Antimicrobial Drug interaction

Question 1

Combination of the use of Antimicrobial drug may produce a different effect from that achieved by the individual drugs used separately such as;

Answer 1

✓ indifference
✓ additive
✓ synergism
✓ antagonism

Question 2

where the combined action is no greater than that of the more effective drug used alone

Answer 2

indifference

Question 3

where the combined action is equivalent to the sum of the actions of each drug when used alone

Answer 3

additive

Question 4

where the combined action is significantly greater than the sum of both effects

Answer 4

synergism

Question 5

where the combined action is less than that of the more effective agent when used alone

Answer 5

antagonism

Question 6

example of antagonism

Answer 6

✓ bacteriostatic drugs (chloramphamicol and tetracycline)
✓ bactericidal drugs (penicillin or an aminoglycosides)

Question 7

Forms of Antimicrobial synergy

Answer 7

✓ two drugs may sequentially block a microbial metabolic pathway
✓ one drug may prevent the inactivation of a second drug by microbial enzymes
✓ one drug may promote the uptake of a second drug thereby increasing the overall antimicrobial effect
✓ one drug may affect the cell membrane and facilitate the entry of a second drug
✓ a drug combination may also prevent the emergence of resistant populations

Question 8

considerations when administering two antimicrobials drugs

Answer 8

1. drugs are not antagonistic to each other
2. treatment of mixed bacterial infection
3. treatment of severe infections of uncertain aetiology
4. use of synergistic combinations with documented efficacy against specific infections

Question 9

the inherent disadvantages in combine antimicrobial treatment regimens such as;

Answer 9

✓ additive toxic effect from the drugs used
✓ an increased risk of superinfection with overgrowth of fungi
✓ resistant bacteria and a danger of enhanced spread of R plasmids