Correct Answer: C

Rationale: The correct answer is C: Contaminated wounds. Tetanus is caused by the bacterium Clostridium tetani, which enters the body through breaks in the skin such as wounds or cuts. The bacteria produce a toxin that affects the nervous system, leading to muscle stiffness and spasms. Ingestion of contaminated food (choice A) is not a mode of transmission for tetanus. Inhalation of droplets (choice B) is more relevant for respiratory infections. Direct physical contact (choice D) is not the primary mode of transmission for tetanus as the bacteria need a portal of entry such as a wound to cause infection.

Correct Answer: A

Rationale: The correct answer is Amebiasis. The patient's symptoms of abdominal pain, loose stools with mucus and blood, along with the presence of protozoa containing phagocytosed erythrocytes in stool analysis are indicative of Entamoeba histolytica infection. The size (30-40 microns) and pseudopodia characteristics match E. histolytica. Amebiasis commonly presents with dysentery, while Leishmaniasis (B) typically causes skin ulcers. Trichomoniasis (C) is a sexually transmitted infection, not associated with the described symptoms. Giardiasis (D) is characterized by foul-smelling diarrhea and steatorrhea, not bloody diarrhea as seen in this case.

Correct Answer: D

Rationale: The correct answer is D because all the factors listed can contribute to the transmission of nosocomial infections. Medical dressings can harbor pathogens, breast milk can be a source of infection if not handled properly, and toys can serve as fomites for spreading germs. Choosing any other option would be incorrect as they all play a role in facilitating the transmission of nosocomial infections. It is important to consider all potential sources of infection in healthcare settings to effectively prevent the spread of nosocomial infections.

Correct Answer: B

Rationale: The correct answer is B: Corynebacterium diphtheriae. This bacterium produces a toxin that causes diphtheria by inhibiting protein synthesis, leading to the formation of a pseudomembrane in the throat. Bordetella pertussis causes whooping cough, Streptococcus pyogenes causes strep throat, and Neisseria meningitidis causes meningitis. Corynebacterium diphtheriae is the only bacterium among the choices known to cause diphtheria due to its specific toxin production.

Correct Answer: A

Rationale: The correct answer is A: Tryptic soy agar is a general-purpose medium suitable for cultivating a wide range of microorganisms. It provides essential nutrients for growth without inhibiting specific types of bacteria. Blood agar (B), Mannitol salt agar (C), and MacConkey agar (D) are selective or differential media designed to promote the growth of specific types of bacteria or differentiate between different bacterial species. Therefore, they are not considered general-purpose mediums.