In the Journals

Lung microbiome may predict ICU outcomes

New data suggest that important features of the lung microbiome may predict ventilator-free days among critically ill, mechanically ventilated patients.

In a prospective observational cohort study, Robert P. Dickson, MD, assistant professor of pulmonary and critical care medicine and microbiology and immunology at the University of Michigan, and colleagues used mini-bronchoalveolar lavage samples taken within 24 hours of admission to the ICU to assess the bacterial burden, community diversity and community composition of lung microbiota in 91 patients at a university hospital.

Ventilator-free days at 28 days after admission served as the primary outcome.

Results demonstrated a significant association between increased lung bacterial burden and fewer ventilator-free days (HR = 0.43; 95% CI, 0.21-0.88), with patients in the highest tertile of baseline lung bacterial burden being less likely to be extubated and alive at 7, 14, 21 and 28 days vs. those with lower bacterial burden (HR = 0.45; 95% CI, 0.25-0.81). Notably, the relationship also persisted after controlling for age, sex, severity of illness, suspected pneumonia or acute respiratory distress syndrome (HR = 0.4; 95% CI, 0.18-0.86).

New data suggest that important features of the lung microbiome may predict ventilator-free days among critically ill, mechanically ventilated patients.
Source: Shutterstock

The community composition of lung bacteria also appeared to predict ventilator-free days (P = .003), with the gut-associated bacteria Lachnospiraceae spp. and Enterobacteriaceae spp. being the most strongly predictive of fewer ventilator-free days.

Detection of gut-associated bacteria, such as Enterobacteriaceae, was also linked to presence of ARDS, according to the data.

“We already knew that lung microbiota are altered in critically ill patients and that this disruption is associated with altered lung immunity,” Dickson said in a press release. “What the current study tells us is that this disruption of lung microbiota is clinically meaningful. In otherwise similar patients, differences in lung bacteria help explain who recovers and who doesn’t.”

Given these findings, the researchers noted, the lung microbiome may represent a new therapeutic target for critically ill patients.

“The microbiome is something we can potentially manipulate, unlike other risk factors in the ICU,” Lieuwe Bos, MD, PhD, senior author and research in pulmonology and critical care and pulmonologist in training at Amsterdam University Medical Center, said in the release. “We can’t change our patients’ genes or their chronic disease, but we can potentially change their bodies’ microbiota.”

The study was not without limitations, according to the researchers. For instance, they were unable to control for medications, including antibiotics, that the patients may have taken before ICU admission and they were unable to determine if the gut-associated bacteria in patients’ lungs had migrated from the lower gastrointestinal tract or whether they were present because of aspiration. Future studies addressing these issues therefore are warranted, the researchers noted.

These data overall, though, are an important step forward, according to James Kiley, PhD, director of the division of lung diseases at the National Heart, Lung, and Blood Institute of the NIH.

“This study adds to growing evidence that the lung microbiome plays a key role in lung disease,” he said in the release. “It is important that we continue to explore the microbiome and other factors that contribute to lung disease and clinical outcomes.” – by Melissa Foster

Disclosure: Healio Pulmonology could not confirm the authors’ relevant financial disclosures at the time of publication.

New data suggest that important features of the lung microbiome may predict ventilator-free days among critically ill, mechanically ventilated patients.

In a prospective observational cohort study, Robert P. Dickson, MD, assistant professor of pulmonary and critical care medicine and microbiology and immunology at the University of Michigan, and colleagues used mini-bronchoalveolar lavage samples taken within 24 hours of admission to the ICU to assess the bacterial burden, community diversity and community composition of lung microbiota in 91 patients at a university hospital.

Ventilator-free days at 28 days after admission served as the primary outcome.

Results demonstrated a significant association between increased lung bacterial burden and fewer ventilator-free days (HR = 0.43; 95% CI, 0.21-0.88), with patients in the highest tertile of baseline lung bacterial burden being less likely to be extubated and alive at 7, 14, 21 and 28 days vs. those with lower bacterial burden (HR = 0.45; 95% CI, 0.25-0.81). Notably, the relationship also persisted after controlling for age, sex, severity of illness, suspected pneumonia or acute respiratory distress syndrome (HR = 0.4; 95% CI, 0.18-0.86).

New data suggest that important features of the lung microbiome may predict ventilator-free days among critically ill, mechanically ventilated patients.
Source: Shutterstock

The community composition of lung bacteria also appeared to predict ventilator-free days (P = .003), with the gut-associated bacteria Lachnospiraceae spp. and Enterobacteriaceae spp. being the most strongly predictive of fewer ventilator-free days.

Detection of gut-associated bacteria, such as Enterobacteriaceae, was also linked to presence of ARDS, according to the data.

“We already knew that lung microbiota are altered in critically ill patients and that this disruption is associated with altered lung immunity,” Dickson said in a press release. “What the current study tells us is that this disruption of lung microbiota is clinically meaningful. In otherwise similar patients, differences in lung bacteria help explain who recovers and who doesn’t.”

Given these findings, the researchers noted, the lung microbiome may represent a new therapeutic target for critically ill patients.

“The microbiome is something we can potentially manipulate, unlike other risk factors in the ICU,” Lieuwe Bos, MD, PhD, senior author and research in pulmonology and critical care and pulmonologist in training at Amsterdam University Medical Center, said in the release. “We can’t change our patients’ genes or their chronic disease, but we can potentially change their bodies’ microbiota.”

The study was not without limitations, according to the researchers. For instance, they were unable to control for medications, including antibiotics, that the patients may have taken before ICU admission and they were unable to determine if the gut-associated bacteria in patients’ lungs had migrated from the lower gastrointestinal tract or whether they were present because of aspiration. Future studies addressing these issues therefore are warranted, the researchers noted.

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These data overall, though, are an important step forward, according to James Kiley, PhD, director of the division of lung diseases at the National Heart, Lung, and Blood Institute of the NIH.

“This study adds to growing evidence that the lung microbiome plays a key role in lung disease,” he said in the release. “It is important that we continue to explore the microbiome and other factors that contribute to lung disease and clinical outcomes.” – by Melissa Foster

Disclosure: Healio Pulmonology could not confirm the authors’ relevant financial disclosures at the time of publication.