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Renal Exam > Urinary Tract Infections > Flashcards

Urinary Tract Infections Flashcards

1
Q

urinary tract infections (UTIs) - overview

A

*UTIs are the most common infection encountered in the outpatient setting
*common problem in hospitalized patients, particularly those with urinary catheters
*clinical manifestations differ based on affected portion of urinary tract
*treatment regimen differs based on anatomic location of infection

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2
Q

bacteriuria - defined

A

*bacteria in the urine, > 10^5 organisms per milliliter

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3
Q

pyuria - defined

A
  • > 10 WBCs per high power field
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4
Q

cystitis - defined

A

*inflammation of the bladder

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5
Q

complicated UTI - defined

A

*anatomic, functional, or pharmacologic factors that predispose the patient to persistent infection, recurrent infection, or treatment failure

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6
Q

CA-UTI - defined

A

*catheter-associated UTI

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7
Q

pyelonephritis - defined

A

*inflammation of the kidneys

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8
Q

prostatitis - defined

A

*inflammation of the prostate

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9
Q

pathogenesis of UTIs

A

*most commonly, bacteria cause infection by ascending the urinary system (95% of the time)
*in some cases, bacteria (esp. Staph aureus) can cause infection hematogenously (bloodstream infection causing a UTI; check blood cultures if S. aureus grows in urine)

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10
Q

bacterial factors contributing to the pathogenesis of UTIs: increased bacterial adherence to uroepithelial cells

A

*mediated via fimbria (aka pili)
*2 important types in E. coli:
-Type 1 fimbriae
-P fimbriae

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11
Q

E. coli bacterial factor: Type-1 Fimbriae

A

*mannose-sensitive
*adhere to mannosylated proteins on uroepithelial cells
*can be detached by exposure to mannose
*bacterial tropism for BLADDER (cystitis)

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12
Q

E. coli bacterial factor: P fimbriae

A

*mannose-resistant
*adhere to glycophospholipids embedded in outer surface of plasma membrane of uroepithelial cells
*tropism for upper urinary tract (PYELONEPHRITIS)

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13
Q

bacterial factors contributing to the pathogenesis of UTIs: resistance to serum cidal activity

A

*allows the bacteria to evade normal host defences

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14
Q

bacterial factors contributing to the pathogenesis of UTIs: hemolysin production

A

*hemolysin is a cell toxin
*important in pyelonephritis

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15
Q

bacterial factors contributing to the pathogenesis of UTIs: ability to synthesize essential amino acids

A

*guanine, arginine, and glutamine required for bacterial growth in urine

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16
Q

bacterial factors contributing to the pathogenesis of UTIs: urease production

A

*Proteus mirabilis
*important in pyelonephritis and urolithiasis
*associated with STRUVITE stones and staghorn calculi

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17
Q

bacterial factors contributing to the pathogenesis of UTIs: bacterial motility

A

*ascend against urine flow

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18
Q

bacterial factors contributing to the pathogenesis of UTIs: endotoxin production

A

*decreases ureteral peristalsis, allowing bacteria to ascend

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19
Q

host factors that prevent UTIs

A

*urine: inhibits bacterial growth
-high urea concentration
-low pH
*mechanical flow: flushes out urinary tract
*urethra (longer urethra is protective)

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20
Q

host factors contributing to the pathogenesis of UTIs: obstruction or reflux

A

*urethral stenosis
*posterior urethral valves
*kidney stones
*polycystic kidney disease
*spinal cord injury or neurogenic bladder
*prostatic hypertrophy
*pregnancy

21
Q

host factors of WOMEN contributing to the pathogenesis of UTIs

A

*short urethra
*bacterial colonization of vagina and periurethral area
*sexual intercourse:
-facilitates movement of bacteria from anterior urethra to bladder
-trauma to urethra
-diaphragm use (can cause urethral trauma)
-spermacide use (inhibit lactobacillus)

22
Q

host factors contributing to the pathogenesis of UTIs: bladder catheterization

A

*catheters bypass the urethra
*100% of patients will have bacteriuria within 3 days of catheter placement

23
Q

host factors contributing to the pathogenesis of UTIs: susceptibility of renal medulla

A

*high ammonia concentrations inactivate complement
*high osmolality inhibits migration of neutrophils

24
Q

pathogens that commonly cause community-acquired UTIs

A

*E. coli (gram negative) is by far the leading cause
*followed by Klebsiella (esp. in people with hx of DM) and Proteus spp.
*Staph saprophyticus if young woman, sexually active, gram positive

