Intro to Antimicrobial drugs Flashcards
facts about the human microbiome
1 in 10 cells in the body are human
1-3 pounds of your total body weight is microbes
more than 3.3 million genes are bacterial only 22,000 are human
antibiotic
a low molecular substance produced by a microorganism that inhibits or kills other microorganisms while causing little or no damage to itself
antimicrobial
is any substance of natural, semisynthetic,, or synthetic origin that kills or inhibits the growth of microorgansims while causing little or no damage tot he host
T/F all antibiotics are antimicrobials, not all antimicrobials are antibiotics
true
T/F a drugs spectrum of action is not the same as its useful therapeutic range
true
is there a antimicrobial that is effective against all microbes?
nope
disc diffusion test
estimates the minimal inhibitory concentration of antimicrobials (MIC)
what is the MIC
it is the minimum concentration of an antibiotic that will inhibit the growth of a bacterial strain
broth dilution test
- determines both MIC and MBC (minimum bactericidal concentration).
- look at broth tubes for lack of turbidity=MIC
- then plate out the dilutions until there are no colonies=MBC
bactericidal antibiotics usually have very similar or different MIC and MBC values?
similar, narrow range between the two values
bacteriostatic antibiotics have much lower or higher MBC than MIC values?
much wider or high range of values
may not have a MBC value
prophylaxis treatment
treatment when there is no infection
pre-emtive treatment
treatment of an infection
empiric treatment
treatment of symptoms
definitive treatment
treatment of an isolated pathogen
suppressive treatment
treatment to complete resolution
what is the difference between a prophylactic and a definitive treatment?
definitive treatment is when successful identification of the infection pathogen has happened
pharmacokinetics
the relationship of the time course of drug absorption, distribution, metabolism and excretion.
*Body working on the drug
ADME
pharmacodynamics
the relationship of the drug concentration at the site of action and the resulting effects, including time course and intensity of therapeutic and adverse effects
*drug effect on the body
what is important to keep in mind about MIC levels in the body?
the MIC is compared to plasma concentrations, but these may or may not reflection the concentration at the site of infection
what should doses provide overkill without causing toxicity in the host?
- need to achieve a bactericidal concentration at the site
- need to discourage emergency of resistant bacteria
what phase of bacterial growth is most sensitive to antimicrobial intervention?
the log or exponential phase
bactericidal antibiotics
kill bacteria
bacteriostatic antibiotics
stop bacteria from growing or reporducing
Type I pattern of activity of antimirobials
concentration dependent killing and prolonged persistent effects
*maximize concentrations is the goal
Type II pattern of activity of antimicrobials
time dependent killing and minimal persistent effects
**maximize duration of exposure
type III pattern of activity of anitmicrobials
time-dependent killing and moderate to prolonged persistent effects
**maximize amount of drug
persistent post-antibiotic effect (PAE)
Persistent Post-Antibiotic Effect
provide suppression of bacterial growth following exposure.
in type II antibiotic why is there a reduced risk of adverse effects?
because you are taking multiple doses at a lower concentration, yet providing more time above the MIC than with a type I antibiotic which gives a large dose at a high concentration.
what are the 5 key rules for treating serious infections?
- begin treatment ASAP
- Use the safest effective drug
- Use the largest reasonable dose
- Monitor plasma concentrations of antibiotic if it is needed to guide dose or to avoid toxicity
- must continue treatment at least 2 days past apparent cure
the ideal AMT is defined by what?
specificity of action in host vs bacteria
*high selectivity=reduced adverse effects
All adverse effects are dose-dependent T/F?
false, many are but some are not
what is the therapeutic index
the ratio of dose toxic to the host to the effective therapeutic dose (TD/ED)
-higher or wider the therapeutic index the better (safer) the antibiotic .
analogous adverse effects
an effect on human cells resulting from the same mechanism as the antimicrobial effect
independent adverse effects
irritation
allergy
Mechanisms of AMT
cell wall synthesis/function/permeability
protein synthesis (50s and 30s)
inhibition of metabolic pathways (folic acid)
nucleic acid synthesis disruption
why use combination therapy?
broaden spectrum of infection improve efficacy (synergism) lower drug concentrations delay emergence of resistance empiric therapy of uncharacterized serious infection
what is a superinfection
the overgrowth of pathogens resulting from use of antimicrobial drugs
*the larger the disruption of the microbiome, the greater the opportunity for pathogens to overgrow
what are some was a superinfection can happen?
- use of a broad-spectrum antimicrobial agent
- use of a higher than normal concentration of even a narrower-spectrum antimicrobial drug
no new classes of antibiotics have been introduced since when?
1987
what is the GAIN act?
it is an act to incentivize discovery and development of new antimicrobials
