Patients after splenectomy are of high risk of infections caused by:

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.

Correct Answer: B

Rationale: The correct answer is B: biofilms. Biofilms refer to complex communities of microorganisms that adhere to surfaces. They are characterized by a protective matrix that allows the microorganisms to communicate and cooperate. Colonies (A) typically refer to groups of a single species, not diverse communities. Biospheres (C) refer to the regions of the Earth where life exists, not specific microbial communities. Flora (D) generally refers to the plant life in a particular region, not microbial communities on surfaces.

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.

Correct Answer: A

Rationale: Rheumatic fever is caused by untreated strep throat. Step 1: Strep throat is caused by Streptococcus bacteria. Step 2: If strep throat is not treated with antibiotics, it may lead to rheumatic fever due to the body's immune response attacking its own tissues. Summary: Gangrene, brucellosis, and tularemia are not associated with rheumatic fever.

Correct Answer: A

Rationale: The correct answer is A: Clostridium tetani. This bacterium is known for causing tetanus due to its ability to produce tetanospasmin, a neurotoxin that leads to the characteristic muscle stiffness and spasms seen in tetanus. Clostridium perfringens (Choice B) is associated with gas gangrene, Streptococcus pyogenes (Choice C) causes streptococcal infections, and Escherichia coli (Choice D) is known for causing various gastrointestinal infections. Therefore, Choices B, C, and D are incorrect as they are not the causative agents of tetanus.

Correct Answer: A

Rationale: The correct answer is A: Pseudomonas aeruginosa. P. aeruginosa is a Gram-negative rod that is oxidase-positive and lactose non-fermenting. The positive oxidase test indicates the presence of cytochrome c oxidase, a characteristic of P. aerugin. E. coli is lactose fermenting. Salmonella and Shigella are also Gram-negative rods, but they are lactose fermenters, unlike the lactose non-fermenting P. aeruginosa.

Correct Answer: B

Rationale: During latency, HSV1 exists as episomes in neurons. This is because HSV1 establishes a lifelong latent infection in sensory neurons, where the viral genome remains as a circular episome in the nucleus. This form allows the virus to persist in a dormant state, avoiding detection by the immune system. Choice A is incorrect as HSV1 does not integrate into the host chromosome. Choice C is incorrect as latency is a well-documented phenomenon for HSV1. Choice D is incorrect as the correct answer is B.

Correct Answer: B

Rationale: The correct answer is B: protein filaments made of flagellin. Bacterial flagella are composed of flagellin proteins arranged in helical filaments. This structure allows for movement and propulsion of bacteria. A: 9+2 microtubule arrangement is incorrect because this structure is typically found in eukaryotic flagella, not bacterial flagella. C: Lipid bilayer is incorrect as it is a structural component of cell membranes, not bacterial flagella. D: Peptidoglycan layer is incorrect as it is a component of bacterial cell walls, not flagella.

Correct Answer: A

Rationale: The most likely diagnosis is Epidemic typhus (Choice A) based on the symptoms described. The presence of roseolous-petechial rash, high fever (41oC), hyperemia of face, reddening of scleras, tremor of the tongue, tachycardia, and splenomegaly are classic signs of epidemic typhus. The rash typically appears around the 5th day of the disease. Summary: - B: Measles typically presents with a maculopapular rash starting on the face and spreading downward. It doesn't usually present with tremor of the tongue or splenomegaly. - C: Alcohol delirium is characterized by confusion, disorientation, and hallucinations due to alcohol consumption. It doesn't match the symptoms described. - D: Leptospirosis presents with fever, muscle pain, and conjunctival suffusion. It doesn't typically present with the specific rash and trem