A 37-year-old male was admitted to a hospital complaining of abdominal pain, difficulty in swallowing and breathing, constipation, and nausea. He developed respiratory failure and required endotracheal intubation and ventilation. Two days before, the patient consumed dried salted fish bought from an artisanal producer. Laboratory investigation for infectious pathogen was performed using Kitt-Tarozzi's method. Observation under a bright field microscopy revealed the presence of typical microorganisms with tennis racket appearance. Which of the following is the most likely diagnosis?

Correct Answer: A

Rationale: The correct answer is A: Botulism. Botulism is caused by the toxin produced by Clostridium botulinum bacteria found in improperly preserved or canned foods. The symptoms described align with botulism, such as difficulty swallowing and breathing due to muscle paralysis. The tennis racket appearance seen under microscopy corresponds to the characteristic appearance of Clostridium botulinum spores. The other choices can be ruled out based on the clinical presentation and microscopy findings. Cholera typically presents with severe watery diarrhea, Nontyphoidal Salmonella infection with fever and gastrointestinal symptoms, and Typhoid fever with high fever and abdominal pain. Therefore, the most likely diagnosis in this case is botulism.

Correct Answer: B

Rationale: The primary function of bacterial capsules is to aid in adhesion and protect against phagocytosis. Capsules help bacteria adhere to surfaces and evade immune system detection by preventing phagocytosis. This is important for bacterial survival and colonization in host organisms. Choice A, protein synthesis, is incorrect as capsules do not directly participate in this process. Choice C, facilitate motility, is incorrect as capsules are not involved in bacterial movement. Choice D, synthesize DNA, is incorrect as capsules do not have a role in DNA synthesis. Thus, the correct answer is B.

Correct Answer: C

Rationale: The correct answer is C: Bacteriophages are viruses that infect bacteria. Firstly, bacteriophages are viruses, not white blood cells or bacteria. They specifically target and infect bacteria, not fungi. This is known as a bacteriophage cycle where the virus injects its genetic material into the bacterial cell to replicate and eventually lyse the cell. This process is specific to bacteria and distinguishes bacteriophages from other microorganisms. Therefore, the correct answer is C as it accurately describes the nature and function of bacteriophages.

Correct Answer: B

Rationale: The correct answer is B: Vibrio cholerae. Vibrio cholerae is a comma-shaped rod bacterium that causes high volume watery diarrhea by producing cholera toxin. This toxin leads to the secretion of large amounts of fluid into the intestines. Campylobacter jejuni (A) typically causes bloody diarrhea. Pseudomonas aeruginosa (C) and Proteus mirabilis (D) are not associated with high volume watery diarrhea.

Correct Answer: B

Rationale: The correct answer is B: pertussis toxin. This toxin is the most important virulence factor of Bordetella pertussis because it plays a key role in causing the characteristic symptoms of whooping cough. Pertussis toxin interferes with the host's immune response, leading to inflammation and tissue damage in the respiratory tract. The other choices (A: the flagellum, C: P fimbriae, D: mannose-resistant adhesins) are important for bacterial attachment and colonization, but they do not directly contribute to the severity of the disease like pertussis toxin does.

Correct Answer: B

Rationale: The correct answer is B: septicemia. Septicemia specifically refers to the presence of bacteria in the bloodstream, leading to a systemic inflammatory response. Bacteremia (choice A) is simply the presence of bacteria in the blood without the systemic inflammatory response. Shock (choice C) is a state of circulatory collapse, often seen in severe septicemia. Bloodborne infection (choice D) is a general term for infections transmitted through the blood but does not specifically refer to the condition of bacterial multiplication causing toxicity.

Correct Answer: C

Rationale: The primary target of beta-lactam antibiotics is cell wall synthesis. These antibiotics inhibit enzymes called penicillin-binding proteins, which are essential for building the bacterial cell wall. By disrupting cell wall synthesis, beta-lactam antibiotics weaken the cell wall, leading to bacterial cell lysis and death. Protein synthesis (Choice A), DNA replication (Choice B), and folic acid synthesis (Choice D) are not directly targeted by beta-lactam antibiotics, making them incorrect choices.

Correct Answer: A

Rationale: The correct answer is A: Motility. Native microscopic slides are ideal for observing motility because they allow for the observation of living microorganisms in their natural state. By observing the movement of microorganisms on a native slide, one can assess their motility characteristics accurately. Choice B (Division) is incorrect because native slides may not provide the ideal conditions for observing cell division, as it may be difficult to capture the exact moment of division in a live organism. Choice C (Presence of capsules) is also incorrect because observing capsules usually requires specific staining techniques that may not be suitable for native slides. Choice D (None of the above) is incorrect as native slides are indeed beneficial for observing motility.

Correct Answer: C

Rationale: Rationale: 1. Psychrophilic: Grow best in cold temperatures 2. Mesophilic: Grow best in moderate temperatures 3. Thermophilic: Grow best in high temperatures - Choice A is incorrect as "thermophobic" is not a recognized term. - Choice B is incorrect as "psychophobic" is not a recognized term. - Choice D is incorrect as "mesophobic" is not a recognized term.