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Flashcards in Final Exam Deck (146)
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1

Cell wall synthesis inhibitors

Glycopeptides/lipopeptides- includes
vancomycin, daptomycin and teichoplanin

2

b-lactam antibiotics-

The four main
types are penicillins, cephalosporins,
carbapenams, and monobactams.

3

can function as a
barrier to certain antibiotics.

outer membrane

4

Porins-

proteins in the OM of Gram-
negatives that allow diffusion of nutrients
and other molecules.

5

how does outer membrane become antibiotic resistant?

mutations in porin genes limit permeability of small molecules like antibiotics

6

can function as a barrier (relatively rarely) to antibiotics

cytoplasmic membrane

7

_______ are composed of
membrane proteins that use energy to
pump small molecules out of the
bacterial cytoplasm.

efflux pumps

8

Two types of efflux pumps:

antiporters and
ABC transporters.

9

What 3 general ways can bacteria be resistant to antibiotics?

1. limiting the antibiotic's access
2. enzymatic inactivation of the antibiotic
3. modification or protection of the antibiotic target

10

enyzmes that cleave the
b-lactam ring of b-lactam antibiotics

b-lactamases

11

chloramphenicol acetyltransferases will add _____ to chloramphenicol, preventing it from ______

acetyl groups
binding to the 23s rRNA in the 50s subunit

12

examples of enzymatic inactivation of antibiotics are B-lacamases, _________ and ________

Aminoglycoside-modifying enzymes, Chloramphenicol and streptogramin
acetyltransferases

13

modification of b-lactams target occurs by-

alteration of the transpeptidase or
one of the other penicillin-
binding proteins (PBPs) in the cell.

14

what gene in Staph aureus encodes a modified PBP2?

mecA

15

Resistance to glycopeptide
antibiotics involves alteration of-

the peptide portion of peptidoglycan.

16

Bacteria resistant to glycopeptide antibiotics can have 3 enzymes that work together to confer resistance. name them and tell how they cause resistance:

VanH catalyzes conversion of pyruvate to D-lactate
VanA or B leads to formation of D-Ala-D-lactate instead of D-Ala-D-Ala (vancomycin's target)
VanX cleaves any D-Ala-D-Ala that might have formed

17

Resistance to tetracycline involves-

“ribosome protection” or alteration
of the ribosome

18

Resistance to macrolides,
streptogramins, and lincosamides involves-

RNA methylases add a methyl group(s)
to 23S rRNA (part of 50S subunit)

19

Resistance to quinolones, rifampin,
and streptomycin (an aminoglycoside) involves-

alterations (through mutation) of the
particular target of the antibiotic

20

Resistance to trimethoprim and
sulfonamide involves-

alterations (through mutation) of the enzymes in the tetrahydrofolate biosynthesis pathway.

21

resistance genes are regulated by: (3)

repression, translational attenuation, activation

22

name the way in which each gene is regulated:
tetB-
erm-
blaZ-
ampC-
vanH/A/X-

-repression
-translational attenuation
-repression
-activation
-activation

23

what does each of these genes encode:
tetB-
erm-
blaZ-
ampC-
vanH/A/X-

-TetB efflux pump
-RNA methylase
-b-lactamase
-b-lactamase
-vancomycin resistance

24

the 3 general mechanisms for horizontal gene transfer:

transformation, transduction, conjugation

25

what region of the F plasmid encodes conjugation proteins?

tra region

26

what is the origin of transfer in the F plasmid?

oriT

27

name the 5 general characteristics of plasmids:

Extrachromosomal
Replicate autonomously
Most are circular
Often contain resistance genes
May be self-transmissible or mobilizable

28

the plasmid R100 transfers via conjugation among which species?

Escherichia, Klebsiella, Proteus, Salmonella, and Shigella species

29

the resistance plasmid R100 confers resistance to what?

mercury, sulfonamide, streptomycin, chloramphenicol, tetracycline

30

what two ways does multi-drug resistance arise in bacteria?

1) A single mechanism that confers
resistance to multiple antibiotics
(e.g., multi-drug efflux pump).

2) Acquisition of a plasmid or other
conjugative genetic element that
contains multiple resistance genes.