Chronic infection is associated with adverse outcomes among people with bronchiectasis. However, it is not known which factors are associated with a bacterial infection, and with persistence of an infection after the first episode. We aimed to determine factors associated with a new infection and with chronicity of Pseudomonas aeruginosa (PA) and H. influenzae (HI), the most common organisms in bronchiectasis infection.

Using an Israeli population database, we identified individuals diagnosed with bronchiectasis. Cox proportional hazard models were used to assess risk factors for first isolation and Logistic regression for chronicity of infection after a first isolation of PA and HI.

We included 1305 people with a median of 5 respiratory samples per individual. PA was initially isolated in 297 people, of whom 97 (33%) developed chronic PA infection. HI was newly identified in 169 people, of whom 39 (23%) developed chronic infection (p = 0.029). Factors associated with increased risk of a new infection with PA were COPD (HR 1.87 [1.52–2.28], previous isolation of HI (HR 1.38 [1.07–1.78]), and alcohol abuse (HR 2.22 [1.13–4.3]). Younger age was associated with increased risk of HI infection, while COPD was associated with a lower risk of HI infection. Prescription of an anti- PA antibiotic was associated with chronic PA after a new infection (OR = 1.8 [1.09–2.9], p = 0.02). A landmark analysis showed that survival was worse in people with chronic PA infection vs. single or intermittent infection (Log rank: p = 0.034)

Younger age and presence of PCD are associated with a new isolation of HI. A new infection with PA is associated with previous HI infection, PCD, COPD, and alcohol abuse. Unexpectedly, treatment with appropriate anti-PA antimicrobials was not associated with a reduced risk of chronicity.