Final answer:
The correct action a nurse should take when admitting an infant with pertussis is to administer antibiotics, as they can be effective in early treatment and reduce transmission rates.
Step-by-step explanation:
When admitting an infant with pertussis, also known as whooping cough, the most appropriate action for a nurse to take would be to administer antibiotics. Pertussis is caused by the Gram-negative coccobacillus Bordetella pertussis and is characterized by severe coughing with a distinctive 'whoop' sound during inhalation. While the disease is typically self-limiting, early antibiotic treatment can be effective and can also reduce transmission rates. Erythromycin or tetracycline may be prescribed at the early stages of the disease.
It's worth noting that while antipyretics may be used to manage fever and provide comfort, antibiotics are essential for treating the infection itself. Bronchodilators are not the primary treatment for pertussis and would likely be ineffective against the bacterial infection. Similarly, a live attenuated vaccine is not used to treat an active infection and would not be appropriate to administer at this stage.
Therefore, the correct choice is a) Administer antibiotics.