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CRRAB II > PBL #6 > Flashcards

PBL #6 Flashcards

1
Q

Trimethoprim: mechanism, side effects, and use

A
  • MOA = inhibits bacterial dihydrofolate reductase
  • Use = cystitis (no resistance). Can do prophylactically for 6mo.
  • AE = megaloblastic anemia, leukopenia, granulocytopenia.
  • Bugs = shigella, salmonella, pneumo jirovecii
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2
Q

Sulfamethoxazole

A
  • MOA
    • bacteriostatic on its own
    • inhibits folate synthesis by blocking dihydropteroate synthase
  • Use = cystitis. prophylactic for 6mo.
  • DO NOT USE W/PREGNANCY.
  • AE = hypersensitivity, hemolysis, nephrotoxic, photosensitivity, kernicterus in infants.
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3
Q

Nitrofurantoin

A
  • MOA: reduced by bacterial flavoproteins to DNA damaging intermediate. Inhibits protein, DNA, RNA, aerobic energy and cell wall synthesis.
  • Use = lower UTIs
  • AE = nausea, vomiting, pulmonary fibrosis, hemolytic anemia
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4
Q

Fluoroquinolones (ciprofloxacin, levofloxacin)

A
  • MOA: inhibit prokaryotic topoisomerase II and IV - bactericidal
  • Use = 1st line pyelonephritis. more complicated cystitis.
  • Bugs = gram negative rods of urinary and GI tract.
  • CP = pregnant women, nursing mothers, children, >60 be careful
  • AE = C. dif. Leg cramps & mylagias. Tendon rupture.
  • Excreted by kidney - reduce dose w/reduced function. Calcium can decrease absorption.
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5
Q

Beta Lactams (Ampicillin, Amoxicillin)

A
  • bind penicillin binding proteins (transpeptidases)
    • block transpeptidase cross linking of peptidoglycan in cell wall
  • USE = pregnancy and UTI. alternative for uncomplicated UTI. Ued for severely ill complicated.
  • Bugs = wider spectrum - influenza, H pyloria, e coli, entero, shigella.
  • AE = hypersensitivity rxn, rash, pseudomembranous colitis.
  • resistance = penicillinase.
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6
Q

Cephalosporins

(1st gen = cefalexin. 2nd gen = cefoxitin. 3rd gen=cefiximie)

A
  • MOA = inhibit cell wall syntheisis (less susceptible to penicillinase.
  • Bugs =
    • 1st gen - gram +, PM, E coli, KP
    • 2nd gen - PM, E coli, KP, SM
    • 3rd gen - serious gram negative - used w/UTIs in kids
  • Use: 2nd and 3rd gen for severely ill complicated UTI
  • can be used in pregnancy.
  • AE = hypersensitivity rxn, autoimmune hemolytic anemia, disulfram rxn. Vitamin K definiciency. Increases nephrotoxicity of aminoglycosides.
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7
Q

When would you use alternative treatments for uncomplicated cystitis?

A
  • allergic to first line
  • tx of antibiotics in prior 3 months
  • infection while on TMP-SMX

tx includes fluroquinolones, B lactams, cephalosporins then.

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8
Q

What are the signs/symptoms of cystitis?

A
  • freqency
  • urgency
  • dysuria
  • cloudy + odor
    • WBC in urine
  • suprapubic pain
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9
Q

What are the signs/symptoms of Pyelonephritis?

A
  • Flank pain - CVA tenderness
  • nausea vomitting
  • hematuria/proteinria
  • fever, chills, diaphoresis
  • cloudy urine, casts, smells bad
  • increased creatinine
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10
Q

What can be risk factors for cystitis/pyelonephritis?

A
  • Poor hygiene
  • pregnancy
  • freqent sexual intercourse
  • UTI
  • use of spermacide/diaphragm
  • catheteres
  • no estrogen
  • diabetes
  • incontinece
  • female gender
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11
Q

How do E. coli invade the bladder?

A
  • bind to uroepithelial cells by expressing type I pili (adhesion proteins)
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12
Q

How do E. coli invade the kidney?

A
  • expression of P. fimbrae (hairline adhesion proteins) leads to attachment to renal epithelial cells.
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13
Q

Epidemiology of UTIs

A
  • more common in females due to shorter uretha and colonization w/fecal material
    • 1-4/100 females per year
  • neonatal males are actually at increased risk though
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14
Q

What does the urine dipstick test tell you and what are the sens/specificity ?

A
  • Nitrite test
    • 100% specific
    • if positive, rule in.
    • detects bacteria converting nitrate to nitrite.
  • Leukocyte esterase
    • ​detects WBC in urine.
      • 80% sensitive (lower specificity)
      • if negative, rule out.
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15
Q

what is the gold standard for diagnosing a UTI?

A
  • urine culture
    • ​good sensitivity - if negative you can rule out.
    • need >10,000 CFU
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16
Q

List the leading bugs that cause bacterial UTIs.

A
  1. E. coli - #1
  2. Staphylococcus saprophyticus - #2 in in sexually active women
  3. Klebsiella pneumoniae - #3
  4. Serratia marcescens
  5. Enterococcus
  6. Proteus mirabilis
  7. Psuedomonas aeruginosa
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17
Q

What UTI bugs are urease positive?

A
  • Staphylococcus saprophyticus
  • Klebsiella pneumoniae
  • Proteus mirabilis
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18
Q

What are the characteristics, virulence factors, and growth of E. coli?

