UTI

Question 1

What is it

Answer 1

(Infection of the urinary tract with typical signs and symptoms.)
Pure growth of over 10^5 organisms per ml collected from a fresh clean catch urine sample.

Question 2

Signs and symptoms of lower UTI

Answer 2

Dysuria
Frequency
Urgency
Suprapubic pain

Question 3

Signs and symptoms of upper UTI

Answer 3

Fever/chills
Flank pain
Haematuria

Question 4

Risk factors

Answer 4

Female gender
Sexual intercourse
Catheterisation
Pregnancy
Menopause
Diabetes mellitus
Genitourinary malformation
Immunosuppression
Urinary tract obstruction e.g. stones

Question 5

*Defences of the urinary system to prevent UTI

Answer 5

Micturition
Urine: osmolarity, pH and organic acids are antibacterial
Secreted factors
Mucosal defences

Question 6

Antibacterial properties of urine

Answer 6

Osmolarity
pH
Organic acids

Question 7

*Secreted factors that help prevent UTI

Answer 7

Tamm-Horsfall protein (binds to bacteria non-specifically)
IgA (against specific bacteria)
Lactoferrin (hoovers up free iron)

Question 8

Where is Tamm-Horsfall protein produced

Answer 8

Cells of the thick ascending loop of Henle

Question 9

What can result from mutations in genetic material that codes for Tamm-Horsfall protein

Answer 9

Progressive renal failure

Medullary cysts

Question 10

What coats the mucosal surfaces of the bladder to prevent against UTI

Answer 10

Mucopolysaccharides

Question 11

*If defence mechanisms of urinary tract to UTI are overcome by bacterial virulence factors, then the patient is prone to developing a UTI. Give examples of virulence factors

Answer 11

Uropathogenic E.coli (UPEC)

Proteus mirabilis

Question 12

Pathological features of Uropathogenic E.coli (virulence factor)

Answer 12

Type 1 fimbriae = binds to mannose residues, associated with cystitis
Type P fimbriae = binds to glycolipid residues, associated with pyelonephritis
Bacterial capsule (antigen K) = resists phagocytosis, associated with pyelonephritis

Question 13

Pathological features of Proteus mirabilis (virulence factor)

Answer 13

Produces urease
Increases pH of urine

Associated with staghorn calculi

Question 14

*Top 3 most common causes of UTIs in order

Answer 14

Escherichia coli (leading cause in community and also in nosocomial infection)
Staphylococcus saprophyticus (2nd leading cause in sexually active females)
Klebsiella pneumoniae (3rd leading cause)

Question 15

Other causative organisms of UTIs (except Escherichia coli, Staphylococcus saprophyticus, Klebsiella pneumoniae)

Answer 15

Proteus mirabilis
Pseudomonas aeruginosa
Adenovirus
BK and JC viruses (associates with graft failure post-transplant)
Schistosoma haematobium (parasitic infection)

Question 16

Investigations

Answer 16

Urine dipstick - positive for leucocytes and nitrites
Urine culture - diagnosis for causative organisms (>10^5 organisms per mL of midstream urine)
Radiology - ultrasound or cystoscopy if UTI occurs in children, in men or if UTI is recurrent

Question 17

Conservative treatment

Answer 17

Education about the condition and avoidance of predisposing risk factors

Question 18

**Medical treatment

Answer 18

Trimethoprim

Consider prophylactic antibiotics if UTI is recurrent (>4 UTIs per year)

Question 19

Recurrent (>4/yr) UTI treatment

Answer 19

Seek to exclude anatomical variant or abnormality of renal tract

Question 20

Complications

Answer 20

Pyelonephritis
Renal failure
Sepsis

Question 21

What would you look for in urine dipstick test

Answer 21

Leucocytes and nitrites

Question 22

Gold standard for diagnosis of UTI

Answer 22

MSU-MCS

Mid-stream urine microscopy, culture and sensitivity

Question 23

Example of Upper and Lower UTI

Answer 23

Upper = Ureteritis, Pyelonephritis
Lower = Postatitis, Cystitis

Question 24

Sensitivity vs Specificity

Answer 24

sensitivity is the ability of a test to correctly identify those with the disease (true positive rate), whereas test specificity is the ability of the test to correctly identify those without the disease (true negative rate)