During the staining of sputum smear of a patient with suspected croupous pneumonia the following reactives and stainers were used: gentian violet solution, Lugol's solution, 960 spiritus and water fuchsin. What method of staining is used in this case?

Correct Answer: A

Rationale: The correct answer is A: Leffler's method. In this staining method, gentian violet solution is used as the primary stain, followed by Lugol's solution as a mordant, 960 spiritus as a decolorizer, and water fuchsin as a counterstain. Gentian violet stains the organisms purple, Lugol's solution helps in fixing the dye, 960 spiritus decolorizes non-specifically, and water fuchsin acts as a counterstain to help visualize the bacteria. Leffler's method is specifically used for staining sputum smears in suspected cases of croupous pneumonia. Summary: B: Gram's staining uses crystal violet, iodine, alcohol, and safranin. It is mainly used for distinguishing between Gram-positive and Gram-negative bacteria. C: Ziehl-Neelsen's staining is used for acid-fast bacteria like Mycobacterium tuberculosis using carbol fuchsin and acid-alcohol

Correct Answer: A

Rationale: The correct answer is A: Entamoeba gingivalis. This organism matches the description provided in the question - unicellular with pseudopodia and ingested white blood cells, commonly found in dental plaque. Entamoeba gingivalis is known to inhabit the oral cavity and is associated with periodontal disease. Trichomonas vaginalis, Giardia lamblia, and Balantidium coli do not match the characteristics mentioned in the question and are not typically found in the oral cavity.

Correct Answer: D

Rationale: The correct answer is D because all three bacteria listed produce toxins that cause damage to host tissues. Clostridium tetani produces tetanospasmin toxin causing tetanus, Vibrio cholerae produces cholera toxin leading to severe diarrhea, and Staphylococcus aureus releases toxins causing tissue damage in various infections. Therefore, all of the above choices are correct in terms of producing toxins that harm host tissues.

Correct Answer: A

Rationale: The correct answer is A: Protozoa. Protozoa are single-celled eukaryotic organisms, meaning they have a nucleus and other membrane-bound organelles. Eukaryotes have complex cellular structures that include a nucleus, mitochondria, and other organelles. Therefore, protozoa are eukaryotes. Viruses (B) are not considered cells and lack cellular structures. Viroids (C) are smaller infectious agents that consist of only RNA, lacking the cellular structure of eukaryotes. Prions (D) are infectious proteins and do not possess cellular structures like eukaryotes. So, protozoa are the only choice that relates to eukaryotes due to their cellular structure.

Correct Answer: B

Rationale: Bacillus cereus is known to cause food poisoning due to the production of toxins in contaminated food. It is not the causative agent of anthrax or endocarditis. The correct answer is B because Bacillus cereus is commonly associated with foodborne illnesses, leading to symptoms such as nausea, vomiting, and diarrhea. It's essential to understand the specific characteristics and pathogenicity of Bacillus cereus to differentiate it from other bacterial infections.

Correct Answer: B

Rationale: The correct answer is B: Phylum. After class in the classification system comes phylum. The classification system starts with the broadest category, which is the kingdom, followed by phylum, class, order, family, genus, and species. Phylum is a higher level of classification than class, so it comes next in the hierarchy. Domain is a higher level than kingdom, and order is a lower level of classification than class. Therefore, the correct sequence is kingdom, phylum, class, order.

Correct Answer: A

Rationale: Rationale: A: Early application of gentamicin is not recommended as a specific treatment for C. difficile-associated post antibiotic diarrhea because it does not have efficacy against C. difficile. B: Metronidazole is recommended as first-line treatment for mild to moderate C. difficile infection. C: Stopping antibiotic treatment and observing the clinical response for 48 hours is not a recommended strategy as prompt treatment is crucial in C. difficile infection. D: Vancomycin per os is an appropriate treatment for severe C. difficile infection. In summary, A is incorrect because gentamicin is not effective against C. difficile, while B, C, and D are potential treatment strategies based on severity of the infection.

Correct Answer: D

Rationale: The correct answer is D because all three bacteria listed (Staphylococcus aureus, Escherichia coli, Clostridium botulinum) can produce toxins leading to food poisoning. Staphylococcus aureus produces heat-stable toxins causing rapid onset of symptoms. Escherichia coli can produce toxins like Shiga toxin leading to severe foodborne illness. Clostridium botulinum produces neurotoxins causing botulism. Choice A, B, and C are incorrect because each bacteria can produce toxins that are harmful if ingested.

Correct Answer: C

Rationale: The correct answer is C: Negative stain. Negative staining uses acidic dyes which are repelled by the bacterial cell wall components, highlighting bacteria with a large amount of peptidoglycan. Acid-fast stain (A) is used to identify Mycobacterium species with waxy cell walls. Gram stain (B) differentiates bacteria into Gram-positive and Gram-negative based on cell wall composition. Option D is a duplicate of option C and is incorrect.