When Microbes in Lungs Fight Invading Pathogens

(Image Caption :  Microscopy image of lung sections of mice. Commensal bacteria are stained in red-pink colours and lung cells are coloured in purple/gray. © UNIGE/Schmolke)

Sometimes, commensal bacteria that live inside our body provides a competitive barrier against invading bacterial pathogens. A study done by researchers at University of Geneva has found that commensal bacteria, Lactobacillus murinus (L murinus) is present in lung tissue of mice. Treating mice with L murinus, following influenza A-the flu virus- infection, provided a better barrier against pneumococcal colonisation in the animals. These results suggest that resident commensals in the lung could be applied as probiotics to counteract lung colonisation by pathogenic bacteria.

They found that L. murinus inhibited the growth of the pathogen through the release of lactic acid. “This antibacterial activity was not limited to pneumococcus,” says co-first author João Pereira Bonifacio Lopes, PhD student at the UNIGE. “It also affected S. aureaus, the pathogen that can cause bloodstream, bone and joint infections, as well as pneumonia.” By treating mice with L. murinus following influenza A infection, they found that the bacteria provided a barrier against pneumococcal colonisation in the animals.

“This suggests that resident commensals in the lung could be applied as probiotics to counteract lung colonisation by pathogenic bacteria,” concludes senior author Mirco Schmolke, Professor at the Department of Microbiology and Molecular Medicine of UNIGE Faculty of Medicine. “However, further studies are needed before this can be explored as a potential treatment in humans. If it one day proves to be effective, the approach could improve the clinical outcomes for patients who are susceptible to respiratory tract infections.”