Module 5.6 Gram Negative Aerobic Enterobacterales NLF

Question 1

What are the main lactose fermenting enterobacterales?

Answer 1

Escherichia, Klebsiella, Enterobacter

Question 2

What are the main non-lactose fermenting enterobacterales?

Answer 2

Salmonella, Yersinia, Proteus

Question 3

Klebsiella species 3-OPP

Answer 3

• LF
• Klebsiella pneumoniae which is largely opportunistic causing pneumonia in horses, mastitis in cattle, UTI in companion animals, part of ESKAPE
  Klebsiella oxytoca which is a cause of antibiotic associated hemorrhagic enterocolitis in humans and animals

Question 4

Enterobacter species 3-OPP

Answer 4

• Enterobacter cloacae
• LF
• part of ESKAPE

Question 5

Case Report:
- veal calf, fever, not drinking, depressed and dull
-abdominal pain
- watery feces with mucus, necrotic tissue, blood flecked
- healthy again after 2 weeks, other calves developed similar disease and 5% died
- cultured with selective media and a lactose fermentation test
PCR and serology
- result was gram negative rods that were NLF
- upon necropsy there was mucosa inflammation and fibrin
What is the likely cause?

Answer 5

Salmonella!

Question 6

Salmonella species

Answer 6

• enterobacterales NLF
• main species is Salmonella enterica
• 6 subspecies
• live in the large intestine of carrier animals
• can survive and multiply in the environment and food
• not normal flora except reptiles

Question 7

Elaborate on the Salmonella serovars

Answer 7

• many serovars
• serotype using agglutination for O antigen = LPS and H antigen = flagella
• salmonella is named with genus, species, subspecies and then tack on a serovar

Question 8

What are the two major types of diseases of Salmonellosis?

Answer 8

1. Diarrhea (severe inflammation)
2. Septicemia (shock, death, abortion)

Question 9

What is Salmonellosis?

Answer 9

• host adapted serovars
• cause systemic infection/septicemia
• there are non-host adapted serovars that usually cause gastroenteritis

Question 10

Salmonella enterica 1-PR-Z

Answer 10

• invasive (facultative intracellular)
• pathogenicity islands (SPIs)
• SPI-1 causes apoptosis and inflammation (will see damaged ruffling of cells)
• SPI-2 causes survival in macrophages

Question 11

What is the virulence of Salmonella enterica?

Answer 11

• plasmid (host adapted serovars) = spv genes cause intracellular multiplication and survival
• LPS = inflammatory enteritis with secretory diarrhea
• systemic dissemination (septicemia and endotoxic shock)

Question 12

Pathogenesis of Salmonella enterica.

Answer 12

• invasion of epithelia cells
• neutrophil extravasation and increase in vascular permeability
• inflammatory response with effusion of neutrophil and protein rich fluid into the intestinal lumen
• pseudomembrane formation/fibrin deposit and diarrhea

Question 13

What would be a classic recipe for Salmonellosis?

Answer 13

Young animals mixed from different sources where hygiene is poor and immune status is uncertain

Question 14

How do we diagnose Salmonellosis?

Answer 14

• selective media for feces
• liquid enrichment media
• solid selective/indicator (MacConkey)

Question 15

Control and treatment of Salmonellosis

Answer 15

• immunization (cell mediated immunity)
• probiotics causing competitive exclusion within the flora
• antimicrobial therapy against self-limiting infections, severe diseases and septicemia
• there is multidrug resistance

Question 16

What is food borne salmonellosis?

Answer 16

• often poultry/eggs
• contamination of meat with feces
• cross-contamination
• multiplication in food
• very robust bacterium

Question 17

Yersinia species 3-PR-Z

Answer 17

• Yersinia pestis: bubonic plague of fleas
• Yersinia enterocolitica (pork and tonsils)
• NLF

Question 18

Proteus species 3-OPP

Answer 18

• Proteus mirabilis
• NLF
• can be seen in otitis externa
• susceptible to most common antimicrobial drugs