A bacteriological laboratory received sputum sample of a patient suffering from tuberculosis. Bacterioscopic examination of smears and detection of tuberculosis bacillus can be realized by one of enrichment methods that involves processing of sputum only with solution of caustic soda. What is this method called?

Correct Answer: B

Rationale: The correct answer is B: Inactivation. In this method, the sputum sample is processed with a solution of caustic soda, which helps to kill any contaminants present and preserve the tuberculosis bacillus for microscopic examination. This step is crucial in ensuring accurate detection of the bacillus. A: Homogenization involves breaking down the sample to make it uniform, but it does not necessarily involve using caustic soda for inactivation. C: Flotation is a method used to separate different components based on their density and is not specific to inactivating tuberculosis bacillus. D: Filtration involves passing a sample through a filter to separate particles based on size and is not related to inactivating the tuberculosis bacillus.

Correct Answer: A

Rationale: Rationale: The description matches that of Streptococcus pneumoniae, which appears as gram-positive diplococci with slightly pointed opposite ends. Staphylococcus aureus, Neisseria gonorrhoeae, and Neisseria meningitidis do not match the specific characteristics described in the question. Staphylococcus aureus appears in grape-like clusters, while Neisseria species are typically seen as diplococci but lack the pointed shape described. Therefore, the correct answer is A: Staphylococcus aureus.

Correct Answer: A

Rationale: The correct answer is A: Corynebacterium diphtheriae. This bacterium produces the diphtheria toxin, which is responsible for causing diphtheria. The other choices, B, C, and D, are incorrect because Bacillus anthracis produces anthrax toxins, Clostridium tetani produces tetanus toxin, and Listeria monocytogenes does not produce the diphtheria toxin. Understanding the specific bacteria-toxin associations is crucial in correctly identifying the pathogen responsible for a particular disease.

Correct Answer: D

Rationale: The correct answer is D: All of the above. - Streptococcus pneumoniae is a common cause of community-acquired pneumonia. - Mycobacterium tuberculosis can cause pulmonary tuberculosis, which can present as pneumonia-like symptoms. - Pseudomonas aeruginosa is an opportunistic pathogen that can cause pneumonia in immunocompromised individuals. Therefore, all three bacteria can cause pneumonia, making option D the correct choice. Options A, B, and C are incorrect because they each represent a bacterium that can cause pneumonia, so only selecting one of them would not encompass all common causes of pneumonia.

Correct Answer: A

Rationale: Rationale: 1. Bacillary dysentery primarily affects the intestinal tract, not the bloodstream. 2. Bacteremia is rare in bacillary dysentery, as the infection is localized. 3. Isolating bacteria from the blood is not a typical diagnostic feature. 4. Therefore, the correct answer is A. Summary: Bacteria causing bacillary dysentery are not typically isolated from the patient's blood due to the localized nature of the infection. Choices B and C are incorrect as they suggest specific timeframes, which are not relevant to bacteremia in this context. Choice D is incorrect as bacteremia is not associated with bacillary dysentery.

Correct Answer: A

Rationale: The correct answer is A: Homemade canned meat. Botulism is caused by the Clostridium botulinum bacteria, which thrives in low-oxygen environments like improperly canned food. Homemade canned meat poses a higher risk of contamination as it may not have been processed correctly, allowing the bacteria to grow and produce toxins. Custard pastry, sour cream, and strawberries are less likely to cause botulism as they are not typically associated with the bacteria unless improperly handled or stored. Homemade canned meat is the most probable cause based on the characteristic symptoms of botulism and the conditions that favor the growth of Clostridium botulinum in canned food.

Correct Answer: A

Rationale: The correct answer is A: Protozoa. Protozoa are eukaryotic microorganisms, meaning they have a true nucleus and membrane-bound organelles. This relates to the question as eukaryotes are organisms with complex cells containing these features. Viruses (B) are non-living entities that require a host cell to replicate, lacking cellular structures. Viroids (C) are smaller than viruses and consist of only RNA, lacking a protein coat. Prions (D) are misfolded proteins causing diseases but are not considered microorganisms nor do they have cellular structure. Thus, protozoa are the only eukaryotic microorganism group among the options.

Correct Answer: A

Rationale: Step-by-step rationale for answer A: 1. Pseudomonas aeruginosa is known to cause burn wounds infections due to its ability to survive in moist environments. 2. It can cause severe pneumonia in patients with cystic fibrosis due to its resistance to antibiotics and ability to form biofilms. 3. It is a common cause of nosocomial infections in hospitals due to its ability to colonize medical equipment and surfaces. Summary of other choices: B. Pseudomonas aeruginosa typically does not cause food poisoning, as it is not a common pathogen associated with foodborne illnesses. C. Bacterial pharyngitis is usually caused by Streptococcus pyogenes, not Pseudomonas aeruginosa, making this choice incorrect. D. None of the above is incorrect as Pseudomonas aeruginosa is associated with specific infections mentioned in option A.

Correct Answer: A

Rationale: Step-by-step rationale: 1. Warts are caused by human papillomavirus (HPV) due to its ability to infect the skin. 2. HPV infects the top layer of skin and causes the rapid growth of cells, leading to the formation of warts. 3. Herpesvirus (choice B) causes herpes, not warts. 4. HIV (choice C) weakens the immune system but does not directly cause warts. 5. Varicella-zoster virus (choice D) causes chickenpox and shingles, not warts. Summary: Choice A is correct as warts are primarily caused by HPV, which infects the skin cells. Choices B, C, and D are incorrect as they are associated with different viral infections that do not lead to the development of warts.