UTIs Flashcards
What is a UTI?
An inflammatory response of the urothelium (all transitional cell epithelium) to bacterial invasion, usually associated with bacteriuria and pyuria
How do you define a UTI depending on the amount of bacteria?
- Bacterial infection of urine with >10^5 colony forming units/ml of urine
- In symptomatic patients allow lower counts - > 10^2 cfu/ml
What is bacteriuria?
Describes the presence of bacteria in the urine, which may be asymptomatic or symptomatic
What is a CSU?
Catheter urine sample
What is pyuria?
The presence of white blood cells ( >10 per HPF x 400) in the urine
Simple/uncomplicated UTIs are UTIs in which patients?
- Female
- First presentation
- Not pregnant
- No signs of pyelonephritis
What are signs of pyelonephritis?
- Fever
- Sepsis signs - high WBCs, lactate, fever
- Loin pain
Complicated UTIs are UTIs in which patients?
- Male
- Recurrent UTIs
- Pregnancy
- Elderly
- Catheter related
- Children
What is the definition of recurrent UTIs?
> 2 in 6 months or > 3 in 1 year (different from persistent UTI)
What are the types of lower UTIs (bladder and lower)?
1) Urethritis
2) Cystitis
3) Prostatitis
What are the types of upper UTIs (higher than bladder)?
1) Pyelonephritis
2) Intrarenal/perinephric abscess (complication of pyelonephritis)
What are the risks factors for UTIs in anyone?
1) Previous UTI
2) Instrumentation or surgery
3) Catheterisation
4) Upper tract obstruction e.g. stones
5) Neurogenic bladder e.g. due to stroke
6) Renal transplantation (immunosuppressed)
What are the risks factors for UTIs in adults?
1) Sex
2) Spermicides
3) Diaphragm
4) Pregnancy
5) Diabetes mellitus
6) Benign prostate enlargement (BPE)
What are the risk factors for UTIs in women of older age?
1) Oestrogen deficiency - vaginal dryness and atrophy
2) Prolapse
What are UTI complicating factors?
1) Catheters
2) Bladder outlet obstruction (BOO), PVR > 100ml
3) Diabetes, CKD
4) Males, elderly
5) Vesico ureteric reflux
6) Pregnancy
7) Previous upper tract surgery
8) Bladder or renal stones
9) Chemo or radiotherapy to bladder
10) Upper tract reconstruction with bowel
What is the PVR?
Post-void residual - the amount of urine left in the bladder after urination
What is the vesico ureteric reflex?
When urine goes back into the kidneys
What uropathogens cause UTIs?
1) Streptococci
2) Proteus - makes kidney stones, recurrent proteus infections leads to infection stones
3) Klebsiella
4) E.coli
5) Staphylococci
What are the gram positive bacteria?
1) Staphylococcus
2) Streptococcus
3) Enterococcus
What are the gram negative bacteria?
1) Neisseria gonorrhoea
2) Escherichia (coli)
3) Klebsiella
4) Proteus
5) Pseudomonas (long term stents)
6) Chlamydia trachomatis
How does chlamydia typically present in females?
Typically asymptomatic in females but can present with dysuria, discharge or PID
How do you investigate an STD (chlamydia)?
- Send urinalysis, urine culture (if pyuria seen, but no bacteria, suspect chlamydia)
- Pelvic exam - send discharge from cervix/urethra for chlamydia PCR
- Low oestrogen in post menopausal women
What are the host defence mechanisms against UTIs?
1) Commensal flora
2) Integrity of skin/mucus membrane
3) Secretions - lysosomes, IgA
4) Long male urethra
5) Urine flow
6) Bladder surface mucin/GAG layer
7) Tamm - Horsfall protein (uromucoid) → secreted by cells of ascending loop of Henle, bind to E.coli expressing type 1 mannose sensitive fimbriae
8) Mucosal shedding
9) Local immune response
What are the clinical features of a UTI?
Dysuria, frequency, urgency, pain