12.5 Urinary Tract Infection

Question 1

UTI

risk factors (list 3)

Answer 1

1. sexual intercourse
2. urinary stasis
3. catheters

Question 2

UTI

common symptoms (4)

what type of symptoms are usually absent?

Answer 2

1. dysuria (pain on urination)
2. urinary frequency
3. urgency
4. suprapubic pain

Note: systemic signs of infection (eg fever) usu absent!

Question 3

Infectious cystitis:

lab tests and their findings (3 tests)

which is gold standard?

Answer 3

1. urinalysis: cloudy urine with >10 WBCs/hpf (high power field)
2. urine dipstick: positive for leukocyte esterase (from pyuria–pus in urine) and nitrites (bacteria convert nitrates to nitrites)
3. Culture: >100,000 colony forming units (gold std for cystitis)

Question 4

what is most common cause of cystitis?

what %?

Answer 4

E Coli

80% of cystitis

Question 5

Cystitis: most common infectious agents

Answer 5

1. E Coli (80%)
2. Staph saprophyticus – sexually active young women (although still usu E coli)
3. Klebsiella pneumoniae
4. proteus mirabilis (alkaline urine with ammonia scent)
5. Enterococcus faecalis

Question 6

pt with suspected UTI: What if you get these lab tests?

1. urinalysis: >10 WBCs/hpf
2. dipstick: leukocyte esterase

BUT:

3. Culture: negative

Answer 6

Sterile pyuria: presence of pyuria with negative culture. Remember culture is gold std for dx of cystitis.

-suggests urethritis, due to Chlamydia or Neisseria gonorrhoeae

Question 7

Cystitis in sexually active young women: what microbe(s) to suspect?

Answer 7

Staph saprophyticus.

however, E Coli still most common

Question 8

what is the gold standard test for dx of cystitis?

Answer 8

positive Urine culture:

>100,000 colony forming units

Question 9

what is the dominating symptom of urethritis?

Answer 9

dysuria

Question 10

How does urethritis diagnosed differently from cystitis?

Answer 10

If you urethritis due to Chlamydia or Gonorrhoeae, you can get sterile pyuria.

-Presence of pyuria (>10 WBCs/hpf and leukocyte esterase) with negative culture

Question 11

Pyelonephritis

-in addition to symptoms of cystitis, how does it present? (4)

Answer 11

infection of kidney

1. fever (now systemic is involved, as opposed to cystitis)
2. flank pain (nerves of kidney capsule)
3. WBC casts (leukocytes travel into tubules)
4. leukocytosis (systemic now)

Question 12

pyelonephritis

-most common pathogens (3)

Answer 12

• pathogens usu ascend from bladder
  1. E Coli (90%)
  2. Enterococcus faecalis
  3. Klebsiella

Question 13

Chronic pyelonephritis

• what is it, what happens
• causes

Answer 13

-interstitial fibrosis, tubule atropy due to multiple bouts of acute pyelonephritis.

2 main causes:

1. VUR (vesiculoureteral reflux–children)
2. obstruction (BPH, cervical carcinoma)

Question 14

chronic pyelonephritis

-what happens to the kidney? gross and histological

Answer 14

• cortical scarring with blunted calyces.
• scarring at upper and lower poles is characteristic of VUR.

Histology: “Thyroidization”: atrophic tubules are loaded with a pink material that resembles thyroid colloid. It’s a eosinophilic proteinaceous material.

Question 15

what is VUR? vesicoureteral reflux

Answer 15

1 of 2 causes of chronic pyelonephritis (the other is uretal obstruction)

-Caused by malformation of the connection btwn ureter and bladder. This can cause urine reflux back to kidney, causing interstitial fibrosis and tubular atrophy

Question 16

how can obstruction of the ureter damage the kidney?

Answer 16

• obstruction can cause chronic pyelonephritis–urine that stays stuck in kidney can cause interstitial fibrosis and tubular atrophy
• causes: BPH, cervical carcinoma