Impression smear of mucosa biopsy material has been obtained from a patient with peptic ulcer disease of the stomach. Gram-negative arcuate bent microorganisms were detected, urease activity test was positive. What microorganisms were detected in the patient?

Correct Answer: A

Rationale: The correct answer is A: Helicobacter. Helicobacter pylori is the main causative agent of peptic ulcer disease and is characterized by its gram-negative arcuate bent shape and positive urease activity. Helicobacter pylori specifically colonizes the stomach mucosa and is associated with various gastrointestinal disorders. Spirochetes (choice B), spirilla (choice C), and Leptospira (choice D) are not typically associated with peptic ulcer disease or stomach mucosa infections, making them incorrect choices in this context.

Correct Answer: B

Rationale: The correct answer is B: Agglutination reaction. This is the most suitable serological reaction for the quick determination of the antigen of the epizootic agent causing mass rodent deaths. In agglutination reaction, antibodies cause the clumping of antigens, allowing for easy visual detection of the presence of the specific antigen. This is efficient for rapid diagnosis in cases of suspected infectious diseases like plague. A: Precipitation reaction is more suitable for identifying soluble antigens, not for quick determination of a specific antigen in this scenario. C: Reaction of passive hemagglutination is used for measuring the presence of antibodies, not antigens. D: Bordet-Gengou test is a specific test for the identification of Bordetella pertussis bacterium, not suitable for this scenario.

Correct Answer: D

Rationale: The correct answer is D: All of the above. Hepatitis B infection can present with jaundice due to liver inflammation, elevated serum aminotransferase levels due to liver damage, and sometimes no symptoms in the acute phase. This comprehensive presentation covers the spectrum of possible clinical manifestations of hepatitis B infection. Choices A and B are correct as they are common manifestations of hepatitis B infection. Choice C is incorrect as hepatitis B infection can indeed present with symptoms, making option D the most appropriate choice.

Correct Answer: A

Rationale: The correct answer is A: Serological. Serological testing involves analyzing blood samples for specific antibodies produced in response to the pertussis infection. This method can detect past infections by identifying the presence of antibodies against the pertussis bacteria in the blood. In this case, since the doctor suspects pertussis infection in both children, serological testing can confirm if they have been exposed to the bacteria. Summary: B: Biological testing does not specifically target pertussis antibodies in the blood. C: Bacteriological testing involves culturing bacteria from samples, which may not be as sensitive for retrospective diagnosis. D: Molecular biological testing focuses on genetic material of the bacteria, which may not provide direct evidence of past infection.

Correct Answer: A

Rationale: 1. Vaccination introduces antigens to stimulate immune response. 2. T and B cells are activated to produce memory cells for long-lasting protection. 3. Active immunity develops over time post-vaccination. 4. Choice A is correct as it accurately describes the process and outcomes. 5. Choice B is incorrect as it contradicts the process of active immunity. 6. Choice C is incorrect as the process of active immunity is consistent regardless of the situation. 7. Therefore, the correct answer is A as it aligns with the mechanism and characteristics of artificial active immunity.

Correct Answer: A

Rationale: The correct answer is A: Bacillus anthracis. The presence of Gram-positive rods in chains with central spores on the Gram stain indicates Bacillus anthracis. This bacterium is known to cause severe pneumonia. Clostridium tetani does not typically cause pneumonia but rather tetanus. Streptococcus pneumoniae is a Gram-positive cocci, not rods. Klebsiella pneumoniae is a Gram-negative bacterium commonly associated with pneumonia, but it does not form central spores.

Correct Answer: C

Rationale: The correct answer is C: It is non-motile and non-spore forming. Pseudomonas aeruginosa is motile due to its flagella and is non-spore forming. A is correct because it is a Gram-negative bacterium, and B is correct as it is oxidase-positive. D is incorrect because C is not true.

Correct Answer: D

Rationale: The correct answer is D: LT enterotoxin. This toxin is specific for Enterotoxigenic E. coli (ETEC) and is responsible for causing diarrhea by increasing cyclic AMP levels in intestinal cells. TSST-1 (choice A) is produced by Staphylococcus aureus, not ETEC. Shiga-like toxin (choice B) is produced by Shigella and EHEC, not ETEC. Erythrogenic toxin (choice C) is produced by Streptococcus pyogenes, not ETEC. Therefore, the LT enterotoxin is the specific toxin associated with ETEC.

Correct Answer: A

Rationale: The likely diagnosis is Meningococcal meningitis (Choice A) due to the presence of Gram-negative diplococci in the cerebrospinal fluid. Neisseria meningitidis is a Gram-negative diplococcus commonly associated with meningococcal meningitis. Fever, chills, and neck stiffness are classic symptoms of bacterial meningitis, and Neisseria meningitidis often presents with these symptoms. Pneumococcal meningitis (Choice B) is caused by Streptococcus pneumoniae, a Gram-positive organism. Haemophilus influenzae (Choice C) is also a Gram-negative organism but typically presents with a different clinical picture. Listeria monocytogenes (Choice D) is a Gram-positive rod and is more commonly associated with meningitis in neonates, elderly, and immunocompromised individuals.