Classification and mechanism of action of ANTIMICROBIALS by DR.PRINCE.C.P

An antibiotic is a selective poison.
It has been chosen so that it will kill the desired bacteria, but not the cells in your body. Each different type of antibiotic affects different bacteria in different ways.
For example, an antibiotic might inhibit a bacteria's ability to turn glucose into energy, or the bacteria's ability to construct its cell wall.
Therefore the bacteria dies instead of reproducing.
this ppt on antimicrobials is a brief description of antimicrobials used for treatment .
by
Dr.C.P.PRINCE
Pondicherry

1. Antimicrobials DR.PRINCE C P HOD & Associate Professor Department of Microbiology Mother Theresa Post Graduate & Research Institute of Health Sciences (Government of Puducherry Institution

2. What are Antimicrobials? An antimicrobial is a substance that either kills or inhibits the growth of microorganisms such as bacteria, fungi, or protozoans . The history of antimicrobials begins with the observations of Pasteur and Joubert , who discovered that one type of bacteria could prevent the growth of another Paul Ehrlich : Selective toxicity Alexander Flemming : Pencillin

3. Antibiotic An antibiotic is a selective poison. It has been chosen so that it will kill the desired bacteria, but not the cells in your body. Each different type of antibiotic affects different bacteria in different ways. For example, an antibiotic might inhibit a bacteria's ability to turn glucose into energy, or the bacteria's ability to construct its cell wall. Therefore the bacteria dies instead of reproducing.

4. Terminology… INFECTION - An infection is the invasion of body tissues by disease causing microorganisms. MICROBIOCIDAL - kills the microbes. MICROBIOSTATIC - inhibits the growth of microbes DISINFECTANT - used on non-living objects or outside the body. ANTISEPTIC - substances that are applied to living tissue/skin to reduce the possibility infection. CHEMOTHERAPY - Treatment of systemic infection with specific drug without affecting the host.

5. Basis of Classification of Antimicrobial Agents 1. CHEMICAL STRUCTURE 2. MECHANISM OF ACTION 3. TYPE OF ORGANISM 4. SPECTRUM OF ACTIVITY 5. TYPE OF ACTION 6. ANTIBIOTICS OBTAINING FROM

6. ON THE BASIS OF CHEMICAL STRUCTURE 1.Sulphonamide and related drugs- Dapson (DDS), Para- aminosalisylic acid 2.Diaminopyridines- Trimethoprim , Pyrimethamin 3.Quinolones- Nalidixic acid 4.B-lactum antibiotics- Penicilines , Cephalosporin 5.Tetracyclin- Oxytetracyclin , Doxytetracyclin 6.Nitrobenzene derivative- Chloramphenicol 7.Amino glycosides- Streptomycin, Gentamicin 8.Macrolide antibiotics- Erythromycin, Clarithromycin 9.Lincosamide antibiotic- Lincomycin, Clindamycin 10.Glycopeptide antibiotics- Vancomycin 11.Nitrofuran derivative- Nitrofurantoin derivatives 12.Nitroimidazoles- Metronidazoles 13.Polyene antibiotics- Nystatin , Amphoterecin -B 14.Azole derivatives- Ketoconazole, Fluconazole

7. ON THE BASIS OF MECHANISM OF ACTION 1. Inhibit cell wall synthesis: Penicillin, Cephalosporin 2. Cause leakage from cell membrane: Amphoterecin -B Nystatin 3. Inhibit protein synthesis: Tetracycline, Chloramphenicol, Erythromycin 4. Cause misreading of m-RNA code and affect permeability : Streptomycin, Gentamycin 5. Inhibit DNA gyrase: Fluroquinolones , Ciprofloxacin 6. Interfere with DNA function: Rifampin , Metronidazole. 7. Interfere with DNA synthesis : Acyclovir, Zidovudine 8. Interfere with intermediary metabolism: Sulphonamides, Sulphones , Ethambutol

8. ON THE BASIS OF TYPES OF ORGANISM AGAINST WHICH PRIMARILY ACTIVE 1. Antibacterial- Penicillin’s, Aminoglycosides 2. Antifungal- Griseofulvin, Amphoterecin -B, Ketoconazole 3. Antiviral-Acyclovir, Amantidin , Zidovudine 4. Antiprotozoal - Chloroquine , Pyrimethamine 5. Anthelmentic - Mebendazole, Pyrantel

9. ON THE BASIS OF SPECTRUM OF ACTIVITY 1. Narrow Spectrum- Penicillin-G, Erythromycin 2. Broad Spectrum- Tetracycline, Chloramphenicol

10. ON THE BASIS OF TYPE OF ACTION 1. Primarily bacteriostatic - Sulphonamide, Erythromycin, ethambutol 2. Primarily bactericidal- Rifampin , isoniazide , penicillin

11. PROBLEMS THAT ARISE WITH THE USE OF AMAs 1.Toxicity 2.Hypersensitivity reactions 3.Drug resistance 4.Superinfection 5.Nutrirional Deficiencies 6. Masking an action

12. CHOICE OF AN ANTIMICROBIAL AGENT PATIENT RELATED FACTORS 1. Age 2. Renal & hepatic function 3. Drug allergy 4. Impaired host defense 5. Pregnancy 6. Genetic factors

13. DRUG RELATED FACTORS 1. Spectrum of activity 2. Type of activity 3. Sensitivity of organism 4. Relative toxicity 5. Pharmacokinetic profile 6. Route of administration 7. Cost

14. COMBINED USE OF ANTIMICROBIALS 1. To achieve synergism 2. To reduce adverse effects 3. To prevent emergence of resistance 4. To broaden the spectrum of antimicrobial action

15. PROPHYLACTIC USE OF ANTIMICROBIALS 1.Prophylaxis against Specific organism- E.g.. Rheumatic fever, T.B , HIV infection, Cholera, Plague 2.Prevention of infection in high risk situation- E.g.. Dental extraction, Catheterization, Chronic obstructive lung disease. 3.Prevention of infection in general – E.g. Neonates, Viral upper respiratory tract infection.

16. Combined use of antimicrobials To achieve synergism To reduce adverse effect To prevent resistance To broaden the spectrum of antimicrobial action

17. Thank you