Test 3: antibiotics part 4 Flashcards
6 innapropriate uses of AB
use antibiotics for viral infection
use broad spectrum
use AB to make animals grow faster
use old or outdated antibiotics
not finishing antibiotics
not using correct dose
intrinisic resistance of gram negative bacteria to penicillin
penicillin works on proteins in the cytoplasmic membrane
the outer membrane prevents pencillin from getting in
The Acquisition of antibiotic resistance is usually via the—
transfer of genetic material between bacteria.
resistant bacteria give genetic info (plasmids) to other bacteria
3 ways plasmids can be transfered from one bacteria to another
conjugation (via pilus)
transduction
transformation
how does conjugation of plasmid work
- Pilus extends between bacteria
- Donor DNA strands separate
- Strand passes through Pilus
- Plasmid replicates in new host - resistance !
transformation of plasmid
Bacteria take up “free” DNA (ie. from dead bacteria)
The free DNA may encode a resistance gene
bacteriophage transduction
Viruses that specifically attack bacteria.
*Injects DNA into bacteria that incorporates into chromosome or Plasmid.
*When virus replicates host DNA may become incorporated.
*This may carry the resistance gene (e.g. transport protein).
*New bacteriophages infect new bacteria.
example of drug inactivation of bacteria that leads to resistance
some bacteria make β lacatmase to inactivate penicillin
some baceria will phophorylate or acetylate aminoglycosides to prevent them from working
example of mutation induced target modification of bacteria to prevent AB
bacteria can change shape of 50S ribosomal subunit so chloramphenicol and erythromycin can’t bind
can change 30s so aminoglycoside can’t bind
some bacteria have active efflux pumps that can pump out — antibiotics
Tetracyclines
Flouroquinolones
one way bacteria can reduce uptake of AB
can reduce size of porin so β lactam can’t get through to the cytoplasmic membrane
Antibiotics that target cell wall synthesis are:
a. Usually bacteriostatic
b. Only active against bacteria in an active growth phase
c. Only effective against Gram positive bacteria
d. Only effective against Gram negative bacteria
e. Never used in combination with other drugs.
b. Only active against bacteria in an active growth phase
usually bacteriocidal
All of the following drugs inhibit protein synthesis by targeting the bacterial ribosome EXCEPT:
a. Chloramphenicol
b. Bacitracin
c. Erythromycin (macrolide)
d. Streptomycin (aminoglycoside)
e. Lincomycin (lincosamide)
b. Bacitracin (attacks cell wall synthesis)
Prevents dephosphorylation of a Lipid carrier during glycopeptide transfer through the cell membrane required for cell wall synthesis
