Correct Answer: A

Rationale: The correct answer is A: Lowestein-Jensen. This is because Lowestein-Jensen medium is specifically designed to cultivate Mycobacterium tuberculosis, providing necessary nutrients and conditions for its growth. Loefller's medium is not optimal for cultivating M. tuberculosis.
Choice C (All of the above) is incorrect as not all the options listed are suitable for cultivating M. tuberculosis.
Choice D (None of the above) is also incorrect as Lowestein-Jensen is indeed the recommended growth medium for this bacterium.

Correct Answer: C

Rationale: The correct answer is C: Escherichia coli. E. coli is the most common cause of acute cystitis. It typically presents with leukocytes and gram-negative bacilli in the urine. The green pigment production indicates pyocyanin, which is a characteristic of E. coli. Pseudomonas aeruginosa (
A) can also produce green pigment, but it is less common in urinary tract infections. Proteus mirabilis (
B) is associated with a swarming motility pattern on agar, not mucous colonies. Klebsiella pneumoniae (
D) is associated with pneumonia and other respiratory infections, not cystitis.

Correct Answer: A

Rationale: The correct answer is A: Escherichia coli.
Step-by-step rationale:
1. Gram-negative rods: E. coli is a Gram-negative rod bacterium.
2. Fermented lactose: E. coli is known to ferment lactose.
3. Common cause of diarrhea: E. coli is a common causative agent of infectious diarrhea.
Summary:
B: Salmonella typhi causes typhoid fever, not typically associated with lactose fermentation.
C: Shigella dysenteriae causes dysentery, not known for lactose fermentation.
D: Proteus vulgaris is not a common cause of infectious diarrhea and does not typically ferment lactose.

Correct Answer: B

Rationale: The correct answer is B: Bacillus subtilis. Bacillus subtilis is a Gram-positive bacterium known for forming endospores, which are resistant structures that allow the bacteria to survive harsh conditions like heat, radiation, and desiccation. This ability to form spores helps Bacillus subtilis to endure unfavorable environments. Staphylococcus aureus (
A), Pseudomonas aeruginosa (
C), and Neisseria gonorrhoeae (
D) do not form spores and lack the same level of resistance to extreme conditions as Bacillus subtilis.

Correct Answer: D

Rationale: The correct answer is D because during the incubation period of Salmonella Typhi infection, the bacteria multiply in the macrophages of the Peyer's patches and solitary follicles. This is supported by the fact that S. Typhi is an intracellular pathogen that targets the lymphoid tissues of the intestines. Macrophages in these areas serve as the primary host cells for the bacteria, allowing for their replication and evasion of the host immune response.

Choices A, B, and C are incorrect because S. Typhi does not primarily multiply in the small intestine enterocytes, the lumen of the small intestine, or hepatocytes during the initial stages of infection.