Gi Infections Ii Small Group

Front 1

What are the most common causes of typhoid and non-typhoid Salmonella infections?

Back 1

Typhoid infections are more commonly due to traveling

Non-typhoid infections are more commonly due to animal transmission.

Front 2

What are the typical epidemiological features of infection with non-typhoidal Salmonella?

Back 2

Fecal-oral transmission
Non-typhoidal Salmonella is associated with animal reservoirs including agricultural products, eggs, poultry, fresh produce, meats, dogfood, milk, spices, contaminated marijuana, etc... It is also associated with certain pets including reptiles and amphibians, hamsters, mice, rats, hedge-hogs, cats, dogs, and ducks.

Front 3

What age group is Non-typhoidal Salmonella the biggest problem in?

Back 3

People over 60 years old and infants

Front 4

What is an additional complication of non-typhoidal Salmonella compared with other bacterial causes of Gastroenteritis?

Back 4

Non-typhoidal Salmonella is more likely to increase one's risk of invasive illness.

Front 5

What factors lead to an increased risk of illness in elder individuals with non-typhoid Salmonella?

Back 5

Wanning immune system and they are usually taking medications that decrease gastric acid.

Front 6

Do kids produce more or less gastric acid that adults?

Back 6

LESS

Front 7

What are the host defenses against Salmonella?

Back 7

Stomach acid, mucus, motility, IgA, cell membrane, GI flora, lysosomes, macrophages and PMNs.

Front 8

What are the virulence factors of Salmonella?

Back 8

Adhesins (fimbriae), Type III secretion systems (#1- helps the bacteria get into the cell; #2 helps the bacteria avoid lysosomes inside the cell), and a Vi capsule in S. typhi.

Front 9

How should you treat a non-typhoid Salmonella infection?

Back 9

Fluids and electrolytes. Antibiotics SHOULD NOT be given because this can prolong fecal transmission of the bug and they can become prolonged carriers. You want to do symptomatic treatment.

Front 10

In what type of patients would you treat a non-typhoid Salmonella infection?

Back 10

If the patients are younger than 3 months old or immunocompromised.

Front 11

How would you diagnose this disease?

Back 11

You can culture the bloody diarrhea

Front 12

What is the common reservoir and transmission of S. typhi and S. paratyphi?

Back 12

Humans are the reservoir. These bacteria are transmitted through fecal-oral spread generally in food or water.

Front 13

What can happen with an initial infection of S. typhi/S. paratyphi?

Back 13

You can get a localized infection in your gut which can become systemic and have a long latent period. You could also become a carrier of this bacteria and not know it.

Front 14

What are some common symptoms associated with Typhoid fever?

Back 14

Low WBC count, tender abdomen, fever, low heart rate, low blood pressure, initial diarrhea followed by constipation, etc...

Front 15

What is a CLASSIC finding with typhoid fever in terms of blood pressure and pulse?

Back 15

People with typhoid fever usually have high temperature and decreased pulses (a dissociation between their pulse and blood pressure).

Front 16

What type of agar is used to grow Salmonella?

Back 16

Hectoenteric agar. Salmonella will show up green/blue on the plate (due to being lactose positive) with black dots in the center of the colonies (due to their production of H2S). It could also be visualized on MacConkey's agar.

Front 17

What are the structural characteristics of S. typhi?

Back 17

It is a gram negative organism that is lactose negative and has a capsule.

Front 18

Would you take a stool culture for a person with Typhoid fever?

Back 18

Yes! This will help tell you whether or not the person is a carrier.

Front 19

How should you treat Typhoid fever?

Back 19

Antibiotics are NECESSARY or the patient will die. You treat them with ceftriaxone or ciprofloxacin for 5-7 days.

Front 20

What are the requirements by the Health Department if your patient has Typhoid fever?

Back 20

You must report it. The patient must get approval to go back to school or work and food workers need 3 continuous negative stool cultures to go back to work.

Front 21

How can you prevent Typhoid fever?

Back 21

Vaccination is a key with prevention. There are 2 vaccines available. The first vaccine is a killed version of hte bacteria that is given via an IM shot and lasts 2 years. The second vaccine is a live, attenuated bacteria that is given orally in 4 doses over 2 weeks. It lasts 5 years but SHOULD not be given to kids under the age or 2 and should be taken 2 weeks prior to travel. Both vaccines are 70% effective.

Other ways to prevent typhoid fever include hygiene, sanitation, and hydration.

Front 22

Under what conditions would the live, attenuated S. typhi vaccine not work?

Back 22

If the patient is taking antibiotics alongside the live, attenuated vaccine, the vaccine will be inactivated.

Front 23

Are Salmonella typhimurium, P. vulgaris and Shigella flexneri lactose positive or negative?

Back 23

Lactose negative

Front 24

What type of media is MacConkey's agar?

Back 24

Differential- it allows you to distinguish different types of bacteria by the appearance of their colonies

This media is NOT selective (it does not inhibit the majority of gram-negative enteric bacteria despite it inhibiting gram positive bacteria).

Front 25

What is a selective medium?

Back 25

It is an agar that suppresses the growth of certain components of the indigenous flora.

Front 26

What type of agar is SS agar similar to?

Back 26

Hectoenteric agar

Front 27

Is Heteroenteric agar and SS agar differential or selective or both?

Back 27

Both

Front 28

What do Shigella colonies look like on Hecteroenteric agar?

Back 28

Clear

Front 29

What do Salmonella colonies look like on Hecteroenteric agar?

Back 29

Black- due to H2S produced reacting with Fe in the medium

Front 30

What is a problem associated with culturing V. cholerae?

Back 30

It does not grow on media commonly used to isolate enteric pathogens.

Front 31

What does MacConkey's agar contain and what role does each ingredient serve?

Back 31

MacConkey's agar contains lactose, peptone, bile salts, crystal violet, NaCl and neutral red.

Lactose helps with differentiation of the bacteria. Peptone is a nutrient. Bile salts and crystal violet inhibit gram positive bacterial growth. Neutral red is the pH indicator that detects the acidification of the agar with lactose fermentation.

Front 32

What causes the hazy outline of lactose-fermenting colonies on MacConkey's agar?

Back 32

Bile salts precipitating due to the drop in pH

Front 33

What is SS agar?

Back 33

Salmonella and Shigella agar

Front 34

What does SS agar contain and what role does each ingredient play?

Back 34

Beef extract and peptone as nutrients, lactose for fermentation, bile salts, citrate, brilliant green to suppress the growth of coliform or gram positive bacteria, ferrous ions to indicate H2S production, and neutral red to detect pH changes.

Front 35

Why do Salmonella and Shigella turn SS agar a bright blue/green?

Back 35

They metabolize peptones and turn the agar an alkaline pH.

Front 36

What color do non-lactose fermenters turn the SS agar?

Back 36

Yellow

Front 37

If you see a colorless colony growing on SS agar is it Salmonella or Shigella?

Back 37

Not necessarily, it suggests that it is but further confirmatory tests are required.

Front 38

Which two components of SS agar are most important for its selective actions?

Back 38

Citrate and bile salts.