20b: Intestines & Diarrhea

Salmonella serovars likely to cause enteritis in young v older calves

Typhimurium in younger calves, Dublin in older calves

When are sheep more likeley to experience salmonellosis

Cold weather and when stressed

Distinguishing features of salmonellosis in pigs

Rectal strictures and red/purple ear tips

What are foals at higher risk for if they have salmonellosis

Septicemia

Disease caused by Salmonella enterica ser Pullorum in chickens

Bacillary white diarrhea (pullorum disease)

Disease caused by Salmonella enterica ser Callinarum in chickens

Fowl typhoid

Disease caused by Salmonella enterica ser Enteritidis and Typhimurium in chickens

Fowl parathyroid

Clinical picture of neonatal large/production animals with salmonellosis

Acute enteritis with septicemia

How does a Salmonella carrier develop

Had enteritis or septicemia and recovered without completely clearing the pathogen

Species that are commonly asymptomatic carriers of Salmonella

• Cattle

• Chickens

• Rodents

• Reptiles

• Amphibians

Why are bacterial cultures not the answer to everything for a case of salmonellosis

A positive culture in a healthy animal is not diagnostic, and a negative culture is not diagnostic in sick animals because fecal cultures may have low sensitivity

Testing that is recommended after running a fecal culture for Salmonella

Serotyping

Treatment for salmonellosis

• IVF

• NSAIDs

• ± ABs

When should you use antibiotics for cases of salmonellosis

Use antibiotics if the patient is at risk for septicemia

When should you not use antibiotics for cases of salmonellosis and why

Enteric cases with no or low septicemic risk; if treated with ABs may create chronic carriers or promote resistance

Why does wiping out normal flora predispose an animal to infection

Commensal bacteria compete with pathogenic bacteria

Major sources of Salmonella infection

Carriers and contaminated feedstuffs

What type of vaccine is used for Salmonella

Inactivated bacterins, live attenuated only for swine

Key prevention for salmonellosis

Good sanitation and biosecurity

General term for the disease caused by E. coli

Colibacillosis

What type of bacteria is E. coli

G- facultative anaerobic rod; family enterobacteriaceae

Transmission for E. coli

Fecal oral transmission

Primary strains that cause colibacillosis in animals

• ETEC: enterotoxigenic/enterotoxemic

• EPEC: enteropathogenic

• EHEC: enterohemorrhagic

What species experience disease associated with E. coli

Any specie :)

Strain of E. coli that causes neonatal diarrhea

ETEC

Demographic affected by neonatal diarrhea (ETEC)

Usually <1 week old

Virulence factors associated with ETEC causing neonatal diarrhea in piglets

F4 (K88)

Virulence factors associated with ETEC causing neonatal diarrhea in calves

F5 (K99) or F41

What do you need to do before treating E. coli with antibiotics

Susceptibility, there is lots of resistance

How does ETEC interact with cells

It sits on the surface of enterocytes and does not invade the cells

Why is ETEC a cause of diarrhea primarily in neonates

The binding of the virulence factors gradually decreases as they age

Type of diarrhea induced by ETEC

Secretory diarrhea

Types of enterotoxins produced by ETEC

Heat labile (LT) and heat stable (ST) enterotoxins

Difference between heat labile and heat stable ETEC enterotoxins

LT is immunogenic while ST is not

Prevention for neonatal diarrhea (ETEC)

Biosecurity and sanitation

Type of vaccine used for neonatal diarrhea (ETEC)

Either cloned subunits of enterotoxins or antibodies against F5 (K99)

Strain of E. coli that causes postweaning diarrhea of pigs

ETEC

Virulence factors associated with postweaning diarrhea of pigs (ETEC)

F4 (K88) and F18

Demographic affected by postweaning diarrhea of pigs

2-3 week old pigs

Types of pigs that are immune to postweaning diarrhea of pigs

Piglets lacking adhesins

Strain of E. coli that causes edema disease of swine

ETEC

Virulence factors associated with edema disease of swine

F18 and Shiga toxin 2e

Demographic affected by edema disease of swine

Best-doing pigs in the group

CS associated with edema disease of swine

• Peracute death

• CNS signs: ataxia, paralysis, recumbency

• Facial and GI edema

• Diarrhea

Pathogenesis of edema disease of swine

Endothelial and vascular wall necrosis caused by Shiga toxin 2e

Diet that can help prevent edema disease of swine

High fiber and low protein

Other name for EPEC

Attaching and effacing E. coli

How does EPEC interact with host cells

Attaches to the brush border

Type of diarrhea caused by EPEC

Osmotic and secretory diarrhea

Type of disease caused by EHEC

Hemorrhagic colitis

Specific E. coli that tends to cause septicemia

Enteroinvasive

How does enteroinvasive E. coli tend to infect the animal

Through the umbilicus

Pathogenesis of enteroinvasive E. coli

Arterial damage → vasculitis → sepsis → death, or otherwise localized infections like polyarthritis

Strain of E. coli that is of largest zoonotic concern

E. coli O125:H7

Source of zoonotic E. coli O125:H7 infections

Asymptomatic carriers

Disease caused by E. coli O125:H7 in people

Hemorrhagic diarrhea

Pathogenesis of ETEC

Ingestion → sits on surface of enterocytes → LT and ST enterotoxins produced → chloride secretion and decreased Na absorption → secretory diarrhea

Pathogenesis of EPEC

Ingestion → attaches to and damages microvilli → loss of microvilli → osmotic diarrhea leading to secretory diarrhea

Pathogenesis of EHEC

Ingestion → attaches to colon enterocytes → production of Shiga toxins → severe inflammation and mucosal destruction → LPS absorption → mucosal necrosis → hemorrhagic colitis