Enterobacteriacerae: Salmonella & Shigella

What is the shape of the enterobacteriaeceae group?

gram negative, rod-shaped

Aerobic, Anaerobic, or Facultative?

Facultative

True or False: All enterbacteriaceae ferment lactose.

FALSE - they may or may not

Where are enterbacteriaceae found in people?

GI tract

Where can salmonella be found on certain animals?

skin of all warm and cold-blooded animals

What feature allows salmonella to be motile?

peritrichous flagella

Salmonella is _____ to eliminate and can persist for ______ in feed and ______.

difficult; months; biofilms

Which subspecies of salmonella is commonly carried by reptiles and causes egg-transmitted losses in turkey poults?

S. Enterica subspecies arizonae

Salmonella serotypes are classified based on its:

O and H antigen

O antigen is on the:

LPS

H antigen is on the:

flagella

O antigen is designated:

1, 2, 3

H antigen is designated:

a, b, c

True or False: The genus, species, and subspecies are all italic but not the serotype.

TRUE

Generalized, non-typhoidal salmonella typically has a _____ host range and is ________.

broad; self-limiting

Host adapted salmonella has a ______ preferred host and causes __________, ________, and they can be lifelong _______.

narrow; systemic disease; abortion; carriers

Host restricted salmonella have ____ host and are classified as _______ or ______-like.

one; typhoid; typhoid

What is the host of S. Typhimurium?

broad

WHat is the host of S. Enteritidis?

poultry

What is the host of S. Dublin?

Cattle

What is the host of S. Choleraesuis?

swine

What is the host of S. Pullorum?

chicks and poults

What is the host of S. Gallinarum?

adult birds

What is the host of S. Abortuovis and S. Abortusequi?

sheep / horses

Which salmonella species has been historically called bacillary white diarrhea?

S. Pullorum

Which species of salmonella is responsible for egg associated human illness?

S. Enteritidis

True or False: poultry infected with S. Enteritidis are typically subclinical.

TRUEq

What are the two vertically transmitted poultry serovars?

Pullorum disease and fowl typhoid

What species of salmonella are we at risk for if we drink raw milk?

S. Dublin

What are the four predisposing factors for salmonella infection?

• stress

• Antimicrobials

• Young or impaired immunity

• New arrivals (asymptomatic carriers)

How do salmonella invade?

Type III secretion (T3SS) to inject effector protiens into host cell

What cells do salmonella live in?

Phagocytic cells (Macrophages)

True or False: Salmonella resists oxidative killing with catalase and SOD.

TRUE

How do salmonella multiply and spread?

macrophages → lymph nodes → bloodstream → liver & spleen

List the three things salmonella has that causes host damage and what they do.

• Enterotoxins: fluid secretion

• Cytotoxins: cell damage

• LPS: inflammation/endotoxemia

In an intestinal infection with salmonella, describe how it causes diarrhea?

1. Infection → Mucosal injury in ileum → Enterocytes loss → decreased absorption

2. Inflammation → neutrophils + increased mucus + increased water and electrolyte secretion

3. DIARRHEA

If the infection is latent in lymphoid tissue, patients can have _______ shedding.

intermittent

Where does salmonella persist in carriers?

gallbladder and biliary biofilm

How can you diagnose salmonellosis in horses?

• clinical signs and neutropenia

• Fecal culture with serial samples up to 5, 12-24 hrs apart

• Environmental sampling

True or False: Salmonella is not part of the normal GI flora in canines.

TRUE

When should you consider salmonella cultures in canines?

• fed raw diet

• Interacts with reptiles

What are the key concerns in salmonellosis in cattle?

herd persistence with systemic disease and zoonoses

Which two species of salmonellosis are considered paratyhpoid in poultry?

E. Enteritidis and S. Typhimurium

Which poultry salmonellosis is considered fowl typhoid?

S. Gallinarum

What is the most common type of salmonellosis in humans?

nontyphoidal gastroenteritis

What are the two salmonella species that affect humans and are nontyphoidal?

• S. Typhimurium

• S. Enteritidis

Which type species of salmonella are typhoidal in humans?

• S. Typhi

• S. Paratyphi A, B, C

Which two species of salmonella are multidrug resistant?

Typhimurium DT 104 and Newport

• both cattle associated

What type of plate should you use to culture Salmonella?

• Teteathionate broth

• MacConkey XLT-4 BG

What are the four species of Shigella?

• S. Dysenteriae

• S. Flexneri

• S. Boydii

• S. Sonnei

What is the host of shigella?

humans and higher primates

What is the source of shigella?

infected keeper or handler (reverse zoonosis)

Which species of shigella has the shiga toxins (similar to E. Coli)?

S. Dysenteriae

How do you treat shigella?

supportive care and antibiotics guided by susceptibility