Antibiotics

AntibioticsDefinition, Classes etc.

Antibiotics, Chemotherapeutic agents, anti-infective drugs,

antimicrobial drugs

• Obtained from other microorganisms e.g. bacteria, fungi etc.

OR

• Produced/derived from microorganisms used to suppress the growth or to kill the other microorganisms

NOTE: All antibiotics are chemotherapeutic agents but not all chemotherapeutic agents are antibiotics.

Principle/Base of chemotherapy

• Known as “concept of selective toxicity”.

• Proposed by a scientist “Paul Ehrlich” in 1909. He is now a days considered as “founder of chemotherapy”.

• For the first time, he treated STD i.e. “syphilis” caused by “Treponema pallidum” by using “arsphenamine” or (salvarsan ).℞

• Biochemical difference between microbial cells and human cells provided base for chemotherapy.

Classes of antibiotics

1. Type (1) Nature of microbes/microorganisms

2. Type (2) Mechanism of action

3. Type (3) Nature of spectrum

4. Type (4) Chemistry/chemical structure

5. Type (5) Nature of action

6. Type (6) Source

Type (1) Nature of microbe/microorganisms

a. Antibacterial therapy

b. Antifungal therapy

c. Antiviral therapy

d. Antiparasitic therapyi. Antimalarial drugs

ii. Antiamoebic drugs

e. Antihelminths/ anthelmintic therapy

Type (2) Mechanism of action

a. Cell wall synthesis inhibitors

b. Cell membrane disruptor

c. Protein synthesis inhibitors

d. Folic acid synthesis inhibitors/ folate antagonists

e. DNA, Nucleic acid synthesis/function inbitors

a. Cell wall synthesis inhibitors

BC

• Beta lactam drugs.

• Caspofungins

b. Cell membrane disruptor

APP

• Azole drugs

• Polyene drugs

• Polymyxin B

c. Protein synthesis inhibitors

• 30s ribosomal subunit inhibitor:

AT

• Aminoglycosides

• Tetracyclins

• 50s ribosomal subunit inhibitor:

LCM LS

• Lincosamides

• Chloramphenicol

• Macrolides

• Linezolid

• Streptogramin

d. Folic acid synthesis inhibitor/folate antagonist

PTS

• Pyrimethamine

• Trimethoprim

• Sulphonamides

e. DNA, Nucleic acid synthesis/function Inhibitors

• Flouroquinolones

• Quinolones

• Anti malarial

• Anti TB

• Anti parasitic

Type (3) Nature of spectrum

a. Very narrow spectrum

b. Narrow spectrum

c. Extended Spectrum

a. Very Narrow Spectrum

• Penicillinases

• Anti staphyloccal drugs

b. Narrow Spectrum

• Penicillin G (Benzyl Penicillin)

c. Extended Spectrum

• Wide Spectrum:

ACA

• Ampicillin

• Clarithromycin

• Azithromycin

• Broad Spectrum:

TC

• Tetracycline

• Chloramphenicol

Type (4) Chemistry/ Chemical Structure

1. ß-lactam antibiotics e.g. penicillin, cephalosporin, carbopenems, monobactam

2. Sulphonamindes

e.g.Sulfacetamide,

sulfadoxine etc.

3. Tetracyclines e.g.

Oxytetracyclines, Rolitetracyclines

etc.

4. Nitrobenzene derivatives e.g.

Chloramphenicol etc.

5. Macrolide e.g.

Erythromycin, clarithromycin

etc.

6. Polyene antibiotics e.g.

Nystatin, amphotericin B

etc.

7. Azole antibiotics e.g.

Diazole (Clotrimazole,

Metronidazole), Triazole etc.

8. Polypeptides e.g. Polymyxin B

9. Glycopeptides e.g. vancomycin

Type (5) Nature of action

a. Microbiostatic

b. Microbicidal

a. Microbistatic

• Bacteriostatic:

TCS

• Tetracyclines

• Chloramphenicol

• Sulphonamides

• Fungistatic:

AG

• Azole drugs

• Griseofulvin

b. Microbicidal

• Bactericidal:

FB

• Fluoroquinolones

• Beta lactam drugs

• Fungicidal:

• Amphotericin B

Type (6) Source

a. Microbiological origin

b. Semisynthetic

c. Synthetic

a. Microbiological origin

• Fungi:

• E.g. Penicillium species

• Bacteria:

• E.g. Bacillus species (Bacitracin)

• Soil:

• Streptomycetes, actinomycetes e.g.

TMC

• Tetracyclines

• Macrolides

• Chloramphenicol

b. Semi Synthetic

AC

• Aminopenicillin (amoxicillin)

• Cephalosporins (Ceftriaxone)

c. Synthetic

SF

• Sulphonamides (co trimoxazole)

• Fluoroquinolones (Ciprofloxacin)

• Certain anti TB

• Certain Antimalarial