Nokea
Which of the following infectious disease is considered a newly emerging disease?
- A. Hantavirus
- B. Malaria
- C. Tuberculosis
- D. Chlamydia
Correct Answer: A
Rationale: The correct answer is A: Hantavirus. Hantavirus is considered a newly emerging disease because it was first identified in the late 20th century. It is transmitted to humans through rodents and can lead to severe respiratory illness. Malaria, Tuberculosis, and Chlamydia are not considered newly emerging diseases as they have been known for centuries and continue to be prevalent worldwide. Therefore, based on the timeline of discovery and emergence, Hantavirus is the most recent infectious disease among the options provided.
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Which of the following is a disease caused by a protozoan?
- A. Cat scratch disease
- B. Toxoplasmosis
- C. Relapsing fever
- D. Plague
Correct Answer: B
Rationale: The correct answer is B: Toxoplasmosis. Toxoplasmosis is caused by the protozoan Toxoplasma gondii. The rationale for this is that protozoa are single-celled organisms that can cause diseases in humans. Cat scratch disease (A) is caused by a bacterium, Bartonella henselae. Relapsing fever (C) is caused by the bacterium Borrelia recurrentis. Plague (D) is caused by the bacterium Yersinia pestis. Therefore, the only choice caused by a protozoan is toxoplasmosis, making it the correct answer.
After continuous treatment with antibiotics a patient got symptoms of stomatitis. Examination of specimens of oral mucous membrane revealed some oval polymorphous Gram-positive microorganisms arranged in clusters. What microorganism may be the cause of such manifestations?
- A. С.albicans
- B. C.perfringens
- C. S.aureus
- D. S.pyogenes
Correct Answer: C
Rationale: The correct answer is C: S.aureus. Stomatitis is commonly caused by S.aureus due to its ability to form clusters of oval polymorphous Gram-positive microorganisms. S.aureus is known to colonize the oral mucous membrane and can cause infections, especially after prolonged antibiotic use.
Explanation for other choices:
A: С.albicans - Candida albicans is a fungus commonly associated with oral thrush, not typically causing stomatitis.
B: C.perfringens - Clostridium perfringens is a bacterium associated with food poisoning and gas gangrene, not commonly causing stomatitis.
D: S.pyogenes - Streptococcus pyogenes is known to cause strep throat and skin infections, but not typically associated with stomatitis.
For enteropathogenic E. coli is true:
- A. They attach to enterocytes and destroy microvillus
- B. They are invasive and produce enterotoxin (no enterotoxin)
- C. Cause disease clinically similar to bacterial
- D. None of the above
Correct Answer: A
Rationale: Correct Answer: A
Rationale:
1. Enteropathogenic E. coli (EPEC) attach to enterocytes via a type III secretion system.
2. Once attached, they form attaching and effacing lesions on the microvilli, leading to microvillus destruction.
3. This mechanism allows EPEC to cause diarrhea by disrupting the normal absorptive function of the intestines.
Summary:
- B (They are invasive and produce enterotoxin) is incorrect because EPEC are non-invasive and do not produce enterotoxins.
- C (Cause disease clinically similar to bacterial) is vague and does not provide specific information about EPEC pathogenesis.
- D (None of the above) is incorrect as A is the correct explanation for EPEC pathogenicity.
Which of the following methods is the simplest heat-related method to sterilize metal?
- A. Incineration
- B. Autoclaving
- C. Direct flaming
- D. Indirect heating
Correct Answer: C
Rationale: The correct answer is C: Direct flaming. Direct flaming is the simplest heat-related method to sterilize metal because it involves passing the metal through a flame to kill microorganisms. The high temperature of the flame effectively destroys any bacteria or spores present on the metal surface. Incineration (A) is not practical for sterilizing metal as it involves burning at extremely high temperatures. Autoclaving (B) uses steam under pressure to sterilize, which is effective but more complex than direct flaming. Indirect heating (D) is not an effective method for sterilizing metal as it does not directly expose the metal to high temperatures required for sterilization.
Which bacteria are responsible for causing the disease known as syphilis?
- A. Treponema pallidum
- B. Neisseria gonorrhoeae
- C. Chlamydia trachomatis
- D. Escherichia coli
Correct Answer: A
Rationale: The correct answer is A: Treponema pallidum. This bacterium is responsible for causing syphilis due to its unique spiral shape and ability to penetrate intact mucous membranes. It is transmitted through sexual contact or from mother to child during pregnancy. Neisseria gonorrhoeae causes gonorrhea, Chlamydia trachomatis causes chlamydia, and Escherichia coli is a common bacterium found in the gut and not associated with syphilis. Treponema pallidum's specific characteristics and mode of transmission distinguish it from the other choices, making it the correct answer.