Intro Flashcards
contrast antibiotic to antimicrobial
antibiotic: low molecular weight substance produced by a microorganism (NOT synthetic)
antimicrobial: ANY substance that kills or inhibits growth of microorganisms
contrast antimicrobial resistance to intrinsic resistance
antimicrobial resistance (AMR): a characteristic a microorganism has DEVELOPED in response to antimicrobial pressure
intrinsic resistance: and INHERENT feature of a microorganism that makes it unsusceptible to an antimicrobial drug
list and define the 4 aspects of pharmacodynamics
minimum inhibitory concentration (MIC):
-primary measure of antibiotic activity; the lowest concentration of antibiotic that inhibits growth
time dependent:
-bacterial killing is most effective if the plasma concentration is maintained above the MIC (for the pathogen) for the majority of the dosing interval (T>MIC)
concentration (peak) dependent:
-bacterial killing or inhibition of growth is most effective if the plasma concentration reached is many factors above the MIC
exposure (AUC:MIC) dependent:
-ratio of the free drug area under the curve (AUC) to the MIC
-divide the 24 hour AUC by the MIC of the pathogen
goal of all these factors is to maximize efficacy and minimize resistance pressure
how are concentration dependent, exposure dependent, and time dependent antibiotics classified?
concentration dependent: Cmax/MIC: aminoglycosides and fluroquinolones
exposure dependent: AUC/MIC: vancomycin, azythromycin, fluroquinolones, aminoglycosides
time dependent: T>MIC: beta-lactams, vancomycin, macrolides, clindamycin
use these factors to determine dose and frequency of administration
describe 4 mechanisms of synergistic antimicrobial combinations
- sequential inhibition of successive steps in metabolism: sulfonamides -trimethoprim
- facilitation of drug entry of one antibiotic by another: beta lactam-aminoglycoside
- inhibition of inactivating enzymes: amoxicillin-clavulonic acid
- prevention of emergence of resistant populations: macrolide- rifampin
what factors impact the decision of route of administration? (8)
- how sick is patient? if hella, IV
- where is infection
- patient and owner compliance
- FDA regulations (food animals)
- delivery device required?
- technical expertise (intrasynovial, IV catheter maintenance)
- cost
- toxicity/contraindication
describe the 3 types of drug distribution
polar: hydrophilic, remain in water compartments of tissue (plasma, ECF); use channels/diffusion to enter bacteria
lipophilic: penetrate into tissues and are able to pass through lipid bilayer (high volume of distribution), can cross BBB and enter abscesses
protein binding: carried around on protein; influences the half life (longer) and can act as a reservoir/depot; when protein bound cannot interact with target
what are challenging factors that can thwart successful therapy?
- avascular tissue (bone sequestrum)
- necrotic tissue (avascular + cellular debris + acidic environment)
- purulent exudate
- systemic compromise (hypovolemia, acid-base disturbances, fluid disturbances)
- successful treatment is virtually impossible when there is infection associated with a foreign body without removing the foreign body!
minimum additional requirements: rest, nursing care, adequate nutrition, immune function
what are 5 privileged sites in the body? what drugs can access?
CNS (BBB)
postate (BPB)
eye (BOB)
bone
abscess
lipophilic drugs can access!
what are the most likely opportunitistic commensal bacteria in the respiratory, skin, oral cavity, genitourinary tract, and GI tract?
respiratory:
1. streptococcus pasteruellecea
2. staphylococcus actinobacillus
skin: gram positive cocci: staphylococcus and streptococcus
oral cavity:
1. anaerobes: prevotella
2. facultative anaerobes
3. pasteurellacea
4. actinobacillus
genitourinary tract:
1. ascending infections: combo of skin and GI tract flora (gram positive and anaerobes)
GI tract:
1. gram negative enteric bacteria
2. gram positiv cellulolytic bacteria
3. anaerobes
