Correct Answer: A

Rationale:
Step-by-step rationale for why A is correct:
1. Clostridium tetani is known to produce tetanus toxin.
2. The tetanus toxin causes muscle rigidity and spasms characteristic of tetanus.
3. Clostridium perfringens is associated with gas gangrene, not tetanus.
4. Neisseria gonorrhoeae causes gonorrhea, not tetanus.
5. Bacillus anthracis causes anthrax, not tetanus.

In summary, Clostridium tetani is the correct answer as it is specifically associated with causing tetanus, while the other choices are associated with different diseases.

Correct Answer: B

Rationale:
Rationale:
1. Enteropathogenic E.coli (EPE
C) adheres to the intestinal wall using bundle-forming pili.
2. EPEC produces toxins that disrupt cell structure and function, leading to diarrhea.
3. Shigella spp. invade intestinal cells, Salmonella spp. invade and multiply within cells, and Vibrio cholerae produces cholera toxin causing profuse watery diarrhea.
Summary:
A, C, and D choices are incorrect because they do not specifically adhere to the intestine wall and produce toxins like EPEC does.

Correct Answer: B

Rationale: The correct answer is B: antitoxin. Antitoxin is the specific antidote to botulinum toxin as it helps neutralize the toxin in the body. Sodium bicarbonate (
A) is used to treat acidosis, pralidoxime (
C) is used for organophosphate poisoning, and naloxone (
D) is used for opioid overdose. Antitoxin directly targets and counteracts the botulinum toxin, making it the appropriate antidote in cases of botulism.

Correct Answer: B

Rationale: The correct answer is B: Candida albicans. Candida albicans is the most common cause of vaginal yeast infections due to its ability to overgrow in warm, moist environments like the vagina. It is a type of fungus that naturally resides in the body, but can cause infection when its growth is not regulated. Histoplasma capsulatum (
A) causes a lung infection, Aspergillus niger (
C) causes fungal sinusitis, and Saccharomyces cerevisiae (
D) is a type of yeast used in baking and brewing, not typically associated with vaginal infections.

Correct Answer: D

Rationale: The correct answer is D: All of the above. Hospital-acquired infections can be caused by a variety of bacteria commonly found in healthcare settings. Staphylococcus aureus is a common cause of surgical site infections. Escherichia coli can cause urinary tract infections. Klebsiella pneumoniae is associated with pneumonia and bloodstream infections.
Therefore, all three bacteria are frequently implicated in hospital-acquired infections due to their prevalence and ability to cause different types of infections in healthcare settings. Thus, the correct answer is D, as all of the listed bacteria are commonly associated with hospital-acquired infections.