Principles of Anti-INfective Therapy Flashcards
Chemotherapeutic agents
any drug used to treat illness or disease, infectious disease generally refers to antibiotics
Antimicrobial agent
substance that interferes with the proliferation of microorganisms
Antibiotics agent
antimicrobial activity whose source is “natural” living organisms
Antimicrobial spectrum - Bacteristatic
antimicrobial agent that inhibits growth when present, but does not kill; reversible; relies on immune system to eliminate pathogen
Bactericidal
Agents that kill pathogen, but do not eliminate the dead cells/viruses; irreversible
Narrow spectrum antibiotics
antibiotics that target a narrow range of microorganisms
Broad spectrum antibiotics
antibiotics effective in killing both gram (+) and gram(-) bacteria, not preferred bc it wipes out NF and may lead to superinfections
Resistant
microorganisms that are NOT inhibited
Sensitive
microorganisms that are ARE inhibited
Kirby-Bauer Disc diffusion Assay
antimicrobial sensitivity test to determine if the particular pathogen is sensitive or resistant to a specific antibiotic by measuring the zone of growth inhibition
Kirby-Bauer Disc diffusion Assay down-side
cannot distinguish between bacteristatic and bactericidal, qualitative test
Minimum Inhibitory Concentration (MIC) test
antimicrobial susceptibility test to measure the minimal concentration of antibodies necessary to inhibit the growth of microorganisms
Minimum Inhibitory Concentration (MIC) test down-side
cannot distinguish between bacteristatic and bactericidal, quantitative test
Minimum Bactericidal Concentration (MBC) test
antimicrobial susceptibility test to measure least amount of antibiotics to KILL 99.9% of the microorganism, MICs are grown on agar plates to determine if they were killed or inhibited by the antibiotics
MBC =
most diluted MIC that did not have growth after plating on agar
Dosage of antibiotics should ___________ the MBC and MIC
exceed
Antimicrobial serumcidal concentrations
antimicrobial susceptibility test to measure the lowest concentration of antibiotics needed to kill microorganism in the presence of patient’s serum
Antibiogram
detailed account of a hospitals trends of antibiotic usage, in comparison to resistance and susceptibility patterns
Antibiogram can help prevent
antibiotic resistance by alleviating pressures
Poor Selective Toxicity
target is more similar to self, drugs that target cell membrane exhibit poor selectivity - harmful to patient and microbe
Good Selective Toxicity
target is less similar to self, drugs that target peptidoglycan cell walls exhibit good selectivity - harmful to microbe not to patient
Why abscess formation is difficult to treat…
poor blood flow, difficult to deliver drugs/antibodies, multiply slower and are less effected by drugs, phagocytes do not reach site, tissue necrosis releases nutrients needed for bacterial growth, low pH at site effects drug effectiveness
Treating an abscess
drainage and removal of necrotic tissue
Why foreign bodies allow growth of microorganisms..
biofilms are allowed to grow on foreign objects, they should be removed ASAP
Immunosuppression
even with antimicrobials, an intact immune system is necessary for removal of debris and effective treatment
Superinfect
treat one disease and a new and different disease develops, generally as a result of overgrowth of NF
Location of infection
antibiotics can penetrate tissues differently, must be considered when prescribing a medication
Chemoprophylaxis
administering an antimicrobial to a patient who is not infected but at increased risk
Justified prophylaxis
erythromycin eye drops to prevent opthalmia neonatorium, prophylaxis against malaria in travelers, rheumatic heart disease patients to prevent strep, bowel surgery, recurrent UTI, bite wound, exposure to meningococcal meningitis, MTB, HIV
Unjustified prophylaxis
prevent secondary bacterial pneumonia in viral respiratory case, clean surgery, because patient insists
Synergism (2 antimicrobials)
when used in conjunction with one another are much stronger (cidal) than separately
Additive
when used in conjunction with one another they are additive in nature 1 + 1 = 2
Antagonism
when used together, they reduce the effectiveness in comparison to being separate (drug/drug interaction or competition)
Indifference
drugs used in conjunction has no effect on one another
When to use combination therapy
polymicrobic infection, to lower dose of toxic drug, increase cidal effect, treat life-threatening illness, prevent emergence of resistance (TB, HIV)
Drug resistance mechanisms - altering target
alter binding proteins, alter DNA gyrase, alter expression of dehydrofolate reductase
Drug resistance mechanisms - inactivation of drug
ability to hydrolyze and breakdown drug, circumvent drug action by acquiring a different enzyme with same function (beta-lactamase)
Drug resistance mechanisms - tolerance
evasion of killing by depression of bacterial growth rate
