Urinary Tract Infection Flashcards
What is a Urinary Tract Infection (UTI)?
Infection of urethra, bladder or kidney
How does UTI most commonly occur?
Most commonly arises due to ascending infection
What population has a higher incidence of UTIs?
Females
What are the most common risk factors for UTIs?
Sexual intercourse, Urinary stasis (inc. risk for bacteria to grow in urine) and catheters.
What is Cystitis?
Infection of the bladder
What does Cystitis present with?
Dysuria (pain when urinating), urinary frequency, urgency and suprapubic pain
What symptoms are usually absent with Cystitis?
Systemic signs (e.g. fever) are usually absent
What are three important laboratory tests for UTI?
- Urinalysis
- Dipstick
- Culture
What does a Urinalysis show with UTI?
Cloudy urine with > 10 WBCs/high power field (hpf)
What does a Dipstick test show with UTI?
Positive leukocyte esterase (due to pyuria) and nitrites (bacteria convert nitrates to nitrites)
What does a Culture show with UTI?
Greater than 100,000 colony forming units (gold standard)
What is the most common cause of UTIs? What percentage of UTIs does it represent?
E. coli, 80%
What is the second most common cause of UTIs?
Staphylococcus saprophyticus
In what age/group is Staphylococcus saprophyticus most common?
Increased incidence in young, sexually active women (but E. coli is still more common in this population)
What is the third most common cause of UTIs?
Klebsiella pneumoniae
What is the fourth most common cause of UTIs?
Proteus mirabilis
What do you find in UTIs caused by proteus mirabilis?
Alkaline urine with ammonia scent
What is the fifth most common cause of UTIs?
Enterococcus faecalis
What is Sterile Pyuria?
Presence of pyuria (>10 WBCs/hpf and leukocyte esterase) with a negative urine culture.
What is pyuria?
Presence of pus in the urine
What does the finding of Sterile Pyuria suggest?
Urethritis due to Chlamydia trachomatis or Neisseria gonorrhoeae
What is the dominant presenting sign of urethritis?
Dysuria
What is Pyelonephritis?
Infection of the kidney
What usually causes Pyelonephritis?
Usually due to ascending infection
When is there an increased risk for Pyelonephritis?
With vesicoureteral reflux
What does pyelonephritis present with?
Fever, flank pain, WBC casts, and leukocytosis in addition to symptoms of cystitis.
What is the most common pathogen associated with Pyelonephritis?
E. coli (90%)
What are the second and third most common pathogens associated with Pyelonephritis?
- Enterococcus faecalis
3. Klebsiella species
What is Chronic Pyelonephritis?
Interstitial fibrosis and atrophy of tubules due to multiple bouts of acute pyelonephritis.
What causes Chronic Pyelonephritis?
Due to vesicoureteral reflux (children) or obstruction (e.g. BPH (benign prostatic hyperplasia) or cervical carcinoma)
What is vesicoureteral reflux?
- Angle between bladder and ureter is malformed –>
- Inc. risk of reflux to kidney –>
- Inc. scarring
What does Chronic Pyelonephritis lead to?
Cortical scarring with blunted calyces
What type of scarring is characteristic of vesicoureteral reflux?
Scarring at the upper and lower poles is characteristic of vesicoureteral reflux
What is seen in a histological slide of Chronic Pyelonephritis?
Atrophic tubules containing eosinophilic proteinaceous material –> they resemble thyroid follicles (‘thyroidization’ of the kidney)
What can be seen in the urine of Chronic Pyelonephritis?
Waxy casts
