A patient complains of acute spastic abdominal pain, frequent urge to defecate, liquid bloody feces with mucus. Laboratory analysis of fecal smear revealed inconstant in shape organisms with erythrocyte. What is the most likely diagnosis?

Correct Answer: A

Rationale: The correct answer is A: Amebiasis. Amebiasis is caused by the parasite Entamoeba histolytica, presenting with symptoms like acute abdominal pain, bloody diarrhea with mucus, and inconstant shape organisms seen in fecal smear. The presence of erythrocytes supports the diagnosis due to the parasite's ability to invade intestinal mucosa causing bleeding. Choice B (Lambliasis) presents with different symptoms like steatorrhea and fatigue. Choice C (Schistosomiasis) is mainly associated with liver and urinary symptoms. Choice D (Intestinal trichomoniasis) commonly presents with watery diarrhea and does not typically cause bloody stools. Therefore, based on the patient's symptoms and fecal smear findings, Amebiasis is the most likely diagnosis.

Correct Answer: A

Rationale: Step-by-step rationale for the correct answer (A - Clostridium tetani): 1. The patient has convulsive contractions of facial muscles, indicating tetanus. 2. Isolation of bacteria with terminal endospores that have a drumstick appearance is characteristic of Clostridium tetani. 3. Clostridium tetani produces tetanospasmin toxin causing muscle spasms. 4. Therefore, the correct answer is Clostridium tetani (A). Summary of why other choices are incorrect: B: Clostridium botulinum causes botulism, not tetanus. C: Clostridium perfringens causes gas gangrene, not tetanus. D: Bacillus anthracis causes anthrax, not tetanus.

Correct Answer: D

Rationale: The correct answer is D: reemerging diseases. Group II category diseases by the NIAID are those that have reemerged or have the potential to reemerge. This classification helps prioritize research and resources. Choice A is incorrect because new foodborne pathogens fall under different categories. Choice B is incorrect as eradicated diseases are not part of the reemerging group. Choice C is incorrect because bioterrorism agents are classified separately. Therefore, the correct answer is D as it aligns with the purpose of Group II category diseases.

Correct Answer: C

Rationale: The correct answer is C: psychrophiles. Psychrophiles are bacteria that can grow at low temperatures, typically below 20°C. This is because they have adapted to survive and thrive in cold environments. Mesophiles (A) grow best at moderate temperatures, thermophiles (B) thrive in high temperatures, and halophiles (D) prefer high salt concentrations. Psychrophiles are specifically adapted to cold temperatures, making them the correct choice in this scenario.

Correct Answer: C

Rationale: Step 1: Actinomycotic granules are colonies of actinomycetes located in purulent secretions. Step 2: Actinomycosis is a disease caused by actinomycetes forming these granules. Step 3: Actinomycotic granules are typically found in tissue exudates or pus. Step 4: Therefore, choice C is correct as it accurately describes actinomycotic granules. Summary: Choice A is incorrect because actinomycotic granules are not a form of actinomycosis itself, but a characteristic of the disease. Choice B is incorrect as actinomycotic granules are not an additional outer membrane but rather colonies of actinomycetes. Choice D is incorrect as actinomycotic granules are not intracellular inclusions but extracellular colonies found in purulent secretions.

Correct Answer: A

Rationale: Peptidoglycan is a major component of bacterial cell walls, providing structural support and protection. The correct answer is A because peptidoglycan is typically found in the cell wall of bacteria. The cell wall is crucial for maintaining the shape of the bacterial cell and protecting it from external stresses. The plasma membrane (choice B) is primarily composed of phospholipids and proteins, not peptidoglycan. The nucleus (choice C) is found in eukaryotic cells and contains genetic material, not peptidoglycan. The endoplasmic reticulum (choice D) is an organelle involved in protein synthesis and lipid metabolism, but it does not contain peptidoglycan. Therefore, the correct answer is A as peptidoglycan is typically found in the cell wall of bacteria.

Correct Answer: A

Rationale: Step 1: Clostridia of tetanus, botulism, anaerobic gas infection are spore-forming bacteria. Step 2: Spores are resistant structures that allow bacteria to survive in harsh conditions. Step 3: Feces contain these spore-forming bacteria due to contamination. Step 4: When feces are deposited on soil, the spores of these bacteria enter the soil. Step 5: Spores can remain dormant in soil for long periods. Summary: Choice A is correct as spore-forming bacteria enter soil through feces, which act as a source of contamination. Choices B, C, and D are incorrect as they do not involve the direct introduction of spores into soil like feces do.

Correct Answer: B

Rationale: The correct answer is B: Gram's staining method. The rationale for this is as follows: Gentian violet and Lugol's solution are used as primary and mordant stains in the Gram's staining method. Spiritus 960 is used as a decolorizer, and water fuchsin is used as a counterstain. This staining method is commonly used in microbiology to differentiate bacteria into Gram-positive and Gram-negative based on their cell wall characteristics. A: Leffler's staining method is used for the identification of diphtheria bacilli. C: Ziehl-Neelsen's staining method is used for acid-fast bacteria like Mycobacterium tuberculosis. D: Neisser's staining method is used for the identification of Neisseria species. In summary, the use of specific reactives and stainers in the question indicates the application of the Gram's staining method for bacterial differentiation.

Correct Answer: A

Rationale: The correct answer is A: Blood agar. Streptococcus pneumoniae is a fastidious bacterium that requires enriched media for growth. Blood agar provides the necessary nutrients and growth factors for the cultivation of S. pneumoniae, such as blood proteins and hemin. MacConkey agar (B) is selective for gram-negative bacteria and would not support the growth of S. pneumoniae. Peptone water (C) is a liquid medium that lacks the necessary nutrients for the growth of S. pneumoniae. Choice D is incorrect as blood agar is a suitable medium for cultivating S. pneumoniae.