Diebel- Bacterial UTI

Question 1

What are the main defenses of the UT?

Answer 1

1. Urine flow
2. Urine chemistry (Acidic, lysozyme, lactoferrin)
3. Different cell surface proteins on epithelial cells in the UT vs the GI tract
4. Secretory IgA in UT
5. Normal flora

Question 2

What are major threats to the urinary system?

Answer 2

1. Micro-organisms that move form GI tract to the urinary system
2. Community acquired- normal biota, Hospital- catheter insertion
3. Immune system malfunciton> glomerular nephritis (Inappropriate IS response> type II/III hypersensitivities > kidney damage)

Question 3

What are sxs of cystitis?

Answer 3

Acute uncomplicated UTI

Sudden onset
pain
burining
dysuria
frequent urges to urinate

Question 4

What causes cloudy urine seen with cystitis?

Answer 4

1. WBC

2. Bacteria

Question 5

What causes orange-tinged urine?

Answer 5

Infections break epithelial lining> blood

Question 6

What sx is indicative of pyelonephritis? What happens if it’s inadequately treated?

Answer 6

back pain

septicemia

Question 7

What percent of UTI are caused by bacteria of hte normal biota of the GI tract?

Answer 7

95%

Question 8

What is the most common bacteria causing UTI? what other bacteria are also common?

Answer 8

E. coli

staph saprophyticus
enterococcus
klebsiella pneumoniae
proteus mirabilis

Question 9

Are the e.coli that cause UTI the same species that cause diarrhea?

Answer 9

NO

e. coli that cause UTI are species of the normal flora of the GI tract

Question 10

What causes UTI in children?

Answer 10

anatomic or functional abnormalities–> blockage of UF–> micro-orgs take hold and grow

Question 11

What can use UTI in men?

Answer 11

Obstruction from an enlarged prostate> prostatits and epidyimitis

Question 12

What does E. Coli colonization depend on? How does it cause disease?

Answer 12

Specific adhesions on the ends of long fimbriae–> colonization>
inflammation>
tissue damage and disease

Question 13

How much more common is UTI in women than men?

Answer 13

10x-50x

Pass organ to organ

Question 14

Nosocomial UTIs are associated with?

Answer 14

Urinary catheters

Question 15

How do you prevent UTI?

Answer 15

regular urination
good hygiene
cranberry juice

Question 16

How do you tx UTI in women?

Answer 16

Nitrofurantoin- conc more in women, TMP-SMX

Question 17

How do you tx UTI in men?

Answer 17

fluoroquinolones, TMP-SMX

Question 18

How do you diagnose UTI?

Answer 18

Presence of bacteria in the urine and the host inflammatory response to finection

Question 19

What are common laboratory findings for uncomplicated UTIs?

Answer 19

Pyuria- 10 or more neutrophils per high power field (midstream urine)

Bacteriuria- > 10^5 CFU per mL from midstream urine

Question 20

Why can colony counts often be much lower with complicated UTIs?

Answer 20

Sign that the bacteria has progressed out of the bladder to hte kidney

Question 21

What is a selective media?

Answer 21

Compounds that selectively inhibit growth of some microbes but not others

Question 22

What is a differential media?

Answer 22

Contains an indicator, usually a dye that detects particular chemical reactions/metabolic pathways occurring during growth

Question 23

What is thiglycolate agar used for?

Answer 23

Measures abilitly of microorg to utilize O2

Question 24

What are sugar fermentation broths used for?

Answer 24

detect whether microorg uses sugar

Question 25

What is blood agar used for?

Answer 25

Hemolysis profile of microorg

Question 26

If you have a gram + occus from a urine sample, how do you determine staph or strep?

Answer 26

Catalase test!

Question 27

What is the purpose of a catalase test?

Answer 27

Differentiate between catalase positive micrococall and staphylococcal species from catalase negative strep species

Question 28

How does a catalase test work?

Answer 28

If you put a small inoculum of bacteria into hydrogen bacteria you know catalase is present if there is a RAPID RELEASE of oxygen bubbles. The LACK of ctalase is evident by a lack of or weak bubble production. Aerobic and facultative anaerobic orgs produce ROS species (H2O2 and 02) during normal metabolism. They have multiple enzymes that detoxify the products of normal metabolism. CATALASE can convert hydrogen peroxide to water and oxygen.

Question 29

How do you determine if a bacteria is s. aureus or s. saprophyticus?

Answer 29

Coagulase test!

Question 30

What is a coagulate test used for?

Answer 30

Differentiate between s. aureus (POSITIVE) from coag negative staph (saphrophyticus, epidermidis)

Question 31

How does a coagulase test work?

Answer 31

S. Aureus--> coagulation S. epi/sapro--> stays liquid S. aureus produces TWO forms of coagulase bound and free. BOUND COAGULASE (clumping factor) is bound to the bacterial cell wall and reacts directly w/ FIBRINOGEN. This leads to precipitation of fibrinogen on the staphylococcal cell which leads cells to CLUMP when a bacterial suspension is mixed in the plasma.

Question 32

How do you determine if a bacteria is s. epidermidis or s. saprophyticus?

Answer 32

Novobiocin sensitivity

Question 33

How does a novobiocin sensitivity test work?

Answer 33

S. saprophyticus is resistant to novobiocin while S. epidermidis is sensitive. Therefore S epidermidis won't grow where the drug is. Novobiocin inhibits bacterial DNA gyrase in susceptible microorgs and blocks their ability to grow and divide.

Question 34

What pathogen most likely causes itching and vaginal discharge following a UTI?

Answer 34

Candida albicans After taking antibiotics women are susceptible to yeast infections.

Question 35

Why is a drop in pH often seen with yeast infections?

Answer 35

Yeast undergoes fermentation as part of hte metabolic cycle of growth and releases acidic byproducts from metabolism.

Question 36

What UTI causing microorganism causes abundant white cells in the urine and gama hemolysis with a white growth?

Answer 36

Staph saprophyticus (MC in young women) Enterococcus)

Question 37

What does macConkey agar do?

Answer 37

1. Selects against growth of gram + orgs so only gram NEGATIVE can grow 2. Differentiates among gram - based on LACTOSE fermentation

Question 38

What is the difference between fermentors and non-fermentors on a macconkey agar plate?

Answer 38

Fermentors- colonies are reddish pink non-fermentors- colorless

Question 39

How does e. coli relate to indole and lactose fermentation?

Answer 39

indole + | lactose fermentation +