Antibiotic Resistance Flashcards
List and describe the three bacterial ways of transmitting genes of resistance.
Transformation, Transduction, Conjugation.
Transformation - the uptake of naked DNA from the environment and incorporation into the genome. Must be from the same or related bacteria.
Transduction - transfer of DNA from one bacteria to another via bacteriophages, bacterial viruses. Receptor is typically conserved among highly related bacteria.
Conjugation - transfer of genetic material in the form of a plasmid from one cell to another through a pilus. Can take place between unrelated bacteria, even gram +’ve and -‘ve.
List the various ways antibiotics function.
Inhibition of:
cell wall synthesis, protein synthesis, RNA synthesis, DNA synthesis, Folic acid synthesis.
List the four main mechanisms of how bacteria become resistant.
Efflux pump, drug-inactivating enzyme change in site where antibiotic binds, decreased uptake.
How does staphlycoccus aureus confer penicillin resistance?
By a drug inactivating enzyme, beta lactamase, which is produced by the bacteria and destroys the beta lactam ring (active constituent) of penicillin.
How does staphylococcus aureus confer methicillin resistane?
Through gain of mecA gene, changes the site of the penicillin binding protein preventing the binding of beta lactam. Results in resistance to all antibiotics in the beta lactam class.
What is the definition of multi-resistant MRSA and what are the remaining treatment options?
MR-MRSA is resistant to three or more classes of non-beta lactam antibiotics. Typically healthcare related.
Limited treatment options to vancomycin, rifampicin and fusic acid, linezolid, daptoycin, tigecycline, synercid.
What is the definition of non multi-resistant MRSA and what are the typical treatment options?
NMR-MRSA remains sensitive to most non-beta lactam antibiotics. Typically community related.
Treatment options include clindamycin, doxycycline and co-trimoxazole.
What are the teo main types of gene mutation in vancomycin resistant enterococcus (VRE)?
VanA gene mutation, VanB gene mutation.
