• A Rapid, Simple and Economic Method for Differentiating the Enterobacteriaceae
  • Advanced System for efficient identification of 27 Enterobacteriaceae
  • The media tube contains two layers and a paper cap for indol determination.
  • No need of extra material, lactose free and flexibility to perform other test
is a large family of Gram-negative, catalase positive and oxidase negative. They are distributed worldwide and may be found in soil, water, plants and animals. Most species grow well at 37C, although some species grow better at 25-30C. There is a large number of species included in the family, more than 170, but the clinical and more important specimens which play a major role as infectious agents, belong to 20 to 25 species that are well known for many years. The identification of the members of Enterobacteriaceae is complicated and has been traditionally based on biochemical and antigenic characteristics. Hy-Enterotest, is a method well known by microbiologists worldwide, stabbing the butt and smearing a slant, for biochemical reactions performed in a simple tube as well as bacteria growth motility for further investigations.

The media tube contains:
  • Upper layer (3 ml): a butt and a slant with dextrose, ONPG, enrichments, ferrous sulphate, sodium thiosulfate, agar and phenol-red.
  •  Lower layer (2 ml): semi-solid media, containing urea, enrichments, sodium chloride, agar and phenol-red.
  • Paper cap for indol determination

Hy-Enterotest system, containing special culture media that permits identification of the Enterobacteriaceae. The test allows simultaneous inoculation of media present in the HY Enterotest system for the execution of different biochemical reactions. After 18-24 hours incubation, microorganism is identified on the basis of colour as per positive or negative biochemical reaction. e.g. glucose fermentation (+ve: yellow; -ve: red) etc. Hy-Enterotest gives following essential tests as shown in observation table
S.No. Test Principle of the test Observation
1 Indol Test Bacteria with positive indol test, produce Tryptophanase which breaks down tryptophan and release indol which forms red colour complex with Kovac’s or Ehrlich’s  reagent Positive-Purple-pink
2 ONPG Hydrolysis β-galactosidase  and permease producing bacteria lead breakdown of colourless ONPG by β-galactosidase and release yellow colour compound O-nitrophenol Positive- Orange
Negative- Cherry-Pink
3 Glucose fermentation (acidity without gas) Glucose fermentative bacteria, results in acid production which changes pH of media. Due to this, Bromocresol present in media turns yellow Positive- Yellow
Negative- No Change
4 Glucose fermentation with CO2 gas formation Gas produced during fermentation can be seen in Durham Tube in the form of bubble Positive- Bubble
Negative-No Bubble
5 H2S Production Bacteria reduces ferrous Sulphate to Sulphur and produce black colour due to H2S formation Positive-Black
6 Motility The growth of testing bacteria going out away from the stab line or spread throughout the media Positive- Fuzzy
Negative- Clear
7 Urea Urease producing bacteria, result in breakdown of urea and release of ammonia which produces alkalinity in medium production of pink colour in medium Positive- Pink
Negative- Yellow
8 Bacterial Growth Bacterial growth for further biochemical and serological tests

Kovac’s: 4 (p)-dimethylamino benzaldehyde; ONPG: O-Nitrophenyl-β-D-galactopyranoside

  • To perform test, pickup Hy-Enterotest sytem and using the tip of inoculating needle, placed under the cap, pick up a well isolated colony from agar medium.
  • Attach indole strip to the cap.
  • Replace cap lightly to allow free passage of gas
  • Incubate at 37C for 18-24 hours.
  • Read results and compare to chart provided
Click here to watch video- How to use Hy-Enterotest       

After incubation, observe the change in colour of culture media in the different sectors of Hy-Enterotest system and interpret results with the help of provided table in kit. If there is no change in colour in the sector Glucose/Gas while in some other sectors there are chromatic changes, the microorganism under test does not belong to the family of Enterobacteriaceae. Record the observed results on the data sheet/table with the help of provided chart

HY-ENTEROTEST-Bacteria Identification
1. Salmonella paratyphi A. 15. Yersinia pseudotuberculosis.
2. Salmonella  typhi. 16. Serratia marcescens.
3. Salmonella  choleraesius. 17. Serratia  liquefaciens.
4. Salmonella most serotypes. 18. Serratia  rubidaea.
5. Shigella sonnei. 19. Providencia alkalifaciens.
6. Shigella  O groups, A, B,C. 20. Providencia  rettgeri.
7. Klebsella pneumoniae. 21. Providencia stuartii.
8. Klebsella oxytoca. 22. Proteus mirabilis.
9. Enterobacter cloacae. 23. Proteus  vulgaris.
10. Enterobacter agglomeranns. 24. Morganella (morganii).
11. Enterobacter aerogenes. 25. Hafnia (alvei).
12. Citrobacter freundii. 26. Escherichia (coli).
13. Citrobacter diversus. 27. Edwarsiella (tarda).
14. Yersinia enterocolitica