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75 Cards in this Set

  • Front
  • Back
- Use of chemicals against invading organisms
- Can be to fight cancer or infection
- Chemical produced by microorgansm and has ability to kill other microorganisms
Selective toxicity definition
- Ability of drug to kill target cell w/out killing other cells that are in close proximity with it
The principle of anti microbial therapy is _
Selective toxicity
How do you measure selective toxicity
Therapeutic index - toxic dose/effective dose
Identity and sensitivity to agent is determined by
Empiric therapy
- Immediate administration of drug covering both gram positive and gram negative infections, for critically ill patient
Which organisms are more dangerous
Gram negative
The most common used method to test susceptibility to antibiotics
Disk diffusion - discs containing antibiotics are placed on cultures and you look for rings of inhibition
If there is a ring of inhibition organism is sensitive to the drug, if there is no ring of inhibition organism is resistant to the drug
How is selective toxicity achieved
- Destruction of bacterial cell wall
- Inhibition of enzyme unique to bacteria
- Disruption of bacterial protein synthesis
How do antibiotics destroy cell wall
Inhibit murein synthesis
Example of antibiotic that acts by destroying enzyme unique to bacteria
Sulfonamides inhibit production of folic acid by inhibiting enzyme that converts precursor PABA to folic acid - this is unique to bacteria since humans can get folic acid from diet and bacteria can only make it from PABA
What two drugs compose bactrim and what do they do
Bactrim - sulfonamide + trimethoprim, inhibit production of tetrahydrofolic acid
Sulfonamides inhibit _ enzyme and prevent production of _
Trimethoprim inhibits _ enzyme and prevents production of _
Sulfonamides inhibit DIHYDROPTEROATE SYNTHASE and prevent production of DIHYDROFOLIC ACID
Trimethoprim inhibits DIHYDROFOLATE REDUCTASE and prevents production of TETRAHYDROFOLIC ACID
Patients with _ should not get sulfonamides
Hematologic disorder - hemolytic anemia or G6P dehydrogenase defficiency
Name drugs which inhibit bacterial cell wall synthesis
Name drugs which disrupt bacterial cell wall membrane
Amphotericin B
Name bacteriostatic inhibitors of protein synthesis
Name drugs which interfere with production of bacterial DNA or RNA
Name antimetabolites
Flucytosine (not an antibiotic, antifungal)
(Sulfonamides + trimethoprim = bactrim)
Name inhibitors of viral enzymes
Name mycolic acid synthesis drug
Name drugs that inhibit 50S ribosomes
Name drugs that inhibits 30S ribosomes
Name narrow spectrum antibiotics for gram positive cocci and gram negative bacilli
- Penicillin
- Penicillinase resistant drugs - nafcillin, methycillin
- Vancomycin
- Erythromycin
- Clindamycin
Name narrow spectrum antibiotics for gram negative aerobes
Name 4 TB drugs
Name broad spectrum antibiotics for gram positive and negative microorganisms
- Broad spectrum penicillins such as ampicillin
- Extended spectrum penicillins such as carbencillin
- Cephalosporins
- Tetracyclines
- Imipenem
- Trimethoprim
- Sulfonamides
- Fluoroquinolones
Bacteriostatic drug
- Drug that holds growth of microorganisms without killing them- this allows immune system to take care of the infection, without killing normal bacterial flora and also allows best chance for antibody production to prevent future infections
Bacteriocidal drug
- Drug that rapidly kills microorganisms without a chance for antibody production
Name bactericidal drugs
Co- trimazole
Name bacteriostatic drugs
What is a resistance to the antibiotic
Lack of sensitivity to the drug or less susceptibility over time
How can you overcome resistance to the drug
Increase the dose or switch to another drug
Mechanisms by which resistance is acquired
Spontaneous mutation
Spontaneous mutation gives what kind of resistance
To one drug
Conjugation gives what kind of resistance
To multiple drugs
Describe R (resistance) factor
