Urinary Tract Infections Flashcards
Define bacteriuria.
The presence of bacteria in the urine.
Define cystitis.
Inflammation of the bladder, often caused by infection.
What is an uncomplicated urinary tract infection?
Refers to infection in a structurally and neurologically normal urinary tract.
What is a complicated urinary tract infection?
Refers to infection in a urinary tract with functional or structural abnormalities (including indwelling catheters and calculi).
Summarise the epidemiology of UTIs.
The prevalence of bacteriuria in young nonpregnant women is about 1% to 3%.
Up to 40% to 50% of the female population will experience a symptomatic urinary tract infection at some time during their life.
What is the most common causative organism of acute UTIs?
E. Coli
Which other organisms can cause UTIs?
Proteus mirabilis
Klebsiella aerogenes
Enterococcus faecalis
Staphylococcus saprophyticus
Staphylococcus epidermis
What is the pathophysiology of recurrent urinary tract infections?
In recurrent urinary tract infections, especially in the presence of structural abnormalities of the urinary tract, the relative frequency of infection caused by Proteus, Pseudomonas, Klebsiella, and Enterobacter species and by enterococci and staphylococci increases greatly.
What are antibacterial host defences in the urinary tract?
Urine - Osmolality, pH, organic acids
Urine flow and micturition
Urinary tract mucosa - Bactericidal activity, cytokines
What is the pathophysiology of ascending UTI?
The urethra is usually colonized with bacteria. The female urethra is short and is in proximity to the warm moist vulvar and perianal areas, making contamination likely.
It has been shown that the organisms that cause urinary tract infection in women colonize the vaginal introitus and the periurethral area before urinary infection results.
Massage of the urethra in women and sexual intercourse can force bacteria into the female bladder. Once within the bladder, bacteria may multiply and then pass up the ureters, especially if vesicoureteral reflux is present, to the renal pelvis and parenchyma.
How can renal tract abnormalities contribute to UTIs?
Several abnormalities of the urinary tract interfere with its natural resistance to infection. Obstruction inhibits the normal flow of urine, and the resulting stasis is important in increasing susceptibility to infection.
What are mechanical causes of obstruction?
Extrarenal:
- Valve stenosis, or bands
- Calculi
- Extrinsic ureteral compression from a variety of causes
- Benign prostatic hypertrophy
Intrarenal:
- Nephrocalcinosais
- Uric acid nephropathy
- Analgesic nephropathy
- Polycystic kidney disease
- Hypokalemic nephropathy
- Renal lesions of sickle cell trait or disease
What are neurogenic malfunctions which can lead to obstruction?
Poliomyelitis
Tabes dorsalis
Diabetic neuropathy
Spinal cord injuries
How can reflux contribute to UTIs?
Vesicoureteral reflux tends to perpetuate infection by maintaining a residual pool of infected urine in the bladder after voiding.
What is the haematogenous route and how does it contribute to UTIs?
The kidney is frequently the site of abscesses in patients with Staphylococcus aureus bacteremia or endocarditis, or both.
It appears that in humans, infection of the kidney with gram-negative bacilli rarely occurs by the hematogenous route.
What are symptoms of UTIs in infants?
Symptoms in neonates and children younger than 2 years are nonspecific
Failure to thrive
Vomiting
Fever
What are symptoms of UTIs in children over 2 years?
More likely to display localized symptoms such as:
Frequency
Dysuria
Abdominal or flank pain
What are symptoms of lower UTI?
The lower tract symptoms result from bacteria producing irritation of urethral and vesical mucosa, causing frequent and painful urination of small amounts of turbid urine.
Patients sometimes complain of suprapubic heaviness or pain.
Occasionally, the urine is grossly bloody or shows a bloody tinge at the end of micturition.
Fever tends to be absent in infection limited to the lower tract.
What are symptoms of upper UTI?
Fever (sometimes with rigors)
Flank pain
Additionally frequently lower tract symptoms (e.g., frequency, urgency, and dysuria). At times, the lower tract symptoms antedate the appearance of fever and upper tract symptoms by 1 or 2 days. The symptoms described, although classic, may vary greatly.
What are symptoms of UTIs in older people?
The vast majority of older adult patients with urinary infection are asymptomatic.
Symptoms, when present, are often not diagnostic, because noninfected older adults often experience frequency, dysuria, hesitancy, and incontinence.
Symptoms of upper tract infection are often atypical e.g., abdominal pain, change in mental status.
What are appropriate investigations for a UTI?
Uncomplicated UTI/pyelonephritis:
- Urine dipstick
- MSU for urine microscopy, culture and sensitivities
Bloods: FBC, UE, CRP (inflammatory markers and renal function)
Further investigation of complicated UTI:
- Renal USS
- Intravenous urography
How should catheterised patients with no systemic features and a positive MC+S be treated?
Nothing, bacteriuria is common in catheterised patients
What are methods of sampling?
Midstream clean catch (MSU): preferred for the routine collection of urine for culture.
Catheterisation.
Suprapubic aspiration.
What is this, and what is it a sign of?
White cells pyuria
Indicative of infection
