A 25-year-old patient reports pain, burning at urination and scarce secretion in the morning. Urine samples are taken and cultivated on blood and MacConkey agar. After 24 hours of incubation, the culture are sterile. Which one of the following bacteria is the most probable cause of this disease?

Correct Answer: B

Rationale: The correct answer is B: Chlamydia trachomatis. This is because Chlamydia trachomatis is an obligate intracellular bacterium that cannot be cultured on standard agar plates. The symptoms described by the patient, such as pain, burning at urination, and scarce secretion in the morning, are indicative of a possible chlamydial infection. Additionally, the fact that the urine cultures are sterile after 24 hours of incubation suggests that the causative agent is not a typical bacteria like Escherichia coli, Streptococcus pneumoniae, or Neisseria gonorrhoeae, which would normally grow on agar plates. Therefore, Chlamydia trachomatis is the most probable cause of this disease. Summary: A: Escherichia coli - Incorrect, as it is a common cause of urinary tract infections and would typically grow on agar plates. C: Streptococcus pneumoniae - Incorrect, as it is

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.

Correct Answer: B

Rationale: The correct answer is B: Simpler. Prokaryotic cytoplasm is simpler than eukaryotic cytoplasm because prokaryotic cells lack membrane-bound organelles such as a nucleus, mitochondria, and endoplasmic reticulum that are present in eukaryotic cells. Prokaryotic cytoplasm contains fewer components and structures compared to eukaryotic cytoplasm, making it less complex. Therefore, the prokaryotic cytoplasm is simpler in structure. Choices A, C, and D are incorrect because prokaryotic cytoplasm is not more complex than eukaryotic cytoplasm, there is a clear difference in structure between prokaryotic and eukaryotic cytoplasm, and the statement "None of the above" is not accurate as the correct answer is B.