Are microbes becoming resistant to chemical disinfectants?

After the COVID-19 pandemic, many people have become accustomed to using disinfectants at home profusely and routinely to kill dangerous microbes that may be there. But perhaps this could be generating an unexpected and potentially dangerous effect, judging by the results of a recent study.

The study was carried out by a team led by Xinzhao Tong, from Xi’an Jiaotong-Liverpool University, an institution jointly created in China by Xi’an Jiaotong University, in that country, and the University of Liverpool, in the United.

The study authors collected 738 samples from various artificial environments such as subway lines, residential buildings and public buildings, as well as human skin, in Hong Kong. They then used a special sequencing technique to analyze the microbial genomic content and find out how the microbes have adapted to the urban environment, which is more hostile to them than the natural environment, at least in terms of suffering more chemical attacks than those suffered by their animals. country relatives.

The team identified 363 previously unidentified microbial strains that live on our skin and in the environment around us. Some of the genomes of these strains contain genes to metabolize manufactured products that are common in cities and use them as sources of carbon and energy. One of these cases is that of a strain of the phylum Candidatus Eremiobacterota, which until now was only known to be present in Antarctic soils.

The genome of this new strain of C. Eremiobacterota allows it to metabolize ammonium ions present in cleaning products. The strain also has genes that serve to break down residual alcohol found in common disinfectants.

Microbes that have improved capabilities to use the limited resources of the urban environment and tolerate manufactured products, such as disinfectants, have better survival expectations than those of strains without these improvements, which favors an increase in the population of the first and second in these artificial environments. that of the latter decreases, as well as that the former see their evolution reinforced in such environments. They could therefore pose health risks if they are pathogenic, as Tong argues.

The Human Microbiome Project, launched by the National Institutes of Health (NIH) of the United States in 2007, has in recent years provided the first insight into the microbial diversity of healthy humans and is exploring possible relationships between the microbiome and certain human diseases. Images show, clockwise, from top left: Streptococcus (credit: Tom Schmidt); biofilm, of various microbial species, from the human body (credit: A. Earl/Broad Institute/MIT); bacteria of the genus Bacillus (credit: Tom Schmid); and Malassezia lopophilis (credit: JH, CDC). Composite image credit is: Jonathan Bailey / National Human Genome Research Institute / NIH)

The team identified 11 previously uncharacterized strains of Micrococcus luteus, normally non-pathogenic but capable of causing opportunistic infections in immunocompromised people.

The researchers also characterized two new strains of Patescibacteria, known as “nanobacteria,” because they have tiny genomes that do not contain many genes to produce their own resources.

Some strains of Patescibacteria are considered parasitic, as they depend on bacterial hosts for their nutrients. However, in this study, the researchers discovered that one of the nanobacteria strains, recovered from human skin, contains genes for carotenoid and ubiquinone biosynthesis. These antioxidant compounds, which we normally acquire, especially carotenoids, through diet, are vital for humans. This suggests a possible mutualistic relationship of these bacteria with us as their hosts.

The study is titled “Diverse and specialized metabolic capabilities of microbes in oligotrophic built environments.” And it has been published in the academic journal Microbiome.

The team is now investigating the transmission and evolution of resistance in pathogenic microbes present in intensive care units exposed to strict and extensive disinfection practices. They hope to improve infection control practices and make clinical environments safer for patients and healthcare workers. (Fountain: NCYT by Amazings)