The most common bacterial nonsexually transmitted infection of the male reproductive system is:

Correct Answer: B

Rationale: The correct answer is B: prostatitis. Prostatitis is the most common bacterial infection affecting the male reproductive system. It is characterized by inflammation of the prostate gland due to bacterial infection. Symptoms include pain in the pelvic area, difficulty urinating, and fever. Cystitis (A) is a bladder infection, not specific to the male reproductive system. Mastitis (C) is inflammation of the breast tissue, which is not related to the male reproductive system. Nephritis (D) is inflammation of the kidneys, which is also not specific to the male reproductive system.

Correct Answer: A

Rationale: The correct answer is A: Yersinia pestis. Y. pestis is the causative agent of plague, characterized by fever, enlarged lymph nodes, and bacteremia. The bipolar-staining, Gram-negative rods seen on Gram stain are typical of Y. pestis. Incorrect choices: B: Francisella tularensis causes tularemia, not plague. C: Brucella abortus causes brucellosis, not plague. D: Clostridium botulinum causes botulism, not plague. In summary, the key features of the patient's presentation and the Gram stain findings align with Yersinia pestis as the correct causative agent of plague.

Correct Answer: B

Rationale: The correct answer is B: It causes epidemic meningitis. Neisseria Meningitidis is a bacterium that can cause meningitis, an infection of the protective membranes covering the brain and spinal cord. This bacterium is known to cause outbreaks or epidemics of meningitis, especially in crowded or close-contact settings. The other choices are incorrect because: A: Neisseria Meningitidis does have a capsule, which helps it evade the immune system. C: Neisseria Meningitidis grows on selective media like Thayer-Martin agar, not differential media. D: Neisseria Meningitidis is a Gram-negative diplococcus, not a Gram-positive rod.

Correct Answer: A

Rationale: The correct answer is A. Rubella virus has icosahedral type of symmetry due to its spherical shape with 20 faces. This symmetry allows for efficient packaging of genetic material and structural stability. Choice B is incorrect as rubella virus is an ssRNA virus, not ssDNA. Choice C is incorrect as rubella virus does have an envelope derived from the host cell membrane. Choice D is incorrect as rubella virus does have glycoprotein spikes on its surface that aid in host cell recognition and entry.

Correct Answer: B

Rationale: The correct answer is B: homeostasis. Homeostasis refers to the process by which living organisms maintain a stable internal environment despite external changes. It involves various biological processes and mechanisms that regulate factors such as temperature, pH, and nutrient levels within narrow limits. This is crucial for the proper functioning of cells, tissues, and organs. Now, let's analyze the other choices: A: Infection - Infection refers to the invasion and multiplication of harmful microorganisms in the body, leading to illnesses. It is not the correct answer as it does not encompass the overall maintenance of internal conditions. C: Immunity - Immunity is the body's ability to resist and fight off infections. While immunity is related to defense against foreign agents, it does not fully capture the concept of maintaining internal stability. D: Commensalism - Commensalism is a type of symbiotic relationship between different species where one benefits without harming the other. It is not related to the overall regulation of

Correct Answer: A

Rationale: The correct answer is A: Tetanus. Tetanus is caused by the bacterium Clostridium tetani, which produces a toxin affecting the nervous system. Symptoms such as malaise, irritability, muscular twitching, and high body temperature are characteristic of tetanus due to muscle spasms and rigidity. The 15-day incubation period after trauma aligns with the typical onset of tetanus symptoms. Incorrect choices: B: Anaerobic gas gangrene - This condition usually presents with localized tissue necrosis and gas bubbles in the affected area, not systemic symptoms like malaise and headache. C: Erysipelas - This is a bacterial skin infection presenting with red, swollen patches, not the neurological symptoms seen in tetanus. D: Acute thrombophlebitis - This is a blood clot in a vein causing pain and swelling, not associated with the systemic symptoms and muscle twitching seen in tetanus.

Correct Answer: A

Rationale: The correct answer is A: Streptomycin. Streptomycin is an aminoglycoside antibiotic used to treat tuberculosis that can cause hearing loss as a side effect. It is known to damage the cochlear and vestibular organs in the inner ear. The other choices, B: Isoniazid, C: Rifampicin, and D: Ethionamide, are not associated with causing hearing deterioration as a side effect. Isoniazid can rarely cause peripheral neuropathy, Rifampicin can lead to hepatotoxicity, and Ethionamide may cause gastrointestinal disturbances, but none of these drugs are known to specifically cause hearing loss.

Correct Answer: B

Rationale: The correct answer is B: Clostridium tetani. Endospores are formed by certain bacteria as a survival mechanism in harsh conditions. Clostridium species, including C. tetani, have the ability to form endospores. Staphylococcus aureus (A), Neisseria gonorrhoeae (C), and Escherichia coli (D) do not produce endospores. Staphylococcus aureus is a gram-positive cocci bacterium, Neisseria gonorrhoeae is a gram-negative diplococci bacterium, and Escherichia coli is a gram-negative rod-shaped bacterium. Therefore, the correct choice is Clostridium tetani as it is known for its ability to form endospores.

Correct Answer: A

Rationale: The correct answer is A: Entamoeba histolytica. This is because it is a protozoan parasite known to cause amoebic dysentery, presenting with chronic diarrhea and cysts with four nuclei in the stool sample. Giardia lamblia (B) causes giardiasis with trophozoites and cysts with two nuclei. Balantidium coli (C) is a ciliated parasite causing dysentery with large trophozoites. Trichomonas hominis (D) is a non-pathogenic flagellate often found in the human intestine. Thus, based on the specific characteristics of the cysts and clinical presentation, Entamoeba histolytica is the most likely causative agent.