Ebola viruses need to be handled in which of the following biosafety levels?

Correct Answer: D

Rationale: The correct answer is D: BSL4. Ebola viruses are highly infectious and pose a high risk to laboratory workers. BSL4 facilities are designed to handle agents that pose a severe threat to human health and have no available vaccines or treatments. These facilities have strict guidelines for handling infectious agents, including full-body suits, negative air pressure, and decontamination processes to prevent any possible exposure. BSL1, BSL2, and BSL3 are not adequate for handling Ebola viruses due to their lower levels of containment and safety measures.

Correct Answer: D

Rationale: The correct answer is D: rabbit fever. Tularemia is commonly known as rabbit fever due to the fact that it is often contracted through handling infected rabbits or other rodents. This zoonotic disease is caused by the bacterium Francisella tularensis. Scarlet fever (A) is a streptococcal infection characterized by a rash, not related to tularemia. Strep throat (B) is a bacterial infection caused by Streptococcus bacteria and is not associated with tularemia. Cat scratch fever (C) is caused by Bartonella henselae and typically transmitted through cat scratches or bites, not related to tularemia.

Correct Answer: A

Rationale: The correct choice is A: Binding to IgE fixed to mast cells. The Besredka desensitization method involves injecting small, gradually increasing doses of the allergen to induce tolerance and prevent anaphylactic shock. This process works by binding the allergen to IgE antibodies fixed to mast cells, which prevents the release of histamine and other inflammatory mediators that trigger allergic reactions. This desensitization process helps the immune system become less reactive to the allergen over time. Incorrect choices: B: Inhibited synthesis of mast cells mediators - This choice does not reflect the mechanism of the Besredka desensitization method, which involves binding to IgE on mast cells. C: Stimulation of the immunological antigen tolerance - While this may sound plausible, the Besredka method specifically targets the IgE-mast cell interaction. D: Stimulation of antigen-specific IgG synthesis - While IgG antibodies may play a role in desensitization, the

Correct Answer: A

Rationale: The correct answer is A: Candida fungi. Candida fungi are known to cause oral thrush, characterized by whitish spots on the oral mucosa. The presence of gram-positive oval budding cells in the smear preparations is indicative of Candida species. Staphylococci (choice B) are gram-positive cocci, not oval budding cells. Sarcinae (choice C) are gram-positive bacteria that form cuboidal packets, not oval budding cells. Actinomycetes (choice D) are filamentous gram-positive bacteria, not oval budding cells like Candida fungi.

Correct Answer: A

Rationale: The correct answer is A because penicillins and cephalosporins inactivate transpeptidase activity of penicillin binding proteins, leading to disruption of bacterial cell wall synthesis. This mechanism makes them bactericidal, not bacteriostatic (choice B). Choice C is incorrect as penicillins and cephalosporins target cell wall synthesis, not the cytoplasmic membrane. Choice D is incorrect as option A is the correct statement.

Correct Answer: D

Rationale: The correct answer is D: Tuberculosis. Tuberculosis is considered a reemerging disease due to the increase in drug-resistant strains, high global prevalence, and challenges in diagnosis and treatment. This is supported by global health organizations' reports on the resurgence of TB cases. A: AIDS is not considered a reemerging disease as there has been significant progress in HIV prevention and treatment. B: Ebola outbreaks are sporadic and localized, not considered reemerging on a global scale. C: West Nile virus outbreaks occur periodically, but it is not considered a reemerging disease compared to TB.

Correct Answer: D

Rationale: The correct answer is D: To determine the children that need to receive BCG vaccination. The Mantoux test is used to identify individuals who have been exposed to Tuberculosis (TB) and need BCG vaccination for protection. Parotitis (choice A) is a viral infection unrelated to TB. Allergization rate toward rickettsia (choice B) and immune stress toward diphtheria (choice C) are not related to the Mantoux test or BCG vaccination. Therefore, choice D is the correct answer as it aligns with the purpose of the Mantoux test.

Correct Answer: A

Rationale: The correct answer is A: Gram staining. This method is used to differentiate bacteria based on their cell wall composition. In cholera, the causative agent is Vibrio cholerae, which is Gram-negative. By performing Gram staining, the bacteria will appear pink/red under the microscope, confirming the presence of Gram-negative bacteria. Choice B: Neisser's staining is used for staining capsules of bacteria, not suitable for confirming cholera diagnosis. Choice C: Ziehl-Neelsen staining is used for acid-fast bacteria like Mycobacterium tuberculosis, not for confirming cholera diagnosis. Choice D: Burri-Gins staining is not a standard staining method in microbiology and is not relevant for confirming cholera diagnosis.

Correct Answer: C

Rationale: Rationale: 1. Both Clostridium botulinum and Bacillus anthracis are known to form spores. 2. Spore formation is a mechanism for survival in harsh conditions. 3. Both bacteria are capable of causing severe diseases in humans. Summary: - Choice A and B are incorrect because each bacteria listed is capable of spore formation. - Choice D is incorrect as both bacteria mentioned can form spores to survive extreme conditions.