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Flashcards in PBL #1 Deck (26)
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1
Q

What factors increase UTI risk?

A
  1. Poor hygiene
  2. Sexual activity
  3. Urinary retention
  4. Postmenopausal status
  5. Immunosuppression
  6. Catheter
  7. Urinary tract abnormality (short urethra)
  8. Prostate hypoplasia
2
Q

What is the epidemiology of UTI’s?

A
  • UTI is most commonly occurring bacterial infection in outpatient setting in U.S.
    • Self-reported annual incidence of UTI in 12% of women
    • 50% of women will have UTI by age 32
  • 250,000 cases of acute pyelonephritis occur each year in the U.S.
    • results in >100,000 hospitalizations
3
Q

What are the clinical signs and symptoms of a lower UTI?

A
  • Dysuria
    • Caused by bacterial colony irritating the urinary epithelium
  • Frequency
    • Caused by the stimulation of urinary reflex
  • Urgency
    • Caused by the stimulation of urinary reflex
  • Systemic signs are usually absent!!
4
Q

What are the clinical signs and symptoms of a upper UTI?

A
  • Dysuria, frequency, and urgency PLUS below:
  • Chills and fever
    • Caused by release of cytokines
  • Flank pain → CVA tenderness
    • Caused by inflammation of renal parenchyma and capsule
  • Constitutional symptoms caused by bacterial invasion of the kidney
  • Nausea and vomiting
5
Q

What is the sensitivity and specificity of urine dipstick evaluation?

A
  • performance of ≥ 2 positive findings for prediction of UTI:
    • sensitivity 80.3%
    • specificity 53.7%
6
Q

What is the value of a urine culture?

A
  • GOLD STANDARD
  • Detects and identifies the organism causing UTI
    • indicates definitive treatment
7
Q

Tell me about empiric antibiotic therapy for UTI

A
  • Nitrofurantoin:
    • activated when processed in the kidney
    • Not high levels to have an effect on kidney
    • Accumulates to therapeutic levels in the bladder
    • Doesn’t work in upper UTI
  • Bactrim (Trimethoprim/Sulfamethoxazole)
    • Do not use Bactrim if it has been used within the last 3 months on a given patient
  • Fluoroquinolones
    • Ciprofloxacin
  • Ceftriaxone or aminoglycoside if resistance of E. coli locally is greater 10%
8
Q

What are risk factors for development of nephrolithiasis?

A
  • history of renal stone (50% have single recurrence, 10% have multiple recurrences)
  • reduced intake or increased water loss
  • low urine volume and increased solute production
  • high ion levels (calcium, phosphate, oxalate, sodium, and uric acid)
  • low urinary pH
  • reduced levels of natural calculus inhibitors
  • infections (UTI with urease + organisms)
  • genetic defects/diseases (hyperparathyroidism, metabolic syndrome, GI dz, sarcoidosis, lesch-nyhan, CF, cystinuria)
  • anatomical abnormalities (medullary sponge kidney (tubular ectasia), ureteropelvic junction obstruction, calyceal diverticulum, calyceal cyst, ureteral stricture, vesico-uretero-renal reflux, horseshoe kidney, ureterocele)
  • certain drugs
  • gout/high purine intake - meat
  • oxalate rich foods - spinach, chocolate, nuts
  • insulin resistance
  • prolonged immobilization
  • obesity
  • Vitamin C supplements in Men
9
Q

What are the signs and symptoms associated with nephrolithiasis?

A
  • Symptoms/signs:
    • severe debilitating pain (flank pain)
      • (usually unilateral) w/ radiation to low abdomen, crampy, intermittent)
    • gross and microscopic hematuria
    • N/V
    • dysuria, urgency, frequency
    • fever and chills possible
    • other complications: UTI may present concurrently
10
Q

What is the sensitivity and specificity of x-ray, ultrasound, IVP, and CT for identifying nephrolithiasis?

