Concept of Antibiotics – This book covers the entire syllabus of “Pharmacology” prescribed by BNMC- for a diploma in nursing science & midwifery students. We tried to accommodate the latest information and topics. This book is an examination set up according to the teachers’ lectures and examination questions.
At the end of the book, previous questions are given. We hope in touch with the book students’ knowledge will be upgraded and flourish. The unique way of presentation may make your reading of the book a pleasurable experience.
Concept of Antibiotics
Antibiotics are the substances produced by some microorganisms (or by pharmaceutical chemists) that kill or inhibit the growth of other microorganisms.
Or,
Antibiotics are the chemical therapeutic agents of microbial or synthetic or semi-synthetic origin which in lower concentration inhibit the growth of other microorganisms.
Classification of Antibiotics
1. On the basis of chemical structure
2. On the basis of origin
3. On the basis of range of activity (spectrum of activity)
4. On the basis of mode of action
5. On the basis of effects of their activity
6. On the basis of route of administration
Classification of antibiotics on the basis of chemical structure:
Pure saccharides antibiotics: examples; Streptozotocin
➤ Aminoglycosides: examples; Streptomycin
➤N/O glycosides: eg. Chromomycin
➤ Other: eg; Lincomycin
➤ Macrocyclic lactone antibiotics: eg. Erythromycin
➤ Quinolones antibiotics; eg. Fluroquinolone
➤N-containing heterocyclic antibiotics: eg. Beta-lactum
➤ O-containing heterocyclic antibiotics: eg. Cycloserine
➤ Alicyclic antibiotics: eg. Cycloheximide
➤ Aromatic antibiotics (Nitrobenzene): eg. Chloramphenicol
➤ Aliphatic amine antibiotics: eg. Spermidine
➤ Peptide antibiotics: eg. Polymyxin, Bacitracin, Gramicidin
Classification of antibiotics on the basis of origin:
➤ Microbial origin:
- Bacterial origin:
✔ Bacillus polymyxa: Polymyxin
✔ Chromobacter violaceum: Bacitracin
✔ Micromonospora spp: Gentamycin
- Fungal origin:
✔ Penicillium notatum: Penicillin
✔ Cephalosporin spp: Cephalosporin
- Actimomycetes origin:
✔ Streptomyces griseus: Streptomycin
✔ S. venezuelue: Chloramphenicol
✔ S. erythreus: Erythromycin
✔ S. mediterranae: Rifampicin
✔ S. venezuelae: Chloramphenicol
➤ Semi-synthetic antibiotics:
- Examples: Amoxycillin, Ampicillin, Doxycycline, Tigecycline, Sulfonamide etc
➤ Synthetic antibiotics:
- Examples: Chloramphenicol (* it was extracted from Streptomyces venzuelae but now produced synthetically), 4-quinolones, Sulfonamide
Classification of antibiotics on the basis of range of activity (spectrum of activity)
➤ Narrow spectrum:
- Active towards relatively fewer microorganisms.
- Examples: macrolides, Polymyxin
➤ Moderate spectrum:
- Active towards Gram Positive bacteria as well as some systemic and UTI causing Gram negative bacteria.
- Examples: Aminoglycosides, Sulfonamide
➤ Narrow-Broad spectrum:
- Active against Gram positive and gram negative
- Examples: Beta-lactum
➤ Broad spectrum:
- Active against Gram positive and Gram negative except Pseudomonas and Mycobacteria.
- Examples: Chloramphenicol, Tetracycline
➤ Anti-mycobacterial antibiotics:
- Examples: Ethambutol, Rifampicin, Isoniazid, Pyrazinamide
Classification of antibiotics on the basis of Mode of action
➤ Inhibitor of cell wall synthesis/ Peptidoglycan Inhibitors:
- Examples:
✔ Beta-lactum; Penicillin
✔ Bacitracin
✔ Cycloserine
✔ Phosphomycin Cephalosporin
✔ Vancomycin
➤ Inhibitor of protein synthesis:
- Examples:
✔ Streptomycin
✔ Aminoglycosides
✔ Fusidic acid
✔ Tetracycline
✔ Mupirocin
✔ Chloramphenicol
✔ Macrolides
➤ Inhibitor of Nucleic acid synthesis:
- Examples:
✔ Quinolones
✔ Ciprofloxacin
✔ Nalidixic acid
✔ Metronidazole
✔ Nitrofurantoin
➤Inhibitor of folic acid synthesis (Folate antagonistic)
- Examples:
✔ Sulfonamide
✔ Trimethoprim
➤ Inhibitor of cytoplasmic membrane:
- Examples:
✔Polymyxin; Colistin
Classification of antibiotics on the basis of effects of their activity
➤ Bactericidal:
- Kills bacteria
- Examples: Aminoglycosides, Penicillin, Cephalosporin
➤ Bacteriostatic:
- Inhibits the growth of bacteria
- Examples: Sulfonamide, tetracycline, chloramphenicol, trimethoprim, macrolides, Lincosamide
Classification of antibiotics on the basis of Route of administration:
➤ Oral antibiotics:
- Acid stable antibiotics,
- Examples; Penicillin V
➤ Parenteral route:
- Intravenous administration
- Examples; Penicillin G
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