L21_Enteric Bacteria

Question 1

Name 7 defining features of Enterobacteriaceae

Answer 1

1 Gram Neg
2 Non-Sporulating
3 Straight Rods
4 Facultative Anaerobes
5 Catalase (+)
6 Oxidase (-)
7 GLucose Fermenters

Question 2

What is a common characteristic of all enterobacteriaceae, but not necessarily defining? What is a major problem in their treatment.

Answer 2

promiscuous to new DNA - easily transformed, can help pick up gut virulence factors or antibiotic resistance. (extreme antibiotic resistance is a major problem for the whole group)

Question 3

Name the food borne Enterobacteriaceae

Answer 3

Shigella, E. Coli, Samonella, Yersinia.

Question 4

Name the Enterobacteriaceae that are opportunistic pathogens

Answer 4

Klebsiella, Enterobacter, Serratia, Proteus, Providencia, and Morganella

Question 5

Describe the process of Antimicrobial Sensitivity Testing

Answer 5

Smear agar plate with microbe of interest. Place discs of varying antibiotics on the plate, incubate the plate overnight. Measure zones of clearing and compare to standardized table to determine resistance rating.

Question 6

List two important virulence factors in the gut and how they help bacteria.

Answer 6

Pili- for attaching to the gut and urinary tract which normally push contents out unless properly anchored
Type 3 secretion systems- for adhesion, enterotoxins, and subverting gut macrophages

Question 7

Describe how some salmonella and shigella bacterium infect the gut wall, discuss how S. Typhi takes it one step further (tricky little bastard)

Answer 7

They allow themselves to be sampled by M cells in the Peyer’s pathces, they then alter the local macrophages for bacterial survival and spread to the exterior of the gut using T3SS (Most macrophages are killed in this process). Some species will further use some macrophages as a trojan horse for passage to local (Y enterocolicita, false appendicitis) or system wide (S. Typhi typhoid fever) lymph nodes.

Question 8

How are the food borne Enterobacteriaceae transmitted and what can be done to prevent it?

Answer 8

Fecal-oral and best prevented by water treatment, hand washing, food pasteurization and cooking.

Question 9

What two species carry the risk for Hemolytic-Uremic Syndrome (HUS), and what is the main demographic this is seen in? What is the virulence factor?

Answer 9

Shigella and EHEC infect mainly pediatric patients by release of Shiga toxin into the bloodstream.

Question 10

What are the five bacteria that can cause Reactive Arthritis, what are the signs of this, who is at risk?

Answer 10

Shigella, Salmonella, Yersinia, Campylobacter, or chlamydia, patient postive for HLA-B27, signs are conjunctivitis, urethritis, or arthritis (Cant see, cant pee, cant climb a tree)

Question 11

Name the ICU bugs that are the major opportunistic pathogens that cause many nosocomial infections. How can you help prevent these?

Answer 11

Klebsiella, Enterobacter, Serratia, Proteus, Providencia, and Morganella. Switching of IV lines, catheters, ICU and patient scrubdowns, minimization of hospital stays.

Question 12

What are the virulence factors of Klebsiella?

Answer 12

Large polysaccharide capsule, adhesins, and siderophores

Question 13

What bug is associated with false appendicitis?

Answer 13

Y. enterocolicita

Question 14

What bug is associated with Typhoid Fever?

Answer 14

S. typhi