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Which of the following bacteria is a common cause of pneumonia?
- A. Streptococcus pneumoniae
- B. Mycobacterium tuberculosis
- C. Pseudomonas aeruginosa
- D. All of the above
Correct Answer: D
Rationale: The correct answer is D: All of the above.
- Streptococcus pneumoniae is a common cause of community-acquired pneumonia.
- Mycobacterium tuberculosis can cause pulmonary tuberculosis, which can present as pneumonia-like symptoms.
- Pseudomonas aeruginosa is an opportunistic pathogen that can cause pneumonia in immunocompromised individuals.
Therefore, all three bacteria can cause pneumonia, making option D the correct choice. Options A, B, and C are incorrect because they each represent a bacterium that can cause pneumonia, so only selecting one of them would not encompass all common causes of pneumonia.
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By precipitation of tuberculin, a purified protein derivative (PPD) is obtained. It is used in:
- A. Mantoux test
- B. Schick test
- C. Dick test
- D. None of the above
Correct Answer: A
Rationale: The correct answer is A: Mantoux test. The Mantoux test is used to screen for tuberculosis by injecting PPD intradermally. The presence of a delayed hypersensitivity reaction indicates prior exposure to Mycobacterium tuberculosis. The Schick test (B) is used to test for immunity to diphtheria, while the Dick test (C) is used to test for immunity to scarlet fever. Therefore, the correct use of PPD is in the Mantoux test for tuberculosis screening.
The white pulp and red pulp are part of which immune organ:
- A. Thymus
- B. Lymph node
- C. Spleen
- D. Lymphoid tissue
Correct Answer: C
Rationale: The correct answer is C: Spleen. The white pulp of the spleen contains lymphocytes that help in immune responses. The red pulp filters blood and removes old or damaged red blood cells. The thymus (A) is responsible for T cell maturation, lymph nodes (B) filter lymph, and lymphoid tissue (D) includes various lymphoid organs but does not specifically refer to the spleen's distinct white and red pulp structure. Thus, the spleen is the only organ among the choices that has both white and red pulp components essential for immune functions.
The main structure components of viruses are
- A. nucleic acid and proteins
- B. nucleic acids and lipids
- C. lipids and protein
- D. proteins and glycoproteins
Correct Answer: A
Rationale: The correct answer is A: nucleic acid and proteins. Viruses consist of genetic material (nucleic acid) surrounded by a protein coat. The nucleic acid carries the viral genetic information, while the proteins form the capsid that protects the genetic material. This combination is essential for the virus to infect host cells and replicate. Lipids (choice B) are not typically part of the main structure of viruses. Lipids are more commonly found in the host cell membrane. Lipids and proteins (choice C) may be present in the viral envelope but are not the main structural components. Proteins and glycoproteins (choice D) are important for viral attachment and entry into host cells but do not constitute the main structural components of viruses.
Which bacteria produces an enterotoxin that causes diarrhea?
- A. Vibrio cholerae
- B. Clostridium botulinum
- C. Escherichia coli
- D. Streptococcus pneumoniae
Correct Answer: A
Rationale: The correct answer is A: Vibrio cholerae. This bacterium produces the cholera toxin, an enterotoxin that causes profuse watery diarrhea by disrupting the normal function of the intestines. Vibrio cholerae is specifically known for causing cholera, a severe diarrheal disease. Clostridium botulinum (B) produces botulinum toxin, causing botulism (paralysis, not diarrhea). Escherichia coli (C) can produce enterotoxins, but the question specifies a specific enterotoxin causing diarrhea, which is not a characteristic of all strains of E. coli. Streptococcus pneumoniae (D) is a common cause of respiratory infections but does not produce an enterotoxin causing diarrhea.
Acute hemorrhagic cystitis may be due to:
- A. Parvovirus B19
- B. CMV
- C. Adenovirus
- D. Herpesvirus type 2
Correct Answer: C
Rationale: Rationale for choice C (Adenovirus) being correct:
1. Adenovirus is a common cause of acute hemorrhagic cystitis.
2. Adenovirus infects the bladder epithelium, leading to inflammation and bleeding.
3. Symptoms include hematuria and bladder pain.
4. Diagnosis is confirmed through viral culture or PCR testing.
Summary of why other choices are incorrect:
A: Parvovirus B19 - More commonly associated with erythema infectiosum (fifth disease) and aplastic anemia.
B: CMV - Known to cause congenital infections, mononucleosis, and retinitis, not typically associated with hemorrhagic cystitis.
D: Herpesvirus type 2 - Commonly causes genital herpes, but not typically associated with acute hemorrhagic cystitis.