Pseudomonas aeruginosa is only linked to higher mortality in bronchiectasis if patients have multiple annual exacerbations, research finds.

A multivariate analysis of data from more than 2500 bronchiectasis patients across ten European centres found P. aeruginosa infection had no impact on mortality in those with fewer than two exacerbations per year.

However, patients who had two or more exacerbations annually did have increased mortality (OR: 1.74) and this risk was magnified in people who also had P. aeruginosa infection (OR 2.03).

The work could have implications for healthcare policy, with the data suggesting exacerbation prevention could mitigate the effects of P. aeruginosa, researchers wrote in the European Respiratory Journal.

European Respiratory Society bronchiectasis guidelines provided conditional recommendation for inhaled antibiotics in patients with P. aeruginosa and three or more exacerbations per year, with macrolides added if exacerbations were not controlled.

“Our results reinforce the importance of following these recommendations alongside optimizing airway clearance, vaccination and the use of pulmonary rehabilitation,” researchers said.

After adjusting for multiple confounders, the analysis also showed P. aeruginosa was associated with increased exacerbations, increased hospital admissions and worse quality of life.

There was a 15% prevalence of P. aeruginosa across the study cohort, but this varied by country. Rates were lowest in Serbia (0.9%) and climbed to more than 40% in Israel.

An accompanying editorial welcomed the study but noted other crucial questions to be answered, such as whether P. aeruginosa infection was a marker for the severity of bronchiectasis or the cause of subsequent multiple exacerbations.

Editorial author Dr Miguel Angel Martinez-García of the pneumology department at Valencia’s Hospital Universitario y Politécnico la Fe told the limbic that for now the take home message was the link between exacerbations and poor outcomes.

“[The] other… thing is that exacerbations are important “per se” independently of the microorganism associated,” he said.

“It is very important to use treatments which could reduce the frequency or severity of exacerbations especially in those patients with more [numerous] exacerbations.”