UTIs Flashcards
What host factors are there which allow for infection?
Shorter urethra in females
Obstruction due to stones, enlarged prostate, pregnancy or tumours
Neurological - incomplete emptying
Ureteric reflex
What are the normal UTI tract defence mechanisms?
Regular flushing during voiding to remove organisms from distal urethra Antibacterial secretions into urine and urethra Urine osmolality (high) High urine pH
Why does incomplete emptying increase chance of infection?
Residual urine is left in the b,added and some can be forced back up the ureters
What bacterial factors allow for infection?
Ability to adhere to epithelial cells - determines degree of virulence
How do E. coli get into and adhere to the urinary tract?
Have flagellae for motility
Aerobactin for iron acquisition in an iron-poor environment
Haemolysin - pore forming
Adhesins on fimbrae and on cell surface
What are the more cellular urinary tract defence mechanisms?
Neutrophils which are activated by adhesions. Found on mucosal surfaces
Complement activation with IgA production by urothelium
Commensal organisms
Urothelium has proteins in the mucus which interfere with bacterial binding
What predisposes people to a UTI?
Trauma - due to catheterisation, sex because it affects the urothelium
Define dysuria
Painful/difficult urination
Define pyuria
Pus in urine
What is pyelonephritis?
Infection of the kidneys
What are the symptoms of pyelonephritis?
Fever
Loin pain
Tenderness
Significant bacteriuria
What can be seen with imaging in pyelonephritis?
CT scan shows wedge shaped areas of inflammation
Small renal cortical abscesses and streaks of pus in the renal medulla
Focal infiltration of polymorphonuclear leukocytes and polymorphs in tubular lamina
Complications of acute pyelonephritis if left untreated?
Significant permanent kidney damage (rare)
Inflammation in renal cortex
How does reflux nephropathy occur?
Combination of vesicoureteric reflux and infection acquired in infancy and early childhood
Vesicoureteric valve normally prevents reflux of urine when bladder empties but in some children, the mechanism can be void
Secondary consequence is incomplete emptying as urine returns to bladder - predisposes to infection and kidney damage
How is reflux nephropathy diagnosed?
CT scan showing irregular renal outlines and a reduction in renal size
Can be unilateral or bilateral
Affect all or part of the kidney
When does urine reflux normally stop?
Around puberty
What can occur if damage persists from reflux nephropathy?
Progressive renal fibrosis
Further loss of function in severe cases
Predisposed to hypertension in later life
Who does reflux nephropathy normally affect?
Children
Suspect it if they ‘fail to thrive’
What is chronic interstitial nephritis?
Renal impairment following chronic inflammation
Can be caused by infection or an adverse reaction to drugs
What is bacterial cystitis?
Inflammation of the bladder caused by bacteria
Common in women as a result of sexual intercourse
Symptoms of bacterial cystitis?
Frequency and dysuria
Smelly urine
Pyuria
Haematuria
What is prostatitis?
Inflammation of the prostate gland
Symptoms of prostatitis?
Fever
Dysuria
Frequency
Perineal and lower back pain
Symptoms of an upper UTI?
Loin pain
Fever
Oliguria
Systemic symptoms
Symptoms of a lower UTI?
Frequency and dysuria
Smelly urine
Polyuria
Haematuria
Define oliguria
Production of abnormally small amounts of urine
What are possible complications of UTIs?
Long term renal damage
Common source of life threatening Gram negative bacteraemia
What is covert bacteriuria?
Asymptomatic bacteria in the urine
When is covert bacteriuria important to detect and how is it detected?
Children and pregnancy
Culture
Common organisms responsible for UTIs?
Gram negative rods
Particularly coliforms - E. coli
In young women and hospitalised patients can also be caused by coagulase negative staphylococci
Risk factors for a UTI?
Female Sexual intercourse Spermicide in females Pregnancy Menopause Immunosuppression Urinary tract obstruction Catheterisation Constipation
What is an uncomplicated UTI?
A UTI where the anatomy of the urinary react is normal and renal imaging will be normal.
There is no underlying condition contributing to the infection
Unlikely to result in serious kidney damage
Who would have an uncomplicated UTI?
Women of child-bearing age and healthy
What is a complicated UTI?
Infection of the lower urinary tract with an associated condition such as structural or functional abnormalities of the urinary tract or the presence of an underlying disease, which increases the risk of acquiring an infection or failing therapy
What can complicated UTIs lead to?
Severe and rapid kidney damage
Risk of Gram negative septicaemia
How to diagnose a UTI?
Midstream specimen of urine
Dipstick - Gram negative bacteria will reduce nitrates to nitrites however many false positives -> low sensitivity
Leuokocyte esterase may be present -> pyuria
Test for haematuria and proteinuria
When is dipstick testing not useful to diagnose UTIs?
Acute uncomplicated UTI
Men with typical/severe symptoms
Catheterised patients
Older patients with asymptomatic bacteriuria
How do you collect a sample in small children?
Adhesive bag
Unreliable
Now do you collect a sample from a catheterised patient?
Needle up a special tube in the catheter
What is a suprapubic aspiration?
Put a needle through the abdominal wall to take a urine sample
How is a urine sample transported?
4*C
Boric acid
When is microscopy done with UTIs?
Suspected kidney disease Suspected endocarditis Children under 6 Schistosomiasis Suprapubic aspirates
What is sterile pyuria?
When a UTI is present but unable to be cultured
Why might you get sterile pyuria?
Patient has already been treated with antibiotics
Infected with difficult bacteria to isolate or culture eg chlamydia, TB
Appendicitis
What is urethral syndrome?
When women present with symptoms of a UTI but not due to a bacetrial cause
What can cause urethral syndrome?
Vaginal infection
STI
Mechanical, physical or chemical causes
Treatment of uncomplicated UTIs? (Cystitis)
3 day course of trimethoprim
Treatment of complicated UTI?
Trimethoprim, nitrofurantoin or cephalexin for 7 days
Treatment of pyelonephritis and septicaemia?
14 day course of co-amoxiclav or ciprofloxacin
IV
How does ciprofloxacin work?
It is a quinolone
Inhibits bacterial DNA gyrase, preventing bacterial supercoiling
How do you treat prostatitis?
Ciprofloxacin
When would you give a patient prophylaxis for UTIs and what would you give?
If they have had 3 or more episode in one year and there is no treatable underlying condition
Trimethoprim/nitrofurantoin - 1 at night
