Sputum antimicrobial susceptibility patterns and clinical outcomes among adult Aboriginal Australians with bronchiectasis.

BackgroundPrevalence of bronchiectasis among the adult Aboriginal Australians is high, estimated to be up to 19.4/1000 people, with associated higher morbidity and mortality. However, despite evidence to suggest that adult Aboriginal Australians have higher bronchiectasis disease burden, the knowledge surrounding sputum antimicrobial susceptibility data is sparce.ObjectivesTo assess the sputum antimicrobial susceptibility patterns among adult Aboriginal patients with bronchiectasis in the Northern Territory of Australia.DesignRetrospective study.MethodPatients aged 18 years and over with sputum antimicrobial susceptibility results available between 2011-2020 during a respiratory related hospital admission (restricted to ICD J presentations) were included. The sputum samples were processed and antibacterial susceptibility reported as per recommended selective susceptibility testing guidelines.ResultsA total of 183 patients had positive sputum cultures. Of these, 167 had antimicrobial susceptibility tested. Antimicrobial resistance to at least one antibiotic was noted for Haemophilus spp. 12 (7%), Pseudomonas spp. 26 (15.4%), Streptococcus pneumoniae 18 (23.1%), Staphylococcus spp. 17 (47.2%) and Klebsiella spp. 8 (88.9%). The greatest frequency of antimicrobial resistance was recorded against Ampicillin for Haemophilus spp. (5.8%), Ceftazidime for Pseudomonas spp. (7.7%), Erythromycin for Streptococcus pneumoniae (20.5%), Flucloxacillin and Amoxycillin/Clavulanate for Staphylococcus spp. (27.8%) and Ampicillin for Klebsiella spp. (88.9%). Multi-antimicrobial resistance was recorded in 31 unique patients. In univariate logistic regression models advancing age was associated with increased odds for antimicrobial resistance for Haemophilus spp. and patients with multi-antimicrobial resistance recorded a higher hospitalisation rate (median 14 vs. 8), more hours in intensive care (median 225.5 vs. 131) and left upper lobe bronchiectasis (41.9 vs 20.4%). Although, statistically not significant, the overall mortality was higher among patients demonstrating multi-antimicrobial resistance, including younger age at death.ConclusionThe results of this study may be of utility in advocating antimicrobial stewardship among adult Aboriginal/Indigenous patients with bronchiectasis.