A 40 year old man noticed a reddening and an edema of skin in the area of his neck that later developed into a small abscess. The incised focus is dense, yellowish-green. The pus contains white granules. Histological examination revealed drusen of a fungus, plasmatic and xanthome cells, macrophages. What type of mycosis is the most probable?

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Microbiology A Systems Approach Test Bank Questions

Question 1 of 9

A 40 year old man noticed a reddening and an edema of skin in the area of his neck that later developed into a small abscess. The incised focus is dense, yellowish-green. The pus contains white granules. Histological examination revealed drusen of a fungus, plasmatic and xanthome cells, macrophages. What type of mycosis is the most probable?

Correct Answer: D

Rationale: The correct answer is D: Sporotrichosis. Sporotrichosis is caused by the fungus Sporothrix schenckii, which commonly presents as a subcutaneous infection. In the given case, the presence of a small abscess with yellowish-green pus containing white granules is indicative of sporotrichosis. The histological examination showing drusen of a fungus, plasmatic and xanthome cells, and macrophages further supports the diagnosis of sporotrichosis. Choice A: Actinomycosis is a bacterial infection caused by Actinomyces species, not a fungal infection. Choice B: Aspergillosis is caused by Aspergillus species and typically presents as a pulmonary infection, not a subcutaneous abscess as described in the case. Choice C: Candidosis is caused by Candida species and usually presents as mucocutaneous infections, not a subcutaneous abscess with the

Question 2 of 9

Antibodies against influenza viruses in a patient's serum can be determined by;

Correct Answer: C

Rationale: The correct answer is C: Reaction haemagglutination inhibition. This method is used to detect antibodies against influenza viruses by measuring the ability of the patient's serum to inhibit haemagglutination. This is a specific and sensitive technique for detecting influenza antibodies. A: Agglutination reaction is not specific for influenza viruses and may give false positives. B: Precipitation reaction in agar gel is not typically used for detecting influenza antibodies. D: Ration haemagglutination is not a standard method for detecting influenza antibodies.

Question 3 of 9

A specimen stained by Ozheshko method contains rod-like microorganisms stained blue with round terminal components stained red. What are these components called?

Correct Answer: A

Rationale: The correct answer is A: Spores. In the Ozheshko staining method, spores appear blue with red terminal components. Spores are reproductive structures produced by some bacteria, fungi, and protozoa. Cilia are short, hair-like structures used for movement. Flagella are long, whip-like structures also used for movement. Capsules are outer protective layers surrounding some bacteria. In this case, the description of rod-like microorganisms with blue staining and red terminal components aligns with the characteristics of spores, making it the correct answer.

Question 4 of 9

A man uses dentures. The dentist has noticed mucosal lecions with a white coating in his oral cavity. Microscopy of the coating detected large oval Gram-positive cells. What microorganisms have caused stomatitis in the patient?

Correct Answer: A

Rationale: The correct answer is A: Yeast-like fungi of Candida genus. Candida is a common cause of oral thrush/stomatitis, characterized by mucosal lesions with white coating. The presence of large oval Gram-positive cells is indicative of Candida species. Actinomycetes (B) are filamentous bacteria and not oval Gram-positive cells. Streptococci (C) are spherical bacteria, not oval, and are not commonly associated with stomatitis. Oral spirochetes (D) are spiral-shaped bacteria and not oval Gram-positive cells typically seen in Candida infections. Thus, A is the correct choice based on the characteristic morphology and clinical presentation.

Question 5 of 9

Which of the following food media can be used for cultivation of Streptococcus pneumoniae:

Correct Answer: A

Rationale: The correct answer is A: Blood agar. Streptococcus pneumoniae is a fastidious bacterium that requires enriched media for growth. Blood agar provides the necessary nutrients and growth factors for the cultivation of S. pneumoniae, such as blood proteins and hemin. MacConkey agar (B) is selective for gram-negative bacteria and would not support the growth of S. pneumoniae. Peptone water (C) is a liquid medium that lacks the necessary nutrients for the growth of S. pneumoniae. Choice D is incorrect as blood agar is a suitable medium for cultivating S. pneumoniae.

Question 6 of 9

Generalization of an intestine infection can be seen in

Correct Answer: A

Rationale: Rationale: 1. Salmonella typhi causes typhoid fever, which can lead to intestinal infections. 2. Shigella flexneri causes dysentery, primarily affecting the colon. 3. Helicobacter pylori causes stomach ulcers, not intestine infections. Summary: A is correct as Salmonella typhi causes intestine infection. B and C are incorrect as they cause different gastrointestinal issues. D is incorrect as A is a valid choice.

Question 7 of 9

During the staining of sputum smear of a patient with suspected croupous pneumonia the following reactives and stainers were used: gentian violet solution, Lugol's solution, 960 spiritus and water fuchsin. What method of staining is used in this case?

Correct Answer: B

Rationale: The correct answer is B: Gram's staining method. The rationale for this is as follows: Gentian violet and Lugol's solution are used as primary and mordant stains in the Gram's staining method. Spiritus 960 is used as a decolorizer, and water fuchsin is used as a counterstain. This staining method is commonly used in microbiology to differentiate bacteria into Gram-positive and Gram-negative based on their cell wall characteristics. A: Leffler's staining method is used for the identification of diphtheria bacilli. C: Ziehl-Neelsen's staining method is used for acid-fast bacteria like Mycobacterium tuberculosis. D: Neisser's staining method is used for the identification of Neisseria species. In summary, the use of specific reactives and stainers in the question indicates the application of the Gram's staining method for bacterial differentiation.

Question 8 of 9

Which of the following is true regarding gonorrhea symptoms in men?

Correct Answer: C

Rationale: The correct answer is C: 10% of the infected men have no symptoms. This is true because gonorrhea can be asymptomatic in some individuals, leading to undiagnosed cases. Testicular pain and epididymal tenderness (choice A) are not typical symptoms of gonorrhea in men. Painful urination (choice B) may or may not be present. Purulent discharge (choice D) is a common symptom but not always present. Therefore, choice C is the most accurate statement regarding gonorrhea symptoms in men.

Question 9 of 9

Which of the following bacteria is responsible for causing the disease known as leprosy?

Correct Answer: A

Rationale: Step-by-step rationale: 1. Mycobacterium leprae is the correct answer because it is the bacterium responsible for causing leprosy. 2. Neisseria gonorrhoeae causes gonorrhea, not leprosy. 3. Escherichia coli is associated with gastrointestinal infections, not leprosy. 4. Staphylococcus aureus causes various skin infections, but not leprosy. In summary, Mycobacterium leprae is the correct choice because it is the specific bacterium known to cause leprosy, while the other options are associated with different diseases.

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