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31 Cards in this Set

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bacteristatic
does not kill organism - inhibit metabolic pathway of organism
bactericidal
kills organism generally by lysis or interference with cell wall formation
antibiotics does not cause resistance. explain
antibiotics kill weak organisms allowing resistant ones room to grow.
general priciple of begining treatment with antibiotic
begin w/ broad spectrum RX. to minimize selecting for resistant organizmms switch to narrow spectrum once pathogen is known.
multiple AB therapy can be used synergistically. explain
one may inhance the effect of the other
Use ABs that work by different mechanisms
if bacteria is immune to one mechanism the other may work
fever
does not necessarily mean infection. Could be pyrogen (something that alters thermoregulatory mechanism.
Sulfonamindes
broad spectrum STATIC vs G+/G-
mechanism of sulfonamides
inhibits first step in synthesis of folic acid
- joining PABA (para-aminobenzoic acid) w/ pteridine to form dihydropteroic acid (immediate precursor to folic acid)
Why do sufonamides work
glutamate is added to folate to form dihydrofolate (FH2) which is reduced to dihydrofolate reductase (DHFR) to tetrahydrofolate (FH4) which is used in 1 C transfer to make thmidine -- hense interfere with DNA synthesis and cell replication
Why do these drugs not affect humans
humans can't make folate anywyas we require it from our diet
What drugs are sulfas generally used with for a synergistic effect
DHFRs (dihydrofolate reductase inhibitor)
What is the mechanism of action of DHFR inhibitors
they inhibit the reduction of FH2 back to FH4 to be reused again for the synthesis of thymidine
Why do these 2 drugs act synergistically
inhibit 2 different steps of synthesis of tetrahydrofolate ( block making and recycling of FH4)
Give teh three examples of DHFRIs
Trimethoprim (TMP)
Methotreaxate (MTX)
Pyrimethamine
Trimethoprim (TMP)
inhibits bacterial DHFR - side effects: blood dyscrasias (disorders)
Methotreaxate (MTX)
inhibits mamalian, bacterial & protozoal DHFR, used to treat psoriasis and several cancers
Pyrimethamine
antimalarial - inhibits protozoal DHFR
Pregnancy?
Sulfa drugs can cross the placenta so can cause unwanted side effects on the fetus

Pregnancy category B: animal studies show no risk of effects in animals but not confirmed in humans
CATEGORY: SULFANAMIDES
DRUG: SULFISOXAZOLE
ROUTE: ORAL
prophylaxis in kids with recurrent otitis media.

For acute cases use AMOXACILIN (aminopenicillin OR a 2nd or 3rd generation cephalosporin

Alternate for uncomplicated UTI.
causes of UTIs in community
E coli (80%) G-
Staph saprophyticus (10%) G+
causes of UTIs in hospitals
E-coli (50%)
Klebsiella, Proteus, Enterobacter & Serratia (40%) G-

Enterococcus faecalis, Staph saprophyticus & aureus(10%)
CATEGORY: SULFANAMIDES
DRUG: SULFAMETHOXAZOLE
ROUTE: ORAL & IV
available w/ trimethoprim (bactrim; septra) AKA Co-Trimoxaxole: TMP-SMZ

Sulfa w/ DHFRI

USES:
1) UTI if local resistance to TMP/SMZ is <20%. If > 20% use fluoroquinolone e.g., cipro

2)Respiratory & GI infections

3) High doses for Pneumocystis carinii in AIDS
CATEGORY: SULFANAMIDES
DRUG: SULFACETAMIDE
ROUTE: TOPICAL
AKA Bleph-10; 10% solution used for eyelid infections
Vasosulf
Sulfacetamide + phenylephrine (vasoconstrictor)

for red-eye
Blephamide
Sulfacetamide + prednisolone (antiinflammatory)
ulcerative blepharitis
usually caused by S. aureus & S. epidermidis

1st choice AB is polysporin ointment (bacitracin + polymyxin B) OTC

For better G- coverage, use aminoglycoside AB gentamicing (Garamycin) opthalmic ointment

Alternative to 1st choice use the Sulfa - BLEPHAMIDE
bacterial conjuntivitis
caused by staph aureus, strep pneumonia, H. influenzae & Moraxella catarrhalis

1st choice: Polysporin. For better G- coverage use opthalmic form of fluroquinolone (cipro)

Alternative to 1st choice use the Sulfa - VASOSULF
CATEGORY: SULFANAMIDES
DRUG: SILVER SULFADIAZINE
ROUTE: TOPICAL
for burns to prevent sepsis. Caution: risk of toxicity if over large area
CATEGORY: SULFANAMIDES
DRUG: MAFENIDE
ROUTE: TOPICAL
burns
General Side effects of sulfas
1) crystalluria
2) Kernicterus (bilirubin deposits in CNS) -- don't use in babies under 2 mo
3)blood dyscrasias -- don't use if hx
4)Hypersensitivity -- Stevens-Johnsons Syndrome (erythema multiforme major)