Nokea
A woman delivered a dead child with multiple developmental defects. What protozoan disease might have caused the intrauterine death?
- A. Toxoplasmosis
- B. Leishmaniasis
- C. Malaria
- D. Amebiasis
Correct Answer: A
Rationale: The correct answer is A: Toxoplasmosis. Toxoplasmosis is a parasitic infection caused by Toxoplasma gondii, which can be transmitted from mother to fetus during pregnancy, leading to congenital toxoplasmosis. This infection can result in stillbirth, multiple developmental defects, and intrauterine death. Leishmaniasis (B), Malaria (C), and Amebiasis (D) are caused by different parasites and do not typically lead to intrauterine death or developmental defects in the fetus.
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Which of the statements is false:
- A. Spirochaetes are bacilli
- B. Diplococci possess spherical shape
- C. In rod-shaped bacteria one of the diameters is bigger
- D. Coccobacilli are a type of rod-shaped bacteria
Correct Answer: A
Rationale: The correct answer is A because spirochaetes are not bacilli; they are spiral-shaped bacteria. Bacilli are rod-shaped bacteria, making statement A false. Statement B is true as diplococci are spherical bacteria occurring in pairs. Statement C is true as rod-shaped bacteria have one diameter longer than the other. Statement D is true as coccobacilli are short, oval-shaped bacteria resembling cocci and rods. In summary, spirochaetes are spiral-shaped, not bacilli, making statement A false.
A patient with a deep tissue infection had Gram-negative rods isolated from the wound culture. The bacteria were oxidase-positive and non-lactose fermenters. What is the most likely causative agent?
- A. Pseudomonas aeruginosa
- B. Escherichia coli
- C. Klebsiella pneumoniae
- D. Shigella dysenteriae
Correct Answer: A
Rationale: The correct answer is A: Pseudomonas aeruginosa. This is because Pseudomonas is a Gram-negative rod, oxidase-positive, and non-lactose fermenter. These characteristics are typical of Pseudomonas species.
B: Escherichia coli is a Gram-negative rod but is lactose fermenter and usually oxidase-negative.
C: Klebsiella pneumoniae is a Gram-negative rod, non-lactose fermenter, but is usually oxidase-negative.
D: Shigella dysenteriae is a Gram-negative rod, non-lactose fermenter, but is usually oxidase-negative and is more associated with causing shigellosis rather than deep tissue infections.
For Parvovirus B19 it is true that:
- A. Its genome consists of dsDNA
- B. Is an enveloped virus
- C. Has segmented genome
- D. There are three structural proteins
Correct Answer: A
Rationale: Step-by-step rationale for choice A being correct:
1. Parvovirus B19 is a single-stranded DNA (ssDNA) virus.
2. The prefix "parvo-" indicates small size, characteristic of ssDNA viruses.
3. ssDNA viruses replicate in the host cell by converting their ssDNA genome into double-stranded DNA (dsDNA).
4. Therefore, the correct answer is A: Its genome consists of dsDNA.
Summary of why other choices are incorrect:
B: Parvovirus B19 is a non-enveloped virus, making choice B incorrect.
C: Parvovirus B19 has a linear ssDNA genome, not segmented, making choice C incorrect.
D: Parvovirus B19 has two structural proteins - VP1 and VP2, making choice D incorrect.
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.
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.