Enteric bacteria

Question 0

The enteric bacteria love incorporating foreign DNA in its genome (via plasmids or bacteriophages, etc). What kind of virulence factors do these bacteria pick up?

Answer 0

1. Pili for adhesion
2. Type 3 secretion systems for adhesion and subversion of gut macrophages

•••also pick up abx resistance

Question 1

The enteric bacteria are grouped based on phylogeny. What are 7 defining characteristics of this group?

Answer 1

1. Gram negative (counter stains with safranin)
2. Non-sporulating
3. Straight rods (bacilli)
4. Facultative aerobes (can use both etc and fermentation for ATP)
5. Catalase positive (can break down hydrogen peroxide)
6. Oxidase negative
7. Glucose fermenters

Question 2

Since there’s antibiotic resistance in enteric bacteria, one must perform antibiotic testing before treatment. Explain process aka anti microbial sensitivity assay

Answer 2

1. Spread liquid culture of patient isolate on large agar plates
2. Place disk of filter paper soaked in various abx on plate and incubate overnight
3. Measure clear zones and compare to table to check abx effectiveness

Question 3

List 3 major food-borne enteric bacteria

Answer 3

Shigella, e. Coli, salmonella

Question 4

List 2 minor food borne enteric bacteria

Answer 4

Y. Enterocolitica, y. Pseudo tuberculosis

Question 5

What’s the major ICU enteric bacteria we talked about in class?

Answer 5

Klebisella which is second to E. coli in causing nosocomial outbreaks

Question 6

Major symptom of food borne enteric bacteria

Answer 6

Gastroenteritis

Question 7

Major difference btw symptoms caused by salmonella and shigella

Answer 7

Salmonella along with yersinia and some e. Coli cause WATERY diarrhea.

Shigella and some e. Coli cause BLOODY diarrhea

Question 8

How to prevent food borne enteric bacteria?

Answer 8

Hygiene: food washing and cooking, hand washing, water treatment

Question 9

Enterotoxigenic E. coli (ETEC) and enterohemorrhagic E. coli (EHEC) differences

Answer 9

ETEC causes travelers diarrhea while EHEC causes hemorrhagic colitis leading to hemolytic uremic syndrome (HUS)

Question 10

Common pathogenesis of food borne enteric bacteria

Answer 10

1. Encourage sampling by M cells of peyers patches
2. Use T3SS to alter gut macrophages
3. Bacteria survive in altered macrophage, induce apoptosis, escape to infect exterior surface of intestine
4. Some bacteria (salmonella typhi and yersinia Enterocolitica) can further use altered macrophages as Trojan horses to reach lymph nodes

Question 11

Which infection can be confused for appendicitis?

Answer 11

Infection with yersinia Enterocolitica

Question 12

Who is at higher risk for salmonella infection? What’s protective against infection?

Answer 12

People with gastrectomies and/or on antacids are at higher risk for infection because gastric acid is protective.

Question 13

There are 2 significant complications of enteric bacterial infections: 1) hemolytic uremic syndrome and 2) reactive arthritis. HUC is mainly seen in which 2 enteric bacterial infections? What are symptoms and how best to diagnose?

Answer 13

Shigella and EHEC routinely lead to HUC. Due to release of toxins (ex. Shiga toxin) into bloodstream causing fever, dehydration, hemolysis, thrombocytopenia, uremia requiring dialysis. Blood smears will show schistocytes.

Question 14

Should one use antibiotics for HUC?

Answer 14

No! Gram negative has endotoxins that can cause sepsis if released.

Question 15

HUC and reactive arthritis are consequences of some enteric bacterial infections. In reactive arthritis, which HLA type is more predisposed, which infections trigger this? What are the 3 common symptoms? What’s the treatment,

Answer 15

People with HLA-B27 and either had shigella, salmonella, yersinia and chlamydia. Common symptoms are “can’t see, can’t climb and can’t pee” -conjunctivitis, urethritis, and arthritis. Treat with 4-6 months of NSAIDs

Question 16

The ICU enteric bacteria are not food borne. They are extremely abx resistant and are opportunistic pathogens. List them (6)

Answer 16

Klebsiella, enterobacter, serratia, proteus, providencia, morganella

Question 17

Klebsiella can cause pneumonia in? Serratia can cause what in iv drug users? All non food borne enteric bacteria can cause?

Answer 17

Klebsiella can cause pneumonia in elderly alcoholics. Serratia can cause endocarditis in iv drug users. All can cause catheter associated UTIs and ICU wound infection

Question 18

Klebsiella can be a primary pathogen but is normally nonnpathogenic unless patients have predisposing conditions (alcoholism, long hospital stay, catheters), what are its virulence factors?

Answer 18

Capsule, adhesins, siderophores

Question 19

Since these non food borne enteric bacteria are resistant to so many abx, the best thing to do is prevent it. How?

Answer 19

Switching of catheters and iv lines, scrub downs of ICU, equipment, minimize hospital stay

Question 20

If you grow klebsiella in lab, you will see mucoid gooky appearance due to?

Answer 20

Capsule

Question 21

Transmission of food borne enteric bacteria

Answer 21

Fecal-oral

Question 22

Salmonella can cause entercolitis. What are some symptoms? Why is bacteremia rare?

Answer 22

Inflammation, diarrhea, nausea and vomiting. Bacteremia is rare because salmonella has a high infectious dose and is limited to the gut.

Question 23

Enteric fever/typhoid fever caused by

Answer 23

Salmonella typhi

Question 24

What is the route of transmission in typhoid fever?

Answer 24

Human restricted, fecal-oral

Question 25

Symptoms of typhoid fever

Answer 25

Fever, malaise, diffuse abdominal pain and constipation. In 3-4 weeks will progress into dry cough, stupor, deletion, intestinal hemorrhage, bowel perforation , myocarditis, necrosis of infected peyers patches

Question 26

Survivors of typhoid fever can be chronic carrier and have long term

Answer 26

Neurological issues

Question 27

What are 2 important virulence factors to infect gut?

Answer 27

1) pili

2) type 3 secretion system

Question 28

Both salmonella (enteric bacteria) & vibrio cholera (vibrio) need pretty high infectious doses to cause infection. People who are infected tend to be on what drugs?

Answer 28

Ppl on antacids (increasing pH of stomach, allowing for these pathogens to cause infection).

Question 29

Patient (a young child) presents with fever, dehydration, hemolysis, thrombocytopenia, and uremia requiring dialysis. His past medical history reports infection with shigella and his blood smear shows schistocytes (distorted RBCs). What does the patient have and should antibiotics be prescribed?

Answer 29

The patient has hemolytic uremic syndrome which can be a complication associated with e. coli and shigella infections. Pt should not be given abx.

Question 30

Patient presents with conjuncitivits, urethritis, and arthritis. What should you treat the patient with?

Answer 30

Patient most likely have reactive arthritis secondary to bacterial infection (shigella, salmonella, chlamydia, yersinia, campylobacter). Treatment is 4-6 months of NSAIDS

Question 31

Klebsiella has capsule, adhesins and siderophores as virulence factors. Explain what these virulence factors are helping with..

Answer 31

Capsule = avoids phagocytosis
Adhesins = for attachment
Siderophores = love iron; can tolerate rough living environment

Question 32

An alcoholic homeless man has been in the hospital for a while and has these symptoms: currant jelly sputum, UTI, pneumonia. The culture of the pathogen reveals mucoid (gooky) appearance. You used this and your knowledge of ICU bugs to correctly diagnose the patient with

Answer 32

Klebsiella