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Pharmacy stage 4 > Cell wall synthesis inhibitors: Penicillins > Flashcards

Cell wall synthesis inhibitors: Penicillins Flashcards

1
Q

What do all beta-lactams have in common?

A

The beta-lactam ring in their structure

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2
Q

What are bacterial cell walls made of?

A

Peptidoglycan or muerin

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3
Q

What are peptidoglycan made of?

A

Long strands of amino polysaccharides running in parallel. Also made of segments of NAG and NAM in alternating pattern to make a long chain

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4
Q

What protrudes from the peptidoglycan chain?

A

At the tips of the NAM subunits are tetrapeptide and pentapeptide chains, protruding from NAM subunits.

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5
Q

What is the role of the peptide chains that protrude from the NAM subunits?

A

They link other peptide chains from neighbouring strands through transpeptidation

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6
Q

What enzyme is responsible for transpeptidation?

A

PBP- penicillin binding proteins

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7
Q

How do beta-lactams distrupt the cell wall synthesis?

A

They have a similar structure to the tetrapeptide chains, so the PBP enzyme mistakenly binds to the beta-lactam molecule which disables the enzyme meaning the cell wall becomes weak and unstable

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8
Q

What happens to the bacteria if tries to multiply after a beta-lactam is introduced?

A

The cell wall will collapse- killing the bacteria

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9
Q

How has MRSA developed to resist beta-lactams?

A

It developed an enzyme called beta-lactamase which breaks down the beta-lactam ring in the antibiotic, disabling it

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10
Q

How has the development of beta-lactamase been tackled?

A

By adding a beta-lactamase inhibitor such as clavulanic acid. Or development of a new antibiotic called methicillin which has a large side chain that does not fit in beta-lactamase

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11
Q

How did MRSA further develop to be resistant?

A

It change the active site shape of the PBP enzyme so even if beta-lactamase did not work, the antibiotic can not fit in PBP

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12
Q

What have we resorted to, to treat MRSA?

A

Reserved antibiotics belonging to the glyco-peptide antibiotics like vancomyocin and teicoplanin

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13
Q

What are some examples of narrow spectrum penicillins?

A

Penicillin G or Benzylpenicillin sodium (IV) and Penicillin V or phenoxymethylpenicillin (PO)

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14
Q

What are narrow spectrum penicillins still used for?

A

Common gram positive bacteria: streptococcus pyogenes (pharyngitis)

Gram negative bacteria: neisseria meningitidis (bacterial meningitis)

Spirochetes: teponema pallidum (syphilis) or borrelia burgdorfei (Lyme disease)

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15
Q

Are narrow spectrum penicillins susceptible to beta latctamase?

A

Yes

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16
Q

What bacteria are resistant to narrow spectrum penicillins?

A

A lot of gram-ngeative aerobes and some bacteria they used to treat like: S.aureus, Streptococcus pneumonia and neisseria gonorrhoeae

17
Q

What are examples of broad spectrum beta-lactamase susceptible medication?

A

Amoxicillin and ampicillin

18
Q

What bacteria are broad spectrum beta-lactam antibiotics effective against?

A

Wider range of gram negative e.g.:
-Haemophilus influenzae, moraxella catarrhalis (cause resp infections and pneumonia)
-H.pylori
-Salmonella shigella and listeria (diarrhoea)
(and the same gram positive treated by penicillin but they are less potent)

19
Q

Why is listeria particularly bad in pregnancy and babies?

A

It can lead to meningitis

20
Q

What pregnancy category are these class of antibiotics?

A

Category B, meaning no risks found in pregnancy

21
Q

Which antibiotic is particularly used in pregnancy?

A

Amoxicillin

22
Q

What are some examples of extended spectrum pencillins?

A

Piperacilin and ticarcillin

23
Q

What are extended spectrum penicillins most notably effective against?

A

Pseudomonas aeruginosa

24
Q

What are very narrow spectrum beta-lactamase resistant medication?

A

They are antibiotics made to fight bacteria like S.aureus and S.epidermis. They are also known as antistaphyloccocal penicillins.

25
Q

How are very narrow spectrum beta-lactamase resistant medication able to avoid being broken down by beta-lactamase?

A

They have a large side chain that prevents them from fitting in beta lactamase

26
Q

How did MRSA overcome the large side chain problem?

A

It developed a different active site change for PBP

27
Q

What are some exmaples of very narrow spectrum beta-lactams?

A
  • Methicillin
  • Oxacilin
  • Nafcillin
  • Cloxacilin
  • Dicloxacillin
28
Q

What are some common SE of penicillins?

A
  • GI upset
  • Diarrhoea
  • Taste disturbances
29
Q

How can an allergy to penicillin manifest?

A

A simple case of uriticaria with pruitus up to fever, joint pains, hemolytic anemia, kidney failure and anaphylactic shock

Pharmacy stage 4 (4 decks)

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