UTIs Flashcards
Name 4 predisposing factors for UTIs
Anatomical abnormality Catheterisation Sexual activity Outflow obstruction (BPH) Residual urine (neurogenic bladder) Pregnancy
Types of UTI
uncomplicated lower UTI
Upper UTI - acute bacterial pyelonephritis
Catheter related
Asymptomatic bacteruria
Describe the pathogenesis of UTI
Urinary tract is normally protected from infection by regular flushing during voiding which removes organisims from the distal urethra.
Bacteria colonising the perineum and anterior urethra ascend into the bladder. Normally occurs when natural host defense mechanisms are compromised. Bacteria can also enter via the bloodstream, lymphatics or fistula.
Bacteria multiply in the bladder and established infection may ascend to involve the ureters and kidneys. Symptoms are related to the virulence of the organism and the host response.
Symptoms associated with UTI
Dysuria Frequency Urgency Suprapubic pain Haematuria Smelly urine Loin pain Fever Perineal pain/discomfort (prostatitis)
What are the defense mechanisms that normally prevent UTIs?
Neutrophils: phagocytose bacteria
Urine osmolality and low pH: reduce bacteria survival.
Urine flow: normal micturition washes out bacteria. Stasis promotes colonisation and infection
Commensal organisms: compeitively inhibit growth of pathogens
Uroepithelium: proteins covering the urothelium and antimicrobial properties. Produce IgA which activates complement.
Vesicoureteric reflux
Normally the vesico-ureteric junction acts as a one-way valve of urine entering the bladder from above. The ureter is shut during bladder contraction, preventing reflux of urine during micturition.
If the valve mechanism is incompetent, there is reflux into the ureter on voiding, and incomplete bladder emptying as urine returns to the bladder.
This increases the risk of infection and leads to kidney damage.
Consequence of vesicoureteric reflux
Causes papillary damage, nephritis, cortical scarring, renal fibrosis and reduced function.
Can cause ESRD in adult life
DDx in men with dysuria, frequency and urgency
UTI
Acute prostatitis
Chlamydia
Epididymitis
If back pain - possible pyelonephritis
In an uncomplicated UTI give 7 day course of trimethoprin or nitrofurantoin. Recurrent UTI refer for urological investigation.
Prostatitis give quinolone
Treatment of UTI in non-pregnant women
If limited symptoms - dipstick urine, if positive give 3 day course of trimethoprin or nitrofurantoin
management of pregnant women with bacteriuria
If symptomatic: send a specimen for culture and treat with antimicrobial for 7 days
Do not give quinolones. No trimethoprim 1st trimester. No nitrofurantoin 3rd trimester.
If asymptomatic but >10^5 organisms on 2 occasions treat with antibiotics for 3-7 days and monitor
Why is it important to check pregnant women for bacteriuria
If undetected:
Increased risk of symptomatic UTI
Increases risk of pre-term delivery
Increased risk of low birth weight baby
Features of suggestive of UTIs in catheterised patients
Rigors
Costovertebral tenderness
New onset confusion
Send urine for culture. Dipsticks will be positive in catheterised patients. Remove and replace catheter
Symptoms of Upper UTI
Loin pain
Flank tenderness
Fever
Rigors
Severe: tachycardia, hypotension
Treat with 7 days ciprofloxacin or 14 days coamoxiclav
Risk factors for asymptomatic bacteriuria
Female Sexual activity Diabetes Age Catheter
Lab diagnosis of urine samples
Dipstick test: protein, blood, nitrites, leukocyte esterase
Microscopy: WBC, RBC, bacteria, crystals, casts (renal parenchymal infection). epithelial cells (contaminated sample)
Culture: identification of urinary pathogens
Antibiotic sensitivity
