Species Composition of Microbiota in City Buses

Introduction: Regulatory documents of the Russian sanitary legislation provide no standardization of microbiological indicators for urban public transportation. At the same time, extensive studies of public transport microbiome conducted in dif­ ferent countries demonstrated that the external environment (stations and platforms) and the interior of vehicles contain a large number of various microorganisms, the number of which is independent of air temperature, route duration, or the number of passengers. The objective of our work was to study the species composition of microbiota in urban buses and to assess its structure using methods of synecological and epidemiological analysis. Methods: We analyzed wipe samples from generally accessible bus interior surfaces. In total, 41 buses of 16 routes from three conditional groups (“Nagornaya” (Upland), “Zarechnaya” (Transverse) and “Interdistrict”) were examined. We applied methods of classical bacteriology, MALDI­TOF mass spectrometry for microor­ ganism identification, and synecological analysis. Results and discussion: We identified 85 types of microorganisms, 15 of which were found in all groups of routes. The bus microbiota followed the same ecological laws as natural microbiocenoses. The greatest number of species was represented by genera Staphylococcus (16), Acinetobacter (11), Bacillus (11), Pseudomonas (8), and Pantoea (5). The majority of identified microorganisms belonged to genera Acinetobacter, Enterobacter, and Pantoea. Among 15 species of micro­ organisms “common” to three groups of buses, 60 % were representatives of human microbiota. Microorganisms were found in large quantities on fabric seat backs (up to 18,600 CFU/cm³), seat back handles (up to 76,500 CFU/cm³), leather loop­holders (up to 6,400 CFU/cm³), and visually dirty surfaces (11,200 CFU/cm³). Conclusions: Our findings indicate the need to standardize micro­ biological indicators and develop guidelines for monitoring the efficiency of disinfection of interiors of public passenger vehicles.

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