Heart Disease Risk Factor #3: Germs

The consequences of bacteria and viruses can last well past the immediate symptoms.

The Long-Term Effect

Since bacteria, viruses, and other germs are a common cause of inflammation in general (think about the white blood cells the body dispatches to fight an infection), researchers have begun investigating a possible link between germs and heart disease.

Some of the bugs that have been implicated are the culprits behind chronic, low-grade infections. They include Helicobacter pylori, the bacterium that causes most ulcers; Chlamydia pneumoniae, a bacterial organism that causes mild pneumonia in young adults; and even Streptococcus mutans, the bacteria that cause cavities in your teeth. Also on this list is herpes simplex virus type 1 (HSV-1), the virus that causes cold sores.

A study published in the journal Circulation in 2000 found that older people who had been infected with HSV-1 had twice the risk of having a heart attack or dying from heart disease as those never infected by the virus. Another study looked at 572 heart disease patients who had been admitted to the hospital for tests. The researchers followed the subjects for an average of 3.2 years and found that the death rate was 3.1 percent in those who tested positive for exposure to as many as three infectious agents, 9.8 percent for those exposed to four to five, and 15 percent for those exposed to six to eight. The greatest risk came from exposure to the bacteria Chlamydia pneumoniae, Mycoplasma pneumoniae (which also causes pneumonia), and Helicobacter pylori.

Bacteria and viruses trigger an overall immune response in the body, which may damage arteries. But some may wreak further havoc. Cytomegalovirus, a germ implicated in choronary heart disease, causes endothelial cells to generate large amounts of a molecule that interferes with nitric oxide production. Another study suggests some Chlamydia pneumoniae bacteria may hitch a ride to the heart inside certain immune system cells.

The whole germ theory got a big boost when British doctors gave antibiotics to coronary heart disease patients who tested positive for prior infection with Chlamydia pneumoniae. Blood flow in a major artery in the patients' arms improved with the antibiotics, and blood levels of two markers for endothelial problems dropped, suggesting that the condition of the delicate lining of the arteries and other blood vessels improved. Another study found a three-month course of antibiotics resulted in longer life and reduced the risk of future heart attacks in people hospitalized for heart attack or unstable angina.

Antibiotics

Researchers aren't sure exactly why antibiotics might help. They may kill residual bacteria left over from an acute infection. (Autopsies have revealed Chlamydia pneumoniae living in coronary artery walls.) Another possibility: Certain antibiotics appear to have anti-inflammatory actions. Researchers are actively investigating this mystery.

Meanwhile, don't look for cardiologists to start handing out antibiotics any time soon. The world, and the United States in particular, is facing a serious public health threat from the growing incidence of antibiotic resistance, in which even the most powerful antibiotics are no longer effective against an increasing number of bacteria. The medical community will need many more studies proving conclusively that antibiotics can help with coronary heart disease -- and which antibiotics work best. And despite the above data supporting a germ-heart disease connection, two large studies have found no association between the number of infections a person suffers and subsequent heart attacks and strokes.

Quick Tips

• Maintain a wholesome and balanced diet for optimal immune function. A healthy immune system reduces inflammation and increases your body's defense against infection.


• Quit smoking. Studies find that smoking turns your entire body into a breeding ground for germs. Additionally, smokers are particularly prone to respiratory infections. In a study published in the journal Stroke, researchers found that current and former smokers who had common chronic infections -- such as bronchitis, ulcers, urinary tract infections, and even gum disease -- were more than three times as likely to develop early coronary heart disease as people without such infections.