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A Gram-negative, comma-shaped bacterium was isolated from a patient with cholera. What is the most likely causative agent?
- A. Vibrio cholerae
- B. Shigella dysenteriae
- C. Salmonella typhi
- D. Campylobacter jejuni
Correct Answer: A
Rationale: The correct answer is A: Vibrio cholerae. This is because Vibrio cholerae is a Gram-negative, comma-shaped bacterium known to cause cholera. The characteristic shape and the association with cholera make it the most likely causative agent in this case.
Explanation for incorrect choices:
B: Shigella dysenteriae - Shigella dysenteriae is a Gram-negative bacterium that causes bacillary dysentery, not cholera.
C: Salmonella typhi - Salmonella typhi is a Gram-negative bacterium that causes typhoid fever, not cholera.
D: Campylobacter jejuni - Campylobacter jejuni is a Gram-negative bacterium that commonly causes foodborne gastroenteritis, not cholera.
You may also like to solve these questions
Which statement about the epidemiology and specific prophylactic of Haemophilus influenzae is NOT CORRECT?
- A. Non-encapsulated strains can be isolated from healthy carriers
- B. There is an effective killed vaccine, protective against all capsular types of Haemophilus spp.
- C. The infection is airborne
- D. None of the above
Correct Answer: B
Rationale: The correct answer is B because there is no effective killed vaccine that is protective against all capsular types of Haemophilus spp. The Haemophilus influenzae vaccine primarily targets specific capsular types, not all of them. Choice A is incorrect because non-encapsulated strains can indeed be isolated from healthy carriers. Choice C is incorrect as Haemophilus influenzae is primarily transmitted through respiratory droplets, not through the air. Choice D is not correct because Choice B is indeed incorrect, making it the right answer.
Which of the following bacteria is associated with the disease tuberculosis?
- A. Mycobacterium leprae
- B. Mycobacterium tuberculosis
- C. Streptococcus pneumoniae
- D. Neisseria gonorrhoeae
Correct Answer: B
Rationale: Step 1: Mycobacterium tuberculosis is a bacterium known to cause tuberculosis.
Step 2: Mycobacterium leprae causes leprosy, not tuberculosis.
Step 3: Streptococcus pneumoniae causes pneumonia, not tuberculosis.
Step 4: Neisseria gonorrhoeae causes gonorrhea, not tuberculosis.
Conclusion: Mycobacterium tuberculosis is the correct answer as it is the only bacterium associated with tuberculosis among the choices provided.
Which are the most suitable materials for isolation of polio viruses
- A. feces, duodenal and bile content
- B. blood, sputum and urine
- C. only feces
- D. feces, nasopharyngeal swabs and cerebrospinal fluid
Correct Answer: D
Rationale: The correct answer is D because polio viruses are primarily found in the gastrointestinal tract and respiratory secretions. Feces, nasopharyngeal swabs, and cerebrospinal fluid are the most suitable materials for isolating polio viruses due to their presence in these body fluids. Feces contain the virus shed from the intestines, nasopharyngeal swabs collect respiratory secretions where the virus may be present, and cerebrospinal fluid is important for detecting the virus in cases of neurological complications. Choices A and B include irrelevant body fluids that are not typically associated with polio virus transmission. Option C is too limited as the virus can also be present in respiratory secretions and cerebrospinal fluid, not just feces.
During the skill-building session in microbiology the students need to stain the prepared and fixed sputum smears obtained from a tuberculosis patient. What staining technique should be used in this case?
- A. Gram
- B. Giemsa
- C. Ziehl-Neelsen
- D. Burri
Correct Answer: C
Rationale: The correct staining technique for sputum smears obtained from a tuberculosis patient is Ziehl-Neelsen staining. This technique uses carbol fuchsin dye to stain the acid-fast bacteria, such as Mycobacterium tuberculosis, red. Here's a step-by-step rationale:
1. Ziehl-Neelsen staining is specifically designed to detect acid-fast bacteria like Mycobacterium tuberculosis.
2. Carbol fuchsin dye is used to penetrate the mycolic acid layer in the cell wall of the bacteria, making them resistant to decolorization.
3. Acid-alcohol is used as a decolorizer to remove the stain from non-acid-fast bacteria.
4. Methylene blue is used as a counterstain to visualize non-acid-fast bacteria in blue.
Therefore, Ziehl-Neelsen staining is the most appropriate technique for identifying Mycobacterium tuberculosis in sputum smears.
Other choices like Gram, Giemsa, and
A 28 y.o. patient without permanent residence was admitted to the hospital with the preliminary diagnosis influenza. On the fith day of illness he got a maculopapular petechial rash on his body and internal surfaces of extremities. Body temperature is 410 C, euphoria, face hyperemia, sclera reddening, tongue tremor, tachycardia, splenomegaly, excitement. What is the most probable diagnosis?
- A. Epidemic typhus
- B. Delirium alcoholicum
- C. Leptospirosis
- D. Measles
Correct Answer: A
Rationale: Step 1: Initial diagnosis of influenza suggests a viral illness.
Step 2: Presence of maculopapular petechial rash and high fever indicates a systemic infection.
Step 3: Symptoms like euphoria, hyperemia, tachycardia, splenomegaly, and excitement are characteristic of epidemic typhus.
Step 4: Face hyperemia, sclera reddening, and tongue tremor are specific to epidemic typhus.
Step 5: Epidemic typhus is transmitted by body lice, which fits the scenario of a patient without permanent residence.
Summary:
- Delirium alcoholicum is unlikely due to the specific symptoms and lack of history of alcohol abuse.
- Leptospirosis typically presents with jaundice and renal symptoms, not seen in this case.
- Measles rash is different from the maculopapular petechial rash described.