Lecture 17 - urinary tract infection

Question 1

Urinary defences against infection

Answer 1

Micturition - removes pathogens
Vesico- uretal valves - prevents back flow of urine
Mucosal barrier
Acidic urine 
Immunulogical defense

Question 2

Cystitis

Answer 2

Infection in the bladder

Question 3

Pyelonephritis

Answer 3

Infection in the kidney

Requires longer treatment and further investigation

Question 4

Prevalence of UTI

Answer 4

Infancy - incompetent valve 
Children - poor hygiene
Women - shorter urethras
Adolescents - engage in sexual activity 
elderly - weaker immune system and enlarged prostate

Question 5

Causes of UTIs

Answer 5

Obstruction - stones, enlarged prostate

Impaired emptying of bladder- - multiple sclerosis, stroke

Pregnancy - enlarged uterus compresses bladder

Abnormal renal tract - vesico-uteric reflux in children

Impaired host defense - diabetes mellitus and immunosuppression

Question 6

What bacteria causes UTIs most commonly

Answer 6

E coli - gram negative coliforms

Question 7

Virulence factors of E coli

Answer 7

Flagellar - movement

Pili - attachment to mucus membrane

Lipid polysaccharide membrane - resist host defences

Haemolysin toxins - damages host membranes and causes renal damage

Question 8

Presentation of cystitis

Answer 8

Dysuria
Nocturia
Pyrexia
Cloudy urine
Urgency 
Haematuria 
Suprapubic tenderness

Question 9

Presentation of pyelonephritis

Answer 9

High fever
Rigor 
Loin pain and tenderness
Nausea and vomiting 
\+/- symptoms of cystitis

Question 10

Uncomplicated UTI

Answer 10

Infection by a usual organism in a patient with normal urinary function and tract

Question 11

Complicated UTI

Answer 11

More than 1 factor that predisposes them to persistent, recurrent infection or treatment failure e.g.

• Abnormal urinary tract
• Virulent organism - staph aureus
• Impaired host defence - poorly controlled DM
• Impaired renal function

Requires urine culture

Question 12

Practised complicated cases

Answer 12

Children
Pregnant women
Some men

Question 13

Specimen collection methods

Answer 13

Mid stream urine
Clean catch - children
Collection bag 
Catheter sample
Suprapubic aspiration - invasive so not done 

Culture urine within 4 hours of collection or preserve in refrigerator or boric acid

Question 14

Urine dipstick tests

Answer 14

Leukocyte esterase - WBCs
Nitrates - coliforms
pH 
Protein 
Blood

Question 15

When to do a urine diptick

Answer 15

If 1 or less symptom of:

• dysuria
• Nocturia
• cloudy urine

Question 16

Microscopy of urine

Answer 16

WBC
RBC
Epithelial cells
Bacteria

Question 17

Why use urine culture

Answer 17

Investigation of complicated infections
Epidemiology isolates - create guidlines
Antibiotic susceptibility data

Question 18

Imaging

Answer 18

Consider in all children with UTI
Septic patients for renal involvement
Males - posterior urethral valves
Female - vesicoureteric reflux

Question 19

Sterile pyuria

Answer 19

Raised WBCs in urine due to:

• Prior antibiotics
• Appendicitis
• Vaginal infection or inflammation
• Urethritis
  Tuberculosis

Question 20

Asymptomatic bacteriuria

Answer 20

Only treated in pregnant women as untreated leads to high risk of premature labour and pyelonephritis

Question 21

Treatment of UTIs

Answer 21

Increased fluid intake
Analgesia
Cranberry products
Treated underlying cause

Uncomplicated - 3 day course of antibiotics:

Complicated - 5 -7 day course of antibiotics

Question 22

Treatment of cystitis

Answer 22

Uncomplicated: 3 days 
Complicated - 5 -7 day 
- trimethoprim 
- nitrofurantoin
- pivmecillinam

Question 23

Prophylaxis

Answer 23

Can be given if more than 3 episodes in 1 year without any treatable underlying condition