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31 Cards in this Set
- Front
- Back
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bacteristatic
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does not kill organism - inhibit metabolic pathway of organism
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bactericidal
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kills organism generally by lysis or interference with cell wall formation
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antibiotics does not cause resistance. explain
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antibiotics kill weak organisms allowing resistant ones room to grow.
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general priciple of begining treatment with antibiotic
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begin w/ broad spectrum RX. to minimize selecting for resistant organizmms switch to narrow spectrum once pathogen is known.
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multiple AB therapy can be used synergistically. explain
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one may inhance the effect of the other
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Use ABs that work by different mechanisms
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if bacteria is immune to one mechanism the other may work
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fever
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does not necessarily mean infection. Could be pyrogen (something that alters thermoregulatory mechanism.
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Sulfonamindes
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broad spectrum STATIC vs G+/G-
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mechanism of sulfonamides
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inhibits first step in synthesis of folic acid
- joining PABA (para-aminobenzoic acid) w/ pteridine to form dihydropteroic acid (immediate precursor to folic acid) |
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Why do sufonamides work
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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
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Why do these drugs not affect humans
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humans can't make folate anywyas we require it from our diet
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What drugs are sulfas generally used with for a synergistic effect
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DHFRs (dihydrofolate reductase inhibitor)
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What is the mechanism of action of DHFR inhibitors
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they inhibit the reduction of FH2 back to FH4 to be reused again for the synthesis of thymidine
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Why do these 2 drugs act synergistically
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inhibit 2 different steps of synthesis of tetrahydrofolate ( block making and recycling of FH4)
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Give teh three examples of DHFRIs
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Trimethoprim (TMP)
Methotreaxate (MTX) Pyrimethamine |
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Trimethoprim (TMP)
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inhibits bacterial DHFR - side effects: blood dyscrasias (disorders)
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Methotreaxate (MTX)
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inhibits mamalian, bacterial & protozoal DHFR, used to treat psoriasis and several cancers
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Pyrimethamine
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antimalarial - inhibits protozoal DHFR
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Pregnancy?
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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 |
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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. |
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causes of UTIs in community
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E coli (80%) G-
Staph saprophyticus (10%) G+ |
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causes of UTIs in hospitals
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E-coli (50%)
Klebsiella, Proteus, Enterobacter & Serratia (40%) G- Enterococcus faecalis, Staph saprophyticus & aureus(10%) |
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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 |
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CATEGORY: SULFANAMIDES
DRUG: SULFACETAMIDE ROUTE: TOPICAL |
AKA Bleph-10; 10% solution used for eyelid infections
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Vasosulf
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Sulfacetamide + phenylephrine (vasoconstrictor)
for red-eye |
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Blephamide
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Sulfacetamide + prednisolone (antiinflammatory)
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ulcerative blepharitis
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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 |
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bacterial conjuntivitis
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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 |
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CATEGORY: SULFANAMIDES
DRUG: SILVER SULFADIAZINE ROUTE: TOPICAL |
for burns to prevent sepsis. Caution: risk of toxicity if over large area
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CATEGORY: SULFANAMIDES
DRUG: MAFENIDE ROUTE: TOPICAL |
burns
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General Side effects of sulfas
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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) |
