Nokea
Streptococcus pneumoniae are:
- A. Resistant to bile
- B. Alpha-hemolytic streptococci
- C. Are stained by the Ziehl-Neelsen staining method
- D. Resistant to optochin
Correct Answer: B
Rationale: The correct answer is B: Alpha-hemolytic streptococci. Streptococcus pneumoniae are classified as alpha-hemolytic streptococci based on their ability to partially break down red blood cells, causing a greenish discoloration on blood agar plates. This distinguishes them from beta-hemolytic streptococci, which completely break down red blood cells. Streptococcus pneumoniae are not resistant to bile (choice A), as they are bile soluble. They are not stained by the Ziehl-Neelsen staining method (choice C), which is used for acid-fast bacteria such as Mycobacterium tuberculosis. They are sensitive to optochin (choice D), which is a key differentiating factor in identifying them from other alpha-hemolytic streptococci.
You may also like to solve these questions
Which of the following is commonly referred to as a pinworm?
- A. protozoans
- B. algae
- C. helminths
- D. fungi
Correct Answer: A
Rationale: The correct answer is A: protozoans. Pinworms are commonly referred to as Enterobius vermicularis, which are parasitic worms belonging to the phylum Nematoda. Protozoans are single-celled organisms, and pinworms are multicellular worms. Algae are photosynthetic organisms, helminths are parasitic worms (which pinworms fall under), and fungi are eukaryotic organisms that include molds and yeasts. Therefore, protozoans are the correct choice for organisms commonly referred to as pinworms.
A 3 month old infant has got a white deposition on the mucous membrane of his mouth, tongue and lips. The doctor suspected candidosis. What nutrient medium should be used for inoculation of the material under examination in order to confirm this diagnosis?
- A. Sabouraud
- B. Endo
- C. Loewenstein-Jensen
- D. Roux
Correct Answer: A
Rationale: The correct answer is A: Sabouraud. Sabouraud agar is specifically designed for the cultivation of fungi and yeasts, making it ideal for identifying Candida species causing candidosis. It contains antibiotics to inhibit bacterial growth, promoting the growth of fungi. Endo, Loewenstein-Jensen, and Roux are not suitable for fungal cultures and are used for different purposes like bacterial isolation or mycobacterial cultures. Sabouraud agar is the best choice for confirming candidosis due to its fungal-selective properties.
A fecal sample from a patient with diarrhea was cultured on Endo agar, resulting in colorless colonies. The bacteria were Gram-negative rods. What microorganism is most likely?
- A. Salmonella
- B. Shigella
- C. Escherichia coli
- D. Proteus
Correct Answer: B
Rationale: The correct answer is B: Shigella. On Endo agar, Shigella appears as colorless colonies due to its inability to ferment lactose. Shigella is a Gram-negative rod and is a common cause of diarrhea. Salmonella (A) and Escherichia coli (C) would typically produce pink colonies on Endo agar as they can ferment lactose. Proteus (D) is not commonly associated with diarrhea and would not be expected to grow on Endo agar.
Patients after splenectomy are of high risk of infections caused by:
- A. Streptococcus pneumoniae
- B. Listeria monocytogenes
- C. Salmonella
- D. All are correct
Correct Answer: D
Rationale: Rationale: After a splenectomy, patients are at high risk of infections caused by encapsulated bacteria such as Streptococcus pneumoniae, Listeria monocytogenes, and Salmonella. The spleen plays a crucial role in the immune response against encapsulated bacteria, and its absence increases susceptibility to these specific pathogens. Therefore, all choices are correct as patients are at risk of infections from all three types of bacteria mentioned.
Which of the following bacteria is responsible for causing the disease known as pneumonia?
- A. Streptococcus pneumoniae
- B. Mycobacterium tuberculosis
- C. Escherichia coli
- D. All of the above
Correct Answer: D
Rationale: Rationale:
1. Streptococcus pneumoniae is a common cause of bacterial pneumonia.
2. Mycobacterium tuberculosis can cause a type of pneumonia called tuberculosis.
3. Escherichia coli is not typically associated with pneumonia.
4. "All of the above" includes both Streptococcus pneumoniae and Mycobacterium tuberculosis, which are known to cause pneumonia. Therefore, D is the correct answer.