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
What should be features of a focussed history for UTI?
1) Classify the UTI
2) Triggers e.g. sex, STI, poor oral intake of fluid
3) Microbiology history - E coli could be resistant to abx that took before
4) PMH - diabetes, stones, neurology, childhood UTI
5) Drug history - if on pill will need alternative contraception with abx
What are red flag symptoms in a UTI and why?
1) Visible haematuria - 16% chance of having bladder cancer (ask about cancer symptoms)
2) Persistent microscopic dipstick haematuria 4% chance
What are the parts of a focused examination in UTI presentation?
- Vaginal examination
- Post void residual to check if they are emptying the bladder
What should you do with a MSU - urine dipstick ± microscopy (culture)?
- Ensure accurate collection of MSU
- Process specimen promptly, or refrigerate to prevent overgrowth of contaminants before being sent
- pH, blood, leucocytes, nitrites, protein, glucose
What are indications for further investigation of a UTI?
1) Visible haematuria
2) Persistant non-visible haematuria
3) Pyelonephritis
4) Atypical UTI
5) Obstructive lower urinary tract symptoms
6) Urea-splitting organisms
7) Suspicion of stones
8) Persistent UTI - failure to respond to abx could be cancer
What are further investigations in a UTI?
1) Imaging - USS (renal if flank pain and tenderness), PVR, kidney ureter bladder x ray (± CT if classic renal colic, proteinuria, haematuria)
2) Cystoscopy
Describe how you use antibiotics in a UTI?
- Self-start - make sure to collect urine sample before starting it so can be tested for resistance
- Continuous prophylaxis - change in 3 month cycles
What antibiotics are used to treat a UTI?
1) Nitrofurantoin
2) Trimethoprim
3) Penicillin e.g. amoxicillin
4) Cephalosporin e.g. cefalexin
5) Aminoglycosides
6) Erythromycin - usually IV
7) Tetracyclines
8) Fluroquinolones (ciprofloxacin) - usually in males
What are the two first line antibiotics for uncomplicated lower UTI?
Nitrofurantoin or trimethoprim
When do you treat asymptomatic bacteriuria?
1) Pregnancy
2) Patients prior to undergoing a surgical procedure - give abx before induction
3) Post renal transplant early post-op
Explain treatment of UTI in catheterised patients
1) Bacteriuria with no symptoms = no treatment
2) Bacteriuria with symptoms e.g. fever, urgency, frequency, dysuria or suprapubic tenderness = treat, abx may be unable to penetrate biofilm to removal of the catheter may be necessary if catheter is in place for > 1 week (IV abx?)
3) Routine use of prophylactic abx in catheterised patients is not recommended
What are behavioural treatments/prevention for UTI?
1) Increased fluid intake
2) Post-coital voiding
3) Perineal hygiene - washing
- Cranberry only good for prevention or tablets, sugar good for bacteria not patient
What else can be used to treat UTIs in post-menopausal women?
Oestrogens
- Topical, gradually reduce
- Ensure no contra-indications e.g. DVTs, breast cancer
What type of bacteria are chlamydia and gonorrhoea?
Gram negative diplococci
