Table of Contents
What is selenite F used for?
Selenite F Broth is used as a selective enrichment for the cultivation of Salmonella spp. It is also used as an enrichment medium for the isolation of some species of Shigella.
What does selenite broth do?
Selenite broth is used as a selective medium for the isolation of Salmonella species. Selenite broth was originated by Leifson, while observing good recovery of Salmonella spp. and reduced growth of fecal coliforms. Selenite broth is used as a selective enrichment for the cultivation of Salmonella spp.
What medium is used for culture of Salmonella?
The most commonly used media selective for Salmonella are SS agar, bismuth sulfite agar, Hektoen enteric (HE) medium, brilliant green agar and xylose-lisine-deoxycholate (XLD) agar. All these media contain both selective and differential ingredients and they are commercially available.
Why is pre enrichment necessary for Salmonella and Shigella?
Pre-enrichment in a non-selective medium allows for repair of cell damage and facilitates the recovery of Salmonella.
What are Salmonella species?
Salmonella is a genus of rod-shaped (bacillus) Gram-negative bacteria of the family Enterobacteriaceae. The two species of Salmonella are Salmonella enterica and Salmonella bongori. S. enterica is the type species and is further divided into six subspecies that include over 2,600 serotypes.
What is the purpose of enrichment broth in stool cultures?
The enrichment broth used for stool cultures prolongs the lag phase of the normal fecal flora (E. coli,etc) and allowing fecal pathogens like Salmonella and Shigella to enter into the log phase of growth. (It keeps the normal fecal flora from overgrowing the pathogenic organisms) .
Is Salmonella Shigella Agar selective or differential?
Salmonella Shigella (SS) Agar is moderately selective and differential medium for the isolation, cultivation and differentiation of Salmonella spp. and some strains of Shigella spp. SS Agar is a modification of the Desoxycholate Citrate Agar.
How is Salmonella cultured?
Salmonella bacteria can be detected by stool culture. In cases of bacteremia or invasive illness, the bacteria can also be cultured from blood, urine, or, on rare occasions, from other body tissues. A fecal, blood, or other sample is placed in nutrient broth or on agar and incubated for up to 2-3 days.
What is enrichment broth?
M-Enrichment Broth is used as a non-selective medium for enumeration of bacteria by membrane filter technique and for preliminary enrichment of organisms on membrane filter prior to using selective media.
Why is RV broth used for Salmonella?
It enriches salmonellae because they are better able to survive the high osmotic pressure in the medium and because they can multiply at relatively lower pH and higher temperatures compared with other gut bacteria. RVS broth has a pH around 5.2.
What is enrichment broth in microbiology?
Broth enrichment media are used when high sensitivity is required e.g. for detection of bacteria from CSF, or to detect small numbers of Salmonella in a stool sample containing many millions of other bacteria.
What is enriched media give example?
Enriched media include blood agar, chocolate agar, Loeffler’s serum, MacConkey agar, Lowenstein-Jensen media, and others, whereas enrichment media include Selenite F broth, tetrathionate broth, alkaline peptone water (APW), and others.
What organisms grow on Salmonella Shigella Agar?
Result Interpretation on Salmonella Shigella (SS) Agar
| Organisms | Result |
|---|---|
| Escherichia coli | Small, pink to red |
| Enterobacter, Klebsiella | Larger than E.coli, mucoid, pale, opaque cream to pink |
| Salmonella | Colorless, transparent, with a black center if H2S is produced |
| Proteus | Colorless, with a black center |
Does Klebsiella grow on SS Agar?
Klebsiella pneumoniae shows red colour to SS agar. Salmonella and Shigella along with other microorganisms that are not capable of fermenting lactose are visible as transparent or translucent colonies. E. coli gives pink or red coloured colonies.
Are E coli and Salmonella the same?
Salmonella and E. coli are both bacteria and they are fundamentally very similar. Salmonella actually evolved from E. coli, about 100 million years ago.
Which culture medium is used to culture stool for diagnosis of typhoid?
Conclusions: For the diagnosis of typhoid fever by blood culture the medium should be a rich nutrient broth containing a lysing agent. In adults 1 ml bone marrow or 15 ml blood culture gave similar results.
What is Salmonella species?
What is selenite broth used for in microbiology?
It is also used as an enrichment medium for the isolation of some species of Shigella. The broth is also recommended for the transport of strains of Vibrio cholerae, because these organisms can survive 2 to 5 days in Sodium Selenite Broth.
What is the composition of selenite F broth?
Selenite F Broth- Composition, Principle, Uses, Preparation and Result Interpretation. Selenite F Broth is the medium used for the selective enrichment of Salmonella spp from both clinical and food samples. It is a buffered Lactose Peptone Broth to which Sodium Biselenite is added as the selective agent.
How long should I incubate selenite F broth?
Do not incubate the broth longer than 24 hours as inhibitory effect of selenite decreases after 6 – 12 hours of incubation. Selenite F Broth is used as a selective enrichment for the cultivation of Salmonella spp. It is also used as an enrichment medium for the isolation of some species of Shigella.
Can Vibrio survive in sodium selenite broth?
The broth is also recommended for the transport of strains of Vibrio cholerae, because these organisms can survive 2 to 5 days in Sodium Selenite Broth. Sodium hydrogen selenite (Sodium biselenite) is very toxic, corrosive agent and causes teratogenicity.