Bacterial UTI

Question 1

What are the 5 major defenses of the urinary tract?

Answer 1

1. urine chemistry
2. flushing of the urine
3. different cell surface proteins on epithelialc ells of the urinary tract than the GI tract
4. secreotry IgA from the adaptive immune repsonse
5. normal flora

Question 2

What are the three aspects of urine chemistry that helps against bacteria?

Answer 2

1. acidity
2. lysozyem to break down peptidoglycan
3. lactoferrin to sequester iron away from the bacteria

Question 3

What are the three major threats to the urinary system contributing to infections?

Answer 3

1. microorganisms from the GI tract moving into the urinary tract
2. catheter insertion
3. glomerulonephritis with immune system dysfunction

Question 4

What are the 5 main species causing UTI?

Answer 4

e coli
staph saprophyticus
klebsiella
proteus
enterococcus

Question 5

what are the main two risk factors for uti?

Answer 5

sex

catheters

Question 6

What virulence factors does E coli use to establish infection?

Answer 6

type 1 pili and P pili

Question 7

What recognizes LPS to cause inflammation in response to ecoli?

Answer 7

TLR4

Question 8

Describe a presuably genetic predisposition to more severe UTI?

Answer 8

people with certain TLR4 types are oversensitive to E coli, causing severe inflammation in response to even small colonizations

Question 9

What are the main antibiotic treatments for UTI?

Answer 9

trimethoprim/sulfamethoxazole
nitrofurantoin
fluoroquinolones

Question 10

How do we diagnose UTI?

Answer 10

growth of bacteria in urine culture

Question 11

What will be the lab findings in uncomplicated UTIs?

Answer 11

pyuria (10+ neutrophils per hihg power field of voided midstream urine)

bacteriuria over 10 to the 5th CFUs per mL urine

Question 12

Will colony counts be higher or lower in complicated UTI?

Answer 12

lower actually - bacterial will be more likely to have moved up the urinary tract

Question 13

What are selective media?

Answer 13

media that contains compounds that selectively inhibit the growth of some microbes but not others

Question 14

What is differential media?

Answer 14

contains an indicator (usually a dye) that detects particular chemical reactions occurring during growth to help identify the bacteria

Question 15

What test can you use to differentiate staph frm strep?

Answer 15

catalase test

staph is positive, strep is negative

Question 16

How do you do a catalase test?

Answer 16

aerobic and facultative anaerobes need something to take care of ROS that form during metabolism with oxyegen.

staph uses catalas, which converts hydrogen peroxide to water and O2. So you take a growth, you add hydrogen peroxide. if it bubbles, it’s positive.

Question 17

What test can you use to differentiate staphylococcus aureus from staphylococcus saoprophyticus (or epidermidis)?

Answer 17

coagulase
aureus is positive
saprophyticus and epidermidis are negative

Question 18

How do you do a coagulase test?

Answer 18

add bacteria to rabbit serum
if it coagulates, it’s aurus
if it doesn’t, it’s saprophyticus or epidermidis

Question 19

How can you differentiate epidermidis and saprophyticus?

Answer 19

novobiocin test
saprophycitus is resistant to novobiocin
epidermidis is sensitive to novobiocin

Question 20

How does novobioicin work?

Answer 20

distrupts bacterial DNA gyrase