L35 Antibiotics and Resistance

Flashcards covering key vocabulary and concepts related to antibiotics, their mechanisms of action, and antibiotic resistance.

Selective Toxicity

The ability of an antibiotic to harm bacterial cells without harming the host cells.

Paul Ehrlich's concept

By observing that some dyes stain microbes better than others, he comes up with idea of a chemical 'magic bullet' to kill microbial cells but not the host's cells (selective antibiotic).

Alexander Fleming (1928) Penicillin

Observed that colonies of Staphylococcus bacteria could be destroyed by the mould Penicillium notatum.

How Penicillin works

Interfering with the normal formation of the bacterial cell wall by inhibiting the formation of peptidoglycan cross-links (peptide cross-bridge).

How selective toxicity of antibiotics target bacteria and not host

Eukaryotic DNA Pol, RNA Pol, ribosomes, plasma membrane, are different from those of bacteria, this difference helps in targeting .

Beta Lactamase

Enzyme produced by bacteria and used to destroy (chew up) penicillin. Breaks bond in B-lactam ring of penicillin to disable molecule. Bacteria with this enzyme resists effects of penicillin and other B-lactam antibiotics.

Antibiotics on different cell components

Bacterial cell components targeted by different classes of antibiotics.

Antibiotic Resistance: Selection of Mutants

A proportion of bacterial population gains resistence to antibiotic X by mutation, some bacteria with resistance survive. Then they multiply passing on resistance, which survives subsequent encounters with antibiotic X.

Antibiotic resistence: Vertical Gene Transfer

Transfer of genes from parent to offspring.

Antibiotic resistence: Horizontal Gene Transfer

Transfer of genes between bacteria that are not parent and offspring (e.g., through plasmids).

Reducing antibiotic resistance spread requires

Completing prescribed courses, avoiding inappropriate use for viral infections, implementing combination therapies to prevent resistance emergence, and developing new targets and resistance-blocking molecules.