The U.S. Centers for Disease Control and Prevention is now investigating the link between offices, such as medical and dental clinics, and the Clostridium difficile, or C. diff, bacteria.

C. diff bacteria are normally present in hospitals, but the CDC has warned that the deadly bacteria may also be present in medical offices. The CDC reports that some people who were infected with the bacteria did not visit a hospital but visited a dental or medical clinic instead.

The bug can cause severe diarrhea, and more than 500,000 Americans get the bacterial infection each year. The CDC also said that about 15,000 deaths each year in the U.S. are directly linked to the C. diff bacteria.

A CDC report in 2011 showed the agency collected C. diff infection data from 10 areas in the U.S. The health agency wanted to understand how C. diff infections were related to nursing homes and hospitals and how people were contracting the disease.

The report said about 66 percent of the cases of infection occurred in nursing homes or hospitals. However, the infections were community-associated.

"About 80 percent of patients with community-associated C. difficile infection did have contact with health care settings, like a doctor's office or a dental clinic, and most of those patients were also given antibiotics," said Dr. Michael Bell, a spokesperson for the CDC.

Another CDC study conducted in 2013 said the C. diff bacteria existed in six of the seven Ohio clinics examined. The study found that the bacteria thrived on examining tables and also on the chairs used by patients. The CDC is starting a new national study to assess if patients are getting infected with C. diff mainly at doctors' offices.

Medical experts believe that it is a very important issue that the CDC should address to prevent unwanted C. diff infections.

The CDC also warns that white women over 65 years old are at higher risk of getting a C. diff infection, in comparison with other patients.

People who are visiting a doctor's clinic or dental clinic should ensure they wash their hands properly with water and soap to avoid getting any infection.

The CDC also revealed that alcohol-based gels do not help in getting rid of the dangerous C. diff bacteria.