Why does use of antibiotics and/or proton pump inhibitors contribute to the development of Clostridioides difficile infections?

Why did scientists initially think it was unlikely that a bacterium caused peptic ulcers?

Does it makes a difference in treatment to know if a particular illness is caused by a bacterium (an infection) or a toxin (an intoxication)?

Based on what you know about HBV, what are some ways that its transmission could be reduced in a health-care setting?

Cases of strongyloidiasis are often more severe in patients who are using corticosteroids to treat another disorder. Explain why this might occur.