Why TCBS is used for Vibrio?
TCBS agar is both selective and differential. It is highly selective for Vibrio species and differential due to the presence of sucrose and the dyes. Sucrose fermentation produces acid, which converts the colour of bromothymol blue or thymol blue.
What is the selective agent in TCBS agar?
In BD TCBS Agar, yeast extract and peptone provide the nitrogen and vitamins. Sodium citrate, sodium thiosulfate, oxgall, and cholate are selective agents which provide an alkaline pH to inhibit gram-positive organisms and suppress coliforms.
Is TCBS differential media?
Thiosulfate-citrate-bile salts-sucrose (TCBS) Agar, is a type of selective agar that is used in microbiology laboratories to isolate Vibrio species. TCBS Agar is a selective differential medium for isolating and cultivating Vibrio cholerae and other Vibrio species from clinical specimens and other materials.
What is the morphology of Vibrio cholerae?
V cholerae is a comma-shaped, gram-negative aerobic or facultatively anaerobic bacillus that varies in size from 1-3 µm in length by 0.5-0.8 µm in diameter (see the image below). Its antigenic structure consists of a flagellar H antigen and a somatic O antigen.
What type of bacteria is Vibrio cholerae?
Vibrio cholerae is a species of Gram-negative, facultative anaerobe and comma-shaped bacteria. The bacteria naturally live in brackish or saltwater where they attach themselves easily to the chitin-containing shells of crabs, shrimps, and other shellfish.
Which group of Vibrio spp would have an appearance of yellow colonies in TCBS agar?
Vibrio cholerae (Cholera) After 24 hours of incubation at 37°C, V. cholerae colonies grown on TCBS agar are large (2–4 mm in diameter) and yellow with opaque centers and translucent edges.
Is Vibrio Gram positive or negative?
Vibrio are gram-negative bacteria that are naturally found in warm, salty marine environments, such as salt water and brackish water. More than 20 Vibrio species can cause the human illness vibriosis.
What is the shape and arrangement of Vibrio cholerae?
V. cholerae is described as a ‘comma-shaped’ bacterium. Unlike Escherichia coli and other bacilli, where the rod-shaped cell is described as a regular cylinder capped by two hemispheres, the V. cholera cell consists of a bent tubular shape capped by hemispheres.
What does Vibrio cholerae look like on TCBS?
Vibrio cholerae on TCBS. Colonies of V. cholerae on TCBS agar are large (2-4 mm) and yellow because of the fermentation of sucrose. TCBS agar is green when prepared. Overnight growth (18 to 24 hours) of V. cholerae will produce large (2 to 4 mm in diameter), slightly flattened, yellow colonies with opaque centers and translucent peripheries.
What is the typical colonial morphology of Vibrio on TCBS agar?
Typical colonial morphology on TCBS Agar are as follows: Due to nutritional variation, some strains may be encountered that grow poorly or fail to grow on this medium. Further tests are necessary for confirmation of Vibrio spp.
What are the different serotypes of Vibrio cholerae?
Serotypes of V. cholerae O1. Isolates of the O1 serogroup of V. choleraehave been further divided into three serotypes, Inaba, Ogawa, and Hikojima (very rare). Serotype identification is based on agglutination in antisera to type-specific O antigens (see Table VI-3).
How is Vibrio cholerae identified and treated?
The use of antisera is one of the most rapid and specific methods of identifying V. cholerae O1. Although identifying the serogroup and serotype of V. choleraeisolates is not necessary for treatment of cholera, this information may be of epidemiologic and public health importance (Table VI-2.) Laboratory Identification of Vibrio cholerae