principles of anti microbial therapy

Question 1

what are some egs of antimicrobial agents that inhibits metabolism

Answer 1

sulfonamides, trimethoprim

Question 2

what is prophylaxis

Answer 2

to prevent infection/ development of infections in highly susceptible atients

Question 3

what type of treatment are there

Answer 3

prophylaxis, preemptive, suppressive antibiotic therapy

Question 4

What is preemptive therapy

Answer 4

delivery of therapy prior to development of symptoms aborts impending disease, therapy fo a short and defined duration

Question 5

what is suppressive antibiotic therapy

Answer 5

administration in the long term or indefinitely over time

Question 6

what are the key determinants for successful antimicrobial therapy

Answer 6

susceptibility testing, understand PK of drug, know the PD of drug

Question 7

what is bactericidal

Answer 7

bacteria that are killed at blood or urine concentration

Question 8

what is bacteriostatic drugs

Answer 8

drugs that arrest growth and replication of bacteria at achievable and therapeutic blood concentration

Question 9

What are some broad factors that can affect the PK of the drug

Answer 9

drug drug interaction, host factors and drug penetration

Question 10

what are some factors of drug penetration

Answer 10

1. solubility of drug
2. molecular weight
3. presence of specialised membrane tranporters
4. specialised compartments
5. protein binding in plasma

Question 11

how can drug work

Answer 11

concentration dependent manner
time dependent manner

Question 12

what do you need to ensure in a time dependent manner of killing

Answer 12

drug concentration above MIC

Question 13

Why is there persistent post antibiotic effect

Answer 13

it is not really because there is residual effect of antibiotics, but more of the time taken for bacteria to restore and recover

Recovery from PAE induced by aminoglycoside tobramycin in E coli dependent on re establishment of protein synthesis, and recovery from ciprofloxacin induced PAE depends on restoration of DNA synthesis

Question 14

what is an example of antagonistic drugs

Answer 14

penicillin and tetracyclin

Question 15

what is a disadvantage of broad spectrum AB

Answer 15

may kill or suppress good bacteria, promote development of superinfection caused by pathogenic drug resistant microbes

Question 16

when is narrow spectrum antibiotics used

Answer 16

when causative organism is known, when there is a specific target molecules

Question 17

what are the positives of narrow spectrum antibiotics

Answer 17

less potential to cause a superinfection, normal bacterial flora preserved, discourage proliferation of pathogenic drug resistant bacteria

Question 18

what is the benefit of broad spectrum AB

Answer 18

less need to wait and identify infecting pathogen with real certainty before commencing treatment, as it can penetrate most bacteria cells

Question 19

which is preferred, monotherapy or combination therapy, and why

Answer 19

monotherapy, to decrease risk of antimicrobial toxicity and selection of antimicrobial resistant pathogens

Question 20

when do you use combination therapy

Answer 20

to prevent resistance to mono therapy, to accelerate microbial kill. For synergistic interaction. When you need to reduce toxicity by administering lower doses.

For eg Antiretroviral therapy to treat HIV

Question 21

what could resistance be due to

Answer 21

○ Enhanced export of antibiotic by efflux pump
○ Release of microbial enzyme that destroy antibiotic
○ Alteration of microbial protein that transform pro drugs to effective moieties
○ Alteration of target protein
○ Development of alternative pathways to those inhibited by the antibiotic