principles of anti microbial therapy Flashcards
what are some egs of antimicrobial agents that inhibits metabolism
sulfonamides, trimethoprim
what is prophylaxis
to prevent infection/ development of infections in highly susceptible atients
what type of treatment are there
prophylaxis, preemptive, suppressive antibiotic therapy
What is preemptive therapy
delivery of therapy prior to development of symptoms aborts impending disease, therapy fo a short and defined duration
what is suppressive antibiotic therapy
administration in the long term or indefinitely over time
what are the key determinants for successful antimicrobial therapy
susceptibility testing, understand PK of drug, know the PD of drug
what is bactericidal
bacteria that are killed at blood or urine concentration
what is bacteriostatic drugs
drugs that arrest growth and replication of bacteria at achievable and therapeutic blood concentration
What are some broad factors that can affect the PK of the drug
drug drug interaction, host factors and drug penetration
what are some factors of drug penetration
- solubility of drug
- molecular weight
- presence of specialised membrane tranporters
- specialised compartments
- protein binding in plasma
how can drug work
concentration dependent manner
time dependent manner
what do you need to ensure in a time dependent manner of killing
drug concentration above MIC
Why is there persistent post antibiotic effect
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
what is an example of antagonistic drugs
penicillin and tetracyclin
what is a disadvantage of broad spectrum AB
may kill or suppress good bacteria, promote development of superinfection caused by pathogenic drug resistant microbes
when is narrow spectrum antibiotics used
when causative organism is known, when there is a specific target molecules
what are the positives of narrow spectrum antibiotics
less potential to cause a superinfection, normal bacterial flora preserved, discourage proliferation of pathogenic drug resistant bacteria
what is the benefit of broad spectrum AB
less need to wait and identify infecting pathogen with real certainty before commencing treatment, as it can penetrate most bacteria cells
which is preferred, monotherapy or combination therapy, and why
monotherapy, to decrease risk of antimicrobial toxicity and selection of antimicrobial resistant pathogens
when do you use combination therapy
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
what could resistance be due to
○ 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
