“Streptococci” is a term describing a group of bacteria in our oral cavity from which we mostly benefit. However, if these enter the blood stream they may prove deadly.
Recently, graduated PhD student at DTU Health Tech, Katrine Højholt Iversen published a paper in Scientific Reports on the subject.
“In the paper, we compare bacteria isolated from the mouth with the same type of bacteria isolated from patients with heart valve infection also known as infective endocarditis. We find no difference between the two groups of bacteria. This means that the bacteria we have in the mouth, helping prevent cavities in the teeth, may enter the blood stream and cause an infection with a mortality rate of up to 20-40 percent”, Katrine Højholt Iversen explains.
In Denmark, there are roughly 700 new cases of infective endocarditis every year. Infective endocarditis is a septic condition where the heart valves and/or bordering tissue is infected by microorganisms, most commonly bacteria.
Machine learning
By using machine learning, researchers were able to compare the two groups of bacteria, by identifying which genes the bacteria contained and which were absent.
“Machine learning is a very valuable tool used to discover patterns in large data sets by using mathematical models. The result of the mathematical models proved that there was no difference in the bacteria isolated from the mouth and the ones that had caused a heart valve infection,” Katrine Højholt Iversen says.
Apart from the fact that these two groups of bacteria contained the same gene patterns, it also turned out that they contained the same virulence gene pattern.
“The virulence genes are genes that may contribute to a bacteria’s ability to cause an infection. As bacteria isolated from the mouth and the bacteria isolated from patients with heart valve infection contained the same virulence gene patterns, it may be that they contain the same ability to cause an infection”, Katrine Højholt Iversen says.
The result is a strong indication that the same bacteria which are an asset in the oral cavity may be lethal when they appear in the blood stream.
“We do not find any differences between the two groups. This may mean that they have the same potential to cause infection. Laboratory studies must verify our results, however. Furthermore, there may be a difference on the level these different types of genes are expressed. We have not explored this”, says Katrine Højholt Iversen.
According to chief physician at Slagelse Hospital Jens Jørgen Elmer Christensen, this study has brought valuable knowledge.
”Some patients may have multiple episodes with infective endocarditis, where it is important to establish whether a new episode is caused by an infection with the exact same bacteria as before. If this is the case, it may be that the former treatment with antibiotics has been insufficient in terms of entirely removing the bacteria’s presence in the tissue”, Jens Jørgen Elmer Christensen explains.
The course of infective endocarditis may be very serious, and doctors wish to soften this course and better the prognosis.
“The new molecular biological methods which enable a detailed description of the gene content in the hereditary material together with the development in bioinformatics competences give new and exciting future possibilities”, says Jens Jørgen Elmer Christensen.
Read the scientific paper
here.