On the issue of studying bacterial contamination of indoor surfaces of the Moscow Metro

Introduction. During operation, the passenger rooms of the stations and the rolling stock of the subway are subjected to intense complex effects of mechanical, chemical, and biological factors. According to the literature data of domestic and foreign researchers, on surfaces in the Subway there are found various genera of microorganisms including Dietzia, Brevundimonas, Pseudomonas, Arsenicicoccus, Stenotrophomonas. However, there is no data on the degree of surface contamination in the available literature. However, information about such studies is necessary to take sanitary, hygienic, and anti-epidemic measures to prevent and reduce the risk of contracting infectious diseases in crowded places.
The purpose of the study. To study bacterial contamination of surfaces of the Moscow metro to develop criteria for assessing the degree of contamination of surfaces.
Materials and methods. The assessment of contamination of subway surfaces was carried out according to sanitary and bacteriological indicators by the method of prints and flushes with the determination of the total microbial number (TMN) and bacteria of the E. coli group (Escherichia coli) by classical microbiological methods (Methodological guidelines MUK 4.2.2942–11 "Methods of sanitary and bacteriological studies of environmental objects, air and sterility control in medical organizations"). The obtained results were processed using indicators of variation statistics and determining the degree of reliability according to the Student’s criterion.
Results. The highest level of microbial contamination was detected on the surfaces of the vestibules and passages between the vestibules and the halls of the stations. The contamination of the lobby floor (with a microbial contamination level of 105–107 CFU/100 cm2) was 93% of the total number of samples, while the percentage of samples with the same contamination level in the station halls corresponded to 72%; microbial contamination of the lobby walls (105–107 CFU/100 cm2) was 100%, while in the station halls the percentage of samples with this level of pollution was only 33%. The microbial contamination of the counters at the cash registers turned out to be significantly higher than the contamination of the entrance doors (respectively: 100% and 40%).
Limitations. The research was carried out only at twelve stations (Kurskaya-Radial. Kursk-Koltsevaya, VDNKh, Medvedkovo, Sviblovo, Vykhino, Krestyanskaya Zastava, Proletarskaya, Novokuznetsk, Pushkinskaya, Tverskaya, Chekhov).
Conclusion. Based on the results obtained, for assessing the contamination of surfaces (walls, ceilings, floors, columns, window panes, etc.) at Moscow Metro there have been developed criteria including high, medium, and relatively clean pollution levels.

underground, biological contamination, general microbial contamination, E. coli group bacteria