Lecture 37: Urinary tract infection

Question 1

When a patient presents with issues urinating, what is the information to ascertain and how does this distinguish?

Answer 1

Ascertain:

• Frequency
• Urgency
• Cramping pain in bladder
• Burning

Urgency and cramping probably cystitis, if just burning and Hz then urethritis.

Question 2

What causes urethritis?

Answer 2

UTI, STI (Chlam and Gonn)

Question 3

What causes cystitis?

Answer 3

Predominantly E. Coli.

Question 4

What is dysuria?

Answer 4

Pain urinating

Question 5

How will you diagnose cystitis?

Answer 5

Urine dipstick; Presence of WBC, leukocyte esterase (cheap option)

Midstream urine; Expensive, microscopy culture, susceptible (appropriate if persistent)

Question 6

Whats the issues with midstream urine?

Answer 6

Contamination…. also many commensal organisms

Question 7

When it comes to dysuria and the patient is 65+ Female what are some factors to consider?

Answer 7

• > Post menopausal
• > Urinary tract abnormalities ie urethrocele,
• > Neurological disease
• > Incomplete bladder emptying

Question 8

When it comes to dysuria and the patient is 65+ Male what are some factors to consider?

Answer 8

• Strictures
• Stones
• Prostatic disease
• Neurological disease

Question 9

What bacteria cause cystitis?

Answer 9

• E.Coli 80%

- Staph. saprophyticus

Question 10

Describe E. Coli virulence factors:

Answer 10

• Fimbriae mediate attachment to urothelium
• Sequester iron (more virulent)
• Polysac capsule resists phagocystosis
• Alpha-heamolysin damages urothelial cells and neutrophils

Question 11

How does E.COli cause cystitis?

Answer 11

Alpha heamolysin damages urothelial cells which release:

• IL-8 -> Recruits neutrophils
• IL-1, IL-6, TNF-a -> Fever, Malaise

Question 12

What are the defence mechansims against uropathogenic E. Coli:

Answer 12

• Microbial flora
• Urine: Inhospitable to bugs i.e low pH, Osmolarity fluctuations etc
• Urination: Wash out (unless type 1 fimbriae)
• Tamm-Horsfall protein: Formed by loop of henle (binds bacteria)
• Prostatic fluid: Inhibits bacterial growth

Question 13

What is the treatment for cystitis?

Answer 13

Mostly resolves, symptom management, antimicrobials if persists for months

Question 14

How do sulfur based antibiotics function?

Answer 14

At various stages they inhibit folic acid synthesis / handling and thus DNA synthesis is interfered with.

They are bacteriastatic

Question 15

What are the two most common sulfur based drugs? whats their spectrum:

Answer 15

Trimethoprim

Co-trimoxazole: (Sulfamethoxazole + trimethoprim)

Both broad spectrum activity (bacteriastatic)

Question 16

What are sulfur drugs not appropriate? What allergies?

Answer 16

Avoid in pregnancy, high doses for long periods can suppress bone marrow function

Allergy:

• Typical rash
• Can be severe (Stevens-johnson syndrome)

Question 17

Is there any bacterial resistance against sulfur drugs?

Answer 17

Common but not increasing rapidly

1. Alter enzyme targets
2. Make more enzymes
3. Scavenge thymidine

Question 18

What factors contribute most to repeated cystitis?

Answer 18

1. Sex
2. Form of contraception i.e diaphragm
3. Abnormal urinary tract or urodynamics