Final answer:
A new regurgitant murmur is a common finding during the assessment of a young adult with infective endocarditis, indicating valve dysfunction due to the infection.
Step-by-step explanation:
During the assessment of a young adult with infective endocarditis (IE), a nurse should expect to find a new regurgitant murmur. This is a common finding and indicates the presence of valve dysfunction due to the infection. IE is characterized by inflammation of the endocardium and can lead to heart valve damage resulting from the immune response causing fibrosis of heart valves. The development of heart valve vegetations can be seen in cases of subacute bacterial endocarditis, where blood clots form, and bacteria are protected from phagocytes, leading to a potential murmur.