In order to establish the possible contamination of a medication with fungi, a nutrient medium was inoculated, which resulted in growth of large cream-like colonies. What nutrient medium was used in this case?

Correct Answer: A

Rationale: The correct answer is A: Sabouraud. Sabouraud agar is specifically designed to promote the growth of fungi due to its low pH and high glucose content. The cream-like colonies indicate fungal growth, as fungi often appear as fluffy or powdery colonies on Sabouraud agar. Lowenstein-Jensen is used for mycobacteria, Roux for diphtheria, and Loeffler for Corynebacterium diphtheriae. Therefore, Sabouraud is the most suitable medium for detecting fungal contamination based on the characteristics of the colonies formed.

Correct Answer: D

Rationale: The correct answer is D, "All of the above." E. coli, P. aeruginosa, and S. aureus are all known to cause urinary tract infections. E. coli is the most common causative agent due to its presence in the gut. P. aeruginosa and S. aureus can also infect the urinary tract, although less frequently. Therefore, all three bacteria are potential pathogens for urinary tract infections.

Correct Answer: B

Rationale: The correct answer is B: slime mold. Plasmodium is a type of slime mold, specifically a parasitic protist that causes malaria in humans. Slime molds are a group of organisms that share characteristics of both fungi and protozoa. Plasmodium does not belong to the other categories listed: A) protozoan refers to a broad category of single-celled eukaryotic organisms, C) spirochetes are a type of bacteria, and D) helminths are parasitic worms. Therefore, the correct classification for Plasmodium is slime mold.

Correct Answer: D

Rationale: The correct answer is D because antibody diversity is generated by rearrangements of DNA encoding variable regions of heavy and light chains (choice A) and by the combination of different heavy and light chains that form the antigen binding site (choice B). Step 1: DNA rearrangements create different variable regions in heavy and light chains. Step 2: Combination of different heavy and light chains leads to unique antigen binding sites. Step 3: This diversity allows antibodies to bind to different epitopes on the same antigen. Step 4: Choice C is incorrect as antibodies do not physically change shape to bind different epitopes.

Correct Answer: C

Rationale: The correct answer is C: To perform serodiagnostics of tuberculosis. Rationale: The negative reaction to the Mantoux test indicates absence of TB infection. Performing serodiagnostics will further confirm the absence of active infection. This is important to rule out TB before considering vaccination or isolation measures. Summary: A: BCG vaccination is not necessary as the boy shows a negative reaction to the Mantoux test. B: Repeating the test in a month is unnecessary as the initial test already showed a negative reaction. D: Isolating the boy is not warranted as there is no evidence of active TB infection.

Correct Answer: A

Rationale: The correct answer is A: infants. Staphylococcal scalded skin syndrome is most common in infants because their immune systems are not fully developed, making them more susceptible to Staphylococcus aureus infections. This bacteria produces exotoxins that cause the skin to blister and peel, characteristic of the syndrome. Adolescents, young adults, and the elderly have more mature immune systems, making them less vulnerable to this specific infection. Therefore, infants are at a higher risk for developing Staphylococcal scalded skin syndrome compared to other age groups.

Correct Answer: A

Rationale: The correct answer is A: Escherichia coli. E. coli is the most common bacteria responsible for causing urinary tract infections due to its ability to adhere to the urinary tract lining and multiply rapidly. It is a normal inhabitant of the gut and can enter the urinary tract through improper hygiene practices. Salmonella enterica and Neisseria gonorrhoeae are typically associated with other infections like food poisoning and gonorrhea, respectively. Mycobacterium tuberculosis causes tuberculosis, not urinary tract infections. Thus, based on its prevalence and pathogenicity in the urinary tract, E. coli is the correct choice.

Correct Answer: C

Rationale: The correct answer is C: Carry genes for antibiotic resistance. Bacterial plasmids are small, circular DNA molecules that can be transferred between bacteria, carrying genes such as antibiotic resistance. This allows bacteria to survive in the presence of antibiotics. Plasmids do not directly play a role in protein synthesis (choice A) or DNA replication (choice B). Plasmids are not responsible for motility (choice D) as that function is usually carried out by flagella or other cellular structures.

Correct Answer: C

Rationale: The correct answer is C: All answers are correct. Pneumonia can be caused by various pathogens, including Legionella pneumophila and Mycoplasma pneumoniae. Choice C is correct because both A and B are known causative agents of pneumonia. Choice D is incorrect because we know that Legionella pneumophila and Mycoplasma pneumoniae can cause pneumonia, so the statement "None of the above" is not accurate in this context.