During latency, HSV1 exists in what form:

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: Staphylococcus aureus. This bacterium is commonly found in hospital environments due to its ability to colonize human skin and mucous membranes. It is a leading cause of hospital-acquired infections. Borrelia burgdorferi is mainly associated with Lyme disease transmitted by ticks, not commonly found in hospitals. Bacillus cereus is a foodborne pathogen, not typically prevalent in hospital settings. Staphylococcus haemolyticus is a coagulase-negative staphylococcus species, less pathogenic and less common in hospitals compared to Staphylococcus aureus.

Correct Answer: D

Rationale: The correct answer is D because bacteremia can be caused by a variety of bacteria including S.epidermidis, E.coli, S.aureus, P.aeruginosa, K.pneumoniae, and resident skin diphtheroids. Bacteremia refers to the presence of bacteria in the bloodstream, which can occur due to infections from various sources. Choices A and B include common bacteria known to cause bacteremia, while choice C refers to resident skin diphtheroids that can also enter the bloodstream under certain conditions. Therefore, the correct answer is D as it encompasses all the possible etiological causes of bacteremia.

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.

Correct Answer: D

Rationale: The correct answer is D: Lassa virus. The rationale is as follows: 1. Lassa virus belongs to the family Arenaviridae, known for causing Lassa fever. 2. Rabies virus belongs to the Rhabdoviridae family. 3. Crimean-Congo hemorrhagic fever virus belongs to the Nairoviridae family. 4. Epstein-Barr virus belongs to the Herpesviridae family. In summary, Lassa virus is the correct answer because it is the only virus listed that belongs to the Arenaviridae family.