The Role of the Environment, Especially Surfaces, in the Source of Healthcare-Associated Infections

Professor Hilary Humphreys1

1Department of Clinical Microbiology, RCSI, Smurfit Building, Beaumont Hospital, Dublin D09 YD60


Recent years have seen increasing focus on the inanimate environment, especially surfaces, in the acquisition of healthcare-associated (HCAI) and in the continuation of outbreaks.  Much of the largely circumstantial evidence comes from outbreaks or observational studies.  There are a variety of techniques to sample the environment with differing views on deciding when to culture surfaces.  However, many causes of HCAI, such as MRSA, VRE and others, have adapted to being capable of surviving for months on surfaces.  In the absence of adequate decontamination, these reservoirs contribute to outbreaks.  More recently, it is apparent that Gram-negative bacilli, previously thought not to survive well on dry surfaces, may persist and this probably contributes to the ongoing challenges of extended-spectrum beta-lactamase (ESBLs) producing and carbapenem-resistant Enterobacteriales (CRE).  While it has been well known that moulds such as Aspergillus fumigatus can be airborne and settle on surfaces, the emergence of Candida auris as a virulent pathogen that can contaminate the environment is relatively new and a worrying one.  The innate capacity of microbial pathogens to adapt, evolve and persist in the healthcare environment remains a challenge.  However, ongoing and future studies can inform better strategies to prevent such HCAIs when derived from the environment, and or may break the chain of ongoing transmission.

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