30 June 2020

Cystic Fibrosis Otago is working with the University of Otago to investigate how people with CF are cleaning antibiotic residue from their nebulisers and how this might impact antibiotic resistance.

The objectives of phase 1 of the project were to:

• determine the types of nebulisers and inhaled antibiotics being used in the home by the CF community
• investigate the methods PWCF or their carers use to clean nebulisers and dispose of residual antibiotic solution after treatment with a nebuliser in the home setting
• develop a test to measure the amount of antibiotic remaining in different nebuliser systems after treatment, and the concentration of that residual antibiotic solution in wash water after nebuliser systems are rinsed in wash buckets after use. 

Researchers’ findings from a telephone survey of 9 Otago-based caregivers of PWCF who've used nebuliser antibiotics found that tobramycin was the most common nebulised antibiotic and in most cases antibiotic residue was poured down household drains.

A national-based survey followed with similar findings, with antibiotic residue either drained directly into the sink, rinsed with water then poured into the sink or rinsed with detergent and poured into the sink, before sterilising. 

A Liquid Chromatography Mass Spectrometry (LCMS) assay to detect tobramycin at very low concentrations in nebuliser wash water was developed by University of Otago scientists.

To date, this assay has found that approximately 20% of a standard 300mg tobramycin dose was found in the wash water from a rinsed nebuliser after phantom aerosolisation (i.e. the tobramycin dose was nebulised into a laboratory fume cupboard, rather than inhaled by a PWCF).

Funding for phase 2 of the project has been confirmed and will focus on developing a practical nebuliser cleaning strategy (or strategies) to help reduce the risks of antibiotic resistance due to the variable disposal practices that were found in phase 1.

Researchers will share their findings with the CF community and work to co-development recommendations for the safe and practical disposal of antibiotic residue from nebulisers. It’s hoped the findings can be shared more widely to help raise awareness of antibiotic resistance. 

Why this research is important

Antibiotic resistance is a serious and growing health problem and there’s concern within our CF community that rinsing residual antibiotic solution from nebulisers down the sink may contribute to this problem.

Disposal of unused antibiotics into waste water or landfills has been reported to lead to high rates of resistant bacteria in the environment. The Ministry of Health (MoH), PHARMAC, district health boards and the Pharmaceutical Society of New Zealand recommend unused antibiotics shouldn’t be poured down drains or put in household rubbish but instead should be returned to a pharmacist for safe disposal. However, there’s disconnect between this advice and how residual antibiotics are currently being disposed of. 

Thank you to researchers at Otago University and CF Otago chairperson Julian Cox for providing a project update.