According to a study in the European Respiratory Journal, inhaled corticosteroids (ICS) cause increases in sputum bacterial load in COPD patients with lower eosinophil levels.

By using a randomized controlled interventional study they sought to investigate the direct impact of ICS on sputum bacterial load over a 12-month period and importantly to stratify responses by patient eosinophils levels in both blood and sputum.

The importance of using bacterial load as a key index of microbiological status has long been debated, but its choice is supported by previous observations that higher bacterial loads have been associated with greater levels of neutrophilic airway inflammation and lung function decline.

There were 30 patients in each of the treatment (ICS/long-acting ?2 agonists (LABA)) and control (LABA) arms. Both groups had comparable airway bacterial loads at baseline, but after 1?year of treatment the ICS group had manifest a significant rise in load not seen in the LABA arm.