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Hospital bugs

November 11, 2010

Researchers have developed a process in mice to battle bacteria no longer treatable with prevalent antibiotics. The findings could have significant implications for dealing with hospital-acquired bugs.

laboratory mouse
Mice can effectively battle bacteria with the newly-developed antibodiesImage: AP

Every year, over four million hospital patients in Europe develop an infection during their stay. The culprit is most often a strain of the bacteria Staphylococcus aureus, also known as MRSA, which has proven resistant to antibiotic treatment.

Scientists from the University of Wuerzburg and the Helmholtz Center for Infection Research (HZI) in Braunschweig have now found an approach to treating such infections. They have developed an antibody which specifically targets MRSA in mice.

Staphylococcus aureus
Staphylococcus aureus can cause a range of illnessesImage: HZI Braunschweig

"We have succeeded in activating a defense mechanism against Staphylococcus pathogens in mice with the help of antibodies," said Dr. Udo Lorenz from the university of Wuerzburg's Department of Surgery. Together with Dr. Knut Ohlsen from the Institute for Molecular Infection Biology, Lorenz has spent the last few years pursuing the idea of combating antibiotic-resistant bacteria with antibodies.

"These antibodies attach themselves to a specific point on the bacterium," Lorenz told Deutsche Welle. This in turn marks the bacterium, so that the body's own scavenger cells can detect them and subsequently kill them.

Dr. Christian Erck from HZI worked on actually developing the antibodies in mice.

"These antibodies help make the bacteria visible to the immune system," he told Deutsche Welle. "Even when antibiotics can no longer kill multi-resistant bacterial strains, antibodies still have a good chance against them."

In the experiments, the mice's immune systems were able to kill 30 percent more pathogens with the aid of the antibodies than without.

"This is a very dramatic advantage, which can constitute the difference between death and survival," Lorenz said.

Targeting immune weakness

Most people have Staphylococcus bacteria on their skin and, if they're healthy, it doesn't cause any problems.

"But this is a very flexible bacteria and it can become extremely aggressive," Erck said. If these pathogens make their way inside patients with weakened immune systems, they cause infections which are extremely difficult to cure.

udo lorenz and knut ohlsen
Lorenz (left) and Ohlsen developed this procedureImage: Alice Natter/Main-Post

Lorenz said this would be the target group for treatment.

"These are patients who have just had surgery or are in intensive care, whose immune systems are not functioning in an optimal way," he said.

Mouse to man

The next step now involves transferring the antibody from mice to humans. This means the entire molecule will need to be "humanized" so that people don't develop antibodies against the mice antibodies and reject them.

"We will take only the part of the antibody that docks to the bacterium and build the rest of the molecule artificially, so that it is suitable for people," Lorenz said.

If everything goes according to plan, Lorenz said he expected the first clinical study to take place at the end of 2012.

"Then we can find out which sort of infections are suitable for this treatment," he said.

The scientists have published their findings in the current issue of the journal Antimicrobial Agents and Chemotherapy.

Author: Sabina Casagrande
Editor: Anke Rasper