Microscopy of a smear from a patient with foul-smelling diarrhea revealed large ciliated protozoa with a kidney-shaped macronucleus. What is the diagnosis?
- A. Balantidiasis
- B. Giardiasis
- C. Amoebiasis
- D. Trichomoniasis
Correct Answer: A
Rationale: The correct diagnosis is A: Balantidiasis. The presence of large ciliated protozoa with a kidney-shaped macronucleus is characteristic of Balantidium coli, the causative agent of balantidiasis. The ciliated trophozoites of Balantidium coli are unique compared to the other choices. Giardiasis is caused by Giardia lamblia, which has flagella and not cilia. Amoebiasis is caused by Entamoeba histolytica, which lacks cilia. Trichomoniasis is caused by Trichomonas vaginalis, which also lacks cilia. Therefore, based on the specific morphology described, the correct diagnosis is Balantidiasis.
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Fungi are free-living _________ organisms:
- A. autotrophic
- B. chemotrophic
- C. heterotrophic
- D. phototrophic
Correct Answer: C
Rationale: The correct answer is C: heterotrophic. Fungi are heterotrophic organisms that obtain nutrients by absorbing organic compounds from their environment. They do not produce their own food through photosynthesis (option A: autotrophic) or chemosynthesis (option B: chemotrophic). Fungi also do not rely on light for energy (option D: phototrophic). Therefore, the correct choice is C as it accurately describes the nutritional mode of fungi.
From a medicinal herb a certain phytopathogenic microorganism was secured. In the nutrient medium it forms "fried egg"colonies. What is the most likely agent?
- A. Mycoplasma B.Yeasts C.Actinomycetes D.Nocardia E.Pseudomonas Legionella
Correct Answer: C
Rationale: Step 1: "Fried egg" colonies typically refer to colonies with a raised center and flattened periphery, resembling the appearance of a fried egg.
Step 2: Actinomycetes are filamentous bacteria known to form "fried egg" colonies in nutrient medium.
Step 3: Actinomycetes are commonly found in soil and are known to be phytopathogenic microorganisms.
Step 4: Actinomycetes produce secondary metabolites with medicinal properties, making them a likely agent from a medicinal herb.
Overall, the correct answer is C (Actinomycetes) as they fit the description provided in the question and are commonly associated with the given scenario. The other choices are incorrect as they do not exhibit the specific characteristics mentioned in the question or are not typically associated with forming "fried egg" colonies in nutrient medium.
A wound culture from a patient with an infected ulcer revealed Gram-positive rods with terminal spores. What is the most likely causative agent?
- A. Clostridium perfringens
- B. Bacillus anthracis
- C. Clostridium tetani
- D. Bacillus cereus
Correct Answer: A
Rationale: Step-by-step rationale:
1. Gram-positive rods with terminal spores suggest Clostridium genus.
2. Terminal spores are characteristic of Clostridium perfringens.
3. C. perfringens is known to cause wound infections.
4. Therefore, the most likely causative agent is Clostridium perfringens.
Summary:
A: Clostridium perfringens is correct due to its characteristic features and association with wound infections.
B: Bacillus anthracis does not typically form terminal spores.
C: Clostridium tetani causes tetanus, not wound infections.
D: Bacillus cereus does not produce terminal spores like Clostridium perfringens.
Coxsackie Viruses can cause:
- A. Hemorrhagic conjunctivitis
- B. Herpangina
- C. Mumps
- D. Poliomyelitis
Correct Answer: B
Rationale: The correct answer is B: Herpangina. Coxsackie Viruses are known to cause Herpangina, which is characterized by sore throat, fever, and painful blisters in the mouth and throat. This is because Coxsackie Viruses typically infect the throat and mouth mucosa. Hemorrhagic conjunctivitis (A) is commonly caused by Adenoviruses, not Coxsackie Viruses. Mumps (C) is caused by the Mumps virus, a completely different virus. Poliomyelitis (D) is caused by the Poliovirus, not Coxsackie Viruses. Therefore, the correct answer is B as it aligns with the known pathogenicity of Coxsackie Viruses.
For the structure of rubella virus, it is true that
- A. has icosahedral type of symmetry
- B. is ssDNA virus
- C. does not have an envelope
- D. does not have glycoprotein spikes
Correct Answer: A
Rationale: Step 1: Rubella virus belongs to the Togaviridae family, which typically exhibits icosahedral symmetry.
Step 2: Icosahedral symmetry refers to a structure with 20 equilateral triangular faces, which is characteristic of many viruses, including rubella.
Step 3: Therefore, choice A is correct as rubella virus indeed has icosahedral type of symmetry.
Summary:
- 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.