Urinary tract infections Flashcards
Which parts of the urinary tract are affected in a lower UTI?
- Bladder or urethra
- Cystitis
Which parts of the urinary tract are affected in an upper UTI?
- Kidneys
- Infection has tracked up ureters
- Pyelonephritis
Why is the urinary tract normally sterile and resistant to bacterial colonisation?
- Emptying of bladder during micturition washes bacteria out
- Vesico-uretal valves mean there’s only one direction of urine flow (out of the body)
- Immunological factors
- Mucosal barriers
- Urine acidity
What are the risk factors for UTI?
- Female (short urethra)
- Obstructive causes - stasis of urine and no wash out of urine
- Neurological conditions affecting bladder emptying
- Pregnancy
- Abnormal renal tract
- Impaired host defence
What can cause obstruction and lead to UTI?
- Stones
- Enlarged prostate
- Retroperitoneal fibrosis
What neurological conditions can result in UTI?
- Multiple sclerosis
- Stroke
Why does pregnancy put people at risk of UTI?
- Enlarged uterus
- Hormonal effects on relaxation of musculature
Which abnormal features of the renal tract put people more at risk of developing a UTI?
- Vesico-ureteric reflux in children
- Indwelling urinary catheter
Which conditions can lead to impaired host defence and result in UTIs?
- Diabetes mellitus
- Immunosuppression
What are the important differences between male and female anatomy?
- Males have a much longer urethra
- Male meatus is located far away from the rectum
- Females have a short urethra
- Opening of urethra is very close to vagina and rectum
What are common times in life for people to develop UTIs?
- Infancy
- Preschool
- Honeymoon cystitis (early 20s)
- Pregnancy
- After the age of 60 when prostatism begins
What are the causative agents of UTIs?
- Coliforms
- Escherichia coli is most common
How do coliforms result in UTIs?
- Flagella - movement
- Pili - attachment
- Capsular polysaccharide - colonisation
- Haemolysin, toxins - damages host membranes and cause renal damage
How does cystitis present?
- Dysuria
- Cloudy urine
- Nocturia or frequency
- Urgency
- Suprapubic tenderness
- Haematuria
- Pyrexia (usually mild)
How does pyelonephritis present?
- High fever +/- rigors
- Loin pain and tenderness
- Nausea/vomiting
- +/- symptoms of cystitis e.g. haematuria
What are some differentials for dysuria?
- Other causes of inflammation
- STIs
- Post sexual intercourse
- Contact with irritants
- Symptoms of menopause, atrophic vaginitis, vaginal atrophy
Define an uncomplicated UTI?
- Infection by a usual organism in a patient with a normal urinary tract and normal urinary function
- May occur in females of any age
What factors may predispose a patient to a complicated UTI?
- Abnormal urinary tract
- Virulent organism (staph aureus)
- Impaired host defence (immunosuppression, poorly controlled diabetes)
- Impaired renal function
- Suspected pyelonephritis
- Children
- Males
- Pregnant women
Define a complicated UTI
- 1 or more factors that predispose to persistent infection, recurrent infection or treatment failure
What investigations are done when a patient presents with UTI?
- Urine culture
- Dipstick
- Visual inspection
How do we investigate healthy non-pregnant women of child bearing age?
- Uncomplicated UTI
- No need for urine culture
How do we take a urine culture in complicated UTI?
- Mid-stream urine - cleansing not required, ideally holding labia apart in women
- Clean catch in children
- Culture urine within 4 hours of collection, refrigerate or use boric acid preservative
- Want to know what the organism is so we can find out which antibiotics to use
When is a urine dipstick not useful?
- Patients >65 years old (asymptomatic infection is common)
- Catheterised patients
When is a urine dipstick useful?
- If patient presents with one of the following
- Dysuria
- New nocturia
- Cloudy urine