A
  • gram negative rod, encapsulated, catalase +, nitrite +
  • grows on lactose - green and metallic on EMB agar
  • Fimbrae, pili
  • K capsule
  • H antigen
  • LPS ENDOtoxin
  • Type III secretion system
19
Q

Staphylococcus saprophyticus characteristics and resistance

A
  • gram + cocci
  • urease +
  • catalase +
  • coag negative.
  • resistant to novobiocin
  • 2nd leading cuase of UTI in sexually active women
20
Q

Klebsiella pneumonia traits, virulence, and growth.

A
  • gram negative ROD. Encaspulated. Catalase NEGATIVE. Urease +. IMMOTILE.
  • Fast lactose - purple/black on EMB, pink on MacConkey.
  • normal part of intestine - hospital acquired.
  • MDR - use carabpenem.
  • see + quelling rxn
  • red currant jelly sputum
  • capsule & endotoxin
21
Q

Serratia marcescens traits and grwoth.

A
  • gram negative rod. Catalase POSITIVE.
  • MOTILE
  • red pigment
  • pink on MacConkey but slow lactose fermenter
  • has MDR
22
Q

Which UTI bugs are lactose fermenters

A
  • E. coli
  • Klebsiella
  • Serratia marcescens - slow
  • Enterococcus
23
Q

Characteristics and growth of Enterococcus

A
  • gram pOSITIVE COCCI
  • catalase negative
  • fast lactose
  • has endotoxin
  • grows in 6.5% NACL and bile
  • pink on MacConkey
  • Drug resistant
24
Q

Characteristics and growth of proteus mirabilis

A
  • gram ngeative rod.
  • urease +, catalase +, H2S +
  • oxidase -, lactase -
  • produces fishy odor - has AMMONIA scent
  • MOTILE - see swarming on agars
  • asscoiated w/struvite stones from urease
25
Q

Pseudomonas aeroginosa traits, toxins

A
  • gram negative rod
  • AEROBIC
  • Exotoxin A - host cell death
  • mucoid polysacchardie
  • type III secretion system
  • blue green pigment, fruity odor
  • drug resistant
  • nosocomial
26
Q

Risk factors for nephrolithiasis

A
  • decreased urine output
  • increased calcium in supplements, decreased calcium in diet
  • vesicoureteral reflux
  • diabetes, hyperparathyrodisim
  • decreased fluid intake
  • less citrate
  • increased urine pH
27
Q

Signs & symptoms of nephrolithiasis

A
  • blood in urine
  • nausea & vomitting
  • colicy pain
  • flank tenderness - may radiate to groin
  • increased creatine levels
28
Q

What is the gold standard for diagnosis nephrolithiasis?

A
  • non-contrast helical CT
29
Q

What are the 3 most common bugs causing pyelonephritis?

A
  • E. coli in 90%
  • Enterococcus faecalis
  • Klebsiella species
30
Q

What is the most common type of kidney stone and what causes it?

A
  • Calcium oxalate or calcium phosphate
  • caused by
    • hypercalcemia
    • ethylene glycol
    • vitamin C abuse
    • HYPOcitratuira
    • malabsorption
31
Q

What type of urine precipitates calcium oxalate?

A
  • low pH
32
Q

What type of urine precipitates calcium phosphate

A
  • high pH urine
33
Q

What do calcium oxalate stones look like and how should we treat?

A
  • envelope or dumble shape
  • appears radiopaque on x-ray
  • tx
    • hydration
    • hydrochlorothiazide (ca sparing diuretic)
    • citrate
34
Q

Second most common type of kidney stone and how does it form?

A
  • ammonium magnesiu phosphate (struvite)
  • urease positive bacteria increase pH of urine leading to stone precipitation
  • results in staghorn calciuli in renal calyces which can foster UT
35
Q

Features and tx of struvite stones

A
  • precipitates high pH
  • radiopaque on x-ray
  • appears as coffin lid
  • tx =
    • eradication of infection
    • surgical removal of stone
36
Q

Third most common kidney stone (5%) and risk factors

A
  • Uric acid
  • Risks =
    • hot, arid climate
    • low urine volume
    • acidic pH
    • Gout
    • Hyperuricemia w/leukemia or myeloproliferative disorders
37
Q

What are the features of uric acid stones and what are the treatments?

A
  • decreased pH
  • radioLUCENT on xray (can’t see)
  • rhomboid or rosette shape
  • tx
    • alkalinzation of urine (potassium bicarbonate)
    • allopurinol for gout
38
Q

RARE cause of nephrolithiasis most commonly seen in children

A
  • Cystine stones
  • autosomal recessive condition that decreases reabsorption of cysteine - can form staghorn colliculi
39
Q

What do cystine stones look like and how do they get treated?

A
  • decreased pH
  • hexagonal - 6 side stones
  • cystine is poorly solube so it forms sontes
  • has positive sodium cyanide nitroprusside test
  • Tx
    • alkalinization of urine
40
Q

Explain the sensitivity and specificity of

  • CT
  • US
  • X-ray
  • IVP
A
  • CT = sensitive and specific
  • US = specific
  • X-ray = specific
  • IVP = specific, somewhat sensitive.
41
Q

Prevention options for prevention of kidney stones

A
  1. exercise
  2. lose weight
  3. decrease animal protein
  4. decrease sodium
  5. increase fluid
  6. no calcium supplment
  7. increase fiber
42
Q

Define epistasis, what could be important with it, and what studies need.

A
  • the phenotype of a gene depends on its interaction w/the environment and other genes
    • may be different in the context of where its exerted
  • diet could be important long term
  • need lARGE SAMPLES to group patients according to genetics and phenotype
43
Q

What did the GWAS study for nephrolithiasis show?

A
  • associated claudin family
  • claudin 14 is major gene of nephrolithiasis
44
Q

Why would long term studies be useful for calcium nephrolithiasis?

A

Enviroment and diet can modify genes.

May be epigenetic modifications.

CRRAB II (26 decks)

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