Ideal Antimicrobial Agents and Antimicrobial Classification Overview

 
GENERAL
 CHEMOTHERAPY
 
General Consideration Part  III
……………………………………………………………………………………………………………………………………………………………………………………………………………………………………………
Chemotherapy (VPT-411)
(Lecture-4)
 
Dr. Kumari Anjana
Asstt. Professor
Deptt. of Veterinary Pharmacology & Toxicology
Bihar Veterinary College, Bihar Animal Sciences University,
Patna
 
Content of the chapter
 
Properties of ideal antimicrobial
agents.
Classification of Antimicrobials
Principle of chemotherapy
 
Properties of ideal antimicrobial agents
 
It should exhibit 
selective
 and 
effective
 antimicrobial
activity.
 
It should be 
bactericidal
 rather than 
bacteriostatic
.
 
Bacteria should 
not
 
develop 
resistance
 to the drug.
 
It should be 
effective
 in the presence of 
body fluids
and 
exudates
.
 
Bactericidal levels 
of the drug should be
reached in the 
blood
, 
tissues
 
and 
C.S.F.
immediately and 
maintained for prolonged
periods
.
 
The drug should be 
non toxic
.
 
Drug should be 
excreted
 in 
urine
 in
bactericidal concentration
.
 
Classification
of
Antimicrobials
 
On the basis of 
Chemical structure
 
1. 
Sulfonamides and related drugs:
  
Sulfadiazine and others, Sulfones-
 
Dapsone
 
(DDS), Paraaminosalicylic 
 
acid 
 
(PAS).
 
 2. 
Diaminopyrimidines:
  
Trimethoprim, Pyrimethamine.
 
3. 
Quinolones:
  
Nalidixic acid, Norfloxacin, 
 
Ciprofloxacin,
 
Gatifloxacin, etc.
 
4
. 
β-
Lactam antibiotics:
  
Penicillins, Cephalosporins, Monobactams,
 
Carbapenems.
 
5. 
Tetracyclines:
  
Oxytetracycline, Doxycycline, etc.
 
6. 
Nitrobenzene derivative:
  
Chloramphenicol.
 
7. 
Aminoglycosides:
  
Streptomycin, Gentamicin, Amikacin, 
 
Neomycin,etc.
 
8. 
Macrolide antibiotics:
  
Erythromycin, Clarithromycin,
  
Azithromycin, etc.
 
9
. 
Lincosamide antibiotics:
  
Lincomycin, Clindamycin.
 
10. 
Glycopeptide antibiotics:
  
Vancomycin,Teicoplanin.
 
11. 
Oxazolidinone:
  
 Linezolid.
 
12. 
Polypeptide antibiotics:
 
  
Polymyxin-B, Colistin, Bacitracin, Tyrothricin.
 
13. 
Nitrofuran derivatives:
  
 Nitrofurantoin, Furazolidone.
 
14. 
Nitroimidazoles:
 
  
Metronidazole, Tinidazole, etc.
 
15. Nicotinic acid derivatives:
  
 Isoniazid, Pyrazinamide,Ethionamide.
 
16. Polyene antibiotics:
  
Nystatin, Amphotericin-B, Hamycin.
 
17. Azole derivatives:
  
Miconazole, Clotrimazole,Ketoconazole,
 
Fluconazole.
 
18. Others:
  
Rifampin, Spectinomycin, Sod.fusidate,
 
Cycloserine, Viomycin, Ethambutol,
 
Thiacetazone, Clofazimine, Griseofulvin.
 
On the basis of the mechanism ofaction
 
 
1.
Inhibitors of cell wall synthesis:
   
Penicillins, cephalosporins, bacitracin,
   
vancomycin, 
 
novobiocin.
 
2. Cause leakage from cell membrane:
   
Polymyxin, Nystatin, Amphotericin B, Polyene
  
antibiotics, 
 
Colistin, Cationic  detergent &
  
Aminoglycosides.
 
3. 
Inhibits of protein synthesis:
   
Tetracyclines, Chloramphenicol, Erythromycin,
  
Tylosin 
 
(Macrolides)
 
 
4. 
Cause misreading of m-RNA code and affect permeability:
  
Aminoglycosides
 
Targets of Antimicrobial Agents
 
Source: Mirobiology: A clinical Approach
 
5
. Inhibit DNA Gyrase
:
  
Fluoroquinolones
 
6. 
Interfere with DNA function:
    
   
Rifampin, Metronidazole
7. 
Interfere with DNA synthesis:
    
Acyclovir, Zidovudin
 
8
. Interfere with intermediary metabolism:
    
Sulfonamides, sulfones, PAS,
   
Trimethoprim, Pyrimethamine,
   
Ethambutol.
 
