Chapter 5 Flashcards
(12 cards)
What’s selective toxicity?
The principle that antibiotics aim to kill organisms but cause no harm to the patient.
What type of antibiotics inhibit the late steps of cell wall synthesis? And which ones inhibit the early steps?
Beta lactams inhibit the late steps while glycopeptides and cycloserine inhibit the early steps.
What antimicrobial drugs interfere with cell membrane function?
Antibacterial like polymixins and colistin and antifungals like amphotericin b and imidazole.
Which antibiotics act on 30S unit and which act on 50S unit?
On 30S: tetracycline and aminoglycosides.
On 50S: macrolides and chloramphenicol.
Transposons cause MRSA and tetracycline resistant neisseria gonorrhea. Yes or No?
Yes.
Mention 2 extended-spectrum beta-lactamases.
CTX-M and AmpC.
Why are some bacteria naturally resistant to some antibiotics?
Because their cell envelope is impermeable to that antibiotic.
How does mecA cause resistance?
It encodes an alternative penicillin binding protein that isn’t inhibited by methicillin.
When does resistance to methicillin occur?
If the penicillin binding site on the bacterium cell wall is changed due to mutation in transpeptidase which causes MRSA.
What’s the difference between group and 2 beta lactamases and group 3 and 1?
Group 2 can be inhibited by clavulanic acid while group 1 and 3 cannot.
Which group of beta lactamases does AmpC fall into?
Group 1.
ESBLs fall into which group of beta lactamases?
They fall into group 2b and 2d.
