Which is the preferred mode of transmission of HIV from a mother to a child?

Correct Answer: D

Rationale: The correct answer is D: All of the above. HIV can be transmitted from mother to child during delivery through mixing of blood, during pregnancy through the placenta, and via breastmilk during lactation. Each mode of transmission carries a risk of HIV transmission to the child due to the presence of the virus in the mother's blood and bodily fluids. It is important to note that all three modes contribute to the risk of mother-to-child transmission of HIV, and preventive measures should be taken to reduce this risk. Option A, during delivery through mixing of blood, is correct as HIV can be transmitted through exposure to infected blood during childbirth. Option B, during pregnancy through placenta, is also correct as the virus can cross the placenta and infect the fetus. Option C, via breastmilk during lactation, is correct as HIV can be present in breastmilk and transmitted to the child through breastfeeding. Therefore, the preferred mode of transmission of HIV from a mother to a child

Correct Answer: D

Rationale: The correct answer is D: Yersinia enterocolitica. This bacterium can contaminate foods and grow at refrigerator temperatures due to its psychrotrophic nature. Yersinia enterocolitica is known to cause foodborne illnesses even when stored at cold temperatures. Shigella sonnei is a human pathogen transmitted through fecal-oral route, Campylobacter jejuni is typically found in poultry and causes food poisoning, and E. coli can cause foodborne illnesses but does not grow well at refrigerator temperatures.

Correct Answer: A

Rationale: The correct answer is A: Salk and Sabin vaccines are vaccines against polio. Both Salk and Sabin vaccines are indeed vaccines specifically developed to prevent polio. The Salk vaccine is an inactivated polio vaccine, while the Sabin vaccine is an oral live attenuated vaccine. Therefore, choice B is incorrect as the Sabin vaccine is live attenuated, not inactivated. Choice C is also incorrect because the Salk vaccine is inactivated, not live attenuated. Choice D is incorrect because not all statements are true; only statement A is accurate.

Correct Answer: A

Rationale: The correct answer is A: Balantidium coli. Balantidium coli is a large ciliated protozoa with a kidney-shaped macronucleus, commonly found in the feces of individuals with dysentery symptoms. Its morphology matches the description given in the question, making it the most likely causative agent. Summary of other choices: B: Entamoeba histolytica - This is not the correct answer because Entamoeba histolytica is a small amoeba with no cilia and a different nucleus shape. C: Giardia lamblia - This is not the correct answer as Giardia lamblia is a flagellated protozoa with a pear-shaped nucleus, different from the description provided. D: Trichomonas hominis - This is not the correct answer as Trichomonas hominis is a flagellated protozoa with multiple flagella and an undulating membrane, which does not match the characteristics of the

Correct Answer:

Rationale: Correct Answer: C: opportunists Rationale: 1. Opportunistic microorganisms cause infections only when the host's immune system is compromised. 2. They are typically harmless in healthy individuals but can become pathogenic in weakened hosts. 3. Saprophytic microorganisms are environmental decomposers, not inherently pathogenic. 4. Facultative pathogens can cause disease in both healthy and compromised hosts. 5. Obligate pathogens always cause disease regardless of the host's condition. Summary: A: Facultative pathogens can cause disease in healthy hosts. B: Saprophytes are not inherently pathogenic. D: Obligate pathogens always cause disease.

Correct Answer: A

Rationale: Step-by-step rationale: 1. Mycobacterium tuberculosis is the causative agent of tuberculosis. 2. Mycobacterium tuberculosis is a slow-growing, acid-fast bacterium. 3. It primarily infects the lungs and can spread to other parts of the body. 4. Bacillus anthracis causes anthrax, Clostridium tetani causes tetanus, and Treponema pallidum causes syphilis. 5. Therefore, choice A, Mycobacterium tuberculosis, is the correct answer for the bacteria responsible for tuberculosis.

Correct Answer: B

Rationale: Gas gangrene is caused by Clostridium perfringens due to its ability to produce gas in tissues leading to necrosis. Other choices are incorrect: A (C. difficile causes diarrhea), C (C. tetani causes tetanus), and D (incorrect as B is the causative agent).

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: B

Rationale: The correct answer is B: Typhoid fever, Brucellosis. Both Typhoid fever and Brucellosis are bacterial infections that can lead to bacteremia, the presence of bacteria in the bloodstream. In Typhoid fever, the causative agent Salmonella typhi can enter the bloodstream, causing bacteremia. Similarly, Brucellosis, caused by Brucella species, can also result in bacteremia. Choice A is incorrect because bacteremia is not typically observed in Diphtheria. Choice C, Cholera, is caused by a toxin-producing bacterium and does not usually lead to bacteremia. Choice D, Dysentery, is a condition characterized by bloody diarrhea and is primarily caused by parasites or bacteria that typically do not lead to bacteremia.