Q.'Antibiotics, antiseptics and disinfectants are antimicrobial drugs.' Explain any one of the above mentioned drugs with examples. (Scores : 3)

Antibiotics are chemotherapeutic agents that kill or stop the growth of disease-causing microorganisms by interfering with their vital biochemical processes; penicillin is the classic example.

Antibiotics

Antibiotics are chemical substances, produced wholly or partly by chemical synthesis, which in low concentrations either kill (bactericidal) or inhibit the growth of (bacteriostatic) disease-causing microorganisms (usually bacteria), by interfering with a process essential to the microbe (e.g. blocking cell-wall synthesis, protein synthesis, or DNA replication) without significantly harming the host's own cells.

• Bactericidal antibiotics kill the microorganism directly - examples: penicillin, ofloxacin, and the aminoglycosides (streptomycin, gentamicin).
• Bacteriostatic antibiotics only stop the microorganism from multiplying, relying on the body's own immune system to clear the infection - examples: erythromycin, tetracycline, chloramphenicol. Antibiotics are further classified by their range of action: broad-spectrum antibiotics (e.g. ampicillin, amoxicillin) are effective against a wide range of both gram-positive and gram-negative bacteria, while narrow-spectrum antibiotics act against a single organism or a limited group (e.g. penicillin G, effective mainly against gram-positive bacteria). …