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

9. 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

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

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

12. 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

13. 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

14. 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

15. 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

16. 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.

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

18. Thank you