Nokea
The bacteria that produces a thick pseudomembrane in the throat is:
- A. Corynebacterium diphtheriae
- B. Streptococcus pyogenes
- C. Neisseria meningitidis
- D. Bacillus cereus
Correct Answer: A
Rationale: Rationale:
1. Corynebacterium diphtheriae is the correct answer as it is the bacteria responsible for causing diphtheria, characterized by a thick pseudomembrane in the throat.
2. Streptococcus pyogenes causes strep throat but does not produce a pseudomembrane.
3. Neisseria meningitidis causes meningitis and septicemia, not a throat pseudomembrane.
4. Bacillus cereus causes food poisoning, not throat-related symptoms.
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All are correct except:
- A. Spotted fevers can be caused by Rickettsia mooseri and Rickettsia provazekii
- B. The Q-fever is transmitted only after ticks bite
- C. The Mediterranean fever is present with maculopapular rash
- D. None of the above
Correct Answer: B
Rationale: The correct answer is B because Q-fever is not transmitted only after ticks bite; it can also be transmitted through inhalation of contaminated aerosols. Rickettsia mooseri and Rickettsia provazekii can cause spotted fevers, making choice A correct. Mediterranean fever is associated with a recurrent pattern of fever, not maculopapular rash, making choice C incorrect. "None of the above" is not correct in this case as choice B is incorrect.
Which of the following bacteria produces an endotoxin responsible for septic shock?
- A. Staphylococcus aureus
- B. Escherichia coli
- C. Neisseria meningitidis
- D. All of the above
Correct Answer: D
Rationale: The correct answer is D, "All of the above." Staphylococcus aureus, Escherichia coli, and Neisseria meningitidis all produce endotoxins that can lead to septic shock. Endotoxins are part of the outer membrane of Gram-negative bacteria, such as E. coli and N. meningitidis, which can trigger a severe immune response leading to septic shock. S. aureus, a Gram-positive bacterium, produces toxins that can also contribute to septic shock. Therefore, all of these bacteria can produce endotoxins responsible for septic shock. Choices A, B, and C are incorrect because they only identify individual bacteria that produce endotoxins, whereas the correct answer encompasses all bacteria listed.
A patient who came to the doctor because of his infertility was administered to make tests for toxoplasmosis and chronic gonorrhoea. Which reaction should be performed to reveal latent toxoplasmosis and chronic gonorrhoea in this patient?
- A. RIHA - Reverse indirect hemagglutination assay
- B. RDHA - Reverse direct hemagglutination assay
- C. IFA - Immunofluorescence assay
- D. Immunoblot analysis
Correct Answer: C
Rationale: The correct answer is C: IFA - Immunofluorescence assay. Toxoplasmosis and chronic gonorrhea can be detected using serological tests like IFA. IFA detects specific antibodies in the patient's serum by using fluorescently labeled antibodies. This method is highly sensitive and specific for detecting both acute and latent infections.
Explanation of Incorrect Choices:
A: RIHA - Reverse indirect hemagglutination assay - This test is not commonly used for detecting toxoplasmosis or chronic gonorrhea.
B: RDHA - Reverse direct hemagglutination assay - This test is not typically used for these specific infections.
D: Immunoblot analysis - While Immunoblot analysis is a useful confirmatory test for certain infections, it is not the primary method for detecting toxoplasmosis or chronic gonorrhea.
A 42-year-old woman has foamy purulent vaginal discharges. Microscopy revealed flagellated protozoa with an undulating membrane and pear-shaped structure. What organism was found?
- A. Trichomonas vaginalis
- B. Trypanosoma gambiense
- C. Leishmania donovani
- D. Lamblia intestinalis
Correct Answer: A
Rationale: The correct answer is A: Trichomonas vaginalis. Trichomonas vaginalis is a sexually transmitted protozoan parasite that causes trichomoniasis, characterized by foamy purulent vaginal discharges. Microscopy of vaginal discharge showing flagellated protozoa with an undulating membrane and pear-shaped structure is indicative of Trichomonas vaginalis. Trypanosoma gambiense causes African sleeping sickness and is transmitted by tsetse flies. Leishmania donovani causes visceral leishmaniasis transmitted by sandflies. Lamblia intestinalis causes giardiasis and is characterized by diarrhea and flatulence.
All statements about plasmids are correct except:
- A. Many plasmids contain genes that confer resistance to one or more antibiotics
- B. Are smaller, circular, extrachromosomal DNAs
- C. Plasmids encode essential bacteria properties
- D. Plasmids are responsible for the bacterial conjugation
Correct Answer: C
Rationale: The correct answer is C because plasmids do not encode essential bacterial properties. They are non-essential, extra-chromosomal DNA molecules that can replicate independently within bacterial cells. Plasmids mainly contain genes for antibiotic resistance, genetic transfer, and other specific functions. Choice A is correct as many plasmids do carry antibiotic resistance genes. Choice B is also accurate as plasmids are indeed smaller, circular, and exist outside the bacterial chromosome. Choice D is true as plasmids can facilitate bacterial conjugation, allowing the transfer of genetic material between bacteria.