Salmonella

Who discovered the genus *Salmonella*

D.A. Salmon in 1885

What was the first *Salmonella* species identified, and what was it originally called?

*Salmonella cholerasuis*, originally called "hog cholera bacillus"

Approximately how many serovars of Salmonella exist?

More than 2,000 serovars

Name five typical Salmonella species.

S. cholerasuis, S. enteritidis, S. gallinarum, S. typhi, S. typhimurium

What is an example of an atypical Salmonella species?

S. salamae

Which Salmonella subspecies belong to the Salmonella enterica group?

I - enterica, II - salamae, IIIa - arizonae, IIIb - diarizonae, IV - houtenae, VI - indica

What is the Gram stain reaction and shape of Salmonella?

Gram-negative short rods

Do Salmonella bacteria have a capsule?

No, they are non-capsulated.

Do Salmonella bacteria possess fimbriae?

Yes, they have fimbriae.

What type of flagella do Salmonella bacteria have?

Peritrichous flagella

Which Salmonella species lack flagella?

S. gallinarum and S. pullorum

On what selective media can Salmonella be grown?

Bismuth sulfite agar, MacConkey agar, Brilliant Green Agar (BGA)

What is the optimal growth temperature for *Salmonella*?

37°C, but it can also grow at 43°C

Does Salmonella produce gas from glucose fermentation?

Yes

Can Salmonella ferment lactose?

No

What is phage typing based on?

Sensitivity to bacteriophages at appropriate dilutions

How are Salmonella O antigens designated?

By Arabic numbers (e.g., 1, 5, 7)

What happens when an O antigen changes due to lysogeny?

The serotype of Salmonella may change

What is the difference between smooth (S) and rough (R) colonies in Salmonella?

Smooth colonies have O antigen, while rough colonies lose it and may lose virulence

What is the function of the H antigen in Salmonella?

It is heat-labile, made of protein, and exists in monophasic or diphasic forms

What is the phase of Andrewes phenomenon in Salmonella?

Only one flagellar antigen (FljB or FljC) is expressed at a time

Which genes determine the antigens of phase 1 and phase 2 in Salmonella, and what do they code for?

Genes H1 and H2, which code for flagellar protein flagellin

Which Salmonella species contains the Vi antigen?

S. typhi

What is the primary mode of Salmonella transmission?

Fecal-oral route

What environmental factors predispose animals to Salmonella infections?

Poor sanitation, overcrowding, inclement weather

Which spp of Salmonella are considered Non-Host Adapted ?

(NADTT) S.newport, S. anatum, S. derby, S. tennessee, S. typhimurium

How long does it take to kill Salmonella at 56°C?

10 to 20 minutes (except *S. senftenberg*)

Which animal is more susceptible to salmonellosis’ older or younger?

Young animals

Salmonellosis starts as __________ then reaches the bloodstream

enteric infection

Which animals are sources of infections or carrier?

Wild birds and rodents

What is the first phase of *Salmonella* infection?

Colonization of the intestine

Which bacteria in the large intestine inhibit salmonella growth

Indigenous fusiform/ indigenous flora

How do normal gut bacteria help prevent Salmonella colonization?

They block attachment sites and stimulate peristalsis

Which immune cells invade the villous tips during Phase 2 of Salmonella infection?

Neutrophils

Where do Salmonella bacteria multiply after entering the intestinal epithelium?

lamina propria

How do prostaglandins contribute to fluid loss during Salmonella infection?

They activate adenylate cyclase (leading to the secretion of water, carbonate, and chloride)

What intestinal conditions result from neutrophil invasion of villous cores?

Acute ileitis and colitis

What are the systemic effects of Salmonella endotoxins?

Fever, hemorrhages, leukopenia, hypotension, shock, hypoglycemia

Which Salmonella serotypes are most important in cattle?

S. dublin and S. typhimurium

What two Salmonella species cause disease in poultry?

S. pullorum and S. gallinarum

How is S. pullorum transmitted?

Transovarial transmission (from infected hens to eggs)

What are the clinical signs of S. pullorum* infection in chicks?

Huddling, sleepiness, diarrhea, rapid death (Within few hours)

What disease does S. gallinarum* cause in poultry?

Fowl typhoid

What are the common transmission routes for S. gallinarum?

Vertical (eggs) and horizontal (feces, broken eggs, ticks)

Which ectoparasite is involved in the horizontal transmission of Salmonella gallinarum?

The tick “Argas persicus”

S. gallinarum cross-reacts with _________?

S. pullorum

What are the clinical signs of fowl typhoid?

Weakness, drowsiness, diarrhea, wing drooping, hyperexcitability

What lesions are found in fowl typhoid?

Hemorrhages, liver necrosis, splenomegaly

What are the main clinical signs of paratyphoid?

Enteritis, diarrhea, septicemia

How can S. typhimurium be transmitted through eggs?

Bacteria localize in ovaries and infect eggs

What unique clinical sign does *S. typhimurium* cause in squabs?

Swollen wing joints (megrims)

Gelatinous exudate in joint capsule is caused by?

S. typhimurium

What type of immunity is most important against Salmonella infections?

Cell-mediated immunity

What are the commonly used vaccines for *Salmonella*?

Live attenuated and bacterin vaccines

What diagnostic tests are used for *Salmonella* detection?

Serology (agglutination test, antiglobulin test, ELISA)