Antibiotics Flashcards

1
Q

What is meant by a semi-synthetic antibiotic?

A

An antibiotic that has been modified to increase efficacy

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2
Q

What is meant by a broad spectrum antibiotic?

A

One that works against gram positive and gram negative bacteria

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3
Q

Penicillins, cephalosporins and cephamycins are what class of antibiotics?

A

B-lactam antibiotics

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4
Q

Penicillium chrysogenum is a fungus that produces which type of antibiotic?

A

Penicillin

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5
Q

What is the mechanism of action of B-lactam antibiotics?

A

They inhibit cell wall synthesis
In bacteria, transpeptidation reaction is essential in the crosslinking of the cell wall.
Transpeptidase can also bind to B-lactam ring - the cell wall is still formed but no cross linking takes place making it weak and prone to cell lysis due to osmotic pressure

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6
Q

Which group of antibiotics has a 6 membered dihyrothiazine ring?

A

Cephalosporins

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7
Q

Cephalosporins have a different mode of action to penicillins. True or false?

A

False - same mode of action

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8
Q

Are cephalosporins naturally produced or semi-synthetic?

A

Semi synthetic giving them a broader spectrum of activity

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9
Q

What are B-lactamases?

A

Enzymes produced by bacteria that provide multi-resistance to B-lactam antibiotics

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10
Q

Cephalosporins are often less resistant to B-lactamases. True or false?

A

False - they are more resistant

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11
Q

Streptomycin, kanamycin, neomycin and gentamycin are examples of which group of antibiotics?

A

Aminoglycosides

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12
Q

How do aminoglycosides work?

A

They inhibit the protein synthesis of the 30S ribosomal subunit in bacteria

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13
Q

Are aminoglycosides active against gram negative or gram positive bacteria?

A

Gram negative

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14
Q

Which group of antibiotics contain sugars bonded by glycosidic bonds?

A

Aminoglycosides

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15
Q

Which group of antibiotics contain large lactone rings connected to sugar moieties?

A

Macrolides

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16
Q

Erythromycin is an example of an aminoglycoside. True or false?

A

False - it is a macrolide

17
Q

How do macrolides work?

A

They inhibit protein synthesis at the 50S ribosomal subunit

18
Q

Macrolides are used in patients allergic to penicillin. True or false?

A

True

19
Q

Which group of antibiotics is useful in the treatment of Legionella pneumophila?

A

Macrolides

20
Q

Are tetracyclines broad spectrum or narrow spectrum antibiotics?

A

Broad spectrum

21
Q

Which group of antibiotics has a basic structure which consists of a napthacene ring system?

A

Tetracyclines

22
Q

Tetracyclines interfere with the 50S ribosomal subunit in bacterial. True or false?

A

False - interfere with the 30S subunit

23
Q

Why do microbes require growth factors?

A

Because they cannot synthesise them

24
Q

What are growth factor analogues?

A

It is a synthetic compound that blocks the utilisation of growth factors. It has a similar structure to the growth factor, however, cannot duplicate the growth factor’s function in the cell

25
Q

Sulfanilamide is an analogue of ______ ; a component of folic acid

A

PABA (P-aminobenzoic acid)

26
Q

The synthesis of folic acid is blocked by which sulfa drug?

A

Sulfanilamide

27
Q

Do bacteria get their folic acid in the same way that eukaryotes do?

A

No - they synthesise their own whereas eukaryotes get theirs from their diet

28
Q

What makes Isoniazid a narrow spectrum drug?

A

It works against Mycobacterium only and interferes with the synthesis of mycolic acid

29
Q

Quinolones are antibacterial compounds that interfere with DNA _____

A

gyrase

30
Q

Most antibacterial drugs also target host structures, resulting in toxicity. True or false?

A

False - antiviral drugs do that not antibacterial

31
Q

The least successful antivirals are the nucleoside analogues. True or false?

A

False - they are the most successful

32
Q

How do nucleoside analogues work?

A

They block reverse transciptase (by binding directly to it) and the production of viral DNA

33
Q

What do protease inhibitors do?

A

Inhibit the processing of large viral proteins into individual components

34
Q

What do fusion inhibitors do?

A

Prevent viruses from successfully fusing with the host cell

35
Q

What are interferons?

A

Small proteins that prevent the viral multiplication by stimulating antiviral proteins in uninfected cells

36
Q

Why do fungi pose special problems for chemotherapy?

A

Because they are eukaryotic

37
Q

What do ergosterol inhibitors do?

A

Target the unique fungal plasma membrane component ergosterol

38
Q

1,3 B-D glucan synthase is inhibited by _______

A

echinocandins - used to treat Candida infections