How do you differentiate and identify the family of Enterobacteriaceae characteristics?
Members of the family Enterobacteriaceae have the following characteristics: They are gram-negative rods, either motile with peritrichous flagella or nonmotile; grow on peptone or meat extract media without the addition of sodium chloride or other supplements; grow well on MacConkey agar; grow aerobically and …
How do you identify Enterobacteriaceae?
Members of the Enterobacteriaceae family are identified based on their biochemical properties….Tests for identification of members of Enterobacteriaceae family
- Citrate utilization Test.
- Indole Test.
- Motility Test.
- Methyl Red (MR) Test.
- Voges–Proskauer (VP) Test.
- Triple Sugar Iron (TSI) Agar Test.
- Urease Test.
Can Enterobacter ferment lactose?
Lactose usually is fermented rapidly by Escherichia, Klebsiella and some Enterobacter species and more slowly by Citrobacter and some Serratia species.
What are the biochemical tests which used to identify Enterobacteriaceae?
Biochemical tests, for example Beta-glucoronidase test, citrate utilization test, urease test, indole test, are the basic tests used for Enterobacteriaceae identification in Nigerian hospitals (Cheesebrough, 2000).
Which pathogenic species are lactose fermenters that will grow on MacConkey agar?
What are some potentially pathogenic bacteria that are lactose fermenters that will grow on MacConkey agar? Some potentially pathogenic bacteria that are lactose fermenters include: E. Coli, Citrobacter, and Klebsiella.
Why is it important to identify Enterobacteriaceae?
Some members of the Enterobacteriaceae have had a large impact on infectious diseases, clinical microbiology and public health. They are involved in diarrhoeal diseases and recognised as one of the major bacterial food-borne pathogens.
Which characteristic s are used to distinguish members of the Enterobacteriaceae from one another?
virtually all Enterobacteriaceae perform a one-step reduction of nitrate to nitrite. The nitrate test differentiates them from Gram-negative rods that either do not reduce nitrate or reduce it beyond nitrite to N2 or other compounds.
What are the lactose fermenting bacteria?
Lactose fermenting species will grow pink colonies. Lactose fermentation will produce acidic byproducts that lower the pH, and this turns the pH indicator to pink. Example of Lac positive species: Escherichia coli, Enterobacteria, Klebsiella.
What test is used for lactose fermentation?
MacConkey agar is commonly used to differentiate between the Enterobacteriaceae. Organism on left is positive for lactose fermentation and that on the right is negative.
How do you test for lactose fermentation?
How is the test performed? An inoculum from a pure culture is transferred aseptically to a sterile tube of phenol red lactose broth. The inoculated tube is incubated at 35-37 C for 24 hours and the results are determined. A positive test consists of a color change from red to yellow, indicating a pH change to acidic.
What are some potentially pathogenic bacteria that grow on MacConkey agar and do not ferment lactose?
Colonies that do not change the pH of media: Salmonella, Proteus species, Yersinia, Pseudomonas aeruginosa, and Shigella are examples of this group. These bacteria do not ferment lactose; hence neutral red does not change to pink.
How does MacConkey agar indicate lactose fermentation?
Based on the ability to ferment lactose, different species will yield colonies in varying appearance on a MacConkey medium. This gives McConkey agar its differentiating property. Lactose (Lac) positive (pink colonies): Lactose fermenting species will grow pink colonies.
How to identify members of Enterobacteriaceae family?
Tests for identification of members of Enterobacteriaceae family 1 Citrate utilization Test 2 Indole Test 3 Motility Test 4 Methyl Red (MR) Test 5 Voges–Proskauer (VP) Test 6 Triple Sugar Iron (TSI) Agar Test 7 Urease Test
What is the common antigen of Enterobacteriaceae?
Cell contains a characteristic antigen, called the enterobacterial common antigen. Members of the Enterobacteriaceae family are identified based on their biochemical properties. Commonly used biochemical tests to identify them are (Please click on the test name to know more about that particular test);
Which characteristic distinguishes enteric bacteria from obligately aerobic bacteria?
Usually reduces Nitrate to Nitrite ( distinguishes enteric bacteria from bacteria that reduce nitrate to Nitrogen gas, such as Pseudomonas and many other oxidase-positive bacteria). Produces acid from glucose; ability to ferment lactose- distinguishes enteric from obligately aerobic bacteria.
What is biochemocal test for Enterobacteria?
Biochemocal testsare used to identify species of enterobacteria, usually by means of test kits based on 10 or 20 biochemical tests. Enterobacteria ferment glucose with or without formation of gas, reduce nitrates into nitrites, catalase positive, oxidase negative.