A
  • X-ray:
    • sensitivity: 45-59%
    • specificity: 71-77%
  • US:
    • sensitivity: 19%
    • specificity: 97%
  • IVP:
    • sensitivity: 64-87%
    • specificity: 92-94%
  • CT: detect stones as small as 1-2 mm
    • sensitivity: 95-100%
    • specificity: 94-96%
  • ***Noncontrast CT is first line w/ US as alternative
11
Q

What is a urinary tract antiseptic?

A
  • Drug that is excreted mainly by way of the urine and performs its antiseptic action in the bladder.
  • These drugs may be given before examination of or operation on the urinary tract, and they are sometimes used to treat urinary tract infections.
12
Q

What are the primary mechanisms of action of the urinary tract antiseptics and their major toxicities?

A
  • Nitrofurantoin
    • reactive intermediates generated that inactivate/alter ribosomal proteins interfering with many cellular processes
    • therapeutic doses may not be achieved if patient has Crcl of less than 40
    • Side effects:
      • hypersensitivity
      • hepatotoxicity
      • pulmonary fibrosis in the elderly
      • hemolytic anemia if G6PD deficient
  • Methanamine
    • Antibacterial effect of methenamine hippurate or methenamine mandelate depends on conversion of methenamine to formaldehyde in an acid medium (acidic urine)
    • formaldehyde is an antibiotic
  • nalidixic acid
  • oxolinic acid
13
Q

What situations are considered complicated UTIs?

A
  • Children
  • Males
  • Pregnancy
  • Neurogenic bladder
  • Postmenopausal
  • Stones
  • Obstruction
  • Diabetes Mellitus
  • Renal insufficiency
  • Immunosuppression
14
Q

E. coli and UTI’s

A
  • colonies appear to have a green metallic sheen on EMB agar
  • Gram (–) bacilli
  • Catalase +
  • Oxidase –
  • reduces nitrates to nitrites → will see positive nitrites in urine
15
Q

What virulence factors does E.coli use in UTIs?

A
  • adherence factors: pili, adhesins
    • type 1 pilus (fimbria)
  • immune evasion: capsular antigens
  • other: flagella
16
Q

Staphylococcus saprophyticus in UTIs

A
  • increased incidence in young, sexually active women
  • Gram (+) cocci
17
Q

What virulence factors does Staphylococcus saprophyticus use in UTIs?

A
  • adherence factors: adhesins
  • other: urease
18
Q

Klebsiella pneumoniae in UTIs

A
  • produces urease → will see + Urease test
  • Gram (–) rod
  • Encapsulated
  • Lactose-fermenting
  • Facultative anaerobe
19
Q

What virulence factors does Klebsiella pneumoniae use in UTIs?

A
  • adherence factors: pili
  • immune evasion: capsule
20
Q

Proteus mirabilis in UTIs

A
  • produces urease → will see + Urease test
  • Gram (–) rod
  • Facultative anaerobe
21
Q

What virulence factors does Proteus mirabilis use in UTIs?

A
  • adherence factors: pili, adhesins
  • immune evasion: capsule
  • other: flagella, urease
22
Q

Serratia marcescens in UTIs

A

often nosocomial (hospital-related) and drug resistant

23
Q

Enterococcus faecalis in UTIs

A
  • Gram + rod
  • Facultative anaerobe
  • Catalase –
  • Found in GI tract
  • often nosocomial and drug resistant
24
Q

What virulence factors does Enterococcus faecalis use in UTIs?

A
  • adherence factors: pili, adhesins
  • immune evasion: Epa (enterococcal polysaccharide antigen)
25
Q

How do you relate renal function to appropriate antibiotic dosing?

A
  • Renal impairment → increased [drug] + prolonged t1/2 → increased risk of adverse reaction
  • Cockcroft-Gault equation:
    • for Cr clearance→ [(140-age)*(weight in Kg)] (.82 if female)/(serum Cr * 72)
26
Q

How could monogenic causes of kidney stones be influenced by variable penetrance?

A
  • Single-gene disorders the penetrance = close to 100%
    • i.e. the predictive value of mutations for the disease to manifest
  • Exception:
    • age-dependent penetrance
    • in dominant diseases →
      • incomplete penetrance (skipping of a generation)
      • variable expressivity (different extent and severity of organ involvement)
  • Phenotypes will vary among individuals with same genotype.