Mechanisms of Drug Resistance Flashcards
Genetic composition of the cell undergoes spontaneous alteration by
Mutation of gene transfer
Provides a strong selective pressure in favor of the resistant cell by preventing growth of the wild-type, sensitive cells
Drug
May have mutagenic properties and non-specifically increase the probabilities of many kinds of mutation
Bacteriostatic drugs
Estimated to cause more deaths in the US than AIDs
Methicillin-resistant Staphylococcus Aureus (MRSA)
Anti-microbial resistance is more prevalent in strains that cause infections in
Hospitals
During outbreaks of infections, patients with resistant strains are more likely to have received prior
Animicrobial therapy
Areas in hospitals with highest antibiotic use have highest incidence of
Drug resistant bacteria
What are the four mechanisms by which bacteria can acquire drug resistance?
Transformation, Transduction, Conjugation, Transposition
Small pieces of DNA containing genes for drug resistance are taken up from the environment and incorporated into the genome of a drug-sensitive bacterium
Transformation
Resistance genes are transferred from one bacterium to another by a bacteriophage
Transduction
Drug resistance genes contained in a plasmid are transferred from one cell to another through a direct connection formed by a pilus
Conjugation
Allows resistance genes to move between plasmid and chromosomal (genomic) DNA
Transposition
The first biochemical mechanism of drug resistance is decreased intracellular drug level due to either
Decreased drug entry or increased drug efflux
Gm- bacteria with mutations that alter porin proteins, thereby decreasing passive drug diffusion is an example of
Decreased intracellular drug level
Resistance to tetracyclines can occur through acquisition of genes that encode an active
Efflux of the drug