Methicillin-resistant Staphylococcal aureus (MRSA) is a common and quite dangerous hospital infection that’s resistant to many drugs. Now, researchers at New York University have developed a new treatment path that targets not the bacteria itself, but the toxins they produce. Tests on mice have proved promising so far.
The last thing anybody wants when they go to hospital is to pick up a new disease, but MRSA is often responsible for just that. This bug, often called golden staph, usually forms biofilms on implants, IV lines and catheters, and once it takes hold it can be hard to get rid of. That’s because it’s become resistant to almost all antibiotics.
So for the new study, the researchers decided to try a different tactic. The Staphylococcal family of bacteria all produce toxic molecules called leukocidins, which kill immune cells known as leukocytes. These immune cells fight infections by producing antibodies, so by killing them off the bug not only ensures its own survival, but prevents the host from developing long-term immunity.
That also explains why experimental MRSA vaccines in the past have failed to have much effect – they usually work by boosting the numbers of leukocytes, and golden staph is already shutting those down.
So, the team on the new study focused on leukocidins instead. By disarming the bacteria instead of outright killing them, the vaccine helps the host to mount a stronger immune response.
In initial experiments, the team infected mice with both regular MRSA and a version of the bug that had been engineered to not produce the toxins. Those mice without the toxins showed a much stronger immune response against the superbug, producing twice as many antibodies against it.
Next, the team tested an experimental vaccine that targeted leukocidins. When administered to mice infected with MRSA, 70 percent of the animals survived, while none of the mice in the control group survived without the vaccine.
“By targeting the toxins released by the bacteria, our experimental vaccine not only stops the bacteria from killing neutrophils, a key type of leukocyte the immune system uses to destroy the invading pathogen, but also defends other leukocytes, such as T cells and B cells, needed to provide long-term protection from future infection,” says Dr. Victor Torres, senior investigator of the study.
The technique is promising in mice, but there's the possibility the results might not carry across to humans. The next steps for the team are to conduct clinical trials, and possibly investigate whether other molecules should be targeted as well.
The research was published in the Journal of Experimental Medicine.
Source: New York University