Urinary Tract Infection

Question 1

Definition

Answer 1

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

• 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

Question 2

Sub-classification

Answer 2

o Lower UTI - affecting the urethra (urethritis), bladder (cystitis) or prostate
(prostatitis)

o Upper UTI - affecting the renal pelvis (pyelonephritis)

Question 3

Other classification

Answer 3

o Uncomplicated UTI - normal renal tract and function

o Complicated UTI - abnormal renal/genitourinary tract, voiding
difficulty/obstruction, reduced renal function, impaired host defences, virulent
organism (e.g. S. aureus)

Question 4

Aetiology

Answer 4

• MOST UTIs are caused by Escherichia coli

• 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

Question 5

Risk factors

Answer 5

o FEMALE
o Sexual intercourse
o Exposure to spermicide
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

Presenting symptoms (cystitis - bladder infection)

Answer 7

o Frequency
o Urgency
o Dysuria
o Haematuria
o Suprapubic pain

Question 8

Presenting symptoms (prostatitis - prostate infection)

Answer 8

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

Question 9

Presenting symptoms (acute pyelonephritis - kidney infection)

Answer 9

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

Question 10

Signs on physical examination

Answer 10

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

Question 11

Investigations (urine)

Answer 11

• Urine Dipstick
o Positive leucocyte esterase and nitrites

• Urine Microscopy
o Presence of leucocytes indicates infection

• Urine Culture
o To exclude diagnosis or if the patient failed to respond to empirical antibiotics

Question 12

Investigations (US and bloods)

Answer 12

• Ultrasound
o Rule out obstruction

• Bloods
o FBC
o U&Es - check renal function
o CRP
o Blood cultures - if systemically unwell and risk of urosepsis

Question 13

Management plan

Answer 13

• 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
• Prophylactic antibiotics may be used in certain circumstances (e.g. recurrent cystitis associated with sexual intercourse)

Give amoxicillin or cefalexin in pregnant women

Question 14

Possible complications

Answer 14

• 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 15

Prognosis

Answer 15

• GOOD prognosis with appropriate treatment