Several patients with similar complaints came to the doctor. They all present with weakness, pain in the intestines, indigestion. Feces analysis revealed the need for urgent hospitalization of the patient, who had microbial cysts with four nuclei detected in his samples. Such cysts are characteristic of the following protozoon:

Correct Answer: A

Rationale: The correct answer is A: Entamoeba histolytica. This protozoon is known to cause amoebic dysentery, presenting symptoms of weakness, intestinal pain, and indigestion. The presence of microbial cysts with four nuclei in fecal samples is characteristic of Entamoeba histolytica. These cysts are the infective form of the parasite and can cause severe invasive disease in the intestines. Incorrect choices: B: Entamoeba coli does not typically cause invasive disease or severe symptoms like those described in the question. C: Balantidium is a ciliated protozoan that causes balantidiasis, which presents differently from the symptoms described in the question. D: Trichomonad is a flagellated protozoan that typically infects the urogenital tract, not the intestine, and does not form cysts with four nuclei. In summary, the key clues in the question were the symptoms of weakness, intestinal pain,

Correct Answer: D

Rationale: The correct answer is D because the flu vaccine mainly stimulates systemic immunity, not local immunity. Systemic immunity refers to the immune response throughout the body, while local immunity is specific to a certain area. Choice A is incorrect because the flu vaccine is indeed recommended. Choice B is incorrect as the flu vaccine can be a subunit vaccine, containing only specific antigens. Choice C is incorrect as the flu vaccine is typically administered parenterally, meaning through injection, nasal spray, or oral routes.

Correct Answer: D

Rationale: The correct answer is D because all of these symptoms are early signs of rabies. A short period of depression, nausea, and restlessness are common initial symptoms of rabies infection. These symptoms may be followed by more severe manifestations, such as aggression, confusion, and difficulty swallowing. Therefore, option D is the correct choice as it encompasses all the early symptoms of rabies. Options A, B, and C are incorrect as they focus on individual symptoms, whereas rabies typically presents with a combination of these early signs.

Correct Answer: C

Rationale: The correct answer is C: tapeworms. Taeniasis is specifically caused by tapeworms of the Taenia species, such as Taenia solium. These parasitic worms infect the intestines of humans through consumption of contaminated food or water. Ringworms (choice A), hookworms (choice B), and pinworms (choice D) are all different types of parasites that cause distinct infections in the body, not taeniasis. Tapeworms are the only organisms among the choices that are directly associated with taeniasis due to their unique life cycle and mode of infection.

Correct Answer: B

Rationale: The correct answer is B: Spirochete. Lyme disease is caused by the bacterium Borrelia burgdorferi, which is a spirochete. Spirochetes are spiral-shaped bacteria that move by rotating like a corkscrew, which is characteristic of Borrelia burgdorferi. A: Spirillum - Spirillum bacteria are helical-shaped but are not the causative agent for Lyme disease. C: Vibrio - Vibrio bacteria are curved or comma-shaped and are not associated with Lyme disease. D: Diplococcus - Diplococcus bacteria are spherical-shaped and typically occur in pairs, not the causative agent for Lyme disease. Therefore, the correct answer is B because Borrelia burgdorferi is a spirochete bacterium that causes Lyme disease.

Correct Answer: B

Rationale: The correct answer is B: Thermophiles. Thermophiles are bacteria that can survive in extreme temperatures, typically between 45°C to 80°C. This ability is due to their unique enzymes and cell membrane structures that are adapted to high temperatures. Escherichia coli (A) is a common bacterium found in the human gut and does not thrive in extreme temperatures. Clostridium tetani (C) is a bacterium that causes tetanus and prefers moderate temperatures. Salmonella enterica (D) is a pathogenic bacterium that does not thrive in extreme temperatures. Therefore, Thermophiles are the only bacteria on the list known for surviving in extreme temperatures.

Correct Answer: A

Rationale: The correct answer is A: Bacterial ribosomes synthesize proteins. Ribosomes are cellular organelles responsible for protein synthesis by translating mRNA into amino acids. They are essential for the production of proteins needed for cell function. Choices B, C, and D are incorrect because ribosomes do not synthesize DNA, degrade toxic substances, or assist in cell division. DNA synthesis is carried out by DNA polymerase, degradation of toxic substances is typically done by enzymes, and cell division is primarily regulated by the cell cycle machinery.

Correct Answer: D

Rationale: The correct answer is D: decimal reduction time. This term represents the time required at a specific temperature to kill 90% of a bacterial population. It is a key parameter in microbiology to determine the effectiveness of a given heat treatment. Generation time (A) refers to the time it takes for a population to double in size. Thermal death time (B) is the shortest time needed to kill all organisms at a specific temperature. Sterilization time (C) is a general term and does not specifically refer to the time required to kill 90% of the population.

Correct Answer: A

Rationale: The correct answer is A: Wasserman test, IFT. The patient's symptoms of diffuse alopecia and Pinkus' sign are suggestive of secondary syphilis. The Wasserman test and Immunofluorescence Test (IFT) are used to detect antibodies against Treponema pallidum, the bacterium causing syphilis. This would confirm or rule out syphilis as the underlying cause of the patient's symptoms. Choice B (T.pallidum Immobilization Test) is similar to the Wasserman test but less commonly used. Choice C (Detection of the nasal mucous membrane for M.leprae) is irrelevant as leprosy does not present with the described symptoms. Choice D (Consultation of neuropathist) is premature without ruling out syphilis first. Thus, the Wasserman test, IFT should be the initial examination to investigate the likely cause of the patient's symptoms.