Nontyphoidal Salmonella

Question 1

Classification

Answer 1

Family: Enterobacteriaceae
Genus: Salmonella
Species: S.enterica; S.typhimurium, S.Newport

nontyphoidal Salmonella species

Contaminated meat, poultry, raw milk, eggs, egg products, and water are common sources

Question 2

Morphology

Answer 2

Rod shape
Gram-negative
Motile
Petrichious flagella

Question 3

Growth characteristics

Answer 3

Found normally in the SI and LI

Facultatively anaerobic
Non fastidious

Question 4

Antigenic structure

Answer 4

Somatic O antigens

H antigen (flagella)

Question 5

Virulence factors

Answer 5

Endotoxin
Adhesions- both fimbrial and nonfimbrial
Type III secretion systems and effector molecules- 2 different systems may be found:
- one type is involved in promoting entry into intestinal epithelial cells
- the other type is involved in the ability of Salmonella to survive inside macrophages
Flagella- help bacteria to move through intestinal mucous
Enterotoxins- may be involved in gastroenteritis
Iron capturing ability

Question 6

Disease

Answer 6

Enterocolitis

Septicemia

Question 7

Microbiological diagnosis

Answer 7

DME:

Gram stain is not useful- pathogens cannot be differentiated from normal bowel flora.

Methylene blue stain that reveals many WBCs invasive bowel disease

Culture:
Blood agar plate: for specimens from normally sterile sites
Enrichment broth (GN, Selenite)
Differential medium (Mac Conley’s, EMB agar): lactose-negative colonies
Selective medium (SS agar): colorless colonies with Black center

Biochemical tests
Motile
Do not ferment lactose
Ferment glucose 
Urease negative

Serologic test for identification:
Rapid slide agglutination test

Question 8

Treatment

Answer 8

Salmonella enterocolitis do not require antibiotic therapy- it does not shorten the illness, prolongs the carrier state