25
pathogens that commonly cause hospital-acquired (nosocomial) UTIs
*E. coli is the leading cause *followed by other gram-negative rods (Klebsiella, Proteus, enterococci) *Pseudomonas and Candida (esp. with catheters) *Staph epidermidis
26
asymptomatic bacteriuria (ASB) - overview
*bacteria in the urine with NO symptoms *positive urine culture, > 10^5 cfu/mL *it does NOT prove infection; it is just a number to state that the culture is unlikely due to contamination *pyuria also is not predictive on its own *it is the presence of SYMPTOMS + PYURIA + BACTERURIA that denotes infection
27
asymptomatic bacteriuria (ASB) - treatment in the elderly
*no benefit to treating ASB with antibiotics: -no improvement in "mental status" -no difference in the number of symptomatic UTIs -no improvement in chronic urinary incontinence -no improvement in survival
28
asymptomatic bacteriuria (ASB) - indications to treat
*screen and treat ASB in 2 scenarios: 1. pregnancy 2. patients undergoing urologic procedure in which bleeding is anticipated *children not routinely screened, but if there, treat *otherwise, DO NOT TREAT
29
sterile pyuria
*WBCs in urine, but no bacteria *2 common causes: 1. urethritis, usually due to STIs (Chlamydia trachomatis or Neisseria gonorrhoeae) 2. GU tuberculosis
30
urethritis - clinical presentation
*primary symptom: **burning** on urination ***NO frequency or urgency** *urine culture colony counts lower
31
urethritis - common causes
*E. coli and other common UTI causes *STIs: Chlamydia trachomatis and Neisseria gonorrhoeae (purulent discharge from the urethra) *Ureaplasma urealyticum *noninfectious (trauma, allergic, chemical)
32
cystitis (lower tract infection) - clinical presentation
*dysuria ***frequency *urgency** *suprapubic pain
33
pyelonephritis (upper tract infection) - clinical presentation
*fever *chills *flank pain *costovertebral angle tenderness *nausea & vomiting *hypotension *tachycardia *plus, symptoms of cystitis may be present
34
prostatitis - clinical presentation
*fevers, chills *dysuria *urinary frequency *bladder outlet obstruction can occur *PE: high fever, may appear septic, moderate tenderness of suprapubic region *rectal exam: exquisitely tender and diffusely enlarged prostate
35
prostatitis - treatment
*ABX therapy should be prolonged (4-6 weeks) as most ABX do not penetrate well into acidic, lipophilic environment of prostate *prostatic massage contraindicated
36
diagnosis of UTI
*symptoms plus pyuria on urine dipstick or urinalysis *urine dipstick: -positive LEUKOCYTE ESTERASE -positive nitrites can be seen *U/A required for evaluation of complicated UTI *note - WBC casts can be seen in pyelonephritis
37
urine gram stain for UTIs
*should be performed in all pts with suspected pyelonephritis * > 1 bacteria/hpf correlates with > 10^5 organisms/ml *in combination with pyuria + symptoms = infection
38
urine culture for UTIs
*should be performed in all patients EXCEPT young, sexually active women with suspected (uncomplicated) cystitis *urine in the bladder is normally sterile, but urethra and periurethral areas are very diffiuclty to sterilize, esp in woemn *obtain quantitative culture of midstream clean-voided urine
39
indications for anatomic investigations in UTIs
*all upper tract disease (pyelonephritis) *relapse or failure to improve after appropriate ABX therapy *pre-pubertal females after their 2nd UTI *UTI in males of any age
40
examples of anatomic investigations in UTIs
1. ultrasound - first line test 2. CT scan (to exclude dx of perinephric abscess in pts with pyelonephritis if no improvement after 48 hrs) 3. intravenous pyelogram (after abnormal ultrasound)
41
treatment of uncomplicated cystitis
*short course therapy (3-5 days): -**nitrofurantoin** = treatment of choice -TMP-SMX -ciprofloxacin *beta lactams as an alternative (3-7 days)
42
do NOT use short-course therapy for UTIs in...
*males *upper tract symptoms (pyelonephritis) *recurrent or relapse of symptoms *more than 7 days of symptoms
43
treatment of pyelonephritis
*all patients should have urine culture + susceptibility test performed *adjust antibiotics based on results *7-10 days of antibiotics: -IV ceftriaxone -oral if non-toxic and able to tolerate po (ciprofloxacin, TMP-SMX)
44
complications of pyelonephritis
*bacteremia *septic shock *perinephric abscess *emphysematous pyelonephritis: -aggressive form of pyelonephritis with necrosis, vascular compromise, gas production -most commonly in people with poorly controlled DM -urologic emergency
45
chronic (recurrent) pyelonephritis
*due to multiple episodes of acute pyelonephritis *risk factors: VUR, stone disease *tubular atrophy, corticomedullary scarring, blunted calyces *"thyroidization" of the kidney: -atrophic tubules with eosinophilic proteinaceous material resembling thyroid tissue on pathology -waxy casts in urine
46
xanthogranulomatous pyelonephritis
*unusual variant of chronic pyelonephritis *most cases occur in the setting of obstructive nephrolithiasis *destruction of kidney due to granulomatous tissue containing lipid-laden macrophages *can be confused with renal malignancy (looks like a tumor)
47
xanthogranulomatous pyelonephritis - CT findings
*"bear claw" appearance *massive caliectasis *parenchyma enlargement *often associated with stone
48
prevention of urinary tract infections
*remove urinary catheters ASAP *in and out straight catheterization preferable to indwelling catheterization in patients who are unable to void on their own *long term antibiotic prophylaxis generally NOT effective *ensure liberal fluid intake *contraception change (avoid spermacide) *post-coital prophylaxis can be considered in sexually active women *intravaginal estrogen can be helpful in preventing cystitis in elderly women with atrophic vaginitis *methenamine

Renal Exam (44 decks)

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