How the immune system can help in the fight against germs

Klebsiella pneumoniae

Researchers from Vienna and Belfast have found out how the immune system slows down the growth of the multi-resistant germ Klebsiella pneumoniae. The results could lead to new therapeutic options for treating infections.

Klebsiella pneumoniae is a natural inhabitant of the intestinal flora. The bacterium, named after bacteriologist Edwin Klebs, is harmless for patients with an intact immune system – in immunocompromised patients, however, it can lead to severe to fatal infections, such as pneumonia, urinary tract infections or blood poisoning.

In 2017, two patients in Frankfurt a.M., Germany, died from Klebsiella infections. The germ is difficult to treat because it is resistant to many antibiotics. Carbapenems, the last resort for treating hospital-acquired infections, are also often no longer effective.

How the immune system fights Klebsiella

Researchers from the Medical University of Vienna and Queen’s University Belfast recently deciphered how the immune system fights Klebsiella during pneumonia. They published their results in the trade journal ”PLOS Pathogens”. Klebsiella bacteria activate Type I interferons (IFNs). These in turn stimulate natural killer cells, which allow the macrophages to kill and “eat up“ the Klebsiella pathogens, in other words, render them harmless

This means that future therapies aimed at the germ might not target the bacterium itself, but rather the immune system of the person affected. This new approach could also help in the fight against other antibiotic-resistant pathogens. Instead of attacking the germs, such a treatment supports the immune system in its task. In a current study, the researchers are investigating precisely such therapeutic approaches.


  1. Natural killer cell-intrinsic type I IFN signaling controls Klebsiella pneumoniae growth during lung infection, Ivin M et al., PLOS Pathogens

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