Family Enterobacteriaceae
Members of the Enterobacteriaceae of veterinary importance:
Genus | Species | sub-species | Serotype |
Escherichia | Escherichia coli | ||
Escherichia fergussonii | |||
Escherichia hermannii | |||
Escherichia vulneris | |||
Escherichia alberti | |||
Salmonella | Salmonella enterica | enterica | Typhimurium |
“ | “ | Dublin | |
“ | “ | Pullorum | |
“ | “ | Gallinarum | |
“ | “ | Enteritidis | |
-? | -? | -? | Choleraesuis |
Yersinia | |||
Proteus | |||
Enterobactor | |||
Klebsiella | |||
Shigella | |||
Serratia | |||
Morganella |
Family properties:
- Gram – negative rods up to 3 μ m in length,oxidase – negative, have peritrichous flagella
- non – sporing
- Grow well on MacConkey agar because they are not inhibited by the bile salts in the medium
- Mostly strains are opportunistic pathogens, occasionally causing clinical disease in locations other than the alimentary tract.
- Usual habitat- Intestinal tract
- Enterobacteria can be arbitrarily grouped into three categories: major pathogens, opportunistic pathogens and non – pathogens.
- The major animal pathogens E. coli, Salmonella species and Yersinia species can cause both enteric and systemic disease.
- Opportunistic pathogens: – Proteus species, Enterobacter species, Klebsiella species Some other members of the Enterobacteriaceae.
- Klebsiella is the only NON_MOTILE under this family
- Lactose fermenters form a pink colony due to acid production from Lactose.
- Non-lactose fermenters have pale colonies and are alkaline due to utilisation of peptone.
- Differentiation of Salmonella and E. coli in growth media:
Salmonella: Brilliant green (BG) agar and xylose – lysine deoxycholate (XLD) agar, are used to differentiate Salmonella from other enteropathogens.
- On BGA , Salmonella colonies and the surrounding medium show a red alkaline reaction.
- On XLD medium the colonies of most Salmonella serotypes are red (alkaline reaction) with black centers due to hydrogen sulfide (H2S) production.