What\'s the purpose of this lab and the observation and conclusion? AB 25: IDENT

Question

What's the purpose of this lab and the observation and conclusion?
AB 25: IDENTIFICATION oF GRAM-NEGATIVE INTESTINAL PATHOGENS A. Introduction The most important Gram-negative intestinal pathogens are salmonella and shigella and typhoid pathogens cause enteric fever, food poisoning, dysentery, l. fever (due to Salmonella medical concerns 3. There are 11 species of salmonella and 4 species of la to be prime laboratories 4. Routine testing for these pathogens is being done at various public health also contain a large 5. Isolation and identification of these pathogens are complicated since the intestines 6. variety of bacteria, such as Escherichia, Proteus, Enterobacter, Pseudomonas, and still observed Although the cultures used in this lab are nonpathogenic, universal precautions should be Do not use orang B. Procedure 1. This lab is done in a group of 2-3 students Shigella), a 2. Each group should obtain an unknown culture (a mixed culture of Proteus, Salmonella, and a-shigella) 3. Follow aseptic procedure and streak a loopful of mixed culture onto each plate with a quadrant streak 4. Write your name on the plates, and place them in the designated racks inverted for incubation 5. In the second lab period, recover your DCA and ss plates Compare the amount of growth on the plates, and select the one with better growth 1. From the selected agar plate, transfer (using a sterile inoculating wire the culture into 3 RDS slants (Russell double sugar) on the tubes, and place them in the designated rack for incubation Write your name 9. In the third lab period, recover your 3 RDS slants 10. Observe color changes in the slants a) if the slant remains red, there is no glucose or lactose fermentation b) if the slant turns yellow at the bottom, there is glucose fermentation c) if the slant turns yellow entirely, there is glucose and lactose fermentation 11. Discard the red and yellow slants, and save only the halfyellow slant (glucose fermented) 12. Follow aseptic procedure and transfer from the glucose-fermented slant into 2 special media urea broth and semisolid medium (stab at least half way deep) 13. Write your name on the tubes, and place them in the designated rack for incubation 14. In the fourth lab period, recover your 2 tubes 15. Observe color change in urea broth bright red is 16 Also observe motility in semisolid medium branches extending out of stab line indicates 17. After collecting all the data, determine which genus of Gram- intestinal pathogens is present in each tube a the pink RDS slant from the third lab period contained Pseudomonas b) nonmotile result indicates the presence of Shigella c) urease result indicates the presence of Proteus d) urease result indicates the presence of Salmonella

Explanation / Answer

The purpose of this experiment was to identify the gram negative pathogens which are found in the intestine region and are responsible for the various diseases. The main aim was to identify the type of bacteria from the unknown culture provided for the experiment.

Once the unknown culture is grown on different sets of media, after the incubation period the plates are observed carefully. In the RDS slants if yellow color is observed it means fermentation of glucose and lactose has occurred. E.coli is responsible for the fermentation of sugars. Hence the unknown culture has E. Coli in it. If the RDS shows pink Color then pseudomonas sp. is present in the culture. If urease formed proteus and if not salmonella is present in the culture.

The conclusion of this experiment will be the unknown bacteria in the culture will be identified.

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