UTIs

Question 1

How can UTIs be split into two main groups based on the tissues affected?

Answer 1

Upper and lower UTIs

Lower UTI (cystitis)- Infection of the bladder

Upper UTI - Infection involving the kidneys (pyelonephritis)

Question 2

How can different UTIs be classified depending on their presentation?

Answer 2

Uncomplicated and complicated cases

Question 3

Describe uncomplicated UTIs

Answer 3

No structural or functional abnormalities

Affects healthy premenopausal women of child-bearing age (15-49)

Some authorities initially blanket declare all UTIs in healthy post menopausal and diabetic women to be uncomplicated

Question 4

Describe complicated UTIs

Answer 4

Predisposing factors:
A lesion in the urinary tract, distortion of urinary tract, kidney stones, in dwelling catheter, BPH, control over normal urinary flow

All UTIs in men are considered complicated

Children with recurrent UTIs should be investigated for urinary tract abnormality

Question 5

What is the pathogenesis for STIs?

Answer 5

UTIs will develop by the ascending route

Colonization of vaginal vestibule followed by colonization of urethra

In some women, sexual intercourse is a major determinant for bacterial entry into bladder

Bacteria can spread up ureters to kidney especially if there is vesicoureteral reflux or reduced urethral peristalsis

Can rarely be passed via blood-to-blood contact

Question 6

What are some normal defence mechanisms employed by the body to prevent UTIs?

Answer 6

Urine (chemical defences):
Low pH, extreme osmolality, high urea and organic acids

The act of urination washes organisms out of bladder

Prostatic secretions have antibacterial properties (found only in men, maybe why they don’t have as many UTIs)

Bladder is coated with urinary mucus, discouraging bacterial adherence

Question 7

What are some predisposing factors for UTIs?

Answer 7

Age
Gender
Pregnancy
Spermicides and diaphragms (should use different contraception devices)
Instrumentation of urinary system
Urinary tract obstruction
Incomplete bladder emptying
Renal disease

Question 8

What organisms most commonly cause uncomplicated UTIs?

Answer 8

E. coli is responsible for 80-90% of uncomplicated cases

Other organisms include Staph. saprophyticus, K. pneumoniae, Proteus spp., Enterococcus species

Question 9

What organisms most commonly cause complicated UTIs?

Answer 9

E. coli causes 50% of cases (smaller proportion vs. uncomplicated UTIs)

Other organisms include enterobacter spp., Pseudomonas aeruginosa, Staph aureus (these organisms are also more prone to resistance)

Question 10

How can UTIs be diagnosed?

Answer 10

Urinanalysis: bacteruria(presence of bacteria in urine, 10^8CFU/L) and pyuria (presence of WBC in urine, 10 WBC/mm^3)

Urine culture: take sample of midstream clean-catch method. This is usually only done in complicated or resistant cases

Get a urine sample from a catheter or suprapubic bladder aspiration

Urine dipstick for nitrate and leukocyte esterase (indicator for bacteruria)

Question 11

What is the presentation of lower UTI (cystitis)?

Answer 11

Dysuria, urgency, frequency, noctoria, suprapubic pain heaviness/pain, hematuria (blood in urine)

Question 12

What is the presentation of upper UTI (pyelonephritis)?

Answer 12

Flank pain (below the ribs), fever, nausea, vomiting, malaise, costovertebral tenderness

It can be bacterecemic, be septic, hypotension, renal dysfunction, severe N & V. If you have these symptoms, need hospitalization and IV for 48-72 hrs

Question 13

What are some considerations for modifying therapy for UTIs?

Answer 13

Site of infection (cystitis vs. pyeloephritis)
Renal function
Causative organism
Concurrent diseases
Ability to penetrate urine or kidneys
Drug interactions
Adverse effects and allergies
Cost

Question 14

What are examples of antibiotics that have poor urine concentration?

Answer 14

Erythromycin and Moxifloxacin both are cleared via the liver (biliary secretion)

Question 15

What are some first-line antibiotics for uncomplicated UTIs?

Answer 15

TMP/SMX 1 DS BID x 3 days
TMP alone 100mg BID or 200mg OD x 3 days

Nitrofurantoin (50-100mg QID) or Macrobid 100mg BID x 5 days

Alternates:
Cephalexin 250mg QID or Fosfomycin 3g single dose

Question 16

What are some second-line antibiotics for uncomplicated UTIs?

Answer 16

Amoxicillin 500mg TID or 875mg BID x (3-7 days)

Norfloxacin 400mg BID x 3 days
Ciprofloxacin 250mg BID or 500mg OD x 3 days

Question 17

Are UTIs self-limiting?

Answer 17

In many cases of uncomplicated UTIs, they are self-limiting.

Treatment is still recommended because it reduces pain, severity, and potential consequences

Question 18

What is reinfection in terms of recurrent UTI infections?

Answer 18

Reinfection (most common form of recurrent infection):
Occurs after 2 weeks (medsask says 4 weeks) after completing antibiotic therapy
Caused by a different organism (organism was eliminated originally, so not a flare up)

Question 19

What is relapse in the context of recurrent UTIs?

Answer 19

Relapse:
Occurs within 2 weeks of completing antibiotic therapy
Caused by original organism
Bacteruria persists during therapy or reoccurs after 1-2 weeks following completion of antibiotic therapy

Question 20

What is different in the treatment of recurrent UTIs?

Answer 20

Culture sample to determine causative organisms
Re-assess for upper tract infection
Re-treat for 7-14 days (longer duration of therapy to ensure elimination of infection)
Same antibiotic choices, but tailor choices depending on culture and sensitivity testing

Question 21

What does prophylaxis look like in recurrent UTIs?

Answer 21

First line:
TMP/SMX 1 tab or 1/2 DS tab at night 3 times/week OR post-coital if associated with intercourse

TMP alone 100mg every night OR post-coital

Macrobid 100mg every night OR post-coital

Second line:
Fluoroquinolone 3 times/week OR every other day OR post-coital
Short course self-treatment at onset of symptoms if less than 3 infections/year