Nokea
Which ones of the following symptoms are NOT typical for botulism
- A. descending, flaccid paralysis
- B. dry mouth and difficulty in swallowing and speaking
- C. chills, fever up to 40°C and loss of consciousness
- D. blurred vision, diplopia
Correct Answer: C
Rationale: The correct answer is C because chills, fever, and loss of consciousness are not typical symptoms of botulism. Botulism is characterized by descending, flaccid paralysis (choice A), dry mouth, difficulty swallowing, and speaking (choice B), and blurred vision, diplopia (choice D). These symptoms result from the neurotoxin produced by Clostridium botulinum, leading to muscle weakness and paralysis. Chills, fever, and loss of consciousness are more commonly associated with infections or other conditions, not botulism.
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Which of the following statements is accurate in explaining why gram-negative bacteria are generally more resistant to penicillin than gram-positive bacteria
- A. gram-negative bacteria produce smaller quantities of transpeptidase enzyme
- B. gram-negative bacteria can concentrate β-lactamase enzymes in the periplasmic space
- C. gram-negative bacteria have an outer membrane that acts as an extra barrier
- D. gram-negative bacteria have a thicker cell wall
Correct Answer: C
Rationale: The correct answer is C: gram-negative bacteria have an outer membrane that acts as an extra barrier. This outer membrane in gram-negative bacteria contains lipopolysaccharides and porins, which restrict the entry of antibiotics like penicillin. The outer membrane acts as an additional layer of protection, making it harder for penicillin to penetrate and reach its target, the peptidoglycan layer. Choices A, B, and D do not directly address the specific mechanism of resistance seen in gram-negative bacteria. Choice A focuses on transpeptidase enzyme quantity, which is not the primary reason for penicillin resistance. Choice B refers to β-lactamase enzymes in the periplasmic space, which are actually enzymes that degrade penicillin and contribute to resistance, but this is not unique to gram-negative bacteria. Choice D mentions a thicker cell wall, which is a characteristic of gram-positive bacteria, not gram-negative bacteria.
The development of polioviruses on cell cultures is characterized by:
- A. Cytopathic effect
- B. Cytotoxic effect
- C. Cytolytic effect
- D. They Don't Change The Cell Cultures
Correct Answer: A
Rationale: The correct answer is A: Cytopathic effect. This is because polioviruses cause visible changes in infected cells, leading to cell damage and death, known as cytopathic effect. This is a key characteristic of viral infection. Choice B (Cytotoxic effect) is incorrect as it refers to the toxicity of a substance to cells, not the specific effect of polioviruses. Choice C (Cytolytic effect) is incorrect as it specifically refers to cell lysis, which is not the primary mechanism of poliovirus infection. Choice D (They Don't Change The Cell Cultures) is incorrect because polioviruses do indeed cause changes in cell cultures due to their cytopathic effect.
Which of the following organisms produces toxins that target cholesterol?
- A. Streptococcus pyogenes
- B. Corynebacterium diphtheriae
- C. Escherichia coli
- D. Aeromonas hydrophila
Correct Answer: C
Rationale: Step 1: Escherichia coli is known to produce a toxin called colibactin that targets cholesterol.
Step 2: Colibactin disrupts cholesterol metabolism in host cells.
Step 3: This disruption can lead to various health issues.
Step 4: Streptococcus pyogenes produces different toxins, not specifically targeting cholesterol.
Step 5: Corynebacterium diphtheriae produces diphtheria toxin, not targeting cholesterol.
Step 6: Aeromonas hydrophila produces various toxins, but not known for targeting cholesterol.
Summary: Escherichia coli produces toxins that specifically target cholesterol, making it the correct choice over the other options.
Agents associated with human disease but generally not a serious health risk are classified in which of the following risk groups?
- A. RG1
- B. RG2
- C. RG3
- D. RG4
Correct Answer: B
Rationale: The correct answer is B: RG2. RG2 is appropriate for agents associated with human disease that pose a moderate health risk. These agents may cause disease of varying severity, but generally do not result in serious health consequences. Other choices are incorrect because: A: RG1 is for agents not associated with disease in healthy adults, C: RG3 is for agents associated with serious or lethal human disease, and D: RG4 is for agents that pose a high risk of life-threatening disease and for which there are no treatments.
A patient who has recently come from an endemic area presents with elevated body temperature, headache, chills, malaise, that is with the symptoms which are typical for a common cold. What laboratory tests are necessary to confirm or to refute the diagnosis of malaria?
- A. Microscopy of blood smears
- B. Study of lymph node punctate
- C. Urinalysis
- D. Study of cerebrospinal fluid
Correct Answer: A
Rationale: The correct answer is A: Microscopy of blood smears. Malaria diagnosis is confirmed by identifying the Plasmodium parasite in a blood smear. This step is crucial as it directly visualizes the causative agent. The other choices are incorrect as they do not directly detect malaria parasites. B: Studying lymph node punctate is not specific for malaria. C: Urinalysis does not show malaria parasites. D: Studying cerebrospinal fluid is used to diagnose conditions affecting the brain and spinal cord, not malaria.