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All the statements about Pseudomonas aeruginosa are correct, EXCEPT:
- A. It is a Gram-negative bacterium
- B. It is oxidase-positive
- C. It is non-motile and non-spore forming
- D. None of the above
Correct Answer: C
Rationale: The correct answer is C: It is non-motile and non-spore forming. Pseudomonas aeruginosa is motile due to its flagella and is non-spore forming. A is correct because it is a Gram-negative bacterium, and B is correct as it is oxidase-positive. D is incorrect because C is not true.
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A patient with pneumonia had a sputum culture revealing Gram-positive diplococci. The bacteria were catalase-negative and alpha-hemolytic. What is the most likely causative agent?
- A. Streptococcus pneumoniae
- B. Staphylococcus aureus
- C. Neisseria meningitidis
- D. Klebsiella pneumoniae
Correct Answer: A
Rationale: Step 1: Gram-positive diplococci suggest a pneumococcal infection.
Step 2: Catalase-negative indicates Streptococcus.
Step 3: Alpha-hemolysis matches S. pneumoniae's characteristics.
Therefore, Streptococcus pneumoniae is the most likely causative agent. Staphylococcus aureus (B) is catalase-positive, Neisseria meningitidis (C) is Gram-negative, and Klebsiella pneumoniae (D) is not diplococci or alpha-hemolytic.
Sanitary and bacteriological examination of air in drug-store premises revealed increased content of sanitary representative microorganisms. What microorganisms are these?
- A. Golden staphylococcus and hemolytic streptococcus
- B. Diphtheria and tuberculosis bacilli
- C. Colon and blue pus bacilli
- D. Epidermal staphylococcus and sarcina
Correct Answer: A
Rationale: The correct answer is A (Golden staphylococcus and hemolytic streptococcus) because these microorganisms are commonly found in the air of contaminated environments like drug-store premises. Golden staphylococcus and hemolytic streptococcus are pathogenic bacteria associated with infections in humans, indicating poor sanitation. The other choices are incorrect because:
B: Diphtheria and tuberculosis bacilli are not commonly found in the air in drug-store premises.
C: Colon and blue pus bacilli are not typical microorganisms associated with air contamination.
D: Epidermal staphylococcus and sarcina are not likely to be present in high amounts in the air of drug-store premises.
The cytopathic effect caused by viruses of family paramyxoviridae looks like:
- A. Fine grained degeneration
- B. Giant multinucleated cells syncytia
- C. Large cell degeneration with grape clustering of cells
- D. Do not provoke a cytopathic effect on cell cultures
Correct Answer: B
Rationale: Rationale: The correct answer is B. Viruses of the family Paramyxoviridae cause the formation of giant multinucleated cells called syncytia. This occurs when infected cells fuse together, resulting in large, multinucleated structures. This is a characteristic cytopathic effect of paramyxoviruses.
Summary:
A: Fine grained degeneration is not typically seen in paramyxovirus infections.
C: Large cell degeneration with grape clustering of cells is not a typical cytopathic effect of paramyxoviruses.
D: Paramyxoviruses do provoke a cytopathic effect, so this statement is incorrect.
In the cytoplasm of some bacteria there are substances in the form of granules. They are:
- A. cytoplasmic inclusions
- B. excess products of the metabolism
- C. reserve substances
- D. all of the above
Correct Answer: D
Rationale: The correct answer is D. Cytoplasmic inclusions in bacteria refer to substances like granules. These granules can be excess products of metabolism or reserve substances stored for future use. Therefore, all of the choices are correct as cytoplasmic inclusions can be any of these substances. A is correct as it directly refers to cytoplasmic inclusions. B is correct as some granules can be excess metabolic products. C is correct as certain granules can serve as reserve substances. Therefore, the correct answer is D, as it encompasses all the possible types of substances found as cytoplasmic inclusions in bacteria.
Shigella sonnei can escape phagocytic clearance by which mechanism?
- A. Lysis of phagosome and replication in cytoplasm
- B. capsule-mediated inhibition of phagocytosis
- C. Inhibition of phagosome/lysosome fusion
- D. inhibition of opsonization mediated by protein A
Correct Answer: A
Rationale: The correct answer is A because Shigella sonnei escapes phagocytic clearance by lysing the phagosome and replicating in the cytoplasm. This allows the bacterium to avoid being destroyed by the acidic environment and enzymes in the phagolysosome. Choice B is incorrect as Shigella does not have a capsule. Choice C is incorrect because Shigella actually induces phagosome-lysosome fusion to facilitate its escape. Choice D is incorrect as protein A is a component of Staphylococcus aureus, not Shigella sonnei.