Correct Answer: B

Rationale: The correct answer is B: Anatoxin. An anatoxin is a toxin that has been rendered harmless while retaining its ability to stimulate an immune response. Gas gangrene is caused by the toxins produced by Clostridium perfringens, not the bacteria itself.
Therefore, vaccination with an anatoxin can trigger the immune system to produce antibodies against the toxin, providing immunity against the disease.

A: Killed whole cell vaccine - Gas gangrene is caused by toxins, not the whole bacterium. This type of vaccine may not be effective in preventing the disease.
C: There is no specific prevention by vaccination - This is incorrect, as vaccination with an anatoxin can prevent gas gangrene.
D: Alive attenuated vaccine - Attenuated vaccines contain live, weakened forms of the pathogen. However, for gas gangrene prevention, targeting the specific toxin with an anatoxin vaccine is more appropriate.

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: The correct answer is A: Staphylococcus aureus. Staphylococcus aureus is a Gram-positive bacterium that commonly presents as cocci in clusters. It is a known causative agent of abscesses due to its ability to produce enzymes and toxins that contribute to tissue destruction. In this case, the presence of Gram-positive cocci in clusters aligns with the characteristic morphology of Staphylococcus aureus.

Summary of incorrect choices:
B: Streptococcus pyogenes is a Gram-positive bacterium that typically presents as cocci in chains, not clusters. It is more commonly associated with pharyngitis and skin infections rather than abscesses.
C: Enterococcus faecalis is a Gram-positive bacterium that typically presents as cocci in pairs or short chains, not clusters. It is more commonly associated with urinary tract infections and endocarditis.
D: Micrococcus luteus is a Gram-positive bacterium that typically presents as t

Correct Answer: B

Rationale: The correct answer is B: pasteurization. This process involves heating food to a specific temperature to kill harmful bacteria while preserving the flavor and quality of the food. Sanitation (
A) refers to maintaining cleanliness to prevent contamination. Disinfection (
C) involves killing most, but not all, microbes on surfaces. Purification (
D) typically refers to the process of removing impurities, not specifically targeting microbes. In this case, pasteurization best describes the process of reducing harmful microbes in food without completely eliminating all microorganisms.

Correct Answer: B

Rationale: The correct answer is B: M.tuberculosis. The description of bacillus in the form of accumulations resembling a pack of cigarettes and staining red with Ziehl-Neelsen staining is characteristic of Mycobacterium tuberculosis. M.leprae (
Choice
A) is associated with leprosy and does not typically appear as described. A.bovis (
Choice
C) is a type of Mycobacterium but is not typically found in the oral cavity. A.israilii (
Choice
D) is not associated with the characteristics mentioned in the question.
Therefore, based on the specific characteristics described, M.tuberculosis is the most likely pathogenic organism revealed in the tissue sampling.