A patient with suspected liver abscess was admitted to the surgical department. The patient had been staying for a long time on business in one of African countries and fell repeatedly ill with acute gastrointestinal disorders. What protozoal disease may the patient be now ill with?

Correct Answer: A

Rationale: Rationale: The correct answer is Amebiasis (choice A) because the patient's symptoms of acute gastrointestinal disorders and prolonged stay in an African country suggest exposure to Entamoeba histolytica, the causative agent of amebiasis. This protozoal infection commonly occurs in tropical regions, including Africa. Trypanosomosis (choice B) is caused by Trypanosoma species transmitted by tsetse flies, primarily found in sub-Saharan Africa. Leishmaniasis (choice C) is transmitted by sandflies and presents with skin lesions or visceral involvement, not acute gastrointestinal symptoms. Malaria (choice D) is caused by Plasmodium parasites transmitted by mosquitoes and typically presents with fever, not acute gastrointestinal disorders. Therefore, choices B, C, and D are incorrect based on the patient's clinical presentation and travel history.

Correct Answer: B

Rationale: The correct answer is B: Sexual transmission. The symptoms described are indicative of a vaginal yeast infection caused by Candida albicans. The presence of large gram-positive oval oblong cells forming pseudomycelium is characteristic of Candida infection. Sexual transmission is the most probable channel of infection as Candida can be transmitted through sexual contact. Endogenous infection (A) refers to infections originating from the body's own flora, which is not the case here. Contact infection (C) typically involves direct physical contact or fomite transmission, which is less likely in this scenario. Vector-borne transmission (D) involves transmission through vectors like mosquitoes or ticks, which is not relevant in this case.

Correct Answer: A

Rationale: The correct answer is A: Synthesize proteins. Bacterial ribosomes are responsible for translating mRNA into proteins through a process called translation. Ribosomes do not generate ATP (choice B), produce DNA (choice C), or synthesize lipids (choice D). These processes are carried out by other cellular components such as mitochondria for ATP production, DNA polymerase for DNA replication, and enzymes for lipid synthesis. The primary function of bacterial ribosomes is protein synthesis, making choice A the correct answer.

Correct Answer: A

Rationale: Step 1: Gram-negative bacillus indicates P. aeruginosa, known for causing wound infections. Step 2: Semi-transparent mucous colonies of blue-green color with a pearlescent appearance are characteristic of P. aeruginosa. Step 3: Specific odor of violets or jasmine is a unique feature of P. aeruginosa. Therefore, the correct answer is A: P. aeruginosa. Summary: - B: P. vulgaris typically forms yellow colonies and doesn't have the characteristic odor. - C: S. aureus forms creamy white colonies, not blue-green, and has a distinct odor. - D: S. pyogenes forms grayish-white colonies and doesn't have the unique characteristics described.

Correct Answer: D

Rationale: The correct answer is D: components of the gram-negative cell wall. Bacterial endotoxins are lipopolysaccharides found in the outer membrane of gram-negative bacteria. They are released upon bacterial cell lysis and can cause severe immune responses. A: Proteins in the cell wall - This is incorrect because endotoxins are not proteins but rather lipopolysaccharides. B: Secreted into the environment - Endotoxins are not actively secreted but are released upon cell death or lysis. C: Components of the gram-positive cell wall - Gram-positive bacteria do not have an outer membrane with lipopolysaccharides, so endotoxins are not found in the gram-positive cell wall.

Correct Answer: B

Rationale: The correct answer is B: Uptake of naked DNA from the environment. Bacterial transformation is a process where bacteria take up free DNA from their surroundings and incorporate it into their own genome. This process is essential for genetic recombination and the acquisition of new traits. Plasmids are small DNA molecules that can be transferred between bacteria, but not necessarily through pili. Bacteriophages are viruses that infect bacteria and transfer their DNA, but this is not the primary mechanism of bacterial transformation. Binary fission is a method of bacterial reproduction, not related to the uptake of DNA.

Correct Answer: D

Rationale: The correct answer is D, Late congenital syphilis. This is because the patient presents with Hutchinson's teeth, which are a characteristic feature of late congenital syphilis. Hutchinson's teeth are small, barrel-shaped teeth with a wider cervix and notched incisors. The patient's history of visual impairment and hearing aid use also support the diagnosis of late congenital syphilis, as these are common manifestations of this stage of the disease. Choice A, Primary syphilis, is incorrect because it typically presents with a painless sore at the site of infection, not dental abnormalities. Choice B, Early congenital syphilis, is incorrect as dental abnormalities in this stage are usually more severe, such as mulberry molars. Choice C, Neurosyphilis, is incorrect as it primarily affects the central nervous system and does not typically present with dental abnormalities.

Correct Answer: A

Rationale: The correct answer is A: Giardia lamblia. This protozoan matches the description of the causative agent because it has two nuclei, four flagella, and a ventral adhesive disc. Giardia lamblia is commonly found in the duodenum and causes giardiasis. The other choices can be eliminated because Leishmania donovani causes visceral leishmaniasis, not the described symptoms. Entamoeba coli is a non-pathogenic amoeba found in the large intestine. Trypanosoma gambiense causes African trypanosomiasis and is transmitted by the tsetse fly, not matching the described characteristics.

Correct Answer: D

Rationale: The correct answer is D because antigens can be composed of lipids, proteins, or polysaccharides. Antigens are molecules that can elicit an immune response in the body. They can be diverse in their chemical composition, leading to the recognition and response by the immune system. Therefore, the correct choice is D as antigens can be any of these chemical components. Choices A, B, and C are incorrect because they each represent a possible chemical composition of antigens, but the flexibility of antigens to be made up of any of these components makes D the most accurate choice.