Anti-microbials

Question 1

define ‘antibiotic’

Answer 1

substance produced from a MO that kills or inhibits other MO’s

Question 2

define ‘antibacterial’

Answer 2

synthetic agents which have activity against bacteria

Question 3

define anti-microbial

Answer 3

any substance, natural, synthetic, semi-synthetic that kills or inhibits growth of a MO

Question 4

define ‘selective toxicity’

Answer 4

exploiting the biochemical differences between the invading organism and the host to reduce the toxic effect on the host

Question 5

what are the 4 mechanisms of anti-micorbial action?

Answer 5

1. disrupt cell wall formation
2. disrupt metabolic processes
3. disrupt protein synthesis
4. disrupt bacterial DNA

Question 6

define ‘bacteriostatic’

Answer 6

stops bacterial growth but does not kill the bacteria

Question 7

define ‘bactericidal’

Answer 7

cause bacteria to lyse. phagocytes mop up the debris.

Question 8

describe what happens due to disruption of cell wall

Answer 8

• prevent cross-linking and peptide side chain formation, weakens wall
• pressure from inside cell causes membrane to rupture and cell to lyse

Question 9

describe what happens due to disruption of metabolic pathways

Answer 9

• mainly bacterial folic acid pathway
• inhibits synthesis of nucleotides

Question 10

describe what happens due to disruption of proetin synthesis

Answer 10

acts on bacterial ribosome to prevent/inhibit protein synthesis

Question 11

give 4 examples of drugs that work by disrupting protein synthesis

Answer 11

1. tetracyclines - bacteriostatic
2. aminoglycosides - bacter​iocidal - add nonsense AA into peptide chain
3. chloramphenicol - bacteriostatic - cleave AA chain and form truncated proteins
4. lincosamides/macrolides - bacteriostatic - prevent movement of tRNA from site A to site P

Question 12

give 3 examples of drugs that work by disrupting nucleic acids

Answer 12

1. fluroquinolones - inhibit DNA gyrase
2. rifampacin - inhibits RNA polymerase
3. nitroimidazoles - destroys/damages DNA