Week 7 UTI Flashcards
Who is most at risk of UTI?
Extremes of ages and females
Host factors leading to UTIs
Shorter urethra- females
Obstruction- Enlarged prostate, uterus, stones
Neurological problems- incomplete emptying, residual urine
Ureteric reflux- ascending infection from bladder- dysfunctional valves stopping back flow- common in children
Bacterial factors leading to UTIs
- Flagella and fimbriae- allow attachment to host cells- particularly Gram -ve
- Polysaccharide capsule produced- permitted by K antigens- gram -ve
- Urease breaks down urea creating favourable environment for bacterial growth
- haemolysins produced- damage host membranes and cause re al damage- gram -ve
What are the common causes of UTI?
Normal flora of bowel- if pass through peritoneum- ascending infection
Can be blood stream infection as bacteria trapped in glomerulus of kidney during filtration
- most common coliforms- enterobacteriaceae- E. coli- gram -ve rods- stain pink
What are Lower UTI sympts?
Sometimes lower grade fever
Dysuria
Frequency
Urgency to pass
What are Upper UTI symptoms?
Fever
Loin pain- renal angle
May have dysuria and frequency but pain may localise to kidneys
How are specimens collected from different types of pts?
Mid stream urine- clear those settled in urethra
Clean catch in children- no antiseptic
Collection bag- in children
Catheterised pts- collect sample by entering needle into sleeve near entering
Transported at 4degree- stop over multiplication, +/- boric acid- preservative of cells- host white cells
What are some of the near pt screening tests often used for UTIs?
Turbidity- hold to light- clear= no infection
Dipstick testing- leukocyte esterase- enzyme present in WBC, nitrite- sign of bacterial metabolism- positive reaction- very specific whereas -ve cannot rule out infection, haematuria- not specific, proteinuria- poor for diagnosing infection
How are samples screened, cultured?
Put through screening-automated- looks for white cells, red cells, casts- aggregates of cells and bacteria- if something found then go onto do Microscopy and culture- 4 quarters- can show no bacteria, lactose fermenting coliforms- pink, bacteria but not pink- non lactose fermenting, small growth- not significant- picked up when collecting
Done when requested
What are the standard cut off points for diagnosing infection and non infection?
Only looking at women with pyelonephritis not cystitis, men, children- infection= 10’5 cfu/ml
Generally now lower range of 10’4 cfu/ml indicates infection
What are the common symptoms of UTIs?
- Frequency and dysuria (pain)- lower UTI- inflammation of bladder
- Acute pyelonephritis- Upper UTI- inflammation of kidneys
- Chronic nephritis
- Asymptomatic infections- pregnancy- no symptoms - can lead to symptoms usually upper UTI- also affects pregnancy- more risk of premature and small babies- screening in pregnancy
- Septicaemia +/- shock- death
Why is culture so important?
Pts can not have symptoms etc and therefore need culture to identify or rule of infection
What is typically found from culture of symptomatic adult women?
50% have positive culture
50% will not- why- difficult organism to grow, inflammation not directly of bladder, STI
- both respond to short course of ABs
Complicated- what additional tests may be performed?
Imaging if urinary tract- ultrasound starting point
What are some of the causes of pts presenting with symptoms but don’t show infection when cultured?
Most common- Pt already on ABs
TB
Appendicitis
