This document discusses the history and classification of antimicrobials and antibiotics. It describes their discovery from mouldy curd and various plant and mineral sources. Antimicrobials are classified based on their chemical structure, mechanism of action, spectrum of activity, and source. The mechanisms of action include inhibiting cell wall synthesis, disrupting cell membranes, and interfering with protein synthesis and DNA. Issues like drug resistance, cross-resistance, superinfections, and toxicity are also covered.

1. ANTIMICROBIALS
DR PADMAVATHI S

2. ANTIBIOTICS OR ANTIMICROBIALS ???

3. HISTORY
• Mouldy curd  boils
• Chaulmoogra oil  leprosy
• Mercury  syphilis
• Cinchona bark  fever
• Ehrlich’s phase of dye

4. • PENICILLIN DISCOVERY

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