A patient with foul-smelling diarrhea had a stool sample showing large ciliated protozoa with a kidney-shaped macronucleus. What is the diagnosis?

Correct Answer: A

Rationale: The correct answer is A: Balantidiasis. The large ciliated protozoa with a kidney-shaped macronucleus described in the stool sample is consistent with Balantidium coli, the causative agent of balantidiasis. Balantidium coli is the only ciliated protozoan parasite that infects humans and presents with these specific characteristics. Giardiasis (B) is caused by Giardia intestinalis, which is flagellated, not ciliated. Amoebiasis (C) is caused by Entamoeba histolytica, which has an amoeboid shape, not ciliated. Trichomoniasis (D) is caused by Trichomonas vaginalis, which is a flagellated protozoan and does not have a kidney-shaped macronucleus. Hence, the correct diagnosis in this case is Balantidiasis.

Correct Answer: D

Rationale: The correct answer is D: stereomicroscopes. These types of microscopes, also known as dissecting microscopes, are designed for observing larger objects like insects or worms. They have a lower magnification power compared to electron microscopes (A), which are used to observe smaller objects at a much higher resolution. Dark-field microscopes (B) are used for observing live and unstained samples with high contrast, not specifically for larger objects. Fluorescence microscopes (C) are used to observe specimens that fluoresce under specific wavelengths of light, not necessarily for large objects like insects or worms. Therefore, the most suitable choice for observing fairly large objects like insects or worms is stereomicroscopes.

Correct Answer: C

Rationale: The correct answer is C: ECHO virus infection. ECHO virus is transmitted via the fecal-oral route, meaning the virus is passed from feces to the mouth. This transmission occurs through contaminated food, water, or surfaces. Relapsed fever and spotted fever are generally transmitted by arthropod vectors like ticks. Pertussis, also known as whooping cough, spreads through respiratory droplets. Therefore, the fecal-oral route is not applicable to these diseases.

Correct Answer: B

Rationale: The correct answer is B: Trichomonas vaginalis. Trichomonas vaginalis is a protozoan parasite that can survive and grow in low moisture conditions. It does not require a host cell and can thrive in moist environments, making it able to grow on substances with very low moisture content. Giardia lamblia (A), Balantidium coli (C), and Entamoeba histolytica (D) are all parasites that require a host to survive and reproduce, making them unable to grow on substances with very low moisture content. Trichomonas vaginalis is the only organism among the choices that fits the criteria of being able to grow on low moisture substances.

Correct Answer: A

Rationale: The correct answer is A: BCG vaccine. Step 1: BCG vaccine is specifically designed to protect against tuberculosis, making it the appropriate choice for newborns. Step 2: STI vaccine is for sexually transmitted infections, not tuberculosis. Step 3: EV vaccine is not a recognized vaccine. Step 4: DPT vaccine protects against diphtheria, pertussis, and tetanus, not tuberculosis. In summary, BCG vaccine is the correct choice as it targets tuberculosis specifically, while the other options are designed for different purposes.

Correct Answer: A

Rationale: The correct answer is A: aspergillosis and candidiasis. Detection of galactomannan and free mannan is commonly used in diagnosing these fungal infections. Galactomannan is a component of the cell wall of Aspergillus species, while free mannan is associated with Candida species. This detection method helps in identifying these specific fungal infections accurately. B: Syphilis is caused by a bacterium, Treponema pallidum, and is not diagnosed using galactomannan or free mannan detection. C: Leptospirosis is a bacterial infection caused by the Leptospira species and is not diagnosed using galactomannan or free mannan detection. D: HIV infection is a viral infection caused by the human immunodeficiency virus and is not diagnosed using galactomannan or free mannan detection.

Correct Answer:

Rationale: Correct Answer: C: opportunists Rationale: 1. Opportunistic microorganisms cause infections only when the host's immune system is compromised. 2. They are typically harmless in healthy individuals but can become pathogenic in weakened hosts. 3. Saprophytic microorganisms are environmental decomposers, not inherently pathogenic. 4. Facultative pathogens can cause disease in both healthy and compromised hosts. 5. Obligate pathogens always cause disease regardless of the host's condition. Summary: A: Facultative pathogens can cause disease in healthy hosts. B: Saprophytes are not inherently pathogenic. D: Obligate pathogens always cause disease.

Correct Answer: B

Rationale: The correct answer is B: peak effect. When drug receptors are maximally activated, it means the drug has reached its highest effectiveness, resulting in the peak effect. This occurs when the drug concentration is at its highest level in the body, leading to the maximum response. Threshold level (A) refers to the minimum amount of drug needed to produce a response. Cessation effect (C) is when the drug's effect wears off. Latency time (D) is the time it takes for the drug to start producing an effect. So, the peak effect best describes the scenario where drug receptors are maximally activated.

Correct Answer: A

Rationale: The Burri-Gins staining technique is used to identify capsule formation in bacteria. Capsules are protective layers around bacteria that can be visualized using this staining method. Capsules are important virulence factors for pathogens like Yersinia pestis, the causative agent of plague. This technique helps in differentiating encapsulated bacteria from non-encapsulated ones. Spore formation (B), acid resistance (C), and alkali resistance (D) are not properties that can be identified using the Burri-Gins technique, making them incorrect choices.