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
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.
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
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.
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.
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.
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.
8
Q
What are the signs/symptoms of cystitis?
A
- freqency
- urgency
- dysuria
- cloudy + odor
- WBC in urine
- suprapubic pain
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
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
11
Q
How do E. coli invade the bladder?
A
- bind to uroepithelial cells by expressing type I pili (adhesion proteins)
12
Q
How do E. coli invade the kidney?
A
- expression of P. fimbrae (hairline adhesion proteins) leads to attachment to renal epithelial cells.
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
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.
-
detects WBC in urine.
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
16
Q
List the leading bugs that cause bacterial UTIs.
A
- E. coli - #1
- Staphylococcus saprophyticus - #2 in in sexually active women
- Klebsiella pneumoniae - #3
- Serratia marcescens
- Enterococcus
- Proteus mirabilis
- Psuedomonas aeruginosa
17
Q
What UTI bugs are urease positive?
A
- Staphylococcus saprophyticus
- Klebsiella pneumoniae
- Proteus mirabilis
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
**Pseudomonas aeroginosa** traits, toxins
* gram negative rod
* AEROBIC
* Exotoxin A - host cell death
* mucoid polysacchardie
* type III secretion system
* **blue green pigment, fruity odor**
* drug resistant
* nosocomial
26
Risk factors for **nephrolithiasis**
* decreased urine output
* increased calcium in supplements, decreased calcium in diet
* **vesicoureteral reflux**
* diabetes, hyperparathyrodisim
* decreased fluid intake
* less citrate
* increased urine pH
27
Signs & symptoms of **nephrolithiasis**
* blood in urine
* nausea & vomitting
* **colicy pain**
* **flank** tenderness - may radiate to groin
* increased creatine levels
28
What is the **gold standard** for diagnosis **nephrolithiasis**?
* non-contrast helical CT
29
What are the 3 **most common bugs causing pyelonephritis**?
* E. coli in 90%
* Enterococcus faecalis
* Klebsiella species
30
What is the most common type of kidney stone and what causes it?
* **Calcium oxalate or calcium phosphate**
* caused by
* hypercalcemia
* ethylene glycol
* vitamin C abuse
* HYPOcitratuira
* malabsorption
31
What type of urine precipitates **calcium oxalate?**
* low pH
32
What type of urine precipitates **calcium phosphate**
* high pH urine
33
What do **calcium oxalate** stones look like and how should we treat?
* envelope or dumble shape
* appears **radiopaque** on x-ray
* tx
* hydration
* hydrochlorothiazide (**ca sparing diuretic)**
* citrate
34
Second most common type of kidney stone and how does it form?
* **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
Features and tx of **struvite stones**
* precipitates **high pH**
* radiopaque on x-ray
* appears as **coffin lid**
* tx =
* eradication of infection
* surgical removal of stone
36
Third most common kidney stone (5%) and risk factors
* **Uric acid**
* Risks =
* hot, arid climate
* low urine volume
* acidic pH
* Gout
* Hyperuricemia w/leukemia or myeloproliferative disorders
37
What are the features of **uric acid stones** and what are the treatments?
* decreased pH
* **radioLUCENT on xray** (can't see)
* **rhomboid or rosette shape**
* tx
* alkalinzation of urine (potassium bicarbonate)
* allopurinol for gout
38
RARE cause of nephrolithiasis most commonly seen in **children**
* **Cystine** stones
* autosomal recessive condition that decreases reabsorption of **cysteine** - can form staghorn colliculi
39
What do **cystine stones** look like and how do they get treated?
* 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
Explain the sensitivity and specificity of
* CT
* US
* X-ray
* IVP
* CT = **sensitive and specific**
* US = **specific**
* X-ray = **specific**
* IVP = **specific**, somewhat sensitive.
41
Prevention options for prevention of kidney stones
1. exercise
2. lose weight
3. decrease animal protein
4. decrease sodium
5. increase fluid
6. no calcium supplment
7. increase fiber
42
Define **epistasis**, what could be important with it, and what studies need.
* 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
What did the **GWAS study** for nephrolithiasis show?
* associated **claudin** family
* claudin 14 is major gene of nephrolithiasis
44
Why would long term studies be useful for calcium nephrolithiasis?
Enviroment and diet can modify genes.
May be epigenetic modifications.
