Recording-2025-02-26T15:01:14.353Z

Antimicrobial Drugs Overview

• Efficacy: Refers to the antibiotic's ability to kill bacteria.

• Toxicity to Humans: Important to assess whether the antibiotic is safe for human use.

• Targets: Antimicrobial agents have specific targets in bacterial cells that differ from human cells to minimize harm to the host.

Types of Action in Antimicrobials

• Various mechanisms target bacterial differences:

  • Inhibit Cell Wall Synthesis: Prevent bacteria from forming their protective outer shell.

  • Disrupt Protein Synthesis: Block the production of proteins necessary for bacterial survival.

  • Target Nucleic Acids: Affect the DNA/RNA processes within the bacteria.

  • Interfere with Metabolic Pathways: Disrupt energy production in bacteria.

  • Alter Membrane Integrity: Affect the bacterial cell membrane.

• Study Focus: Bolded drugs and mechanisms of actions are key for understanding and review.

Specific Targets of Antibiotics

Cell Wall Synthesis

• Target: Peptidoglycan, crucial for bacterial cell wall structure.

• Bacterial Types: Both gram-positive and gram-negative bacteria have peptidoglycan, but in different amounts.

• Safety in Use: High therapeutic index allows low doses to effectively kill bacteria without harming human cells.

Categories of Cell Wall Inhibitors

1. Beta Lactams

   • Examples: Penicillins (e.g., penicillin, ampicillin)

   • Mechanism: Inhibit enzymes (penicillin-binding proteins) that cross-link peptidoglycan chains, preventing cell wall formation.

   • Action Mechanism: Block transpeptidase enzyme, inhibiting necessary bond formation in peptidoglycan.

2. Glycopeptides

   • Example: Vancomycin

   • Mechanism: Binds to amino acids in glycan, preventing cross-linking, but does not cleave bonds.

   • Gram-Positive Activity: Limited to gram-positive bacteria due to larger size, which can't penetrate gram-negative outer membranes.

Differences Between Gram-Positive and Gram-Negative

• Gram-Negative Bacteria: Have an outer membrane that protects against certain antibiotics.

• Gram-Positive Bacteria: Lack the outer membrane, making them more susceptible to cell wall-targeting antibiotics.

Implications of Antibiotic Action

• If a bacterial cell wall is compromised, the cell can leak its inner contents, leading to cell lysis.

• Spheroplast Formation: Occurs when the cell wall is inhibited, resulting in a fragile bacterial structure.

Summary of Key Antibiotics**

• Beta Lactams: Include a range of drugs such as penicillins, cephalosporins, and monobactams.

• Understanding Mechanisms: Important to differentiate between various antimicrobial mechanisms for effective study.