A new case study from researchers at Oxford University has tracked, for the first time, the movement of antibiotic-resistant bacteria from a patient's gut microbiome to their lungs. The research presents the first direct evidence of this transmission pathway taking place in critically ill hospital patients.
Pseudomonas aeruginosa is a bacteria commonly responsible for hospital-acquired infections that can lead to pneumonia or sepsis. But some researchers have hypothesized the most antibiotic-resistant forms of the bacteria that appear in critically ill patients may not be acquired in hospital after all.
The hypothesis explored in this new study is that antibiotic-resistant lung infections can originate in a patient's gut microbiome, and certain treatments in hospital can cause the pathogenic bacteria to proliferate and travel from the gut to the lungs. To investigate this hypothesis a single intensive care patient was intensively studied for several weeks during a hospital stay.
While in hospital the patient was treated for a urinary tract infection with an antibiotic called meropenem, which was found to eliminate the majority of Pseudomonas aeruginosa bacteria in the patient. However, what remained was the most antibiotic-resistant strains of the bacteria, and the antibiotic treatment essentially spurred the proliferation of that most pathogenic bacteria.
Over several days the researchers tracked the genomic progression of the bacteria, watching it grow in the gut and then move to the lungs. The researchers note this is the first direct evidence of antibiotic-resistant bacteria traveling from the gut to the lungs.
"Our study shows how gut-lung translocation and antibiotic use can combine to drive the spread of AMR [anti-microbial resistance] within a single patient," explained lead author on the study, Craig MacLean. "Insights such as this are needed in order to develop new interventions to prevent resistant infections."
This novel direct evidence offers new ways to potentially fight the rise of antibiotic-resistant bacteria in hospitals. If this kind of gut-to-lung transmission is found to be common then it's possible to combat these infections by finding ways to prevent the bacteria moving from the gut – or, as MacLean suggests, developing ways to prevent the antibiotic-resistant bacteria from colonizing the gut in the first place.
"… our study highlights a potential benefit of eliminating AMR bacteria like Pseudomonas aeruginosa from the gut microbiome of hospitalized patients, even when these bacteria are not actually causing infection," MacLean said.
The study is published in the journal Nature Medicine.
Source: University of Oxford