Myocardial caries
How a dental bacterium gets into the heartKirill Stasevich, Compulenta
Streptococcus, which forms plaque in the mouth, can cause endocarditis when it enters the blood. The ability of the bacterium to infect the heart depends on a special anchor protein with which it adheres to the cells of the coronary vessels that feed the heart.
The bacterium Streptococcus mutans is a common inhabitant of the oral cavity; it is to it that we owe the appearance of plaque. Streptococcus forms polysaccharide mucus, which allows the bacteria to stay on the surface of the tooth and creates ideal living conditions for it. Releasing acids, streptococcus destroys tooth enamel, and usually the violent activity of this bacterium in the oral cavity ends with a visit to the dentist.
But it happens that Streptococcus mutans is not limited exclusively to the mouth. For example, due to too vigorous flossing, streptococcus can enter the bloodstream. At first glance, it's okay: the immune system will quickly cope with it. But sometimes bacteria manage to reach the heart fairly quickly, and then more serious troubles begin than plaque or caries.
Streptococcus multiplies intensively in the heart, preferring heart valves, which leads to endocarditis, which is fraught with death. Scientists from the University of Rochester (USA) have found out how a bacterium gets into the heart muscle and gets a foothold on it.
(In the picture taken by the authors of the work, the arrow shows streptococcus on the endothelium of one of the arteries feeding the heart muscle – VM.)
The researchers were able to detect bacterial collagen-binding protein CNM. It interacts with the connective tissue protein collagen and the cell membrane protein laminin; as a result, streptococcus is able to settle and gain a foothold on the epithelial cells of the coronary arteries of the heart.
In bacteria deprived of such a protein anchor, the ability to fix on epithelial cells fell 10 times. The pathogenicity of various strains of streptococcus was tested on wax moth larvae: bacteria that had the CNM protein gene caused the death of caterpillars in 90% of cases; if the gene of this protein was turned off in such strains, they lost their lethality. The results of the work (Abranches et al., The Collagen-Binding Protein Cnm Is Required for Streptococcus mutans Adhesion to and Intracellular Invasion of Human Coronary Artery Endothelial Cells) are published in the journal Infection and Immunity.
Among more than 30 strains of Streptococcus mutans, five have a dangerous gene. The most common strain C among people does not pose a threat to the heart, but the rarer types E, F and some others have in their arsenal a protein that allows them to gain a foothold on blood vessel cells and launch an attack on the heart muscle. According to scientists, if you have heart problems, before visiting the dentist, be sure to take a microbiological test to find out if a dangerous strain of streptococcus lives in your mouth. If he lives, the doctor should work as cleanly as possible and do not hesitate to use antibiotics.
Prepared by the University of Rochester: Microbiologists Discover How Cavity-Causing Microbes Invade Heart Microbiologists Discover How Cavity-Causing Microbes Invade Heart.
Portal "Eternal youth" http://vechnayamolodost.ru29.06.2011