The capsule of Bacillus anthracis is made of

Correct Answer: B

Rationale: The capsule of Bacillus anthracis is made of polypeptide. This is because the capsule is composed of a protein-based material that surrounds the bacterium, providing protection and aiding in its virulence. Polysaccharides, lipids, and the absence of capsules are not characteristic of Bacillus anthracis' capsule structure, making choices A, C, and D incorrect, respectively.

Correct Answer: B

Rationale: The correct answer is B: non-spore forming encapsulated gram-negative bacterium. Francisella tularensis is a non-spore forming bacterium, which rules out choices A and D. It is encapsulated, which eliminates choice C. The encapsulation of the bacterium helps it evade the host immune system, leading to its pathogenicity. This encapsulated bacterium is responsible for causing the zoonotic disease tularemia in humans.

Correct Answer: A

Rationale: The correct answer is A: Streptococcus pyogenes. 1. Gram-positive cocci in chains suggest streptococci. 2. Beta-hemolytic activity indicates Streptococcus pyogenes. 3. Streptococcus pyogenes is commonly associated with sore throat (pharyngitis) and fever. 4. Streptococcus pneumoniae (choice B) is alpha-hemolytic and mainly causes pneumonia. 5. Enterococcus faecalis (choice C) is not typically associated with sore throat. 6. Staphylococcus aureus (choice D) is not commonly beta-hemolytic and is not a typical cause of pharyngitis.

Correct Answer: A

Rationale: The correct answer is A: Mycolic acid in the cell wall. Mycolic acid is a unique component of the cell wall of Mycobacterium species, including the causative agent of tuberculosis. The Ziehl-Neelsen method uses acid-fast staining, where mycolic acid confers resistance to decolorization by acid-alcohol, causing the bacteria to retain the red stain. Choices B, C, and D are incorrect as capsules, flagella, and peptidoglycan layers do not directly contribute to acid-fast staining characteristic of Mycobacterium species.

Correct Answer: A

Rationale: The correct answer is A: Tetanus. The symptoms of tonic tension of the masticatory muscles following a dog bite are indicative of tetanus, caused by the bacterium Clostridium tetani. The incubation period of tetanus is usually 3-21 days, consistent with the patient's history of being bitten 12 days ago. Tetanus toxin causes muscle stiffness and spasms, leading to the inability to open the mouth. Rabies (B) presents with hydrophobia and neurological symptoms. Hysteria (C) is a psychological condition. Trigeminal neuralgia (D) is characterized by severe facial pain, not muscle stiffness.

Correct Answer: B

Rationale: The correct answer is B: protein filaments made of flagellin. Bacterial flagella are composed of flagellin proteins arranged in helical filaments. This structure allows for movement and propulsion of bacteria. A: 9+2 microtubule arrangement is incorrect because this structure is typically found in eukaryotic flagella, not bacterial flagella. C: Lipid bilayer is incorrect as it is a structural component of cell membranes, not bacterial flagella. D: Peptidoglycan layer is incorrect as it is a component of bacterial cell walls, not flagella.

Correct Answer: D

Rationale: Step 1: Formic acid is produced during fermentation by Actinomyces. Step 2: Actinomyces are known to produce organic acids like formic acid through fermentation. Step 3: Other choices like Streptococcus, Klebsiella, and Clostridium are not typically associated with formic acid production. Step 4: Actinomyces is the most likely candidate based on its fermentation capabilities. Summary: Actinomyces is the correct answer because it is known to produce formic acid during fermentation, while the other choices lack this specific metabolic function.

Correct Answer: A

Rationale: The correct answer is A: Amikacin sulfate. Pseudomonas aeruginosa is commonly resistant to many antibiotics, but aminoglycosides like Amikacin have good activity against it. Step 1: Identify the pathogen causing the infection. Step 2: Consider the antibiotic's spectrum of activity against the pathogen. Step 3: Choose an antibiotic with proven efficacy. Amikacin is a good choice due to its effectiveness against Pseudomonas. Choice B, Benzylpenicillin, is a penicillin which is not effective against Pseudomonas. Choice C, Cephazolin, is a cephalosporin with limited activity against Pseudomonas. Choice D, Erythromycin, is a macrolide which is not effective against Pseudomonas.

Correct Answer: A

Rationale: The most likely diagnosis is A: Botulism. The symptoms, such as nausea, vomiting after eating canned vegetables, dry mucous membranes, muscular hypotonia, anisocoria, mydriasis, dysphagia, and dysarthria, are classic signs of botulism poisoning. Botulism is caused by the neurotoxin produced by Clostridium botulinum bacteria found in improperly canned or preserved food. The neurotoxin affects the nervous system, leading to symptoms like those described. Shigellosis (B), Salmonellosis (C), and Cholera (D) typically present with different symptoms such as diarrhea, fever, and abdominal pain, which are not seen in this patient.