Passenger-surface microbiome interactions in the subway of Mexico City

Abstract

Interaction between hands and the environment permits the interchange of microorganisms. The Mexico City subway is used daily by millions of passengers that get in contact with its surfaces. In this study, we used 16S rRNA gene sequencing to characterize the microbiomes of frequently touched surfaces and compare regular and women-only wagons. We also explored the effect of surface cleaning on microbial resettling. Finally, we studied passenger behavior and characterized microbial changes after traveling. Most passengers (99%), showed some type of surface interaction during a wagon trip, mostly with the hands (92%). We found microbiome differences associated with surfaces, probably reflecting diverse surface materials and usage frequency. The platform floor was the most bacterial diverse surface, while the stair handrail and pole were the least diverse ones. After pole cleaning, the resettling of microbial diversity was fast (5-30 minutes); however, it did not resemble the initial composition. After traveling, passengers significantly increased their hand microbial diversity and converged to a similar microbial composition among passengers. Additionally, passenger hand microbiomes resembled subway surfaces in diversity. However, microbial fingerprints were preserved within passengers after traveling.

Shaping the subway microbiome through probiotic-based sanitation during the COVID-19 emergency: a pre–post case–control study

“…The passenger microbial input was also well represented in train microbiomes as several human colonizers were detected, although at lower abundance compared with predominantly environmental strains. Staphylococcus , Cutibacterium , Corynebacterium , Streptococcus , Escherichia–Shigella , Acinetobacter , Pseudomonas , and Enterococcus genera were observed at levels of abundance between 0.7 and 2.2%, similarly to what reported in previous studies [ 6 , 36 ].…”

“…To more deeply characterize the control and PCHS train microbiomes, the microbial population was also profiled by NGS to evidence the impact of PCHS on the whole train microbiome. At T0 and all subsequent timepoints, the five most prevalent phyla in both trains were Proteobacteria , Actinobacteria , Firmicutes , Bacteroidota , and Cyanobacteria in order of abundance, confirming previous data obtained in the subway environment [ 1 , 3 , 36 ]. The surface microbiome, compared with that of air, showed a higher abundance of less prevalent species of the Deinococcota , Acidobacteria , Fusobacteria , Chloroflexi , Myxococcota , and Patescibacteria phyla, whereas Proteobacteria and Actinobacteria represented nearly the total microbiome in air filters.…”

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“…It brings people in close contact and facilitates the virus spread by human-to-human transmission. During the daily massive movements, the passengers, sharing the same elements (surfaces, objects) and air, promoted a significant interchange of human or environmental microbiota causing the wider spread of pathogens ( Vargas-Robles et al, 2020 ). The terminal stations such as Indios Verdes in the delegation of Gustavo A. Madero (north of CDMX) and Pantitlan in Venustiano Carranza (east of CDMX) that connect the inner city to suburban areas of Ecatepec de Morelos and Nezahualcóyotl (State of Mexico) were considered among the main “red spots” of COVID-19 contagious in CDMX by national government.…”

Where environmental microbiome meets its host: Subway and passenger microbiome relationships

“…Thus, surface functionality determines which organisms arrive (dispersion), and materials provide different adherence and growth environments for bacteria (filtering). The floor is the most diverse surface, with more unique taxa and the most significant environmental signals (Klimenko et al, 2020; Vargas‐Robles et al, 2020). In Boston, the diversity (Shannon index) of the surfaces correlates with the relative humidity (56%–85%) (Hsu et al, 2016).…”