Nokea
Animals that are capable of transmitting infectious disease are called:
- A. vectors
- B. pathogens
- C. carriers
- D. parasites
Correct Answer: A
Rationale: The correct answer is A: vectors. Vectors are animals that transmit infectious diseases from one host to another, typically through biting or contact. They do not cause the disease themselves but serve as intermediaries. Pathogens (B) are the microorganisms that cause diseases. Carriers (C) are individuals who harbor a pathogen without showing symptoms. Parasites (D) are organisms that live on or inside another organism and may or may not transmit diseases. Therefore, the term "vectors" specifically refers to animals that transmit infectious diseases, making it the correct choice in this context.
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Bacteria associated with hospital-acquired infections:
- A. Streptococcus pneumoniae
- B. Pseudomonas aeruginosa
- C. Vibrio cholerae
- D. None of the above
Correct Answer: B
Rationale: The correct answer is B: Pseudomonas aeruginosa. This bacterium is commonly associated with hospital-acquired infections due to its ability to survive in hospital environments, resist antibiotics, and infect immunocompromised patients. Streptococcus pneumoniae (choice A) is more commonly associated with community-acquired pneumonia. Vibrio cholerae (choice C) causes cholera, a waterborne disease, and is not typically associated with hospital-acquired infections. Choice D is incorrect because Pseudomonas aeruginosa is indeed associated with hospital-acquired infections.
Pathological material taken from a patient suffering from pulpitis was inoculated onto Kitt-Tarozzi cultural medium. It is planned to find the following microorganisms:
- A. Anaerobic
- B. Acid-resistant
- C. Acidophilic
- D. Haemolytic
Correct Answer: A
Rationale: The correct answer is A: Anaerobic. Pulpitis is an inflammatory condition of the dental pulp, often caused by bacterial infection. Anaerobic bacteria are commonly associated with dental infections, making it likely to find them in the inoculated culture medium. Anaerobic bacteria thrive in the absence of oxygen, which is typical of the dental environment. Acid-resistant (B) and acidophilic (C) microorganisms are not specifically linked to pulpitis. Haemolytic (D) microorganisms typically lyse red blood cells, which is not a characteristic feature of bacteria causing pulpitis. Therefore, the most likely microorganisms to be found in the culture medium would be anaerobic bacteria.
All statements of viral neutralization reaction are true except:
- A. A key component of the reaction is the complement system involvement
- B. Specific virus neutralising antibodies block the viral ability to infect cells
- C. The antibodies are titrated and two serum samples are required
- D. It is also used to identify newly isolated virus
Correct Answer: A
Rationale: Rationale:
A: Incorrect - The complement system is not directly involved in the viral neutralization reaction.
B: Correct - Specific antibodies neutralize viruses by blocking their ability to infect cells.
C: Incorrect - Antibodies are titrated, but only one serum sample is required for neutralization testing.
D: Incorrect - Viral neutralization is primarily used to measure antibody response, not to identify newly isolated viruses.
A smear of sputum from the patient with suspected lobar pneumonia was stained with the use of the following stains and reagents: solution of gentian violet, Lugol’s solution, 960 alcohol, watermagenta. What staining method was applied in this case?
- A. Gram
- B. Ziehl-Nielsen's
- C. Romanovsky
- D. Neisser
Correct Answer: A
Rationale: The correct answer is A: Gram staining method. The rationale is as follows:
1. Gentian violet is a primary stain used in the Gram staining procedure to stain the bacterial cells.
2. Lugol's solution is a mordant that helps to fix the crystal violet stain in Gram-positive bacteria.
3. 95% alcohol is used as a decolorizing agent in the Gram staining process to remove the stain from Gram-negative bacteria.
4. Watermagenta is not a standard reagent in the Gram staining method.
Therefore, based on the reagents mentioned, the staining method applied in this case is the Gram staining method.
Other choices are incorrect:
B: Ziehl-Nielsen's - This staining method is used for acid-fast staining, not for lobar pneumonia.
C: Romanovsky - This staining method is used for blood smears, not for bacterial staining in pneumonia.
D: Neisser - This staining method is not commonly used in routine bacterial staining procedures.
A smear prepared from material obtained from patient with suspected diphtheria contains yellow bacilli with blue grains at their ends. What staining was used in this case?
- A. Ziehl-Nielsen
- B. Kozlovsky
- C. Romanovsky
- D. Loefler
Correct Answer: D
Rationale: The correct answer is D: Loefler. This staining method is used for identifying Corynebacterium diphtheriae, the causative agent of diphtheria. It involves using methylene blue and basic fuchsin to stain the bacteria. The yellow bacilli with blue grains at their ends indicate the characteristic appearance of C. diphtheriae when stained using the Loefler method.
Choice A: Ziehl-Nielsen is used for acid-fast bacteria like Mycobacterium tuberculosis.
Choice B: Kozlovsky is not a standard staining method in microbiology.
Choice C: Romanovsky is used for blood smears to identify malaria parasites.