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: 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: A

Rationale: The correct answer is A: Nystatin. Nystatin is an antifungal medication, not an antibiotic used to treat bacterial infections like generalized meningococcal infection. Penicillin G, macrolides, and chloramphenicol are antibiotics commonly used to treat bacterial infections, including meningococcal infections. Penicillin G is the drug of choice for meningococcal infections, while macrolides and chloramphenicol are alternative options. Nystatin is not effective against bacteria, so it is not a suitable treatment for meningococcal infections.

Correct Answer: B

Rationale: The correct answer is B: genotype. The genotype refers to the actual genetic makeup of an organism, including all the genes and alleles present in its DNA. This determines the traits and characteristics of an organism. Phenotype (A) is the observable physical or biochemical characteristics of an organism. Conjugation (C) is a process in bacteria involving the transfer of genetic material. Construct (D) is not a term related to genetics. Therefore, the correct choice is B as it specifically refers to the genetic composition of an organism.

Correct Answer: A

Rationale: The correct answer is A: prions. Prions are misfolded proteins that can cause spongiform encephalopathy by inducing normal proteins to misfold as well. Prions lack genetic material, distinguishing them from viruses (B), bacteria (C), and fungi (D), which all contain genetic material and cannot directly cause spongiform encephalopathy through protein misfolding.

Correct Answer: D

Rationale: The correct answer is D: BSL4. Ebola viruses are highly infectious and pose a high risk to laboratory workers. BSL4 facilities are designed to handle agents that pose a severe threat to human health and have no available vaccines or treatments. These facilities have strict guidelines for handling infectious agents, including full-body suits, negative air pressure, and decontamination processes to prevent any possible exposure. BSL1, BSL2, and BSL3 are not adequate for handling Ebola viruses due to their lower levels of containment and safety measures.

Correct Answer: D

Rationale: The correct answer is D: Agglutination test type Gruber. This is because the Gruber agglutination test is not typically used for the serological identification of Yersinia pestis. The other options (A, B, C) are commonly used methods for serological identification of Y. pestis: A) Precipitation reaction involves the formation of a visible precipitate when Y. pestis antigen reacts with specific antibodies. B) Indirect hemagglutination test detects antibodies against Y. pestis by measuring the agglutination of red blood cells. C) Immunofluorescence test uses fluorescently labeled antibodies to detect specific antigens of Y. pestis. In summary, the Gruber agglutination test is not a standard method for serological identification of Yersinia pestis, unlike the other options provided.

Correct Answer: A

Rationale: The correct answer is A, Clostridium botulinum. This bacterium produces botulinum toxin, leading to botulism. It is commonly found in soil and improperly canned food. Clostridium tetani causes tetanus, Staphylococcus aureus causes food poisoning, and Salmonella enterica causes salmonellosis. Therefore, A is correct due to its association with botulism, while the other choices are incorrect for causing different diseases.

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.