Final answer:
Vaccination of an infant with a contaminated needle is NOT an example of acquiring normal microbiota.
Step-by-step explanation:
The situation that is NOT an example of acquiring normal microbiota is E) vaccination of an infant with a contaminated needle. Acquiring normal microbiota refers to the process of colonization of beneficial microorganisms in the human body, which generally occurs naturally through various means. In this case, vaccination with a contaminated needle would introduce pathogens, rather than normal microbiota, into the body.