Bacteriology

Question 1

What is the major defense mechanism of the small intestine?

Answer 1

Peristalsis - sweeps non-adherent bacteria away

Question 2

What is the major defense mechanism of the large intestine?

Answer 2

Physiochemical properties - low redox potential and fatty acids

Question 3

Why is antimicrobial therapy a risk factor for GI disease?

Answer 3

Decreases normal flora in mouth and GIT, allowing for repopulation with other bacterial organisms

Question 4

What is a toxin that is produced by the cell wall of gram-negative bacteria and contributes to local and systemic inflammation?

Answer 4

Endotoxin

Question 5

What type of exotoxin causes a disruption of fluid and electrolyte regulation of the target cells?

Answer 5

Enterotoxin

Question 6

What type of toxin damages and kills target cells by invading them?

Answer 6

Cytotoxins

Question 7

Give an example of a non-invasive bacteria that causes intra-intestinal infections.

Answer 7

ETEC

Question 8

Why is isolating E. coli from a culture of feces not diagnostic?

Answer 8

E. coli is part of normal flora so you would expect to isolate it

Question 9

T/F: All strains of E. coli cause neonatal colibacillosis.

Answer 9

F

Question 10

In order to cause diarrhea, the strain of E. coli must have what 2 virulence factors?

Answer 10

Fimbriae and ability to produce enterotoxin

Question 11

Enterotoxigenic E. coli (ETEC) produces an enterotoxin that tells the cells to shut off sodium absorption, and as a result sodium and water leak into the lumen. What does this result in?

Answer 11

Watery diarrhea

Question 12

In addition to neonatal colibacillosis of calves (aka white scours), what other disease does ETEC cause?

Answer 12

Pre-weaning diarrhea in piglets

Question 13

How long are the receptors for ETEC pili on the enterocytes

Answer 13

During 1st week of life

Question 14

Because ETEC is not part of the neonate’s normal flora, how is it transmitted?

Answer 14

Feco-oral transmission

Question 15

How do you diagnose ETEC infections?

Answer 15

Presumptive diagnosis based on age and watery diarrhea without presence of blood

Question 16

What is the most important aspect of therapy for diarrhea caused by ETEC?

Answer 16

Replacement of fluids and electrolytes

Question 17

Which invasive bacteria is an important cause of diarrhea in humans, but its role in disease in animals is less clear?

Answer 17

Campylobacter

Question 18

Why is isolating Campylobacter from feces not diagnostic?

Answer 18

Can be isolated from feces of healthy dogs, so have to weigh up evidence to support diagnosis

Question 19

What are the 2 routes of transmission associated with Salmonella?

Answer 19

Feco-oral transmission or recrudescence of existing infection

Question 20

What invasive facultative intracellular pathogen that can localize in macrophages causes a bloody, hypersecretory diarrhea in horses?

Answer 20

Salmonella

Question 21

T/F: Salmonella is part of normal flora

Answer 21

F

Question 22

In addition to bloody, hypersecretory diarrhea, what other disease can Salmonella cause (specifically in foals)?

Answer 22

Septicemia

Question 23

What invasive, gram-negative spirochaetes are obligate anaerobes that have fastidious growth requirements for a special lab?

Answer 23

Brachyspira hyodysenteriae

Question 24

What is the major reservoir of Brachyspira hyodysenteriae?

Answer 24

Asymptomatic pigs

Question 25

T/F: Brachyspira hyodysenteriae are part of normal flora

Answer 25

F

Question 26

What disease does Brachyspira hyodysenteriae cause?

Answer 26

Acute and chronic swine dysentery

Question 27

What type of diarrhea is associated with Brachyspira hyodysenteriae?

Answer 27

Profuse, bloody diarrhea with mucus (dysentery)

Question 28

What pathogen of the GIT of ruminants causes Johne's disease?

Answer 28

Mycobacterium avium ss. paratuberculosis

Question 29

What disease of ruminants is a progressive, persistent, granulomatous enteritis with severe, chronic diarrhea leading to emaciation and death?

