Certain pneumonia-causing bacteria produce compounds that help other pathogenic bacteria to spread through the lungs.

Bret Sellman at MedImmune, a biotechnology firm in Gaithersburg, Maryland, and his colleagues infected mice with a variety of bacterial species, either individually or in combination with Staphylococcus aureus, which can cause respiratory and other infections. Mice that were co-infected with S. aureus had higher levels of both microbe species in their lungs, and were more likely to die than animals infected with a single pathogen. The team found that a protein produced by S. aureus, called α-toxin, aids the growth of several bacterial species by impairing immune-cell function. Early treatment with an antibody against α-toxin helped to eliminate S. aureus and prevented other pathogens from multiplying.

The authors suggest that antibody-based treatments targeting a single bacterial species could help some people who are infected with multiple pathogens.

Sci. Transl. Med. 8, 329ra31 (2016)