Which condition is least likely to be caused by the bacterium responsible for endocarditis in patients with dental procedures?

The bacterium commonly associated with endocarditis following dental procedures is often Streptococcus viridans or other oral flora that can enter the bloodstream through gum manipulation. Among the conditions listed, a sternal wound infection is least likely to be caused by these organisms. This type of infection is more commonly associated with skin flora or environmental pathogens that typically enter the body through surgical sites rather than through the bloodstream.

In contrast, rheumatic fever is an autoimmune condition following a Streptococcus pyogenes infection and is not caused by the same bacteria responsible for dental-related endocarditis. Intravenous drug use infections can occur due to skin flora or other bacteria entering the bloodstream, including the same organisms implicated in endocarditis cases. Valvular heart disease would encompass conditions leading to structural heart changes, which could be exacerbated by recurrent endocarditis from the same oral bacteria after dental procedures.

Therefore, a sternal wound infection is the least typical outcome of infection caused by the bacterium associated with endocarditis after dental work, making it the most suitable answer in this context.