Urinary tract infections Flashcards
How common are UTIs?
2nd only to resp infections; 1-3% of all GP consultations.
Which groups are at risk of morbidity?
Significant cause of morbidity in females of all ages, infant boys and older men.
Who is most likely to get a UTI?
Up to 50% of women in lifetime, many recurrent (20% within 6 months), most not severe
1 to 2% of infants (boys < 3 months old 3x> girls)
Men rare until old age (prostatic enlargement)
____% elderly have asymptomatic bacteriuria
_____% of all nosocomial infections in men and women are UTIs; _______% of these develop secondary to indwelling catheters.
20% elderly have asymptomatic bacteriuria.
Forty percent of all nosocomial infections in men and women are UTIs; 80% of these develop secondary to indwelling catheters.
What are the consequences of UTI?
Societal and individual costs – health care costs (GP, ED and hospital), time missed from work
Frequent recurrences
Uncontrolled infection / sepsis
Renal damage in young children
Preterm birth
Recurrent courses of AB contribute to antimicrobial resistance and risk of CDI (C. difficile infection)
What are the types of uncomplicated UTIs?
Uncomplicated “Lower” UTI
- Cystitis
- Urethritis, prostatitis, epididymo-orchitis
Uncomplicated “Upper” UTI
•Acute pyelonephritis
Uncomplicated = no anatomical or neurological abnormalities of the urinary tract
What are the risk factors for an uncomplicated UTI compared to a complicated UTI?
What is pathogenesis?
Balance between host defences and organism virulence
What are the host factors for a lower UTI?
- Obstruction (prostatic hypertrophy, urethral valves or stricture)
- Poor bladder emptying (neuropathic (MS, spinal cord injury), bladder diverticula, pelvic floor disorders)
- Catheterisation/instrumentation
- Vesico-enteric fistula
- Sex (female – vaginal or anal; male – insertive anal)
- Diabetes
- Genetics: non-secretors of ABH blood group antigens, esp in premenopausal women; and variable expression of the CXCR1 receptor, involved in neutrophil activation
What are the host factors for an upper UTI?
May follow on from lower UTI
Vesico-ureteric reflux
Obstruction (eg calculus, stricture)
What is the pathogenesis of a UTI?
- Contamination of the periurethral area with a uropathogen from the gut
- Colonisation of the urethra and migration to the bladder
- Colonisation and invasion of the bladder, mediated by pili and adhesins
- Neutrophil infiltration
- Bacterial multiplication and immune system subversion
- Biofilm formation
- Epithelial damage by bacterial toxins and proteases
- Colonisation of the kidneys
- Host tissue damage by bacterial toxins
- Bacteremia
What 3 factors does bacterial virulence depend on?
- Adherence
- Invasion
- Evasion
How does UPEC acheive adherence?
In the bladder, uropathogenic Escherichia coli (UPEC) expression of type 1 pili is essential for colonization, invasion and persistence.
P-pili confer tropism to the kidney
UPEC are highly adhesive so are proficient in retrograde ureteral ascent
How is a diagnosis of a UTI made?
Clinical symptoms
Urine dipstick testing
Urine culture
What are the symptoms of cystitis?
bladder and urethral symptoms
overlap with urethritis
dysuria, frequency, urgency, suprapubic pain, nocturia
cloudy urine/visible blood
Children, elderly and catheterised can be non-specific, such as delirium, lethargy so consider the diagnosis among other causes.