Feasibility of shortening intravenous antibiotic therapy for bronchiectasis based on bacterial load: a proof-of-concept randomised controlled trial

Background: There is a lack of evidence to guide the duration of intravenous antibiotics for bronchiectasis exacerbations.

Aims: The aim of this study was to assess whether it is feasible, based on bacterial load, to shorten intravenous antibiotics during exacerbations and whether 14 days of treatment is superior.

Methods: We recruited participants requiring intravenous antibiotics for exacerbations. Participants were randomised into two groups: to receive antibiotics for 14 days (14-day group) or to have a shorter duration of treatment based on bacterial load (bacterial load-guided group (BLGG)). Bacterial load was checked on days 0, 7, 10, 14 and 21. If the bacterial load was <10⁶ CFU·mL^-1 on day 7 or day 10 in the BLGG, antibiotics were stopped the following day.

Results: A total of 47 participants were in the 14-day group and 43 were in the BLGG. 88% of participants in the BLGG were able to stop antibiotics by day 8 and potentially 81% of participants in the 14-day group could have stopped antibiotics at day 8. There was a nonsignificant trend for increased clinical improvement by day 21 in the 14-day group compared to the BLGG. However, overall group data showed the median (interquartile range) time to next exacerbation was 27.5 days (12.5-60 days) in the 14-day group and 60 days (18-110 days) in the in BLGG (p=0.0034). In a Cox proportional hazard model, participants in the 14-day group were more likely to experience exacerbations (HR 1.80, 95% CI 1.16-2.80, p=0.009) than those in the BLGG, and those with mild bronchiectasis were less likely to experience exacerbations than patients with more severe bronchiectasis (HR 0.359, 95% CI 0.13-0.99, p=0.048).

Conclusions: Bacterial load-guided therapy is feasible in most exacerbations requiring intravenous antibiotics. There was a nonsignificant trend for increased clinical improvement by day 21 with 14 days of antibiotics compared with bacterial load-guided therapy but paradoxically there was a prolonged time to next exacerbation in the BLGG.