Urinary tract infection

Question 1

Define

Answer 1

• The presence of a pure growth of > 105 organisms per mL of fresh MSU

Question 2

How can it be classified?

Answer 2

o Lower UTI - affecting the urethra (urethritis), bladder (cystitis) or prostate (prostatitis)
o Upper UTI - affecting the renal pelvis (pyelonephritis)
• NOTE: the laboratory classification mentioned above isn’t a complete necessity for the diagnosis of UTI - 1/3 women with symptoms of UTI will have negative MSU
• Other Classification
o Uncomplicated UTI - normal renal tract and function
o Complicated UTI - abnormal renal/genitourinary tract, voiding difficulty/obstruction, pyelonephritis, UTI in pregnancy reduced renal function, impaired host defences, virulent organism (e.g. S. aureus)
o Acute or chronic – recurrent UTI defined as >3 UTIs in the last 12 months

Question 3

What is defined as recurrent UTIs?

Answer 3

more than 3 UTIs in 12 months

Question 4

What’s the cause?

Answer 4

•	MOST UTIs are caused by Escherichia coli (70-95%)
•	Other causative organisms:
o	Staphylococcus saprophyticus
o	Proteus mirabilis
o	Enterococci
•	Atypical organisms that can cause UTI (usually in immunocompromised individuals):
o	Klebsiella
o	Candida albicans
o	Pseudomonas aeruginosa
o	Citrobacter

Question 5

What are the risk factors?

Answer 5

o	FEMALE 
o	Sexual intercourse 
o	Exposure to spermicide
o	Positive family history and history of recurrent UTI 
o	Pregnancy 
o	Menopause 
o	Immunosuppression
o	Catheterisation 
o	Urinary tract obstruction 
o	Urinary tract malformation

Question 6

Epidemiology

Answer 6

• VERY COMMON
• 1-3% of GP consultations
• The majority of women will have a UTI in their lifetime
• MUCH more common in FEMALES

Question 7

What are the presenting symptoms of cystitis?

Answer 7

o	Frequency 
o	Urgency
o	Dysuria
o	Haematuria
o	Suprapubic pain

Question 8

What are the presenting symptoms of prostatitis?

Answer 8

o Flu-like symptoms
o Low backache
o Few urinary symptoms
o Swollen or tender prostate on PR

Question 9

What are the presenting symptoms of acute pyelonephritis?

Answer 9

o	High fever 
o	Rigors 
o	Vomiting 
o	Loin pain and tenderness 
o	Costovertebral angle tenderness
o	Oliguria (if AKI)

Question 10

What are the signs?

Answer 10

• Fever
• Abdominal or loin tenderness
• Foul-smelling urine
• Distended bladder (occasionally)
• Enlarged prostate (if prostatitis)

Question 11

What are the appropriate investigations?

Answer 11

• Urine Dipstick
o Positive leucocyte esterase and nitrites
• Urine Microscopy
o Presence of leucocytes and WBC indicates infection
• Urine Culture
• If the result is <10^5 colony-forming units per millilitre (CFU/mL) and pyuria is present (>20 WBC/mm^3) or the patient is symptomatic, the result may still be considered positive.
• Ultrasound
o Rule out obstruction
o Hydronephrosis, renal abscess
• Bloods
o FBC
o U&Es - check renal function
o CRP
o Blood cultures - if systemically unwell and risk of urosepsis

Question 12

What’s the management plan?

Answer 12

• Empirical treatment of uncomplicated UTI: TRIMETHOPRIN or NITROFURANTOIN
o Treat for 3-6 days
o NOTE: men with UTI may need a longer course of antibiotics
• Alternative Treatments: Co-amoxiclav or Cefalexin (if antibiotic resistance)
• Prophylactic antibiotics may be used in certain circumstances (e.g. recurrent cystitis associated with sexual intercourse)

Question 13

What are the possible complications?

Answer 13

•	Ascending infection can lead to:
o	Pyelonephritis 
o	Perinephric and intrarenal abscess 
o	Hydronephrosis or pyonephrosis 
o	AKI
o	Sepsis 
•	Prostatic involvement (e.g. prostatitis) in men with UTIs is common

Question 14

What’s the prognosis?

Answer 14

• GOOD prognosis with appropriate treatment