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Medicine Phase 2a GU > UTI > Flashcards

Flashcards in UTI Deck (24):
1

What is it

(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.

2

Signs and symptoms of lower UTI

Dysuria
Frequency
Urgency
Suprapubic pain

3

Signs and symptoms of upper UTI

Fever/chills
Flank pain
Haematuria

4

Risk factors

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

5

*Defences of the urinary system to prevent UTI

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

6

Antibacterial properties of urine

Osmolarity
pH
Organic acids

7

*Secreted factors that help prevent UTI

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

8

Where is Tamm-Horsfall protein produced

Cells of the thick ascending loop of Henle

9

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

Progressive renal failure
Medullary cysts

10

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

Mucopolysaccharides

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

Uropathogenic E.coli (UPEC)
Proteus mirabilis

12

Pathological features of Uropathogenic E.coli (virulence factor)

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

13

Pathological features of Proteus mirabilis (virulence factor)

Produces urease
Increases pH of urine

Associated with staghorn calculi

14

*Top 3 most common causes of UTIs in order

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)

15

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

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

16

Investigations

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

17

Conservative treatment

Education about the condition and avoidance of predisposing risk factors

18

**Medical treatment

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

19

Recurrent (>4/yr) UTI treatment

Seek to exclude anatomical variant or abnormality of renal tract

20

Complications

Pyelonephritis
Renal failure
Sepsis

21

What would you look for in urine dipstick test

Leucocytes and nitrites

22

Gold standard for diagnosis of UTI

MSU-MCS
Mid-stream urine microscopy, culture and sensitivity

23

Example of Upper and Lower UTI

Upper = Ureteritis, Pyelonephritis
Lower = Postatitis, Cystitis

24

Sensitivity vs Specificity

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)