Nokea
Microscopy of sputum revealed acid-fast bacilli stained red against a blue background using Ziehl-Neelsen staining. What disease does this finding suggest?
- A. Tuberculosis
- B. Diphtheria
- C. Pneumonia
- D. Leprosy
Correct Answer: A
Rationale: The presence of acid-fast bacilli stained red against a blue background indicates mycobacteria, specifically Mycobacterium tuberculosis in this case. Ziehl-Neelsen staining is commonly used to detect tuberculosis. Diphtheria is caused by Corynebacterium diphtheriae, which does not stain with Ziehl-Neelsen. Pneumonia is a general term for lung infections caused by various pathogens. Leprosy is caused by Mycobacterium leprae, which requires special staining methods different from Ziehl-Neelsen.
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Which bacteria are known for producing toxins that can cause severe gastrointestinal illness?
- A. Clostridium botulinum
- B. Vibrio cholerae
- C. Escherichia coli
- D. All of the above
Correct Answer: D
Rationale: The correct answer is D, "All of the above." Clostridium botulinum produces botulinum toxin causing botulism, Vibrio cholerae produces cholera toxin leading to severe diarrhea, and certain strains of Escherichia coli produce toxins causing gastrointestinal illness. Therefore, all three bacteria are known for producing toxins that can cause severe gastrointestinal illness. Choices A, B, and C individually represent bacteria known for producing toxins that can cause severe gastrointestinal illness, making them incorrect individual choices.
Some of the basic requirements for the antibacterial chemotherapeutics are:
- A. To be maximally toxic to bacteria, as a result of their accumulation in the body
- B. To disintegrate rapidly and not be water soluble
- C. To be maximally toxic to microorganisms, not to lead to allergic reactions, to be stable, to have a wide spectrum of activity
- D. None of the above
Correct Answer: C
Rationale: The correct answer is C because antibacterial chemotherapeutics need to be maximally toxic to microorganisms, not lead to allergic reactions, be stable, and have a wide spectrum of activity to effectively treat bacterial infections.
A is incorrect because maximum toxicity to bacteria can lead to harmful side effects in the body. B is incorrect because rapid disintegration and insolubility in water would hinder the drug's effectiveness. D is incorrect because the basic requirements for antibacterial chemotherapeutics are outlined in option C.
What is the primary function of bacterial ribosomes?
- A. Synthesize proteins
- B. Generate ATP
- C. Produce DNA
- D. Synthesize lipids
Correct Answer: A
Rationale: The correct answer is A: Synthesize proteins. Bacterial ribosomes are responsible for translating mRNA into proteins through a process called translation. Ribosomes do not generate ATP (choice B), produce DNA (choice C), or synthesize lipids (choice D). These processes are carried out by other cellular components such as mitochondria for ATP production, DNA polymerase for DNA replication, and enzymes for lipid synthesis. The primary function of bacterial ribosomes is protein synthesis, making choice A the correct answer.
In an agar slant, bacterial colonies that appear separate or semiconfluent are referred to as:
- A. filiform
- B. echinulate
- C. beaded
- D. effuse
Correct Answer: C
Rationale: The correct answer is C: beaded. In an agar slant, beaded colonies appear as separate or semiconfluent, forming small, round colonies with gaps between them. This term accurately describes the appearance of the colonies in this context.
A: Filiform colonies are dense and opaque with smooth edges, not separate or semiconfluent.
B: Echinulate colonies have spiny projections, not the characteristic of separate or semiconfluent growth.
D: Effuse colonies spread out extensively and lack defined borders, unlike the distinct appearance of separate or semiconfluent colonies.
The following viruses are referred to the Filoviridae family:
- A. Lassa virus and lymphocytic choriomeningitis viruses
- B. Chikungunya virus and Sindbis virus
- C. Marburg virus and Ebola virus
- D. Crimean-Congo virus and Hantaan virus
Correct Answer: C
Rationale: Step-by-step rationale:
1. The Filoviridae family includes Marburg virus and Ebola virus.
2. Both viruses are characterized by filamentous, enveloped structure.
3. They cause severe hemorrhagic fever in humans.
4. Lassa virus and lymphocytic choriomeningitis viruses belong to Arenaviridae.
5. Chikungunya virus and Sindbis virus are alphaviruses.
6. Crimean-Congo virus and Hantaan virus are bunyaviruses.
7. Therefore, the correct answer is C.