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
What are these fried egg cells and what is this a sign of?
Squamous epithelial cells
Indicative of contamination
What are risk factors for sterile pyuria?
Prior treatment with antibiotics
Calculi
Catheterisation
Bladder neoplasm
TB
Sexually Transmitted Disease
What is indicative of a UTI on culture?
Patients with infection usually have at least 10^5 cfu/mL in urine in the bladder, and therefore voided urine usually contains at least 10^5 cfu/mL.
Patients without infection have sterile bladder urine, and with proper collection, voided urine usually contains less than 10^4 cfu/mL.
It is likely that a significant proportion of patients with both symptomatic and asymptomatic infection have fewer than 10^5 bacteria/mL of urine.
What is the treatment of UTIs in women?
3 days of therapy with standard doses for treatment of uncomplicated lower tract infection in women.
Short-course therapy is not appropriate for women who have a history of previous urinary infection caused by antibiotic-resistant organisms or more than 7 days of symptoms. In these patients (who have an increased likelihood of upper tract infection) and in men, 7 days of therapy are recommended.
What are fungal infections in UTIs and what is the treatment?
Most Candida urinary tract infections occur in patients with indwelling catheters..
Removal of the catheter may result in cure.
Oral fluconazole is no more effective than no therapy.
What is the treatment of fungal UTIs?
There is no demonstrated benefit in the treatment of asymptomatic infection, and therefore therapy is not recommended. Exceptions include renal transplant patients and patients who are to undergo elective urinary tract surgery.
In these instances, attempts should be made to eliminate or at least suppress the candiduria.
What is pyelonephritis?
Infection of the Kidney.
The greater the number of organisms delivered to the kidneys, the greater is the chance of producing infection.
The kidney itself is not uniformly susceptible to infection—very few organisms are needed to infect the medulla, whereas 10,000 times as many are needed to infect the cortex.
What is pyelonephritis associated with?
Sepsis
Septicaemia
What is the management of pyelonephritis?
Requires more aggressive treatment.
Broad spectrum antibiotics.
Co-amoxiclav +/- gentamicin.
Imaging:
- Calculi
- Structural cause
What are complications associated with pyelonephritis?
Perinephric abscess.
Chronic pyelonephritis:
- Scarring
- Chronic renal impairment
Septic shock
Acute papillary necrosis
Can you prophylactically treat UTIs?
Controversial
Likely to promote resistance
Adverse effects
