Question

Explain the various ways that antibiotics work to inhibit bacterial growth, metabolism, and reproduction. Talk about the targets those antibiotics work on, and whether they work against gram +, gram –, or all organisms. Use specific examples of antibiotics to support your explanations. Discuss why antibiotic resistance is on the rise, and what measures can be taken to prevent this.

500 words

Answer 1

Antibiotic action against bacterial cell can be by 5 mechanisms which are:-

1) Inhibition of cell wall synthesis

2) Inhibition of protein synthesis

3) Alteration of cell membranes

4) Inhibition of nucleic acid synthesis

5) Antimetabolite activity

Inhibition of cell wall synthesis- The most commonly used mechanism.Mechanism of action is bactericidal. Egs:- Beta lactam antibiotics uses this mechanism of action by inhibiting the synthesis of proteoglycan layer of bacterial cell walls.They are effective for gram positive bacteria. Resistance to this occurs when Beta lactamase hydrolysis occurs etc.

Vancomycin disrupts the proteoglycan cross linkage.

Inhibition of protein synthesis (Translation)

They usually inhibits 30S Ribosome and 50S Ribosome

Eg. Tetracyclines blocks tRNA binding to 30S ribosome-mRNA complex which leads to bacteriostatic action

Aminoglycosides irreversibly bind to 30S ribosomal proteins leading to bacteriocidal action.

Macrolids binds to 50S ribosome and block peptide elongation.

Alteration of cell membranes

Eg: Bacitracin(topical) which disrupts the cytoplasmic membrane of bacteria.

Inhibition of nucleic acid synthesis

Eg. Quinolones inhibit DNA gyrases or topoisomerases required for supercoiling of DNA and bind to alpha subunit.

Rifampin binds to DNA-dependent RNA polymerase inhibiting initiation & Rifabutin of RNA synthesis.

Antimetabolite activity

​​​​​​Eg: Trimethoprim Inhibit dihydrofolate reductase preventing synthesis of folic acid.

For gram positive and negetive bacteria , broad spectrum antibiotics work well.

Antibiotic resistance:- It usually occurs by 2 ways

1) Through mutations that occur in the DNA of the cell during replication.

2) The other way that bacterial acquires antibiotic resistance is through horizontal gene transfer.

Some of the ways to prevent antibiotic resistance is by limited use of antibiotics, safe food preparation, hand washing , immunization etc.

Hope this outline helps you. Thank you!?