A man who visited his dentist for a routine dental cleaning developed a rare and potentially life-threatening infection.

In a BMJ Case Report, doctors say the man had a liver abscess (a pocket of pus that formed in his liver) that was caused by the rare bacterium Fusobacterium necrophorum. If left untreated, the infection can be life threatening.

The 57-year-old man was admitted to hospital in Pennsylvania with a fever and pain on his upper right body. An MRI of the abdomen confirmed a hepatic abscess, and cultures confirmed it to be caused by F. necrophorum.

They say the only possible cause of the infection is the oral cavity as the patient had routine dental examination and cleaning two weeks before. The patient had good oral health, and did not have any invasive dental work.

This case is interesting, say the doctors, because it suggests that even routine dental cleaning may lead to the presence of bacteria in the blood, which can travel to different areas of the body.

They speculate that the dental cleaning may have involved some trauma to the lining of the mouth that could have served as an entryway to the blood stream.

Doctors treated the man by draining the pus and prescribing a course of antibiotic treatment.