Nokea
Infections of the CNS can be caused by:
- A. Clostridium botulinum
- B. Morbillivirus morbillorum
- C. Clostridium tetani
- D. All are correct
Correct Answer: D
Rationale: The correct answer is D because all three choices, Clostridium botulinum, Morbillivirus morbillorum, and Clostridium tetani, can cause infections of the CNS. Clostridium botulinum can lead to botulism, affecting the nervous system. Morbillivirus morbillorum can cause measles, which can lead to encephalitis. Clostridium tetani can cause tetanus, affecting the central nervous system. Therefore, all three choices can cause infections of the CNS. Choices A, B, and C are incorrect individually because each pathogen can cause CNS infections.
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A wound infection culture grew Gram-positive cocci in clusters. The bacteria were catalase-positive and coagulase-negative. What is the likely microorganism?
- A. Staphylococcus epidermidis
- B. Staphylococcus aureus
- C. Streptococcus pyogenes
- D. Enterococcus faecalis
Correct Answer: A
Rationale: The correct answer is A: Staphylococcus epidermidis. The presence of Gram-positive cocci in clusters, along with being catalase-positive and coagulase-negative, is indicative of Staphylococcus species. Staphylococcus epidermidis is commonly found on the skin, making it likely to cause wound infections.
Summary:
B: Staphylococcus aureus is catalase-positive and coagulase-positive.
C: Streptococcus pyogenes is catalase-negative.
D: Enterococcus faecalis is catalase-negative.
A sputum smear stained by Gram's method revealed Gram-positive cocci in clusters. The patient presented with an abscess. What is the causative agent?
- A. Staphylococcus aureus
- B. Streptococcus pyogenes
- C. Enterococcus faecalis
- D. Micrococcus luteus
Correct Answer: A
Rationale: The correct answer is A: Staphylococcus aureus. Staphylococcus aureus is a Gram-positive bacterium that commonly presents as cocci in clusters. It is a known causative agent of abscesses due to its ability to produce enzymes and toxins that contribute to tissue destruction. In this case, the presence of Gram-positive cocci in clusters aligns with the characteristic morphology of Staphylococcus aureus.
Summary of incorrect choices:
B: Streptococcus pyogenes is a Gram-positive bacterium that typically presents as cocci in chains, not clusters. It is more commonly associated with pharyngitis and skin infections rather than abscesses.
C: Enterococcus faecalis is a Gram-positive bacterium that typically presents as cocci in pairs or short chains, not clusters. It is more commonly associated with urinary tract infections and endocarditis.
D: Micrococcus luteus is a Gram-positive bacterium that typically presents as t
Which of the following statements about family Arenaviridae is true?
- A. Cannot be isolated from clinical materials due to lack of biological models and diagnosis is only serological
- B. Replicate in the nucleus of the infected cells
- C. Lymphocytic choriomeningitis virus belongs to the family
- D. The only host is the human
Correct Answer: C
Rationale: The correct answer is C because lymphocytic choriomeningitis virus belongs to the family Arenaviridae. This virus is a well-known member of the Arenaviridae family and is associated with various diseases. Option A is incorrect as Arenaviruses can be isolated from clinical materials using suitable methods. Option B is incorrect because Arenaviruses replicate in the cytoplasm, not the nucleus. Option D is incorrect as Arenaviruses can infect various hosts, not just humans. Therefore, the statement that lymphocytic choriomeningitis virus belongs to the family Arenaviridae is true.
Which of the following is a preferred mode of transmission of HIV from a mother to a child
- A. during delivery through mixing of blood
- B. during pregnancy through placenta
- C. via breastmilk during lactation
- D. All of the above
Correct Answer: D
Rationale: The correct answer is D because HIV can be transmitted from a mother to a child through multiple modes: during delivery through mixing of blood, during pregnancy through the placenta, and via breastmilk during lactation. Each mode presents a risk of transmission due to the presence of the virus in bodily fluids. Therefore, all of the above options are preferred modes of transmission for HIV from a mother to a child. Choices A, B, and C alone do not fully encompass all the possible routes of transmission, making them incorrect.
A patient who suffered form syphilis took a course of antibiotic therapy and fully recovered. Some time later he was infected again with Treponema pallidum. What form of infection is it?
- A. Reinfection
- B. Recurrence
- C. Superinfection
- D. Secondary infection
Correct Answer: A
Rationale: The correct answer is A: Reinfection. This is because the patient fully recovered from the initial syphilis infection after antibiotic therapy, indicating the elimination of the pathogen. Subsequently getting infected again with Treponema pallidum suggests a new exposure to the same pathogen, resulting in a new infection. Recurrence (B) would imply the reactivation of the same infection, which is not the case here. Superinfection (C) refers to a new infection that occurs on top of an existing infection, which is not the scenario described. Secondary infection (D) typically refers to an infection that occurs after an initial infection weakens the immune system, which is not the case in this scenario.