Study Finds Antibiotics Can Weaken the Immune System

Researchers at Harvard, MIT, the Wyss Institute for Biologically Inspired Engineering and the Broad Institute have found antibiotics can be counterproductive and weaken the immune system’s ability to fight off bacteria. In the study, mice were infected with E. coli bacteria and then treated with a common antibiotic called ciprofloxacin. Results showed the antibiotic directly affected the tissues of the mice, which changed the metabolites (cells released during metabolism), making the E. coli more resistant to the antibiotic. At the same time, the immune cells, called macrophages, were found to be less effective at fighting off infection because the antibiotic cut off their respiration. “You generally assume that antibiotics will significantly impact the bacterial cells, and yet here they seem to be triggering responses in mammalian cells,” said James Collins, senior author of the study. “The drugs are producing changes that are actually counterproductive to the treatment effort. They reduce the bacterial susceptibility to antibiotics, and the drugs themselves reduce the functional benefit of the immune cells.”

The researchers plan to conduct more detailed animal studies using other antibiotics. They may also study the metabolites in human patients who are already being treated with antibiotics to see how well the findings may translate.