 
Antibacterial
  
Penicillins, Aminoglycosides, Erythromycin, etc.
 
Antifungal
  
Griseofulvin, Amphotericin B, Ketoconazole, etc.
 
Antiviral
  
Acyclovir, Amantadine, Zidovudine, etc.
 
Antiprotozoal
  
Chloroquine, Pyrimethamine, Metronidazole,
 
Diloxanide.
 
Anthelmintic
  
Mebendazole, Pyrantel, Niclosamide,Diethyl
 
carbamazine, etc.
 
Classification on the basis of Type of
organism/Therapeutic uses
 
Narrow Spectrum 
:-
 
Effective against a limited group of bacteria.
 
i) 
Gram positive 
:- Penicillin G, erythromycin,
lincomycin, bacitracin etc.
 
ii) 
Gram negative
:- Streptomycin, gentamycin,
polymyxin B etc.
 
Broad spectrum 
:-
 
Effective against both Gram positive & Gram
negative bacteria E.g.:- Tetracyclines,
chloramphenicol, fluoroquinolones, Sulfonamide.
 
Classification on the basis of
spectrum of activity
 
Bacteriostatic:
  
Cause suppression of bacterial growth and
 
multiplication.
  
Eg.Sulphonamides,tetracyclines,
 
erythromycin, chloramphenicol.
 
Bactericidal:
  
Cause death of bacteria.
   
  
Eg.Penicillin,cephalosporins, 
 
streptomycin,
 
kanamycin, colistin, 
bacitracin etc.
 
Classification on the basis of Type of action
 
Fungal Origin:
  
Penicillin, Cephalosporin and Griseofulvin.
 
Bacterial Origin:
  
Bacitracin, Polymyxin, Colistin,
 
tyrothricin.
 
Actinomycetes Origin:
  
Streptomycin, tetracyclines,
 
chloramphenicol,  Macrolides
 
Classification on the basis of Source
 
Principle of chemotherapy
 
The basic principle of chemotherapy is the
selective toxicity 
i,e.  the drug should
selectively inhibit or kill the disease causing
pathogenic organism.
 
Chemotherapy must be 
rational
 and needs to be
supported by either a clinical or microbiological
diagnosis to identify the pathogenic organisms.
 
Characterization of the pathogens including its
sensitivity to an AMAs is essential
.
 
Selection of an appropriate drug based on
  
Pathogenic organism,
  
Patient factors and
  
Drug factors.
 
The drug should be used in 
proper time
,
     
by 
proper route
,
     
at 
appropriate dose rate 
and
    
for a 
proper duration
.
 
Attainment of 
effective concentration 
of a
chemotherapeutic agent for a 
sufficient period 
at the
site of infection (tissue or body fluid) is very
important.
 
Specific and appropriate supportive therapy should be
undertaken to overcome the infection.
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This lecture on general chemotherapy outlines the properties of ideal antimicrobial agents, emphasizing selective and effective activity, bactericidal action, non-toxicity, and more. It also covers the classification of antimicrobials based on chemical structure, including sulfonamides, diaminopyrimidines, quinolones, -lactam antibiotics, tetracyclines, and various other classes crucial in combating infections.


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  1. GENERAL CHEMOTHERAPY General Consideration Part III Chemotherapy (VPT-411) (Lecture-4) Dr. Kumari Anjana Asstt. Professor Deptt. of Veterinary Pharmacology & Toxicology Bihar Veterinary College, Bihar Animal Sciences University, Patna

  2. Content of the chapter Properties of ideal antimicrobial agents. Classification of Antimicrobials Principle of chemotherapy

  3. Properties of ideal antimicrobial agents It should exhibit selective and effective antimicrobial activity. It should be bactericidal rather than bacteriostatic. Bacteria should not develop resistance to the drug. It should be effective in the presence of body fluids and exudates.

  4. Bactericidal levels of the drug should be reached in the blood, tissues and C.S.F. immediately and maintained periods. for prolonged The drug should be non toxic. Drug bactericidal concentration. should be excreted in urine in

  5. Classification of Antimicrobials

  6. On the basis of Chemical structure 1. Sulfonamides and related drugs: Sulfadiazine and others, Sulfones- Dapsone (DDS), Paraaminosalicylic acid (PAS). 2. Diaminopyrimidines: Trimethoprim, Pyrimethamine. 3. Quinolones: Nalidixic acid, Norfloxacin, Ciprofloxacin, Gatifloxacin, etc.

