Can you imagine getting an infection in your brain from bacteria in your mouth? Or maybe an infection of one of your heart valves, or one of your joints? Well, believe it or not, bacteria from the mouth can spread to distant areas of the body, causing serious, sometimes life threatening, infectious diseases.
How do bacteria from the mouth cause infection in these far away places?
It is known that everyday activities such as flossing and brushing the teeth can result in bacteria escaping through the gums into the blood stream. Fortunately, the bacteria tend to remain in the blood stream only transiently, because the immune system springs into action quickly to mop them up and destroy them.
In persons who do not pay attention to oral hygiene, there is overgrowth of bacteria in the mouth, in plaque on the teeth, and below the gums. Over time, cavities form and eventually the pulp of the tooth may become infected. This may progress to an abscess about the tooth. In the meantime, the gums may become increasingly inflamed and infected (gingivitis).
With all this inflammation and infection in the mouth, it becomes much easier for bacteria to escape through the gums into the blood stream. Larger amounts of bacteria in the blood stream may overwhelm the immune system. The bacteria are therefore able to reach distant sites of the body, where they can lodge and cause infection. The sites infected are often areas with abnormal, damaged tissues, or where there is a foreign body present. Sometimes, however, dental infections spread more directly – up into the brain, or down into the neck and chest.
Below are 4 infections resulting from poor dental hygiene, that we infectious disease physicians see more commonly than we would like:
1 – Septic arthritis
This is the term for an infected joint. Bacteria transiently passing through the blood stream can lodge within a joint before being completely cleared away by the immune system. Abnormal joints are much more prone to infection, particularly joints with damage either from osteoarthritis (related to aging or past injury) or rheumatoid arthritis. Usually the hips or knees are affected more often, as they bear the most weight and therefore get most ‘worn out.’ Artificial joints are even more prone to infection. That is because they do not have blood flowing through them like normal tissues. Bacteria passing through the blood stream can therefore stick onto the artificial joint and not get ‘washed away’ by the blood supply. The joints of the spine may also be infected by bacteria from the mouth, particularly the lower (lumbar) spine.
Signs of an infected joint include increased pain and swelling, interfering with walking. The joint may or may not become red. If the spine is infected, the patient usually experiences worsening back pain. Many patients with joint infections develop fever and malaise. Testing a sample of fluid from the joint usually confirms the presence of the infection. Treatment usually entails a surgeon washing out the joint, and a prolonged course of antibiotics.
2 – Infective endocarditis
This the term for an infected heart valve. It occurs when bacteria in the bloodstream lodge onto abnormal heart valves or damaged heart tissue. Chronic diseases such as high blood pressure and atherosclerosis (excess cholesterol plaques in the heart and the arteries) result in abnormal heart valves. The turbulence of blood over the valves when there is longstanding high blood pressure, eventually causes the valves to become thickened and calcified. Long standing high cholesterol levels results in cholesterol plaques forming on heart valves. The valve tissues overtime get thickened and become stiff. Damage to the heart after a heart attack, can also cause the valves to become damaged.
Bacteria circulating in the blood stream can lodge onto the irregular surface of a damaged heart valve. Because the heart valve is damaged, the immune system mechanisms that are supposed to ward off infection, are also compromised. Therefore infection cannot be cleared as efficiently as with a normal valve. Replacement of these abnormal valves with artificial valves is a common occurrence. However, the artificial valves are even more prone to becoming infected, like with artificial joints. Treatment of endocarditis is with a prolonged course of intravenous antibiotics. Sometimes, the valve is so badly destroyed by the infection, that it has to be surgically replaced.
3 – Brain abscess
The other day I had an elderly patient who ended up in the hospital after he had a seizure while getting into his car. As is done for any patient having seizures for the first time, he had a CAT scan done of his brain. The images showed a big abscess. He had neurosurgery done to drain the abscess, and the pus grew a Streptococcus type of bacteria, commonly found in the mouth. It turned out that he had a bad upper molar tooth that was giving him problems for several months. What he never had were headaches or fever (only ~50% of patients with brain abscesses have fever). Sometimes, slowly smoldering infections such as brain abscesses, may not present with fever and other obvious features of infection, especially in older persons, because of their weaker immune systems. The patient eventually had his infected tooth removed and got several weeks of antibiotics for the brain abscess.
With the obvious close proximity to the brain, bacteria from a dental abscess can leak into the surrounding veins, which then drain into the brain. The bacteria lodge into the brain tissue and an abscess forms.
4 – Pneumonia
A sterile environment in the lungs is maintained by an intact cough reflex, and by the action of mucous secretions in the airways, which trap inhaled germs and particulate material. Older persons, or persons whose mental state is impaired from medications or excess alcohol, can accidentally breath (aspirate) contents from their mouth and throat into their lungs. Poor dental hygiene results in much higher loads of bacteria in the mouth and throat. If high loads of bacteria are breathed into the lungs and not cleared efficiently, pneumonia can develop, and sometimes lung abscesses. These lung infections are seen frequently in persons who have had strokes, those with dementia, and in alcoholics.
A note about artificial devices in the body
As we live longer due to improved control of chronic diseases, more and more people have artificial devices in their bodies. These range from artificial joints and heart valves as mentioned above, rods and screws to fix broken bones, cardiac pacemakers, grafts in blood vessels, mesh for hernia repair, spinal stimulators to help with chronic back pain, etc, etc.
Artificial devices do not have a blood supply, therefore it is more difficult to clear infection from their surfaces compared, to natural tissues. As a result, smaller amounts of bacteria can cause infection of artificial devices, compared to the larger amounts needed to infect natural tissues.
There you have it, 4 areas of the body that can develop serious infections as a result of poor dental hygiene – arthritic joints, abnormal heart valves, the brain, and the lungs. Fortunately, everyone can decrease their risk of getting any one of these infections. Brush your teeth at least twice per day, and floss at least once per day, preferably before going to bed at night. Make it a habit to visit the dentist at least once per year for an examination and for professional cleaning.
Fortunately, in the grand scheme of things, all of the above infections are relatively rare (except for aspiration pneumonia which we do see quite commonly). Generally speaking, preventative antibiotics are not routinely recommended during dental procedures since it is known that simple everyday activities such as flossing and brushing the teeth, result in transient bacteria in the blood stream. Because patients with artificial heart valves are at particularly higher risk for infection, they require preventative antibiotics during major dental procedures. Everyone should contact their healthcare provider to have their individual risk for infection evaluated and managed accordingly.