urinary tract infections

Question 1

what bacteria is the most common cause of UTI?

Answer 1

gram negative bacteria
1. E. coli
2. Proteus mirabilis

Question 2

how do fimbriae protect E. coli bacteria?

Answer 2

attach to glyocprotein/glycolipid receptor to help bacteria adhere to bladder wall

Question 3

how does capsular polysaccharide antigen (k antigen) protect E. coli bacteria?

Answer 3

prevent phagocytosis of bacteria –> ascend to kidney to cause pyelonephritis

Question 4

what is haemolysin?

Answer 4

E. coli virulence factor that lyse blood cells –> renal injury

Question 5

what virulence factor does proteus bacteria have?

Answer 5

urease production
urease allows conversion of urea in urine to ammonia –> increases alkalinity of urine –> favours growth of proteus

Question 6

what symptoms differentiate upper UTI from lower UTI?

Answer 6

fever, headache, chills

Question 7

what do nitrites in urine dipstick sample indicate?

Answer 7

gram negative bacteria present (convert nitrates to nitrites)

Question 8

what do leukocytes in urine sample indiciate?

Answer 8

inflammation

Question 9

which agar plate allows for detection of bacteria with haemolysins?

Answer 9

blood agar

Question 10

which agar plate selects for enteric bacteria, lactose fermenters and gram negatives?

Answer 10

MacConkey agar

Question 11

what is normochromic normocytic anaemia a feature of?

Answer 11

Chronic kidney disease

Question 12

what is the first-line drug to treat cystitis?

Answer 12

trimethoprim

Question 13

what is the most common mode of transmission in UTI?

Answer 13

ascending route from urethra to bladder

Question 14

how much bacteria must be present in mid-stream urine sample to diagnose UTI?

Answer 14

> 10^5 organisms/ml

Question 15

how much bacteria must be present in suprapubic aspirate sample to diagnose UTI?

Answer 15

> 10^2

Question 16

how many more times are females likely to get UTI compared to males?

Answer 16

14x more likely

Question 17

what are the risk factors of developing UTIs?

Answer 17

1. female (Shorter urethra)
2. sexual intercourse
3. indwelling catheters
4. diabetes mellitus (Increased glucose levels allow bacteria to thrive)
5. impaired bladder emptying (due to pregnancy, urinary tract obstructions, neurological issues, VUR)

Question 18

The presence of which of these would indicate a contaminated sample on urine microscopy?

a. White blood cells
b. E. Coli
c. Blood
d. Squamous epithelial cells

Answer 18

d. Squamous epithelial cells

Indications of contamination:
- Squamous epithelial cells
- Mixed growth
- Positive culture with no white blood cells