  7. 4. -Lactam antibiotics: Penicillins, Cephalosporins, Monobactams, Carbapenems. 5. Tetracyclines: Oxytetracycline, Doxycycline, etc. 6. Nitrobenzene derivative: Chloramphenicol. 7. Aminoglycosides: Streptomycin, Gentamicin, Amikacin, Neomycin,etc. 8. Macrolide antibiotics: Erythromycin, Clarithromycin, Azithromycin, etc.

  8. 9. Lincosamide antibiotics: Lincomycin, Clindamycin. 10. Glycopeptide antibiotics: Vancomycin,Teicoplanin. 11. Oxazolidinone: Linezolid. 12. Polypeptide antibiotics: Polymyxin-B, Colistin, Bacitracin, Tyrothricin. 13. Nitrofuran derivatives: Nitrofurantoin, Furazolidone. 14. Nitroimidazoles: Metronidazole, Tinidazole, etc.

  9. 15. Nicotinic acid derivatives: Isoniazid, Pyrazinamide,Ethionamide. 16. Polyene antibiotics: Nystatin, Amphotericin-B, Hamycin. 17. Azole derivatives: Miconazole, Clotrimazole,Ketoconazole, Fluconazole. 18. Others: Rifampin, Spectinomycin, Sod.fusidate, Cycloserine, Viomycin, Ethambutol, Thiacetazone, Clofazimine, Griseofulvin.

  10. On the basis of the mechanism ofaction 1.Inhibitors of cell wall synthesis: Penicillins, cephalosporins, bacitracin, vancomycin, novobiocin. 2. Cause leakage from cell membrane: Polymyxin, Nystatin, Amphotericin B, Polyene antibiotics, Colistin, Cationic detergent & Aminoglycosides. 3. Inhibits of protein synthesis: Tetracyclines, Chloramphenicol, Erythromycin, Tylosin (Macrolides) 4. Cause misreading of m-RNA code and affect permeability: Aminoglycosides

  11. Targets of Antimicrobial Agents Source: Mirobiology: A clinical Approach

  12. 5. Inhibit DNA Gyrase: Fluoroquinolones 6. Interfere with DNA function: Rifampin, Metronidazole 7. Interfere with DNA synthesis: Acyclovir, Zidovudin 8. Interfere with intermediary metabolism: Sulfonamides, sulfones, PAS, Trimethoprim, Pyrimethamine, Ethambutol.

  13. Classification on the basis of Type of organism/Therapeutic uses Antibacterial Penicillins, Aminoglycosides, Erythromycin, etc. Antifungal Griseofulvin, Amphotericin B, Ketoconazole, etc. Antiviral Acyclovir, Amantadine, Zidovudine, etc. Antiprotozoal Chloroquine, Pyrimethamine, Metronidazole, Diloxanide. Anthelmintic Mebendazole, Pyrantel, Niclosamide,Diethyl carbamazine, etc.

  14. Classification on the basis of spectrum of activity Narrow Spectrum :- Effective against a limited group of bacteria. i) Gram positive :- Penicillin G, erythromycin, lincomycin, bacitracin etc. ii) Gram negative:- Streptomycin, gentamycin, polymyxin B etc. Broad spectrum :- Effective against both Gram positive & Gram negative bacteria E.g.:- Tetracyclines, chloramphenicol, fluoroquinolones, Sulfonamide.

  15. Classification on the basis of Type of action Bacteriostatic: Cause suppression of bacterial growth and multiplication. Eg.Sulphonamides,tetracyclines, erythromycin, chloramphenicol. Bactericidal: Cause death of bacteria. Eg.Penicillin,cephalosporins, streptomycin, kanamycin, colistin, bacitracin etc.

  16. Classification on the basis of Source Fungal Origin: Penicillin, Cephalosporin and Griseofulvin. Bacterial Origin: Bacitracin, Polymyxin, Colistin, tyrothricin. Actinomycetes Origin: Streptomycin, tetracyclines, chloramphenicol, Macrolides

  17. Principle of chemotherapy The basic principle of chemotherapy is the selective toxicity i,e. the drug should selectively inhibit or kill the disease causing pathogenic organism. Chemotherapy must be rational and needs to be supported by either a clinical or microbiological diagnosis to identify the pathogenic organisms. Characterization of the pathogens including its sensitivity to an AMAs is essential.

  18. Selection of an appropriate drug based on Pathogenic organism, Patient factors and Drug factors. The drug should be used in proper time, by proper route, at appropriate dose rate and for a proper duration. Attainment chemotherapeutic agent for a sufficient period at the site of infection (tissue or body fluid) is very important. of effective concentration of a

  19. Thank You

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