A 3 m.o. baby has white film on the mucous membrane of his mouth, tongue and lips. A doctor suspected candidosis. What nutrient medium should be applied for inoculation of the material under examination in order to confirm this diagnosis?

Correct Answer: A

Rationale: Step-by-step rationale for why Answer A (Sabouraud's) is correct: 1. Sabouraud's agar is a selective medium for fungi. 2. Candida is a type of fungus causing candidosis. 3. Sabouraud's agar promotes fungal growth. 4. Candida will grow on Sabouraud's agar, confirming the diagnosis. 5. Other choices are for bacterial culture, not suitable for fungal growth. Summary: - Endo, Jensen's, and Roux are not appropriate for fungal culture. - Sabouraud's agar specifically supports fungal growth, making it the correct choice for confirming candidosis.

Correct Answer: D

Rationale: The correct answer is D: commensalism. In commensalism, one organism benefits while the other is neither helped nor harmed. In this relationship, the waste product of one organism serves as a nutrient source for another without affecting the first organism. Mutualism (A) involves both organisms benefiting, competition (B) involves a struggle for resources, and synergism (C) involves cooperative interactions. Commensalism is the only choice where one organism benefits from the waste product of another without any impact on the producer.

Correct Answer: A

Rationale: The correct answer is A: Meningitides. H. Influenzae type b (Hib) is a bacterium known to cause meningitis, a serious infection of the protective membranes covering the brain and spinal cord. Hib does not typically cause tonsillitis, urinary tract infections, or gastroenteritis. Meningitis is a life-threatening condition that requires prompt treatment, making it crucial to identify Hib as the causative agent.

Correct Answer: B

Rationale: The correct answer is B: Cholera. Cholera is caused by Gram-negative curved rod-like bacteria called Vibrio cholerae, commonly found in contaminated water or food. The characteristic symptom of cholera is profuse watery diarrhea, which matches the patient's presentation. Typhoid fever (A) is caused by Salmonella typhi, which is not a curved rod-like bacteria. Diphtheria (C) is caused by Corynebacterium diphtheriae, a Gram-positive bacterium, and does not typically cause diarrhea. Intestinal form of plague (D) is caused by Yersinia pestis, which is not a curved rod-like bacteria and does not typically present with diarrhea.

Correct Answer: C

Rationale: The correct answer is C: Clostridium perfringens. This bacterium is the causative agent of gas gangrene due to its ability to produce gas and toxins in anaerobic conditions. Clostridium tetani causes tetanus, Clostridium botulinum causes botulism, and Bacillus anthracis causes anthrax, not gas gangrene. Clostridium perfringens stands out as the correct choice based on its specific association with gas gangrene and its pathogenic mechanisms.