A smear of sputum from the patient with suspected lobar pneumonia was stained with the use of the following stains and reagents: solution of gentian violet, Lugol's solution, 96o alcohol, water-magenta. What staining method was applied in this case?

Correct Answer: A

Rationale: The correct answer is A: Gram staining method. This method involves staining with gentian violet, followed by Lugol's solution, 96% alcohol decolorization, and counterstaining with safranin or water-magenta. This staining sequence allows for the differentiation of bacteria based on their cell wall composition. In the case of lobar pneumonia, the causative agent is typically a bacterium with a cell wall that retains the crystal violet stain after decolorization with alcohol, indicating a Gram-positive bacterium. Summary of Incorrect Choices: B: Ziehl-Nielsen staining is used for acid-fast bacteria like Mycobacterium tuberculosis, not for lobar pneumonia. C: Romanovsky staining is primarily used in the identification of blood cells and blood parasites, not for bacteria. D: Neisser staining is not a commonly used staining method in microbiology for bacterial identification.

Correct Answer: D

Rationale: The correct answer is D because all three bacteria (Salmonella enterica, Escherichia coli, Pseudomonas aeruginosa) are known to produce endotoxins, specifically lipopolysaccharides in their cell walls. Endotoxins are released upon bacterial cell death and can trigger an immune response, leading to septic shock. Salmonella and E. coli are common causes of bacterial infections, while Pseudomonas is associated with nosocomial infections. Therefore, all of the above choices are correct in terms of producing endotoxins that can cause septic shock. Choices A, B, and C are incorrect individually because they do not encompass all the bacteria known to produce endotoxins that can lead to septic shock.

Correct Answer: A

Rationale: The correct answer is A: Streptococcus pneumoniae. This bacterium is a Gram-positive cocci that often appear in pairs and can have a capsule. It is a common cause of sore throat and fever, known as streptococcal pharyngitis. Staphylococcus aureus (B) is a Gram-positive cocci but does not typically form pairs. Neisseria meningitidis (C) is a Gram-negative diplococcus and is more associated with meningitis. Klebsiella pneumoniae (D) is a Gram-negative rod and not typically associated with sore throat and fever.

Correct Answer: B

Rationale: The correct answer is B: Penicillin. Penicillin is the drug of first choice for treating syphilis due to its effectiveness in eradicating the bacterium Treponema pallidum, which causes syphilis. It is the most reliable treatment with well-established efficacy. Gentamicin (A), ciprofloxacin (C), and chloramphenicol (D) are not recommended for treating syphilis as they are not effective against the specific bacteria causing the infection. Penicillin remains the gold standard for syphilis treatment.

Correct Answer: A

Rationale: The correct answer is A: Anthrax. Anthrax is caused by the bacterium Bacillus anthracis, which can form spores that are highly resistant and can survive in the soil for long periods. These spores can remain dormant until they come into contact with a susceptible host, leading to infection. Diphtheria, viral hepatitis, and pertussis are caused by different types of pathogens (bacteria and viruses) that do not have the same ability to persist in soil as anthrax spores. Therefore, the causative agents of these diseases are less likely to exist in the soil for extended periods compared to anthrax spores.

Correct Answer: A

Rationale: The correct answer is A: Mycobacterium tuberculosis. This bacterium is known for causing tuberculosis, as it specifically infects the lungs and can lead to serious respiratory issues. Mycobacterium leprae (Choice B) causes leprosy, not tuberculosis. Escherichia coli (Choice C) is a common bacteria found in the intestines and is not associated with tuberculosis. Streptococcus pneumoniae (Choice D) causes pneumonia, but not tuberculosis. Therefore, the correct choice is A because Mycobacterium tuberculosis is the specific bacterium responsible for causing tuberculosis.

Correct Answer: A

Rationale: The correct answer is A: Chingamin (also known as Chloroquine). Chingamin is the drug of choice for chemoprophylaxis of malaria in regions with high risk. It is effective against Plasmodium falciparum, the most common malaria parasite. Chingamin is well-tolerated, affordable, and has a long track record of use. Sulfalen (Choice B) is not commonly used for malaria prophylaxis. Tetracycline (Choice C) is not recommended for malaria prophylaxis due to poor efficacy and resistance development. Metronidazole (Choice D) is not effective against malaria parasites.

Correct Answer: A

Rationale: The correct answer is A: Mycobacterium tuberculosis. This bacteria is responsible for causing tuberculosis because it is the specific pathogen known to infect the lungs and other parts of the body, leading to the disease. Mycobacterium tuberculosis has unique cell wall components that allow it to evade the immune system and survive in the host. Neisseria meningitidis (B) causes meningitis, not tuberculosis. Salmonella enterica (C) causes food poisoning, not tuberculosis. Streptococcus pneumoniae (D) causes pneumonia, not tuberculosis. Therefore, the correct answer is A based on the specific characteristics and pathogenicity of Mycobacterium tuberculosis.

Correct Answer: D

Rationale: The correct answer is D: Mycobacterium tuberculosis. This bacterium can be transmitted via droplets in the air through coughing or sneezing. It is spread through respiratory droplets containing the bacteria. Streptococcus pneumoniae (A) is transmitted through direct contact with respiratory secretions, not through droplets in the air. Escherichia coli (B) is commonly transmitted through contaminated food or water, not through the air. Clostridium botulinum (C) is typically transmitted through contaminated food, not via respiratory droplets. Therefore, the correct choice is D as it is the only bacterium listed that can be transmitted via droplets in the air.