Antibiotics

Question 1

What is meant by a semi-synthetic antibiotic?

Answer 1

An antibiotic that has been modified to increase efficacy

Question 2

What is meant by a broad spectrum antibiotic?

Answer 2

One that works against gram positive and gram negative bacteria

Question 3

Penicillins, cephalosporins and cephamycins are what class of antibiotics?

Answer 3

B-lactam antibiotics

Question 4

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

Answer 4

Penicillin

Question 5

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

Answer 5

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

Question 6

Which group of antibiotics has a 6 membered dihyrothiazine ring?

Answer 6

Cephalosporins

Question 7

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

Answer 7

False - same mode of action

Question 8

Are cephalosporins naturally produced or semi-synthetic?

Answer 8

Semi synthetic giving them a broader spectrum of activity

Question 9

What are B-lactamases?

Answer 9

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

Question 10

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

Answer 10

False - they are more resistant

Question 11

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

Answer 11

Aminoglycosides

Question 12

How do aminoglycosides work?

Answer 12

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

Question 13

Are aminoglycosides active against gram negative or gram positive bacteria?

Answer 13

Gram negative

Question 14

Which group of antibiotics contain sugars bonded by glycosidic bonds?

Answer 14

Aminoglycosides

Question 15

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

Answer 15

Macrolides

Question 16

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

Answer 16

False - it is a macrolide

Question 17

How do macrolides work?

Answer 17

They inhibit protein synthesis at the 50S ribosomal subunit

Question 18

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

Answer 18

True

Question 19

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

Answer 19

Macrolides

Question 20

Are tetracyclines broad spectrum or narrow spectrum antibiotics?

Answer 20

Broad spectrum

Question 21

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

Answer 21

Tetracyclines

Question 22

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

Answer 22

False - interfere with the 30S subunit

Question 23

Why do microbes require growth factors?

Answer 23

Because they cannot synthesise them

Question 24

What are growth factor analogues?

Answer 24

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

Question 25

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

Answer 25

PABA (P-aminobenzoic acid)

Question 26

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

Answer 26

Sulfanilamide

Question 27

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

Answer 27

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

Question 28

What makes Isoniazid a narrow spectrum drug?

Answer 28

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

Question 29

Quinolones are antibacterial compounds that interfere with DNA _____

Answer 29

gyrase

Question 30

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

Answer 30

False - antiviral drugs do that not antibacterial

Question 31

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

Answer 31

False - they are the most successful

Question 32

How do nucleoside analogues work?

Answer 32

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

Question 33

What do protease inhibitors do?

Answer 33

Inhibit the processing of large viral proteins into individual components

Question 34

What do fusion inhibitors do?

Answer 34

Prevent viruses from successfully fusing with the host cell

Question 35

What are interferons?

Answer 35

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

Question 36

Why do fungi pose special problems for chemotherapy?

Answer 36

Because they are eukaryotic

Question 37

What do ergosterol inhibitors do?

Answer 37

Target the unique fungal plasma membrane component ergosterol

Question 38

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

Answer 38

echinocandins - used to treat Candida infections