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Year 2 intro to clinical sciences > Antibiotics > Flashcards

Antibiotics Flashcards

1
Q

What is an antibiotic?

A

Antibiotics are molecules that work by binding a target site on a bacteria

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2
Q

what class of antibiotic is penicillin

A

B lactam

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3
Q

List some B lactam antibiotics

A

penicillin derivatives

cephalosporins and cephamycins

monobactams

carbapenems and carbacephems

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4
Q

what does the antibiotic polymyxin work on

A

Cell Membrane

Treats gram negative infections, last line of antibiotics, narrow spec

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5
Q

What are the classes of antibiotics that work on 30s

A

Tetracyclines
Aminoglycosides

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6
Q

What are the classes of antibiotics that work on 50s

A

Macrolides
Clindamycin
Linezolid
Chloramphenacol
Streptogramins

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7
Q

what are the classes of antibiotics that work on RNA polymerase

A

Rifampin

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8
Q

What are the classes of antibiotics that work on DNA gyrase

A

Quinolones

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9
Q

What are the classes of antibiotics that work on folalte synthesis

A

Sulfonamides
Trimethoprin

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10
Q

What type of antibiotics are Vancomycin +
Teicoplanin

A

Glycopeptides

Treat beta lactam resistant gram +ve bacteria

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11
Q

Describe how Beta lactam antibiotics
work

A
  • disrupt peptidoglycan production
  • bind covalently and irreversibly to Penicillin Binding Proteins (PBP’s)
  • To bind to the PBPs, the β-lactam antibiotic must first diffuse through bacterial cell wall
  • Gram -ve have an LPS layer that decreases antibiotic penetration
  • cell wall is disrupted and lysis occurs
  • results in a hypo-osmotic or iso-osmotic
  • Active only against rapidly multiplying organisms
  • Differences in broad vs narrow spectrum are due to affinity for PBPs

gram +ve more susceptible to β-lactams than gram-negative bacteria

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12
Q

Briefly describe what a bactericidal antibiotic is

A
  • Kills 99.99% bacteria
  • Inhibits cells wall synthesis

-usually beta lactams
-good for needing to get rid of bacteria quickly (meningitis)

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13
Q

Briefly describe what a bacteriostatic antibiotic is

A

*inhibit growth
*Inhibit protein synthesis, DNA replication or metabolism

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14
Q

How do bacteria become resistant to Penicillins and cephalosproins

A

Both types of antibiotic contain a beta lactam ring

Beta-lactamase hydrolysis this ring and the antibiotic and now unable to bing to the PBP’s

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15
Q

Why do bacteria develop resistance?

A

*Intrinsic - Naturally resistant

*Extrinsic - Naturally acquired through spontaneous gene mutation or horizontal gene transfer (conjunction, transduction, transformation)

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16
Q

what are the two major determinants of anti bacterial effects

A

concentration and the time

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17
Q

Describe intrinsic bacterial resistance.

A

D

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18
Q

Briefly describe Horizontal gene transfer: Transduction with and example.

A

*Insertion of DNA by bacteriophages
*mecA genes for MRSA

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19
Q

Briefly describe horizontal gene transfer: Conjugation and and example.

A

*Sharing of extra chromosomal DNA plasmids
*New Delhi metallo-B-lactamase

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20
Q

Briefly describe horizontal gene transfer: Transformation and example

A

*foreign DNA from S. mitis to S. pneumoniae, conferring penicillin resistance

21
Q

What does MRSA stand for

A

Methicillin resistant Staphylococcus aureus

22
Q

What is MRSA resistant to

A

resistance to all β-lactam antibiotics in addition to methicillin

23
Q

what does VRE stand for

A

vancomycin-resistant enterococci

24
Q

How did MRSA become resistant to antibiotics

A
  • transduction - Bacteriophage mediated acquisition of Staphylococcal cassette chromosome mec (SCCmec)
    containing resistance gene mecA

*encodes penicillin-binding protein 2a (PBP2a)

25
How did VRE become resistant to antibiotics
*Plasmid-mediated acquisition of gene encoding altered amino acid on peptide chain preventing vancomycin binding *Promoted by cephalosporin use
26
What gram is MRSA
+VE
27
What gram is VRE
+ve
28
What gram is ESBL
-VE
29
What does ESBL stand for
extended spectrum beta lactamase (ESBL)
30
what gram bacteria do Vancomycin and Teicoplanin treat
+ve only
31
whe should you use vancomycin and teicoplanin?
*Gram-positive bacteria resistant to beta-lactams *when the patient is allergic to penicillin
32
which classes of antibiotics work on cell wall synthesis
B lactams Vancomycin Bacitracin
33
Which classes of antibiotics work on nucleic acid synthesis
*Rifampin working on RNA pol *Quinolones working on DNA gry *Sulfonamides Trimethoprin working onFolate synthesis
34
what cells can beta-lactams not enter?
*Eukaryotic cell Beta lactams arent so useful for bacteria that can enter euk cells
35
which antibiotics work on protein synthesis
*Tetracyclines and aminoglycosides working on 30s *macrolides clindamycin etc working on 50s
36
what are some consequences (bodily) of antibiotics
Direct- destroy phagocytes cells which bacteria replicate Indirect - inflammation Diarrhoea Toxins- exotoxin (protein product) and endotoxin ( gr -ve)
37
The amount of antibiotic needed is called .....
minimum inhibitor conc (MIC)
38
what is used to treat staph aurious
Flucloxacillin
39
why cannot vancomyocin treat gram negative
Cannoy penetrate the cell membrane.
40
what are some things to consider when prescribing antibiotics
*Drug interactions *risk of c diff *pregnancy *Allergies *age *Renal and liver function
41
gram +ve and catalyse +ve =
Staph coccus
42
gram +ve and Catalase -ve =
Strep coccus
43
Streptococcus when undergoing haemolysis on blood agar if beta will be .....
Group A C G
44
Streptococcus when undergoing haemolysis on blood agar if alpha will be .....
tested with optochin and if sensitive will be Streptococcus pneumoniae
45
What are A C G groups of s. aurius
Flucloxacillin
46
Why cant you treat a CNS infection with vancomycin
Vancomycin does not effectively cross the blood-brain barrier.
47
what could you use to treat necrotizing facsch
Clindamycin
48
which gram negative use lactose as a food source
Klebs, e.coli
49

Year 2 intro to clinical sciences (46 decks)

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