UTIs Flashcards
How can UTIs be split into two main groups based on the tissues affected?
Upper and lower UTIs
Lower UTI (cystitis)- Infection of the bladder
Upper UTI - Infection involving the kidneys (pyelonephritis)
How can different UTIs be classified depending on their presentation?
Uncomplicated and complicated cases
Describe uncomplicated UTIs
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
Describe complicated UTIs
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
What is the pathogenesis for STIs?
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
What are some normal defence mechanisms employed by the body to prevent UTIs?
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
What are some predisposing factors for UTIs?
Age
Gender
Pregnancy
Spermicides and diaphragms (should use different contraception devices)
Instrumentation of urinary system
Urinary tract obstruction
Incomplete bladder emptying
Renal disease
What organisms most commonly cause uncomplicated UTIs?
E. coli is responsible for 80-90% of uncomplicated cases
Other organisms include Staph. saprophyticus, K. pneumoniae, Proteus spp., Enterococcus species
What organisms most commonly cause complicated UTIs?
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)
How can UTIs be diagnosed?
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)
What is the presentation of lower UTI (cystitis)?
Dysuria, urgency, frequency, noctoria, suprapubic pain heaviness/pain, hematuria (blood in urine)
What is the presentation of upper UTI (pyelonephritis)?
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
What are some considerations for modifying therapy for UTIs?
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
What are examples of antibiotics that have poor urine concentration?
Erythromycin and Moxifloxacin both are cleared via the liver (biliary secretion)
What are some first-line antibiotics for uncomplicated UTIs?
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
What are some second-line antibiotics for uncomplicated UTIs?
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
Are UTIs self-limiting?
In many cases of uncomplicated UTIs, they are self-limiting.
Treatment is still recommended because it reduces pain, severity, and potential consequences
What is reinfection in terms of recurrent UTI infections?
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)
What is relapse in the context of recurrent UTIs?
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
What is different in the treatment of recurrent UTIs?
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
What does prophylaxis look like in recurrent UTIs?
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
