classification of antibacterial drugs

Classification of Antibacterial Drugs

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  • Antibacterial drugs help fight infections caused by bacteria. These medicines either kill bacteria or stop them from growing. Knowing how they work helps us use them better and avoid misuse.
  • In this blog, we explain the major classes of antibacterial drugs. We also include clinical use of AntiBacterial Drugs

Classification Based on Mechanism of Action

Antibacterial drugs are mainly classified by how they act inside the body. Each group targets a different part of the bacteria.

Let’s look at classification of antibacterial drugs

A. Drugs That Inhibit Cell Wall Synthesis

These drugs stop bacteria from building their cell wall. Without a wall, bacteria die quickly.

Common examples include:

  • Penicillins – Used for strep throat, syphilis
  • Cephalosporins – Used for skin, respiratory, and urinary infections
  • Carbapenems – Effective in serious hospital infections
  • Monobactams – Used in gram-negative bacterial infections
  • Vancomycin – Reserved for MRSA and C. difficile
  • Cycloserine – Used in tuberculosis
  • Bacitracin – Found in topical creams for skin cuts

B. Drugs That Inhibit Protein Synthesis

These stop bacteria from making proteins. Without proteins, they can’t survive or multiply.

Drugs in this class include:

  • Tetracyclines – Used for acne, Lyme disease
  • Chloramphenicol – Rarely used due to toxicity; treats meningitis
  • Erythromycin and other macrolides – Used for throat and lung infections
  • Clindamycin – Used in skin and soft tissue infections
  • Linezolid – Active against resistant bacteria like MRSA and VRE

C. Drugs That Cause Misreading of mRNA

These drugs bind to ribosomes and cause wrong protein formation. This kills the bacteria.

Main drugs:

  • Aminoglycosides – Includes streptomycin and gentamicin
    Used for serious infections like tuberculosis, sepsis, and hospital-acquired infections

D. Drugs That Cause Leakage from Cell Membranes

These break bacterial cell membranes. The contents leak out, and the bacteria die.

Examples:

  • Polymyxin and Colistin – Used for resistant gram-negative bacteria
  • Bacitracin – Also inhibits wall synthesis
  • Amphotericin B – Mainly for fungal infections but also affects some bacteria

E.Drugs That Inhibit DNA Gyrase

These drugs stop the enzyme DNA gyrase. This enzyme is essential for DNA replication in bacteria.

Main drugs:

  • Ciprofloxacin and other fluoroquinolones
    Used in urinary infections, typhoid, and gastrointestinal infections

F. Drugs That Interfere With DNA Function

These block how bacterial DNA works. Without functional DNA, bacteria can’t reproduce.

Example:

  • Rifampin – Used for tuberculosis and meningitis

G. Drugs That Interfere With Intermediary Metabolism

These drugs stop bacteria from making essential molecules for survival.

Examples:

  • Sulfonamides – Used for urinary and respiratory infections
  • Sulfones – Important in leprosy treatment
  • Trimethoprim – Often used with sulfamethoxazole
  • Pyrimethamine – Used in malaria and toxoplasmosis
  • Para-aminosalicylic acid (PAS) – Used in tuberculosis
  • Metronidazole – Used in bacterial vaginosis, dental, and gut infections

Clinical Use of Antibacterial Drugs

Antibacterial drugs treat many infections. Each drug has a specific role:

DrugCommon Use
PenicillinStrep throat, syphilis
VancomycinMRSA, C. difficile
ErythromycinPneumonia, whooping cough
StreptomycinTuberculosis
CiprofloxacinUrinary tract infections
MetronidazoleAmoebiasis, anaerobic infections
RifampinTuberculosis, meningitis prevention
Trimethoprim-SulfamethoxazoleUTIs, bronchitis

Antibiotic Resistance – A Growing Problem

Overuse of antibiotics leads to resistance. Bacteria learn how to survive the drugs. This makes treatment harder. Patients should only use antibiotics when prescribed. Always complete the full course. This prevents resistance and protects future treatments.

Reference

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