Lesson 89 - Bacterial Diarrhea

What are predisposing factors to bacterial diarrhea?

inadequate transfer of passive immunity, poor management practices, stressful factors

What can avian species act as for yersinia?

amplifier hosts and mechanically transfer organisms

What is important about the serotype O:9 of Yersinia?

shares antigens with Brucella so may give a false positive Brucella agglutination test

What is the number one source of Campylobacter jejuni?

chicken meat

What is the most common reservoir for Campylobacter jejuni?

domestic poultry

What is the causative agent of equine proliferative enteropathy?

Lawsonia intracellularis

What is the causative agent of porcine proliferative enteropathy?

Lawsonia intracellularis

What is porcine proliferative enteropathy also known as?

ileitis

What is an obligate intracellular pathogen?

Lawsonia intracellularis

How can Brachyspira be transmitted?

fecal-oral route; dogs, rats, mice, flies act as vectors

What animals get Brachyspira hyodysenteriae?

weaned pigs 6-12 weeks old

What are clinical signs of Brachyspira hyodysenteriae?

decreased appetite, increased thirst, emaciation, loss of condition, mucohemorrhagic colitis, mucohemorrhagic diarrhea

What are the gram-positive organisms?

Clostridium

What is important about the Clostridium perfringens structure?

thick cell wall and capsule

What are predisposing factors for Clostridium perfringens?

inappropriate husbandry methods, sudden dietary changes, environmental influences

What organ causes paratuberculosis?

Mycobacterium avium

What organism can be shed in the colostrum and milk?

Mycobacterium avium

How long can Mycobacterium last in the environment?

up to a year

When do clinical signs occur in paratuberculosis?

after 2 years of age

What type of organism causes bottle jaw?

Mycobacterium avium

What is a virulence factor for gram negative?

lipopolysaccharide

What are important virulence factors of Salmonella?

type III secretory system, LPS

What is the pathogenesis of Salmonella?

uptake of Salmonella into the cells and Salmonella uses Type III secretory system to inject virulence factors into the cell to damage cells

What is the treatment and control for Salmonella?

resistant to many antibiotics, vaccination, pre and probiotics, biosecurity

What is the virulence factors of E.coli?

LPS, capsules, enterotoxins

What does LPS do with E. coli?

pyrogenic activity and endothelial damage leads to intravascular coagulation and endotoxic shock

What are the important pathotypes of E. coli?

Enterotoxigenic E. coli, Attaching and effacing E. coli, Shiga toxin producing E. coli

What causes neonatal colibacillosis in piglets?

Enterotoxigenic E. coli

What toxins does enterotoxigenic E. coli produce?

heat labile and heat stable toxins

What are the two types of heat stable toxins?

STa and STb

What toxins from ETEC are antigenically related to Vibrio cholerae?

heat labile

What is the affect of heat labile toxin from ETEC?

adenylate cyclase system leading to hypersecretion of fluid into the intestines; diarrhea, hypovolemia, metabolic acidosis

What is affected by STa?

guanylate cyclase system causing fluid accumulation in suckling mice and piglets

What is STa?

plasmid-encoded toxin

What does STb cause?

diarrhea and fluid accumulation in intestines of weaned pigs

What does STEC cause?

edema disease in weaned pigs

What does the STEC produce?

shiga toxin

How does STEC cause edema?

shiga toxins damage blood vessels in target tissues causing edema

What parts of E. coli can be identified in serology testing?

fimbrial antigens, enterotoxins, shigatoxins

What E. coli can be seen with histology?

attaching and effacing E. coli lesions

Why do we need to antimicrobial sensitivity tests for E. coli?

presence of R plasmids

What do toxins from Yersinia cause?

form pores and stimulate guanylate cyclase activity leading to increased cGMP levels and fluid accumulation

What are a virulence factor of Yersinia that interferes with phagocytosis?

Yersinia outer proteins (Yops)

What is the diagnosis of Yersinia?

histological examination of intestinal lesions, microabscesses

What is the treatment for Yersinia?

fluid replacement, formalin killed vaccine, good animal husbandry practices

What are clinical signs of Campylobacter?

mucus-laden, watery, bile-streaked diarrhea, intermittent, pregnant dogs miscarry

How do we diagnose Campylobacter?

feces or blood in airtight container for culture

Why do Campylobacter need airtight container?

require microaerophilic atmosphere

What drugs is Campylobacter resistant to?

fluoroquinolones, tetracyclines, kanamycin

What does Lawsonia intracellularis cause?

cell infection then hyperplasia then mucosa swelling then impaired gut function

What are the ways to diagnose Lawsonia?

immunofluorescence, PCR, cultured only in cell lines

What is the treatment for Lawsonia?

tylosin and tiamulin, vaccination, disinfection

What type of bacteria is Bracyspira?

anaerobic gram-negative spirochete

How long can Brachyspira survive in moist feces?

2 months

Why does Brachyspira hyodysenteriae cause mucus diarrhea?

invade goblet cells and produce hemolysins

What is the treatment for Brachyspira?

medication of drinking water with tiamulin, lincomycin, nitroimidazoles, alteration of diet, depopulation, rodent control

What are the four major toxins from Clostridium perfringens?

alpha, beta, epsilon, iota

What produces alpha?

all strains of clostridium

What does alpha toxin do?

acts on cell membrane and cause hemolysis/cell necrosis

What produces beta toxin?

strains B & C

What does beta toxin?

necrotizing enteritis and contraction of intestinal smooth muscle

What produces epsilon toxin?

strains B & D

What produces iota toxin?

strain E

What is epsilon and iota?

pro-toxin which is activated by proteolytic enzymes

What is caused by overgrowth of Clostridium perfringens type A?

Canine hemorrhagic gastroenteritis

What causes necrotic enteritis in chickens?

C. perfringens type A and sometimes type C

What is the transmission of necrotic enteritis in chickens?

fecal-oral route

What are predisposing factors for necrotic enteritis in chickens?

dietary, mucosal damage, coccidia

What are the clinical signs of necrotic enteritis in chickens?

sudden death, depression, ruffled feathers, diarrhea

What causes hemorrhagic enteritis in pigs?

C. perfringens type C

What is the pathogenesis of hemorrhagic enteritis in pigs?

beta toxin binds to vascular endothelial cells leading to vascular necrosis and necrosis of villi

What are postmortem findings of hemorrhagic enteritis in pigs?

segmental mucosal necrosis with marked hemorrhage in the small intestines

What is the treatment and control of C. perfringens?

hyperimmune serum, vaccination, good husbandry practices

What does Clostridioides difficile cause?

pseudomembraneous colitis, chronic diarrhea in dogs, hemorrhagic enterocolitis in foals, neonatal diarrhea in pigs, antibiotic associated

What are the virulence factors of Clostridioides difficile?

toxin A (enterotoxin) and toxin B (potent cytotoxin)

What does toxin A do?

stimulates fluid secretion, diarrhea

What does toxin B do?

damages enterocytes in the gut causes hemorrhage

What does paratuberculosis cause in the intestine?

granulomatous proliferation of ileo-cecal mucosa