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42 Cards in this Set

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prokaryotic ribosome components
large (50S) + small (30S) = 70S ribosome
eukaryotic ribosome components
large (60S) + small (40S) = 80S ribosome
tRNA formation + checkpoints
aminoacyl synthetase
checkpoints @ aminoacylation of tRNA and codon-reading by ribosome
three steps of bacterial protein synthesis
complexation of mRNA, GTP, IF2, fMet-tRna (start codon)
complex binds to 30S
this new complex binds to 50S and begins protein synth
protein synth inhibitors that act on tRNA synthetase?
mupirocin
protein synth inhibitors that act on 30S?
aminoglycosides, tetracyclines
protein synth inhibitors that act on 50S?
chloramphenicol, macrolides, streptogramins, lincosides
protein synth inhibitors that act on initiation complex
linezolid
mupirocin (bactroban)
inhibit isoleucyl-tRNA-synthetase
gram + only
topical only
stap aureus elimination from nasal mucosa (scabby rash around mouth/nose)
aminoglycosides
injection only
broad spectrum (gram + and gram - )
AE: potential for nephrotoxicity or deafness!
streptomycin (aminoglycoside)
first gen aminoglycoside
gram + usage
can cause deafness
gentamycin (aminoglycoside)
most commonly used aminoglycoside used at present
given at high doses to destroy bacteria to the point where they can't recover
less nephrotoxicity (since no infusion over a long time), but good therapeutic effect
spectinomycin (aminoglycoside relative)
related to aminoglycoside, not one though
parenteral only
previously used for gonorrhea, no current usage though
chloramphenicol
targets 50S peptidyl transferase. stops peptide formation between 2 amino acids (mimics peptide bond). stops protein elongation
can cause anemia (might need bone marrow transplant) and gray baby syndrome
gram + and gram -
quinupristin, dalfopristin
mixture of 2 streptogramins
bind to peptidyl transferase on 23S (large subunit)
used against vanco-resistant enterococcus faecium
lincomycin, clindamycin (lincosides)
similar spectrum to macrolides
for anaerobic infections and methicillin resistant staph aureus
risk for super infection of GI tract w/ clostridium difficil (can cause bloody diarrhea)
ketolides - telithromycin
binds to 2 domains on 50S subunit
tissue concentraiton is much higher than plasma conc. high perfusion
liver toxicity
linezolid
oral + parenteral
against methicillin-resistant staph aureus
inhibits ternary complex formation of fMet-tRNA, ribosome, mRNA
resistance to this drug is developing
infection vs active TB
1. ingestion of bacteria (inhale, food, etc)
2. red rod-like bacteria begin to multiply in lungs and form a ghon complex (aggregate of bacteria surrounded by fibron from inflammatory reponse
3. presence of live bacteria and immune response is what gives positive TB skin test
latent disease = not infectious, but still transmittable

10% of infected will have immune control breakdown and get a hole in their lung--this causes people to cough out sputum containing bacteria
interferon interfering drugs as therapy for autoimmune disease can also cause activation of TB since reducing immune system
susceptible M. tuberculosis strains:
susceptible to the 2 most effective TB drugs
multi-drug resistant (MDR-TB)
resistant to both of the most effective TB drugs
extensively resistant (XDR-TB)
resistant to both of the most effective TB drugs + 1,2,or 3 of the next drugs in line
50% of these patients die
first line TB drugs?
isonizide, rifampin, ethambutol, pyrazinamide
second line TB drugs?
aminoglycosides, polypeptides, flouroquinolones, thioamides, cycloserine, p-aminosalicylic acid
isoniazide (INH)
inhibits synth of mycolic acids (fatty acid cell-wall component of bacteria) by inhibiting fatty acid synthetase 2 (FAS2) enzyme.
MOST EFFECTIVE TB DRUG
can cause hepatotoxicity.
rifampin
complexes w/ bacterial DNA-dependent RNA-polymerase and inhibits RNA synthesis
increases activity of INH (given concurrently)
AE: minor...rash, fever, nausea
ethambutol (EMB)
inhibits arabinosyl transferase (prevents formation of arabinogalactan component of cell wall)
AE: optic neuritis..loss of vision (need eye exams every month)
pyrazinamide (PZA)
inhibits mycolic acid synthesis (part of cell wall) at earlier step than INH
AE: arthralgia, hyperuricemia, hepatoxocity (possibly irreversible..so beware when prescribing)
D-cycloserine
structural analog of d-alanine
prevents extension of peptidoglycan by inhibiting alanine racemase
AE: frequently neurologic (seizures, psychosis, periph neuropathy)
ethionamide (ETH)
inhibits mycolic acid formation
AE: GI problems
capreomycin (polypeptide)
functionally equiv. to aminoglycosides
AE: 8th nerve toxicity (deafness), nephrotoxicity
P-aminosalicylic acid (PAS)
interferes w/ folate synthesis (similar to sulfonamides)
effectiveness specific to mycobacteria (does same thing as trimethoprim)
drug resistance to TB
average TB lesion contains 10^8 M. tuberculosis bacteria.
on average, 100 bacteria per lesion resistant to any one drug--treatment failure w/ monotherapy
mycobacterium avium-complex disease (MAC)
mycobacterium avium has 3 species
+ mycobacterium intracellulare

infection w/ any one of the four subspecies or species listed qualifies as MAC disease
MAC therapy
at least 2 agents: azithromycin or clarithromycin + ethambutol

MAC = totally resistant to INH

no regimen has proven efficacy
MAC prophylaxis
rifabutin (rifamprin derivative
must be continued for life
bactacin
inhibit dephosphorylation of c55-isoprenyl pyrophosphate (which normally assists in bacterial cell wall production by transporting NAG and NAM. carrier recycled for next addition..but bacitracin stops recyclin)

effective only against gram +
clofazimine
binds guanine in bacterial DNA--interferes with DNA polymerase
used w/ rifampin + dapsone for treatment of Hansen's disease
AE: GI intolerance, skin discoleration
orphan drug
dapsone
used w/ rifampin + clofazimine to treat Hansen's
inhibits folate synth.
antiinflam + immunomodulating effects
AE: dose-related hemolysis, methhemoglobinemia (interfers w/ oxygen transfer)
daptomycin
inserts into cell membrane and depolarizes it. loss of membrane potential leading to inhibition of protein, DNA and RNA synthesis, which results in bacterial cell death.
gram +
for skin and soft-tissue infections
AE: myalgia, myositis
metronidazole
effective only in organisms w/ anaerobic metabolism.
forms unstable complexes and disrupts DNA
AE: nausea, metallic taste
dont' take w/ alcohol
polyxcins (B and E)
gram - (ex: e coli)
binds to outer and cytosolic membrane and destroys it--like a detergent
"last resort" antibiotic because of neurotoxicity and nephrotoxicity
can decrease large-intestine bacterial flora if given orally (uncommon)--normally topical use