Nokea
The main function of siderophores in bacteria is:
- A. to enhance antibiotic resistance
- B. to sequester iron from the environment
- C. to form capsules
- D. to perform oxidative phosphorylation
Correct Answer: B
Rationale: The correct answer is B: to sequester iron from the environment. Siderophores are molecules produced by bacteria to chelate and acquire iron, an essential nutrient for their growth and survival. By sequestering iron, bacteria can compete with host cells and other microbes for this vital resource. This enhances their ability to thrive and establish infections. Choices A, C, and D are incorrect because siderophores do not directly enhance antibiotic resistance, form capsules, or perform oxidative phosphorylation. These functions are unrelated to the primary role of siderophores in iron acquisition.
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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.
A 40-year-old man developed skin redness and swelling in the neck area, where eventually a small abscess appeared. On section the focus is dense and yellow-green colored, in the purulent masses there are white granules. Histologically there are fungal druses, plasma and xanthoma cells, and macrophages detected. Specify the most correct etiological name of this pathological process:
- A. Syphilis
- B. Carbuncle
- C. Actinomycosis
- D. Leprosy
Correct Answer: C
Rationale: The correct answer is C: Actinomycosis. Actinomycosis is a chronic suppurative bacterial infection caused by Actinomyces species, which form sulfur granules in purulent masses surrounded by dense fibrous tissue. In this case, the presence of fungal druses, plasma cells, xanthoma cells, and macrophages in the histological examination is characteristic of actinomycosis. The clinical presentation of skin redness, swelling, and abscess formation in the neck area also aligns with actinomycosis.
Choice A: Syphilis is caused by Treponema pallidum, presenting with a painless chancre at the site of infection, not skin redness and swelling in the neck area.
Choice B: Carbuncle is a bacterial skin infection involving a group of hair follicles, typically on the back of the neck, not characterized by fungal druses or sulfur granules.
Choice D: Leprosy
Bacterial families have general:
- A. Morphologic features
- B. Geographic features
- C. Historical features
- D. Physiologic features
Correct Answer: A
Rationale: The correct answer is A: Morphologic features. Bacterial families are classified based on their morphologic features such as shape, size, and arrangement. This classification helps in identifying and studying different bacterial species. Choice B, Geographic features, is incorrect as bacterial classification is not based on their geographic distribution. Choice C, Historical features, is incorrect as it does not play a role in the classification of bacterial families. Choice D, Physiologic features, is also incorrect as physiological characteristics are used for further classification within bacterial families, not as a general characteristic.
A child entering the school for the first time was given Mantoux test in order to determine if there was a need for revaccination. The reaction was negative. What is the meaning of this test result?
- A. No cell-mediated immunity to tuberculosis
- B. Availability of cell-mediated immunity to tuberculosis
- C. No antibodies to the tuberculosis bacteria
- D. No anti-toxic immunity to tuberculosis
Correct Answer: B
Rationale: The correct answer is B: Availability of cell-mediated immunity to tuberculosis. A negative Mantoux test indicates the presence of an immune response to the TB bacteria, as the test measures the body's delayed hypersensitivity reaction to TB antigens. This means the child has been exposed to TB in the past or has been vaccinated, resulting in the development of cell-mediated immunity against TB.
Incorrect choices:
A: No cell-mediated immunity to tuberculosis - This is incorrect as a negative Mantoux test actually indicates the presence of cell-mediated immunity.
C: No antibodies to the tuberculosis bacteria - Mantoux test measures cell-mediated immunity, not antibody response.
D: No anti-toxic immunity to tuberculosis - Mantoux test does not assess anti-toxic immunity, it specifically measures cell-mediated immunity.
The most common causative agents of bacterial meningitis are:
- A. Neisseria meningitidis
- B. Streptococcus pneumonia, Neisseria Meningitidis, hemophilus influenz
- C. Rubella virus
- D. Herpangina
Correct Answer: B
Rationale: The correct answer is B because Streptococcus pneumoniae, Neisseria meningitidis, and Haemophilus influenzae are the most common causative agents of bacterial meningitis. Streptococcus pneumoniae is a leading cause in adults, Neisseria meningitidis is common in adolescents and young adults, and Haemophilus influenzae is more frequent in children. The other choices, Rubella virus (C) and Herpangina (D), are not bacterial agents known to cause meningitis.