Аннотация:Antibiotic resistance (the ability of infectious strains of microorganisms to defeat the antibiotics designed tokill them) is a major and growing concern for global human health. Ever increasingly, there are less and lessoptions left available to us for fighting against the surrounding opportunistic, pathogenic and allergenic strainsof microorganisms. There are very high health risks to humans, primarily, people with a weak immune systemand children, who live in large cities and megacities. Potentially hazardous microorganisms are present in bothnatural and man-made substrates in the urban environment, in particular, in urban dust aerosols circulatingwithin the lower layers of the atmosphere. In natural environments, inorganic components of atmospheric dustare mostly represented by particles of pedogenic and lithogenic origin. In urban environments, such inorganiccomponents also include micro-fragments of man-made materials from roads, buildings, etc.. Atmosphericparticulate matter also contains living organisms that float and drift in the air – aeroplankton, which includescultivated bacterial strains, fungal spores and live cells of algae, lichens, mosses and protozoans.We collected samples of atmospheric depositions of dust aerosols from two study sites within the city ofMoscow (Russia) in the summer of 2019. One site was located in the city centre and the other within thecampus of the Lomonosov Moscow State University. The samples were subjected to submicromorphologicaland microbiological investigations.Microparticles of dried faeces were detected in the atmospheric dust composition using a JEOL JSM-6610LVscanning electron microscope with an INCAx-act energy dispersive detector (SEM-EDS elementalmicroanalysis). Such microparticles are likely to be lifted up from the surface of city soils by wind currents,because the practice of clearing up the faeces of domestic pets has only a very limited application in Moscow.The taxonomic structure of bacterial communities isolated from atmospheric particulate matter from both studysites was characterized by a relative abundance of species from the family Enterobacteriaceae includingEscherichia coli (a total of 31 strains identified by modern molecular genetic techniques based on 16SрRNAgene sequencing) – indicator of substrate contamination by faeces. Sensitivity to antibiotics was tested in 28strains of E.coli by the disc diffusion method using nine antimicrobial drugs, which are well-known and usedextensively worldwide, as follows: Amoxicillin (10 mcg/disc), Ampicillin (10 mcg/disc), Meropenem (10mcg/disc), Pefloxacin (5mcg/disc), Streptomycin (300 mcg/disc), Ticarcillin (75 mcg/disc), Fosfomycin (200mcg/disc), Ceftibuten (30 mcg/disc) and Ciprofloxacin (10 mcg/disc).The percentages of antibiotic-resistant strains of Escherichia coli varied from zero in the Fosfomycin-200 testto 25% in the Ceftibuten-30 test. A relatively high proportion (14.3%) of resistant strains was also detected inthe Streptomycin-300 test.Thus, the studied urban atmospheric dust aerosols were shown to transfer microbial pollution due to thepresence of faecal contamination as well as antibiotic-resistant strains of E.coli, which creates potential healthrisks for the immunosuppressed population of Moscow city. The presence of particles contaminated withantibiotic-resistant strains of E.coli in the air indicates an insufficient activity of urban soils as a bacterial filter.The use of local screening with prospective testing of dust aerosols in any urban environment would be avaluable tool in ecological and monitoring assessments and also in the development of recommendationsregarding the selection of antimicrobial drugs for the treatment of infections in city populations. The studyhighlights the need for administrations of cities such as Moscow to encourage residents to dispose of dogwaste.
