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Antimicrobials general I
- 3. HISTORY • Mouldy curd boils • Chaulmoogra oil leprosy • Mercury syphilis • Cinchona bark fever • Ehrlich’s phase of dye
- 5. Classification BASED ON • Chemical structure • Mechanism of action • Type of organism against which primarily active • Spectrum of activity • Type of action • Source
- 6. Chemical Structure Sulfonamides – sulfadiazine , dapsone Diaminopyridines – trimethoprim, pyrimethamine Quinolones – nalidixic acid, ciprofloxacin Beta lactums – penicillins, cephalosporins Nicotinic acid derivative – isoniazid, pyrazinamide, ethionamide Azole derivatives – miconazole, ketoconazole Macrolides – azithromycin, clarithromycin
- 7. Mechanism of action • Cell wall synthesis inhibitors – penicillin, cephalosporin • Leakage of cell membranes – amphotericin B • Protein synthesis inhibitors – tetracyclines, macrolides • Inhibit DNA gyrase - Fluoroquinolones • Interfere DNA function – rifampicin • Interfere with intermediary metabolism – sulfonamides
- 8. Type of organism against which primarily active • Antibacterial • Antifungal • Antiviral • Antiprotozoal • Anthelmintic
- 9. Spectrum of activity • Narrow spectrum • Broad spectrum
- 10. Type of action • Bacterio static • Bacterio cidal
- 11. Sources • Fungi – penicillin • Bacteria – polymyxin B • Actinomycetes – aminoglycosides
- 12. Problems • Toxicity • Hypersensitivity reactions • DRUG RESISTANCE • Superinfection • Nutritional deficiencies • Masking of an infection
- 13. Drug resistance • Unresponsiveness of a microorganism to an antimicrobial agent • Natural & acquired • Mutation / gene transfer • Stable & heritable genetic change – spontaneously & randomly – vertical transfer • Drug tolerant • Drug destroying • Drug impermeable
- 15. CROSS RESISTANCE • Resistance to one AMA conferring resistance to another AMA • to which the organism has not been exposed • Complete • Partial • No indiscriminate use • Prefer narrow spectrum drugs • Combination of drugs
- 16. Superinfection/ Suprainfection • Appearance of new infection as a result of antimicrobial therapy • Broad & extended spectrum antibiotics • Tetracycline, chloramphenicol
- 17. Predisposing factors • Corticosteroid therapy • Malignancy • AIDS • Agranulocytosis • Diabetes mellitus
- 18. Examples of superinfection • Candida albicans – oral thrush, vulvovaginitis • Resistant staphylococci enteritis • Clostridium difficile – pseudomembranous enterocolitis treatment - vancomycin / metronidazole • Proteus – urinary tract infection • Pseudomonas – UTI, enteritis
- 19. Toxicity • Local irritancy • Systemic toxicity • Aminoglycosides – ototoxicity • Chloramphenicol – bone marrow suppression • Amphotericin B – nephrotoxicity
- 20. Hypersensitivity reactions • Rashes • Anaphylactic shock • Sulfonamides • Penicillins • Cephalosporins
- 21. Masking of an infection • Syphilis masked by single dose penicillin used for gonorrhea