Antibiotics: Basic Knowledge and Additional Information

Antibiotics are substances produced by microorganisms or are semi-synthetic, synthetic chemical substances that, at very low concentrations, have the ability to specifically inhibit or kill microorganisms.

Note:

• Antibiotics are not effective against viruses.

• Incorrect use of antibiotics can lead to drug resistance, more serious infections, and harm to health.

• Always follow your doctor’s instructions regarding dosage, duration of use, and other precautions.

Classification of Antibiotics:

• Specific antibiotics: Act on a particular type of bacterium or a certain group of bacteria.

• Broad-spectrum antibiotics: Active against a variety of different bacteria.

• Narrow-spectrum antibiotics: Active against 1 or a few specific bacteria.

Some examples of antibiotics and their effects:

• Treatment of Mycobacterium tuberculosis: Rifampicin

• Treatment of Salmonella – typhoid fever: Chloramphenicol

• Broad-spectrum antibiotic against Gram (-) and (+): Aminoglycoside

• Antibiotic only effective against Gram (-) bacteria except Pseudomonas aeruginosa: Quinolones 1st generation

Important Concepts:

• MIC (Minimum Inhibitory Concentration): The lowest concentration of an antibiotic that can inhibit the growth of bacteria.

• MBC (Minimum Bactericidal Concentration): The lowest concentration of an antibiotic that can kill bacteria.

Mechanism of Action of Antibiotics:

Antibiotics work by targeting essential biological processes of bacteria, including:

• Inhibition of cell wall synthesis – peptidoglycan:

• Groups of antibiotics: Beta-lactam, Vancomycin, Daptomycin, Telavancin, Fosfomycin

• Altering membrane permeability (MSC):

• Groups of antibiotics: Isoniazid, Amphotericin B, Polymycins

• Inhibition of folic acid metabolism:

• Groups of antibiotics: Sulfonamide, Trimethoprim

• Inhibition of nucleic acid synthesis:

• Groups of antibiotics: Fluoroquinolone, Rifampin

• Inhibition of protein synthesis:

• Groups of antibiotics: Tetracycline, Aminoglycoside, Macrolide, Clindamycin, Chloramphenicol, Linezolid

Substances that inhibit protein synthesis essential for bacteria:

• Bind to 50s ribosomes: Macrolide, Chloramphenicol, Linezolid

• Bind to 30s ribosomes: Tetracycline, Aminoglycoside

Mechanism of Antibiotic Resistance:

• Altering the drug target: Bacteria alter the structure of the antibiotic’s target, preventing the drug from binding and working.

• Decreased antibiotic accumulation: Bacteria reduce antibiotic absorption or increase antibiotic excretion.

• Inactivation of antibiotics by enzymes: Bacteria produce enzymes that can break down or inactivate antibiotics.

Examples of resistance mechanisms of some bacteria:

• Streptococcus pneumoniae, Staphylococcus: Alteration of the drug target.

• Bacteroides (Gram (-), anaerobic bacteria): Reduced antibiotic accumulation, production of pumps to expel antibiotics.

• Enterobacter: Inactivation of antibiotics by enzymes.

Natural resistance:

• It is a genetic property of bacteria.

• Example: E. coli and P. aeruginosa are resistant to penicillin G, Enterobacteries are resistant to macrolides, E. Coli, K. pneumonia are resistant to Vancomycin, Streptococcus are resistant to aminoglycosides.

Mechanism of action of Beta-lactam:

• Binding to PBP (Penicillin Binding Protein) -> inhibits peptidoglycan synthesis -> damage to the bacterial cell wall.

Drugs that inhibit Beta-Lactamase:

• Clavulanic acid

• Sulbactam

• Tazobactam

MSSA:

• Methicillin-susceptible Staphylococcus aureus.

Note:

• Information about antibiotics is vast and complex.

• This article only provides basic knowledge and some examples.

• Always seek information from reputable sources and consult your doctor for accurate and safe knowledge.

Additional information:

• Antibiotics can cause side effects: Each antibiotic has different side effects.

• Antibiotics are not a cure-all: Antibiotics are only effective against bacterial infections.

• Proper use of antibiotics is crucial: Using antibiotics incorrectly can lead to drug resistance, more serious infections, and harm to health.

References:

• Textbook of Microbiology (10th Edition) by Prescott, Harley, Klein

• Medical Microbiology (8th Edition) by Jawetz, Melnick, Adelberg

This draft is a bit more comprehensive, providing more details about the different types of antibiotics, their mechanisms of action, and the issue of antibiotic resistance. I also added some important notes about the responsible use of antibiotics and provided some references.

Remember to always consult with a healthcare professional for any health concerns.