antimicrobial resistance 2 Flashcards
How Bacteria Become Resistant
Intrinsic resistance
Acquired resistance
Intrinsic resistance
Bacteria are naturally resistant because they lack the specific target site for the drug
Drug is unable to cross the organism’s cell wall or cell membrane and therefore cannot reach its site of action.
Acquired resistance
Where bacteria that were once susceptible to a particular drug become resistant.
Causes of antimicrobial resistance
Mutants
Microbes placed under stress (attack from antimicrobial) have the ability to reproduce using information from repair genes
mutant and prevention
As a natural part of life, mutant cells arise spontaneously at the rate of 1:1 000 000 cells.
Mutants may also arise from the transfer of genes from other microbes.
When a mutant is less susceptible to an antimicrobial agent than its parent, mutant growth is favoured during treatment.
The mutant then becomes the dominant member of the pathogen population.
Limiting antimicrobial use or using doses high enough to block mutant growth will slow the process.
Microbes placed under stress (attack from antimicrobial) have the ability to reproduce
using information from repair genes that are more prone to develop mutations as the coding does not necessarily match the original sequence.
If these mutations are growth advantaged they will become the dominant population
How bacteria become resistant
Before a drug enters a bacterial cellit must first bind to proteins on the surface of the cell
Proteins that bind to a cell
Drug binding sites
Chromosomal mutation
Affects the structure of a drug binding site can prevent the deug from binding, resulting to drug resistance
How drug enters
To enter a bacterial cell a drug myst be able to pass tgrought the cell wall and cell membrane
Chromosomal mutations may alter the structure of the cell membrane this preventibg the dryg from entering the cell this results to drug resistance
Bacteria can develop the ability to producd an enzyme that destroys or inactivates a drug
Dna strands that contain multiple genes
Resistance transfer factor
Dna strands that contain multiple genes for drug resistance and can be passed from organism to organism
Beta lactamase
Every penicillin containd a beta lactam ring
Some bacteria produce beta lactamase tgat destroy betalactan ring redering antibiotic useless
Beta lactam inhibitors
To combat beta lactamase and prevents acting on tge anyibiotic
Why does resis emerge
Microorganisms have developed a robyst system if being able to evade destruction by toxic substances
Anti microbial are produces
By microorganisms
Protective mechanism prevent entrabce or destroy tge drug