infections  may give rise to drug resistance.  Example  Tetracycline  Chloramphenicol
  7. 7.  NARROW SPECTRUM  active against a selected group of bacterial types.Either gram negative or gram positive.  used for the specific infection when the causative organism is known.  cause less resistance of the bacteria as it will deal with only specific bacteria.  Examples:  Azithromycin  Clarithromycin  Clindamycin  Erythromycin  Vancomycin  Streptomycin
  8. 8. EXTENDED-SPECTRUM ANTIBIOTIC   As a result of chemical modification, affects additional types of bacteria ie, gram-negative + one or two gram positive & vice versa.  Examples- carboxypenicillins & urideopenicillins.
  9. 9. Targets of antimicrobials  Cell wall  Cell membrane  Protein synthesis  Intermediary metabolism  Intracellular organelles  Nucleic acid metabolism  Muscle fibres
  10. 10. Cell wall synthesis inhibitors  Bacteria – peptidoglycan  Inhibitors of peptidoglycan synthesisBetalactam,Vancomycin,Bacitracin,Cy closerin & Phosphomycin.  Mycobacteria – mycolic acid & arabinoglycans  INH, Ethambutol, Pyrazinamide  Fungi – chitin  Echinocandins
  11. 11. Cell membrane  Cell membrane disrupting drugs  Anti-bacterial - polymixins  Antifungal – polyene antibiotics  Inhibitors of cell membrane synthesis  Azoles  Terbinafine
  12. 12. Protein Synthesis rRNA •30s •Aminoglycosides, Tetracyclines ,Spectinomycin •50s •Macrolides, Choramphenicol, Lincosamides, • Streptogramins, linezolid tRNA •Mupirocin
  13. 13. Intermediary metabolism DHF THF Nucleic acid synthesis PABA DHS DHR Sulfonamides Dapsone PAS Trimethoprim Pyrimethamine Proguanil Trimetrexate
  14. 14. Intracellular organelles  Mitotic spindle  Griseofulvin  Benzimidazoles  Food vacuole  Chloroquine, Quinine, Halofantrine, Mefloquine  Mitochondrial electron transport chain  Atovoquone
  15. 15. Muscle fibre  Ivermectin,  Pyrantel pamoate,  Piperazine
  16. 16. Nucleic acid  RNA synthesis  RNA polymerase  Rifampicin  DNA synthesis  DNA gyrase  Quinolones  DNA polymerase inhibitors  Acyclovir, Ganciclovir  Reverse transcriptase  Anti HIV RT inhibitors  DNA damage - metronidazole
  17. 17. PP DHFA PABA THFA DNA m-RNA INHIBITION OF DNA SYNTHESIS Inhibits DNA gyrase Fluroquinolones DNA-directed RNA polymerase. Inhibits RNA synthesis Rifampicin INHIBITION OF FOLIC ACID SYTHESIS Trimethoprim Pyrimethamine Proguanil Trimetrexate Sulphonamides Dapsone PAS , Inhibition of 50 S Chloramphenic ol Macrolides Clindamycin Telithromycin Linezolid StreptograminsInhibition of 30 S Aminoglycosid es Tetracyclines Spectinomycin INHIBITION OF CELL WALL SYNTHESIS Betalactams,Bacitracin,cycloserin e Vancomycin,Teicoplanin Monobactams,Carbopenems, INH,Ethanbutol,Pyrazinamide Alteration of cell membrane integrity Polymixins Amphotericin B Azoles
  18. 18. THANK YOU

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