Urinary Tract Infections, UPEC, and P. mirabilis

Question 1

Why are urinary tract infections more common in healthy adult women compared to healthy adult males?

Answer 1

The male urethra is longer, so bacteria have to travel farther to infect

Question 2

Why does age affect the occurrence of urinary tract infections in men?

Answer 2

At infancy, the immune system isn’t fully developed yet.
At older age, the prostate is less active and the bladder doesn’t empty as much, which causes for an increase in prevalence

Question 3

What is an uncomplicated urinary tract infection?

Answer 3

Disease is limited to the lower urinary tract
No physiological/anatomical abnormalities of the tract
No recent hospital admissions

Question 4

What is a complicated urinary tract infection?

Answer 4

Disease has most likely spread to the kidneys
Some structural abnormality in urinary tract
Recently admitted to the hospital

Question 5

What is cystitis?

Answer 5

Inflammation of the bladder

Question 6

What is pyelonephritis?

Answer 6

Kidney inflammation associated with P fimbrae

Question 7

What is the most common bacterial pathogen(s) that cause uncomplicated UTI?

Answer 7

Uropathogenic E. coli (UPEC)

Question 8

What is the most common bacterial pathogen(s) that cause complicated UTI?

Answer 8

Uropathogenic E. coli (UPEC)

Proteum mirabilis

Question 9

What are the natural barrier defenses found in the urinary tract?

Answer 9

Complete voidance of bladder
Urovesicle valves
Mucous layer
Normal microbiota
pH

Question 10

How does the UPEC adhere to urinary tract tissue?

Answer 10

Through fimbrae

Question 11

Which UPEC adhesin is associated with cystitis?

Answer 11

Fimbral antigen FimH

Question 12

Which UPEC adhesin is associated with pyelonephritis?

Answer 12

P fimbrae

Question 13

Why are aerobactin and hemolysin important?

Answer 13

They are produced by UPEC.
Aerobactin prevents host cells from getting iron
Hemolysin has the ability to lyse host cells

Question 14

Virulence factors of Proteus mirabilis

Answer 14

Flagella
Hemolysin
IgA protease
Urease

Question 15

Whys is flagella important for P mirabilis virulence?

Answer 15

Allows for motility and chemotaxis

Question 16

Why is hemolysin important for P mirabilis virulence?

Answer 16

Can destroy blood cells

Question 17

Why is IgA protease important for P mitabilis virulence?

Answer 17

IgA is an antibody on the surface of host cells. IgA protease breaks down those antibodies.

Question 18

Why is urease important for P mirabilis virulence?

Answer 18

It raises the pH of urine, making it easier for P mirabilis to survive, and cause further damage

Question 19

Why is the production of urease dangerous in the urinary system?

Answer 19

It neutralizes the pH of urine (or makes it slightly alkaline) creating an environment that is beneficial for P mirabilis, and toxic for renal cells. It also enhances the formation of struvite urinary stones, which can lead to a chronic infeciton

Question 20

How are UTIs diagnosed?

Answer 20

It is difficult because there is always bacteria in the urine, but it is hard to tell where they’re coming from.
Count the bacteria in the urine. Healthy bacteria >10^5 CFU/mL
Individual with dysuria >10^2 CFU/mL

Question 21

When would antibiotics be prescribed in a healthy (or asymptomatic) individual for P. mirabilis?

Answer 21

If a woman was pregnant. We don’t want her to pass P mirabilis to the baby.

Question 22

When would antibiotics be prescribed in a symptomatic patient?

Answer 22

3 day TMP/SMX therapy for acute cystitis

10-14 day therapy for someone with polynephritis

Question 23

How can P. mirabilis be diagnosed?

Answer 23

Consistently alkaline urine

Or, the production of urease is a good indication