Question

8. An isolate of Streptococcus found to be sensitive to O positive for bile solubility test is likely ptochin after incubation on blood agar plate and A. B. Streptococcus pyogenes C. Viridans Streptococcus D. Streptococcus pneumoniae E. Group D enteric Streptococcus treptococcus 9. Which of these test reactions will produce alkaline end products? A. Nitrate reduction and Oxidase tests B. Amylase activity and Lipase activity tests C. Methyl red and Voges Proskauer tests D. Citrate Utilization and Urease tests E. Catalase activity and Lactose fermentation tests 10. The gas released and observed as bubbles when testing for Catalase activity is A. Hydrogen B. Carbon dioxide C. Oxygen D. Nitrogen E. Hydrogen Sulfide 11. Propionibacterium acnes is a normal flora in human skin and depends on skin lipids as a source of nutrients Which of the following enzymes would you expect the bacteria to test positive for? A. Lipase activity B. Amylase activity C. Urease activity D. Oxidase activity E. None of the above 12. A Staphylococcal isolate found to be positive for mannitol fermentation is likely to be A. S aureus B. s. epidermidis C. S saprophyticus D. Either A or C E. Either A or B 13. In the Voges-Proskauer test, the neutral acetoin reacts with Barrit's reagent A &B which consist of A. sulfanilic acid and KOH B. zinc and KOH C. alpha naphtol and KOH D. ferric chloride and KOH E. None of the above is correct 14. Which of the following is true for the IMViC tests? between Escherichia coli and Enterohacter aeregns stand for Indole, Methyl red, Voges Proskauer and Citrate utilzation tests The tests are very useful in differentiating B. C. The D. All the above are correct E. Only (a) and (b) are correet tests can be used to determine motility in microorganisms

Answer 1

Ans-8 ( D) streptococcus pnuemoniae

Optochin (Opt) susceptibility is used largely for the identification of Streptococcus pneumoniae in diagnostic laboratories. Opt-resistant (Opt^r) S. pneumoniae isolates have been reported, however, indicating the potential for misidentification of this important pathogen. Point mutations in the atpC gene have been associated with the emergence of Opt^rS. pneumoniae.

Streptococcus pneumoniae is

1. Alpha hemolysis
2. Bile Soluble
3. Optochin Sensitive

Ans-9 ( D ) Citerate utilization and urease test

Procedure of citrate utilization test:

1. Inoculate Simmons citrate agar lightly on the slant by touching the tip of a needle to a colony that is 18 to 24 hours old.
2. Incubate at 35^oC to 37^oC for 18 to 24 hours. Some organisms may require up to 7 days of incubation due to their limited rate of growth on citrate medium.
3. Observe the development of blue color; denoting alkalinization.

Ans-10 ( C) Oxygen

The catalase test for the presence of catalase, an enzyme that breaks down the harmful substance hydrogen peroxide into water and oxygen. If an organism can produce catalase, it will produce bubbles of oxygen when hydrogen peroxide is added to it.

Ans-12 ( A) S.aureus

Mannitol Salt Agar (MSA) is used as a selective and differential medium for the isolation and identification of Staphylococcus aureus from clinical and non-clinical specimens. It encourages the growth of a group of certain bacteria while inhibiting the growth of others.

Ans- 13 ( C) Alpha napthol and KOH

Voges–Proskauer   is a test used to detect acetoin in a bacterial broth culture. The test is performed by adding alpha-naphthol and potassium hydroxide to the Voges-Proskauer broth which has been inoculated with bacteria. A cherry red color indicates a positive result, while a yellow-brown color indicates a negative result.

Ans-14