Antibiotics 3 Flashcards
Enterococci bacteria is found everywhere and can cause infection of blood and caus inflammation. true or false?
true
where are Enterococci normally found?
Normal flora in the GI and GU tract
what is the most prevalent enteroccoci bacteria found in humans?
E. faecium, E. faecalis
what types of infections are enteroccoci assoaciated with?
Primarily associated with UTI, wound infections and bacteremia, especially following surgical interventions
Enteroccoci is intrinsically less susceptible to b-lactams . TRUE OR FALSE?
TRUE
Penicillin G/ampicillin are not bacteriacidal. true ro false?
true
Cephalosporin use cannot increase the risk of enterococcal infection. true or false?
false
b-lactamases still relatively rare in Enterococci. true or false?
true
what is the mechanims of resistance with enterococci?
- Altered peptidoglycan
- PBPs that are not recognised
- decreased aminoglycoside uptake (low level resistance)
- Folate uptake
- Aminoglycosides modifying enzymes (high level resistance)
Glycopeptide resistance can be linked to thickened peptidoglycan layer in MRSA (mecA). true or false?
true
most VRE are MDR . true or false?
true
what does the structure of vancomycin contain?
- Glucose
- N-methyl leucine
what member of antibiotic family does vancomycin belong to?
- Glycopeptide
how does vancomycin work?
- Binds to the D-Ala-D-Ala in peptidoglycan precursor
- prevents transglycosylation and transpeptidation
Resistance to b-lactams does not confer cross-resistance to vancomycin. true or false?
true
what type of bateria is vancomycin active against?
- Gram positive
vancomycin can cross outer membrane of Gram –ve bacteria. true or false?
false
what type of infections does vancomycin used to treta?
- MDR Staphylococci infections
how do vancomycin resistant bacteria do gain resistance?
- Mutate the D-Ala-D-Alatermination of the pentapeptide to D-Ala-D-Lac
- Leads to loss of H-bonding
E. faecium and E. faecalis containing vanA or vanB gene clusters produce modified peptidoglycan containing D-Ala-D-lactate or D-Ala-D-Ser that does not bind vancomycin. true or false
true
VanY Band VanW sit between VanS Band VanH Bin Tn1547. true or false?
true
Describe VanA and VanH?
VanA:
- Enzyme homologous to bacterial ligase
- Catalyzes the formation of ester bonds between D-Ala and D-Lac to produce the depsipeptide D-Ala-D-Lac preferentially to the usual dipeptide D-Ala-D-Ala
VanH:
- Dehydrogenase, reduces pyruvate to D-Lac, the substrate for VanA
- Affects cross-linking of precursors to the growing peptidoglycan processed by the PBPs
describe VanX?
- D,D-dipeptidase that hydrolyzes D-Ala-D-Ala but can not hydrolyse D-Ala-D-Lac
- Prevents synthesis of precursors ending in D-Ala
vanA, vanH, and vanX resistance genes are regulated at the transcriptional level by the VanR-VanS two-component regulatory system. true or false?
true
VanZ confers low-level resistance to teicoplanin. true or false?
true
Vancomycin is no longer the drug of last resort as resistance becomes widespread, transferred horizontally to other species. TRUE OR FALSE?
TRUE