R factor consists of two unique DNA segments - one coding for the resistance and one coding for sexual apparatus required for DNA transfer
Selection pressure
Killing of sensitive bacteria and favoring survival of resistant bacteria
Which antibiotics promote resistance more then others
Broad spectrum antibiotics
Mechanism of resistance to penicillins
- Antibiotic inactivating enzyme - beta lactamase or penicillinase
- Alteration of target site - penicillin binding proteins
- Reduced permeability
Describe mechanism of resistance to aminoglycosides
- Antibiotic inactivating enzyme (via plasmid)
- Alteration in bacterial influx
- Decreased ribosomal binding
Describe mechanism of resistance to macrolides
- Altered ribosomal binding
- Altered bacterial efflux
Describe mechanism of resistance to fluoroquinolones
- Alteration of target site (DNA synthesis)
- Alteration in bacterial influx/efflux
Describe mechanism of resistance to sulfonamides
- Alteration of target site
- Reduced permability
New infection that appears during the treatment of current infection
In immunocompromised patients which antibiotics should be used
Bactericidal (not bacteriostatic)
To be effective antibiotic must be present at the site of infection at concentration _
Greater then MIC - minimum inhibitory concentration
Which conditions can impeded access of drug
- Meningitis - BBB
- Endocarditis - heart vegetations
- Infected abscesses - bad circulation
What happens to antibiotics in elderly
Slow metabolism and excretion of drug leads to accumulation of antibiotics that can lead to toxic levels
What happens to antibiotics in neonates
Slow excretion due to underdeveloped kidneys and liver
Use of sulfonamides in newborns can produce what
KERNICTERUS - severe neurologic disorder caused by displacement of billirubin from plasma proteins (yellowing of the brain)
Use of tetracyclines in newborns can produce what
Discoloration of the teeth
Use of gentamycin during pregnancy can cause what
Irreversible hearing loss
Use of tetracyclines during pregnancy can cause what
Hepatic necrosis, pancreatitis and renal damage
Which antibiotic can enter breast milk and can be dangerous for baby
Which antibiotics cause allergies and which one is most common
Most common - penicillins
Also sulfonamides, trimethoprim, erythromycin
Which antibiotics can cause hemolysis
Sulfonamides and nalidixic acid
Which drug shows variable hepatic activation between Caucasians and African Americans
Isoniazid - slower in African Americans
What is the most common indication for use of multiple antibiotics
- Infection of unknown etiology especially in neutropenic host (AIDS, cancer)
Which disease requires combination of 4 drugs
Combination of drugs for treatment of fungal meningitis
Amphotericin B + flucytosine
Treatment of enterococcal endocarditis
Penicillin + aminoglycosides
Two important host determinants of antibiotic metabolism
Liver and kidney function
How do you test kidney function
BUN + creatinine clearance
Which conditions require prophylactic use of antibiotics
- Surgery
- Bacterial endocarditis
- Neutropenia
- Recurrent UTI's (bactrim)
- Influenza A (amantadine)
- Rheumatic carditis (penicillin)
- Exposure to STD (penicillin)
Site of cleavage by bacterial penicillinase or by acid
C-N bond (weak bond)
What determines drugs stability to enzymatic or acid hydrolysis and affects bacterial spectrum
Side chain
Which part of penicillin necessary for antimicrobial activity
Thiazolidine ring
How is penicillin administered
Only IV or IM, not orally
Name aminopenicillins
Amoxicillin and ampicillin
Name penicillins against pseudomonal infections
Narrow spectrum antibiotic
Penicillinase sensitive
Penicillin G
Narrow spectrum antibiotic
Penicillinase resistant
3 major phases of bacterial cell wall synthesis
- Synthesis of murein monomers from amino acids and sugar building blocks
- Polymerization of murein monomers to linear peptidoglycan polymers
- Cross linking of polymers to complete the wall