Bacterial UTIs

Question 1

In general, what are most UTIs caused by?

Answer 1

enteric bacteria

Question 2

What do we cause a UTI that doesn’t have symptoms?

Answer 2

asymptomatic bacteriuria (ABU)

Question 3

What is the gold standard for UTI diagnosis?

Answer 3

growth of bacteria in urine culture

Question 4

What are the main innate mechanisms the keep the urinary tract free of infection (despite frequent exposure to potentially harmful enteric pathogens)?

Answer 4

1. acidity of urine
2. urine flushing the system
3. mucosal lining of the urinary tract acts as a physical barrier

Question 5

What percentage of UTIs are of hematogenous origin and not ascension from the urethra?

Answer 5

only 10%

Question 6

When is a UTI considered to be complicated?

Answer 6

when there are underlying factors that predispose an idnvidiaul to ascending bacterial infections - catheters, anatomic/functional abnormalities, obstructions, poor bladder emptying, neuroggenic disorders, pregnancy, prostatic enlargement, uterine prolapse, and cystocele

Question 7

When is a UTI considered “uncomplicated”

Answer 7

when it occurs without an underlying abnormality or impairment of urine flow - most common in young women

Question 8

WHat are the risk factors for uncomplicated UTI?

Answer 8

sex
diaphragm and spermicide use
antibiotic use - alter normal vaginal and urinary flora allowing for overgrowth of E coli
hx of recurrent uTI

Question 9

What are the main bacterial causes of uncomplicated UTIs?

Answer 9

E COLI is the huge one - esp the strains that have attachment factors for transitional epithelium

Staph saprophyticus

Klebsiella, proteus, enterococcus, citrobacter

Question 10

What are the main bacterial causes of complicated UTI?

Answer 10

E COLI AGAIN
but also other aerobic and facutlative anaerobic gram negative rids - klebsiella, proteus, cirtobacteria, acinetobacter, morganella, pseudomonas
some gram positives too - enterococci and staph aureus

Question 11

Specifically, what adhsion molecules does E coli use to cause UTIs?

Answer 11

type 1 pilus (fibria) - bind to uroplakins on the luminal surface of bladder uroepitelial cells (initiating)

P pilli (fibriae) - hair like protein strucutres that interact with a specific receptor on renal epithelial cells to cause pyelonephritis and subsequent sepsis