Research and analysis

Review of airborne antimicrobial resistance

Published 18 February 2020

1. Chief Scientist’s Group research summary

Resistance to antibiotics and other antimicrobial substances is becoming a major risk for human health and it is now clear that many of the resistant infections seen in hospitals have been contracted elsewhere. This report presents the findings of a short project that explored the current state of knowledge on airborne antimicrobial resistance.

There is limited understanding of the sources, loads and pathways of antimicrobial resistance in the environment. Moreover, most of the existing research has focused on wastewater or farm practice. However, the Environment Agency also has duties relating to air emissions from a range of installations. This project sought to review what is known of antimicrobial resistance in the air and to highlight knowledge gaps and potential future research. This review confirmed that there has been very limited research in this area and exposures are expected but unquantified.

1.1 Background

Until recently antimicrobial resistance was largely perceived as a problem for, and from, clinics and animal husbandry. News stories of “superbugs” and actions to combat methicillin resistant Staphylococcus aureus (MRSA) have typically focussed on hospital cleanliness and contamination.

However, it is now appreciated that the environment may play a hugely important role in the genesis, maintenance and spread of antimicrobial resistance.

An important consideration is that people colonised by a resistant organism may harbour it for long periods before needing treatment for an unrelated condition, for example following an accident. Only then may the resistance manifest itself.

In contrast to clinical research, study of environmental resistance in the environment is still in its infancy and study of airborne AMR even more so.

1.2 Aims and approach

The aims of this project were to:

• establish the degree of knowledge of different organisms, antimicrobials and environments
• identify environments with the highest risk of producing or receiving antibiotic resistant microbes (or genes) via the airborne route
• draw out any general patterns emerging from the research and identify knowledge gaps

To do this, a systematic search of the titles and abstracts of 3 databases of academic journal papers (Scopus, Web of Science and Entrez) was carried out for evidence relating to antimicrobial resistance in the air. Relevant papers were obtained and reviewed. Academic groups active in the study of airborne antimicrobial resistance were interviewed by phone and in person.

1.3 Findings

Despite differences in the methods used, the study environments, the antibiotics studied, target organisms and other factors among the studies, some basic conclusions emerged.

• Industrial activities involving faecal matter (including farms) are associated with the highest levels of airborne multi-antibiotic resistance reported to date.
• A major gap is the lack of studies of airborne antimicrobial resistance in the UK. The literature search did not find a single study.
• Antifungal resistance is currently considered to be less of an immediate threat. Nonetheless, the ubiquitous use of azole antifungals in agriculture and medicine, plus the ability of fungi to travel long distances in air, makes antifungal resistance a particularly relevant problem regarding airborne antimicrobial resistance. One UK research group recently began to investigate this topic.

The work also highlighted clear knowledge gaps in the current evidence base on airborne antimicrobial resistance summed up in the following questions:

• Is the air a primary route of antimicrobial resistance transmission to vulnerable hosts?
• How does the resulting risk compare with other transmission methods?

Many of the answers to these questions will come from a better understanding of the biophysics of airborne antimicrobial resistance. A good starting point to achieve this would be research into:

• the size distributions of particles from different sources with differing levels of aerosolisation (production of airborne particles)
• the distribution and survivability of microbes carrying antimicrobial resistance

The project’s findings highlight the need for the Environment Agency and other bodies to ensure that all environmental sources and pathways are considered in situations where they may contribute to antimicrobial resistance risks.

1.4 Publishing details

This summary relates to information from the following project:

Title:

Review of airborne antimicrobial resistance

February 2020

Project manager:

Alwyn Hart, Research, Analysis and Evaluation

Main author:

Matt Jones, Research, Analysis and Evaluation

This project was funded by the Environment Agency’s Research, Analysis and Evaluation group, which provides scientific knowledge, tools and techniques to enable us to protect and manage the environment as effectively as possible.

Enquiries: research@environment-agency.gov.uk

© Environment Agency