2023-06-12 17:45:46
Hospitals are centers of reference for the attention and care of the sick to which hundreds of people go daily, not only for their medical appointments or emergencies, but also to visit hospitalized patients and to work. Many of the pathologies that are consulted and treated in these centers are caused by infectious agents such as bacteria, fungi and viruses that, due to their microscopic size, can easily spread through the air and be inhaled during breathing. For this reason, the question is also raised as to whether hospitals can act as points of emission of these microbes to the rest of the city and the harmful consequences on health that this would cause.
A study carried out by researchers from the Escuela Técnica Superior de Ingenieros Industriales (ETSII) of the Universidad Politécnica de Madrid (UPM) in Spain, has addressed this and other issues at the Hospital Clínico San Carlos in Madrid, within the framework of a research funded by the Community of Madrid (AIRTEC-CM Program).
Specifically, the team led by Andrés Núñez and Ana M. García collected numerous air samples from inside a hospital room and from areas outside during two sampling campaigns that lasted several weeks in the summer of 2020 and the winter 2021. In these samples, the presence of bacteria and fungi was studied using techniques based on the analysis of genetic material (DNA).
All living beings, including microorganisms, have a characteristic region in their DNA that allows them to be distinguished from one another, making it possible to identify existing biodiversity (different microorganisms) and estimate their relative abundance.
By comparing the air samples from inside and outside the hospital, it was found that most of the bacteria and fungi detected in the hospital room (which was kept closed and without human activity) were also present in the outside air. Seasonal variations in composition and relative abundance experienced by microorganisms outdoors were also observed indoors. This would indicate that its origin is mainly environmental and that the microorganisms manage to infiltrate the interior of the building through the cracks in doors and windows driven by the wind, something common in all types of buildings including our houses.
Another interesting finding was to identify a group of bacteria that are typically associated with human skin in air samples. The levels of these bacteria were always higher in the hospital room, which would indicate that the activity carried out inside the buildings leaves a particular mark, influencing the set of microorganisms that can be found there.
Air sampler used in research (left) and culture plates with some bacteria isolated from air (right). (Photos: AIRTEC-CM)
One of the most important questions was to find out if pathogenic microorganisms accumulated in the hospital and if they could spread abroad. The researchers detected low levels of potentially dangerous microorganisms inside the building, but also outside and in areas far from the possible influence of the hospital. Numerous studies conducted in urban environments around the world have also detected some level of potentially pathogenic microbes in the air of cities regardless of the presence of nearby hospitals.
According to Ana M García, researcher in charge of the BIO-MAT group at the UPM: “The results we have obtained suggest that this hospital environment does not act as a relevant pathogen emission point in the city.” In addition, the researchers clarify that DNA-based study techniques do not make it possible to distinguish whether these pathogens are viable (with the ability to cause disease) or not, which would further reduce the possible health risk.
Additionally, the researchers analyzed whether opening the bedroom window had any impact on the microorganisms inside. Their results indicate that after two hours with the window open no significant changes are produced. Along with similar results from other previous studies, the authors clarify that, in order to achieve good ventilation in terms of fungi and bacteria, opening windows should be accompanied by opening doors or other active systems such as fans to create currents that mobilize this specific type. of particles.
The study is titled “The aerobiome in a hospital environment: Characterization, seasonal trends and the effect of window opening ventilation”. And it has been published in the academic journal Building and Environment. (Source: UPM)
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