The bacteria that steals DNA from its surroundings

Streptococcus pneumoniae stjeler DNA fra sine omgivelser.

Streptococcus pneumoniae steals DNA from its surroundings.


Professor Håvarstein has been working with the same bacteria for 20 years. The bacterium is a type of Streptococcus called S. pneumoniae. Before the discovery of antibiotics, in the form of penicillin, this was probably the deadliest bacteria in the world. It is still a great threat, and many children in developing countries die of the bacteria every year, frequently due to pneumonia.

Picking up DNA
Pneumococci have a very special ability. They can pick up the properties they need by absorbing DNA from their surroundings.

When you take antibiotics, all the bacteria in your body are put under stress, and the bacteria turn on genes to resist this pressure. This is when these special streptococcus bacteria can make use of their unusual ability: they can search for the properties they wish to make use of, such as resistance to antibiotics. The genes are mixed and new combinations of genes arise that make the pneumococci more resistant.

Must turn to the family
S. pneumoniae cannot pick what is around it at random. There must be a certain similarity between the DNA being absorbed and its own in order for the bacteria to be able to make use of it. These means that it usually picks DNA from its relatives. Sometimes the pneumococci can also absorb DNA from unrelated bacteria that give them completely new properties. Compared with bacteria, you would probably not be able to get wings from a bird; you would have to mainly stay with your own species. You would do better, for example, to think that you might like brown eyes and that you could get your wish fulfilled by obtaining DNA from someone with brown eyes.

S. pneumoniae can pull a number of different skills from their sleeves. They act as nomads and can come and go as they will. We have 20-30 species of streptococcus as part of the natural bacterial flora in the mouth and throat, while S. pneumoniae is only found in the throat.

"We do not yet know for certain why it suddenly breaks out. Probably, it is when our immune system is weakened or as a result of another respiratory infection, such as influenza. The bacteria can cause sinusitis, blood infections, pneumonia and inflammation of the middle ear, among other things. About 5% of adults have one or more strains of S. pneumoniae in their throats. These various strains can exchange genes with each other, or with some of the other "resident" streptococcus species in the throat.”

Leiv Sigve Håvarstein has been researching into streptococci for 20 years.

Leiv Sigve Håvarstein and his research colleagues study the mechanisms that help the bacteria to develop resistance. There are four people working on this bacterium at NMBU, and for hundreds of researchers around the world, S. pneumoniae is a specialist area.

Bildet viser Leiv Sigve Håvarstein IKBM UMB

Leiv Sigve Håvarstein has been researching into streptococci for 20 years.

Håkon Sparre @ UMB
"We are working to understand the mechanisms the bacteria use to absorb DNA from their environment, so-called natural genetic transformation. We also study how antibiotic-resistant genes occur and become spread between bacteria," he says. They have made important findings, which have helped to clarify parts of these mechanisms. If we do not understand the mechanisms, it is not possible to create a sensible strategy for combating antibiotic resistance in bacteria.

Must share in global efforts
From a historical point of view, the causes of death in people have changed completely. In 1900, most people died of pneumococcal infections and tuberculosis. This situation has changed dramatically. By 1997, most people died of cardiovascular disease and cancer.

Antibiotic resistance in bacteria has increased enormously in recent years. In many ways, Norway is different. We do not have so much resistance to antibiotics in this country. But with increasing foreign travel and immigration, the degree of resistance is also rising here.

Antibiotic resistance is already costing Europe about 25,000 deaths and 1.5 billion euro a year. Restrictive and correct use of antibiotics and better, faster diagnosis are important measures for reversing the trend.

"The authorities must devise strategies for halting the trend. We must not only ensure healthy conditions in Norway, but also take on an international role. Globally, we have a long way to go. ­Norway cannot just wait for the others, we must take the lead," says Håvarstein.

A race against bacteria
"There must be incentives to ensure that research into bacteria is attractive to young people. It costs so much to develop and test new antibiotics that it is difficult to get the pharmaceutical industry to pay for development. The authorities must step in here. Norway has contributed very little to the development of antibiotics and other vital medicines, but we are happy to buy these medicines cheaply from abroad after others have borne the costs of developing them. We are a small country with a limited biomedical industry. It is therefore perhaps unreasonable to expect us to take new medicines all the way from idea to market. But we must be able to contribute to part of the process," says Håvarstein.

He is uncertain how great the antibiotic-resistance problem will become, but believes we must be prepared for the problem to increase.

"Quite simply, we must develop new antibiotics faster than the bacteria develop resistance. There will be a continuous race between us and the bacteria," says Håvarstein.


Published 13. April 2015 - 14:14 - Updated 20. April 2015 - 13:40