CPA #16 Questions Flashcards
Define: diffusion susceptibility test
aka Kirby-Bauer tests
- inoculate Petri dish with standard amount of pathogen
- small circles of paper containing the standard drug concentration are applied
- the bacteria grow a “lawn” everywhere that the drug is not
- examine plates for the zone of inhibition
- a larger zone of inhibition = more effective drug
Define: zone of inhibition
clear area where bacteria do not grow
what are the 3 classifications of pathogens
- susceptible
- intermediate
- resistant
Define: MIC Test and what 2 tests are used
a way to express a drugs potency as a minimum inhibitory concentration; aka the smallest amount of the drug that will inhibit bacterial growth
determined via:
1. broth dilution test
2. Etest
define: Broth Dilution Test (MIC)
bacteria is added to a bacterial agent in a tube or well and observed for turbidity; turbidity indicates bacterial growth, lack of turbidity indicates inhibition of growth
Define: Etest (MIC)
plastic strip containing a gradient (various levels) of microbial agent is placed onto a Petri dish; after incubation a larger inhibition zone will be noted toward the higher concentration of microbial agent, the zone will get smaller as the concentration decreases
Define: MCB Test
minimal bacterial concentration test; amount of drug required to kill the microbe
Identify 3 routes of drug administration for internal infections
- orally
- intramuscular
- intravenous
pros of oral drug administration
simplest; self-administered
cons of oral drug administration
lower drug concentration; d/t being self-administered, people do not always follow prescribed timeframes
pros of IM drug administration
allows drug to slowly diffuse into blood vessels
cons of IM drug administration
concentration is never as high was IV; damage to liver and kidneys
pros of IV drug administration
directly into bloodstream; high initial concentration
cons of IV drug administration
needs continuously administered; damage to liver and kidneys
what are the 3 main antimicrobial drug safety and side effects
Toxicity, allergies, disruption of normal microbiota
define: toxicity
adverse reactions to drugs that may cause damage to kidneys, liver, or nerves, and fetus (if applicable); therapeutic window
define: therapeutic window/range
range of concentrations of the drug that are effective without being excessively toxic
define: allergies
some drugs trigger immune responses; most severe and rare is anaphylactic shock
define: disruption of normal microbiota
may allow opportunistic pathogens to proliferate as secondary infections
list 7 ways that microorganisms can be resistant to antimicrobial drugs
- produce an enzyme that destroys/deactivates drug
- may slow/prevent entry of drug
- alter the target of drug so drug cannot attach effectively
- may alter metabolic chemistry
- pump antimicrobial out of cell before drug can act
- create biofilms
- some strains of mycobacterium tuberculosis can resist fluoroquinolone drugs (create decoy)
define: multiple drug resistant pathogens
aka superbugs; resistant to 3 or more different types of antimicrobials; concerning because caregivers must be able to take care of patients without effective drugs without infecting themselves or spreading it to others
Define: cross resistance
when resistance to one antimicrobial confers resistance to another similar antimicrobial
four ways that we can reduce microbial resistance
- maintain high enough concentration of drug for a long enough time (take full prescription)
- use multiple drugs in combination (synergism)
- limit the use of the drugs to a necessary basis
- using semi-synthetic drugs by adding different chains to original molecule
define: synergism
when use of one drug enhances the effects of another drug
what are the 3 things a pathogen must do to be able to cause disease?
- gain access either by penetrating the surface of the skin or enter through another portal of entry
- attach itself to host cells
- evade the bodies defensive mechanisms long enough to produce harmful changes
