L35: Urinary tract infection

Question 1

Differentiate between cystitis or urethritis in UTI- associated symptoms, f vs m, infectious agent

Answer 1

Cystitis: bladder infection

• Bladder dysfunction (frequency, urgency- not emptying well )
• Cramping pain/ dysuria

More likely in females with shorter urethra

-Caused by Ecoli, Staphlyococcus saprophyticus (young women- doesn’t cause kidney infection)

Urethritis: urethral/ut infection

• Lack of condom use
• No bladder dysfunction, only pain on urination
• Discharge from the urethra

More likely in males with longer urethra - females get more severe infections- eg. cervicitis

• Caused by STI: gonorrhea (much more severe for men) or chlamydia (generally assymptomatic for females)

Question 2

What are the risk factors for Cystitis for male (4) vs female (4) and for both (3)

Answer 2

Both

• Anything that interferes with normal bladder movement
• Institutionalisation
• Neurological disease - eg. stroke, dementia

F:

• Sexually active, young
• Diaphragm use
• Pregnancy, diabetes
• Post menopause changes in flora

M

• Lack of circumcision
• MSM
• AIDS
• Prostate enlargement in older men.

-Chlamydia common within female population

Question 3

How do you diagnose Cystitis vs Urethritis and in what case is it important t

Answer 3

Cystitis
1. Test Midstream urine (not contaminated w bacteria from the urethra)
with a Dipstick: looking for WBC/ leukocyte esterase

Urethritis
1. Test first pass urine (more reliable in men for gonorrhoea rather than chlamydia)

a) Also if suspecting gonorrhoea, do a urethral swab - look for gram - cocci and lots of neutrophils.
3. Only send to Lab for microscopy, culture or susceptibility if it doesn’t respond to treatment. (contamination is a greater issue for women > men)

Question 4

How is E-coli virulent (5)

Answer 4

Ecoli
- has a flagella which allows it to move up the UT

• fimbrae attach to urothelium
  type 2: pyelonephritis
  t3: cystitis
• Fe3+ strains sequester iron
• Polysaccharide capsule resists phagocytes and can withstand changes in osmolality (and pH
• a-haemolysin damages urothelial cells and neutrophils

Question 5

What are the natural defences of the body (UT) and some ways bacteria overcome it (cause UTI) (5)

Answer 5

1. Microbial flora
   - mainly lactobacilli make H2O2 which kills competing flora (e coli)
   - staph catalase detoxifies H2O2
   - low E2 in post menopausal women can cause floral changes
2. Urine: has low pH, osomolality changes, organic acids.
3. Urination gets rid of bacteria: some bacteria has fimbrae which stick
4. Tamm Horsfall protein in LoH bind to bacteria (especially type 1)
5. Prostatic fluid: inhibits bacterial growth

Question 6

What antibiotics are used to treat cystitis

Answer 6

Bacteriostatic - inhibiting bacterial versions of enzymes along the folate synthesis pathway –> have broad spectrum activity

1. Trimethoprim 300mg nocte for 3 days - sits in the bladder - 71% effective. dihydrofolate synthetase inhibitor
2. Nitrofurantoin 50mg 4xday for 3 days - 99% effective. Reduced by bacterial flavoproteins to reactive intermediates which inactivate/alter bacterial ribosomal proteins

Question 7

What are the SE and contra-indications for antibiotics used to treat cystitis

Answer 7

• avoid in pregnancy (esp 1st trimester
• high doses for long periods can suppress bone marrow function (haematology ward)
• allergy is typically rash but can be severe (Steven -johnson syndrome)

Question 8

What are 3 ways Bacteria come resistant to antibiotics used to treat cystitis

Which antibiotics can’t be used to treat EBSL e coli

Answer 8

1. alter the enzyme target so antibiotic doesn’t bind well
2. Make more enzyme to overwhelm antibiotic function
3. Scavenge thymidine

EBSL e coli dissolve all penicillin and cephalosporins: leaving potential for pyelonephritis

Question 9

What are 3 risk factors for recurrent cystitis and how can it be avioded

Answer 9

1. Intercourse: void after intercourse, complete bladder emptying
2. Form of contraception; avoid diaphragm/spermicides
3. Abnormal urinary tract /urodynamics: Prophylactic antibiotic - after sex - ? 3 nights a week

Question 10

What is the serious complication of untreated cystitis / urethritis : how does it present and how should be managed/ treated

Answer 10

Pyelonephritis

Presents:

• Flank pain radiating to the groin
• dysuria, haematuria
• signs of bacteremia: fever, nausea, tachycardia

Management:
1. Investigate blood and urine culture, blood tests to look for organ impairment

2. USS used if stones suspected or if deterioration despite treatment/failure to improve 48hr+
3. Treatment:
   Gentamicin IV at first, then rapid change to oral treatment after response
   -alt = cefuroxime

-7-14 days