Antibiotics and Bacterial Resistance - lect 18

Flashcards covering key vocabulary and concepts from a lecture on antibiotics, their mechanisms of action, and how bacteria develop resistance.

Valinomycin

A compound isolated from bacteria that is toxic to other bacteria, particularly effective at chelating potassium ions, leading to cell equilibrating and cell death.

Polymyxin B

A compound isolated from bacteria, contains unusual amino acids and a long fatty chain, anchors into the cell membrane causing leakage of small molecules, which can be tolerated by humans.

Bacterial Ribosomes

Differ enough from human ribosomes that they can be targeted with compounds that won't affect human ribosomes, interfering with the process of translation.

Bill Clemmons

Based at Caltech, did a lot of work in elucidating the structure of ribosome subunits and making it a potential target for a number of antibiotics.

Aminoglycosides

Carbohydrate-based compounds with nitrogen replacements, showing good activity against gram-negative bacteria. They are protonated around neutral pH to help transport in the membrane of gram-negative bacteria.

Lipinski's Rule

Generally, aminoglycosides are not great based on this rule. They have too many hydrogen bond donors and acceptors, which is not good for bioavailability.

Anionic Sites

Phosphate groups where protonated amino acids can form good ionic pairs with these phosphate groups, interfering with the ribosome-mRNA interaction.

Bacterial Resistance

Bacteria develop resistance by acetylating amines with enzymes or phosphorylating hydroxide groups in sugars, preventing protonation or causing repulsion.

Tetracyclines

Broad-spectrum antibiotics that work against both gram-positive and gram-negative bacteria, inhibiting protein synthesis by preventing tRNA from binding on the ribosome.

Tetracycline Structure

Four fused rings with a hydrophobic top half and a hydrophilic edge, with a precise array of hydrogen bonds essential for its activity.

Bacterial Immunity to Tetracyclines

Bacteria resist by developing efflux pumps to expel the molecules or through ribosome mutation, reducing complementarity.

Chloramphenicol

An antibacterial compound, originally isolated from a microorganism, broad-spectrum, but toxic to humans. It conjugates to glucuronic acid.

Bacterial Resistance to Chloramphenicol

Bacteria develop resistance by acylating a hydroxy group, which is necessary for chelating to potassium ions.

Gene Transfer

The process by which bacteria can evolve and become more resistant.