BASIC CHARACTERISTICS OF ANTIBIOTICS

BASIC CHARACTERISTICS OF ANTIBIOTICS

Today, there are about 4000 compounds with antibiotic properties. Antibiotics are used to treat and prevent infections, and to promote growth in animals.

Antibiotics are derived from three sources:

1: Moulds or fungi

2:  Bacteria

3: Synthetic or semi-synthetic compounds. 

They can be used either internally or externally and their functions are to either inhibit the growth of pathogens or to kill them. Antibiotics can thus be divided into Bacteriostatic drugs, which merely inhibit the growth of the pathogen, and Bactericidal drugs, which actually kill the bacteria. However, the distinction is not absolute, and depends on the drug concentration, the bacterial species, and the phase of growth.

Antibiotics are more effective against actively growing bacteria, than against non-growing spores. When two antibiotics are used in combination, the effect could be additive, synergistic, or antagonistic.

Antibiotics can also be divided into broad-spectrum and narrow-spectrum antibiotics. For example, Tetracycline, a broad spectrum antibiotic, is active against Gram-positive bacteria, and against mycobacteria; whereas penicillin, which has a relatively narrow spectrum, can be used mainly against Gram-positive bacteria. Other antibiotics, such as Pyrazinamide, have an even narrower spectrum, and can be used merely against Mycobacterium tuberculosis.

Antibiotics fight against bacteria by inhibiting certain vital processes of bacterial cells or metabolism. Based on these processes,

ANTIBIOTICS IS DIVIDED INTO FIVE MAJOR CLASSES:

1. Cell wall inhibitors, such as Penicillin and Vancomycin.

2. Inhibitors of nucleic acid synthesis, such as Fluoroquinolones, which inhibits DNA synthesis, and Rifampin, which inhibits RNA synthesis.

3. Protein synthesis inhibitors, such as Aminoglycoside.

4. Anti-metabolites, such as the sulfa drugs.

5. Antibiotics that can damage the membrane of the cell, such as Polymyxin B, Gramicidin and Daptomycin.