Lecture 22. GI Infections 3

Campylobacter jejuni etiology

1. Gram-negative, gull-wing or S-shaped rod

2. microaerophilic (5% O₂, 10% CO₂); grows at 42°C.

C. jejuni

what bacteria is indicated by this image and is associated with hemorrhagic enterocolitis

Transmission of Campylobacter jejuni

Fecal-oral route from inapparent carriers, milk, or frozen chicken.

Factors increasing spread of Campylobacter jejuni

Poor immune status and concurrent infections (e.g., parvo, salmonella, corona).

Main virulence factors of Campylobacter jejuni

1. Cytolethal distending toxin (CDT) - destroys villi and induces inflammation

2. adhesions- attach to mucosal epi cells

Clinical signs of Campylobacter jejuni

Hemorrhagic enterocolitis, bacteremia, fever, diarrhea;

what bacteria is associated with hemorrhagic enterocolitis

C. jejuni

who is primarily infected with C. jejuni

mainly affects animals <6 months old.

Diagnosis of Campylobacter jejuni

1. History, clinical signs

2. direct fecal exam

3. microaerophilic fecal culture.

what is revealed on dark field fecal exam that points to C. jejuni

darting motility

Primary treatment for Campylobacter jejuni infection

1. Fluid therapy

2. erythromycin (efficacy unknown).

Prevention of Campylobacter jejuni

Sanitation.

Clostridium perfringens morphology

Gram-positive, obligate anaerobic rod; forms spores and exotoxins.

C. perfringens

this bacteria is associated with hemorrhagic enterotoxemia

C. perfringens type associated with hemorrhagic enterotoxemia

Type C - produces alpha and beta toxins.

Predisposing factors for C. perfringens infection

1. High-energy diets

2. reduced peristalsis

3. antibiotic disruption of flora,

4. low trypsin in neonates.

transmission of C. perfringens

fecal-oral

what exotoxins are associated with type A clostridium

alpha

what exotoxins are associated with type B clostridium

alpha, beta, epsilon

what exotoxins are associated with type C clostridium

alpha, beta

what exotoxins are associated with type D clostridium

alpha, epsilon

what exotoxins are associated with type E clostridium

alpha, lota

how does C. perfringens type C cause disease

damage intestinal microvilli and lead to damage of leukocytes, platelets, and RBCs

Common clinical signs of clostridial diarrhea

Sudden death, ADR, colic, abdominal pain, brown/bloody diarrhea, high mortality (50-100%).

Diagnosis of C. perfringens

1. History, clinical signs

2. necropsy (intestinal lesions)

3. anaerobic culture

4. toxin neutralization test.

what test is confirmatory for C. perfringens

toxin neutralization test (but not all produce toxins)

Treatment for C. perfringens infection

1. C-type antitoxin

2. antibiotics (metronidazole or penicillin)

3. supportive fluids and electrolytes.

Prevention of C. perfringens infection

Colostrum antibodies, vaccinating dams (multivalent vaccine), and sanitation.

Cause of CDAD (Clostridium Difficile Associated Diarrhea)

Clostridium difficile.

Major toxins produced by C. difficile

1. Toxin A (enterotoxin - fluid secretion)

2. Toxin B (cytotoxin - epithelial necrosis).

Pathogenesis of C. difficile

1. Causes pseudomembranous colitis in humans

2. acute necrotizing enterocolitis in animals.

Diagnosis of C. difficile

Detection of toxins in feces via cytotoxin test (toxin B), ELISA, or PCR (toxin genes)

Treatment for C. difficile infection

Tylosin, fluid therapy, sanitation.

C. difficile

the disease state seen is this equine is associated w/ what pathogen

Clinical syndromes associated with C. perfringens type A

1. Necrotic enteritis in chickens, suckling pigs

2. yellow lamb disease

C. perfringens type A

the disease state in this pig is associated with what pathogen

Clinical syndromes associated with C. perfringens type B

1. hemorrhagic enteritis

2. lamb dysentery (Europe, South Africa).

Condition caused by C. perfringens type D

"Overeating disease" and enterotoxemia in lambs - causes diarrhea and nervous signs.