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