Nokea
A lymph node punctate of a patient with suspected protozoa disease was examined. Examination of the stained specimen (Romanovsky's stain) revealed some crescent bodies with pointed end, blue cytoplasm and red nucleus. What protozoan were revealed in the smears?
- A. Toxoplasmas
- B. Malarial plasmodiums
- C. Dermotropic leishmania
- D. Viscerotropic leishmania
Correct Answer: B
Rationale: The correct answer is B: Malarial plasmodiums. The description of crescent bodies with a pointed end, blue cytoplasm, and red nucleus corresponds to the characteristics of Plasmodium species seen in Romanovsky's stain. Plasmodium species are known to cause malaria and have distinct features like the ones described.
Incorrect choices:
A: Toxoplasmas - Toxoplasma gondii typically appear as tachyzoites or bradyzoites under staining, not crescent bodies.
C: Dermotropic leishmania - Leishmania species appear as amastigotes in tissue smears, not crescent bodies.
D: Viscerotropic leishmania - Similar to choice C, Leishmania species do not typically present as crescent bodies in stained specimens.
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Unlike eukaryotic cytoplasm, the prokaryotic one is:
- A. More complex
- B. Simpler
- C. There is no difference in the structure
- D. None of the above
Correct Answer: B
Rationale: The correct answer is B: Simpler. Prokaryotic cytoplasm is simpler than eukaryotic cytoplasm because prokaryotic cells lack membrane-bound organelles such as a nucleus, mitochondria, and endoplasmic reticulum that are present in eukaryotic cells. Prokaryotic cytoplasm contains fewer components and structures compared to eukaryotic cytoplasm, making it less complex. Therefore, the prokaryotic cytoplasm is simpler in structure. Choices A, C, and D are incorrect because prokaryotic cytoplasm is not more complex than eukaryotic cytoplasm, there is a clear difference in structure between prokaryotic and eukaryotic cytoplasm, and the statement "None of the above" is not accurate as the correct answer is B.
It is often difficult for antibiotics to effectively reach the infection site of osteomyelitis primarily because of:
- A. destruction of the local blood supply
- B. denaturing of the drug by normal flora
- C. inflammation and edema
- D. excessive production of pus at the infection site
Correct Answer: A
Rationale: The correct answer is A: destruction of the local blood supply. In osteomyelitis, the infection occurs in the bone, which has a relatively poor blood supply compared to soft tissues. This limited blood flow makes it challenging for antibiotics to reach the infection site effectively, hindering their ability to combat the infection. Destruction of the local blood supply restricts the delivery of antibiotics and immune cells to the infected bone, leading to poor treatment outcomes.
Summary:
- Option A is correct because the limited blood supply in bones hinders antibiotic delivery.
- Option B is incorrect as denaturing by normal flora does not impact antibiotic reach to the infection site.
- Option C is incorrect as inflammation and edema, while present, do not primarily hinder antibiotic delivery.
- Option D is incorrect as excessive pus production does not directly impede antibiotic access to the infection site.
Which bacteria are capable of producing endospores?
- A. Staphylococcus aureus
- B. Clostridium botulinum
- C. Escherichia coli
- D. Neisseria gonorrhoeae
Correct Answer: B
Rationale: The correct answer is B: Clostridium botulinum. This bacterium belongs to the Clostridium genus, known for its ability to produce endospores. Endospores are dormant, resistant structures that help bacteria survive harsh conditions. Staphylococcus aureus (A), Escherichia coli (C), and Neisseria gonorrhoeae (D) do not produce endospores. Staphylococcus aureus is a gram-positive bacterium known for causing various infections, but it does not form endospores. Escherichia coli is a gram-negative bacterium commonly found in the intestines of humans and animals, but it does not produce endospores. Neisseria gonorrhoeae is a gram-negative bacterium that causes the sexually transmitted infection gonorrhea, but it also does not form endospores.
The most important mechanism of tetracycline resistance is
- A. Reduced active influx by alteration of transport molecules
- B. Reduced passive influx due to altered cell membrane components
- C. Increased active efflux from the bacterial cell
- D. Direct enzymatic inactivation of the antibiotic
Correct Answer: C
Rationale: The correct answer is C: Increased active efflux from the bacterial cell. This is the most important mechanism of tetracycline resistance because it involves the bacteria actively pumping out the antibiotic, reducing its intracellular concentration. This prevents tetracycline from effectively targeting bacterial ribosomes. Choice A is incorrect as tetracycline resistance typically involves active efflux rather than reduced influx. Choice B is incorrect because tetracycline resistance mechanisms do not primarily involve altered cell membrane components affecting passive influx. Choice D is also incorrect as tetracycline resistance mechanisms do not typically involve direct enzymatic inactivation of the antibiotic.
The time response measures all of the following except:
- A. ED50
- B. Peak effect time
- C. Onset of response
- D. Threshold level
Correct Answer: A
Rationale: The correct answer is A: ED50. The time response does not measure the ED50 because ED50 refers to the effective dose needed to produce a response in 50% of the population, which is a dose-related concept, not a time-related one. Peak effect time, onset of response, and threshold level are all time-related measures in pharmacology. Peak effect time is the time taken to reach the maximum response, onset of response is the time taken for the response to start, and threshold level is the minimum dose or concentration required to produce a response. Therefore, A is the correct answer as it is the only choice that is not a time-related measure in this context.