Answer 29

Johne's disease

Question 30

How is Johne's disease transmitted?

Answer 30

Ingestion of feed and water contaminated with Johne's-positive feces

Question 31

T/F: M. avium ss. paratuberculosis is resistant in the environment and subclinical carriers are an important reservoir

Answer 31

T

Question 32

The granulomatous enteritis associated with Johne's disease causes malabsorption. What clinical sign (besides emaciation) can you appreciate in cows with this disease that occurs as a result of malabsorption and hypoproteinemia?

Answer 32

Bottle jaw - edema in submandibular region

Question 33

What 2 invasive intestinal bacteria cause inflammation and intestinal thickening in addition to diarrhea?

Answer 33

Mycobacterium avium ss. paratuberculosis and Lawsonia intracellularis

Question 34

Why is fecal culture not the best diagnostic test for Johne's disease?

Answer 34

Bacteria is slow growing and can take up to 3 months before you would get results

Question 35

Lawsonia intracellularis is a gram-negative curved rod and is an obligate intracellular parasite. What does this indicate in terms of diagnostics?

Answer 35

Cannot be cultured

Question 36

What 2 GIT disorders in pigs does Lawsonia intracellularis cause?

Answer 36

Porcine Proliferative Enteropathy and Porcine Hemorrhagic Enteropathy

Question 37

Porcine proliferative enteropathy is most important in what 2 species?

Answer 37

Foals and pigs

Question 38

What disease caused by Lawsonia intracellularis causes chronic, mild diarrhea and reduced performance in young, growing pigs and foals?

Answer 38

Porcine proliferative enteropathy

Question 39

What disease is the most common reason for putting antibiotics into feed for growing pigs?

Answer 39

Porcine proliferative enteropathy

Question 40

You have been called out to a swine breeding operation to check out a few pigs that have bloody/tarry diarrhea. 3 of the pigs in the herd have died. On necropsy, you find grossly thickened mucosa of the terminal ileum with hemorrhage and a blood clot in the lumen of the intestine. What is your diagnosis?

Answer 40

Porcine Hemorrhagic Enteropathy

Question 41

How do you diagnose Lawsonia infections?

Answer 41

Histopathology or PCR

Question 42

What pathogen causes enterotoxaemia in lambs, calves, and goats and is associated with overeating of rich grains or from suckling heavily lactating ewes feeding on lush grass, leading to gut stasis and acidosis?

Answer 42

Clostridium perfringens type D

Question 43

Where are clostridium perfringens pathogens normally found in the GIT?

Answer 43

Large intestine

Question 44

Due to metabolic acidosis, Clostridium perfringens are able to move to the ____________ _______________, where they will release an exotoxin called _____________ ___________ that is activated by ______________.

Answer 44

small intestine, epsilon prototoxin, trypsin

Question 45

Epsilon toxin produced by Clostridium perfringens causes decreased/increased capillary permeability, leading to brain edema and necrosis.

Answer 45

Increased

Question 46

What disease caused by Clostridium perfringens type D causes accelerated post-mortem autolysis and is often referred to as "Pulpy Kidney Disease"?

Answer 46

Enterotoxaemia

Question 47

What disease of thriving weaner or grower pigs (6-14 weeks of age) is caused by hemolytic Shiga toxin E. coli that causes damage to the endothelial cell wall, leading to increased vascular permeability, edema, and sometimes CNS signs?

Answer 47

Edema disease of pigs

Question 48

What is the term for the passage of viable bacteria from the GIT to extraintestinal sites?

Answer 48

Bacterial transolcation

Question 49

What is the most important factor that promotes bacterial translocation?

Answer 49

Injury to intestinal mucosa resulting in increased intestinal permeability

Question 50

What does bacterial translocation lead to?

Answer 50

Lethal sepsis

Question 51

Give 2 examples of bacteria that are extraintestinal, meaning the bacteria stay in the intestines but the toxins are absorbed somewhere else.

Answer 51

Clostridium perfringens type D and STEC in edema disease