Swabbing public transport to identify urban microbiomes, Pg II

Key Highlights:

• Researchers from IIT Madras conducted a study on the urban microbiome and Antimicrobial Resistance (AMR) patterns within the Chennai Metro Rail system.
• The study, carried out in late 2021 and early 2022, identified a distinct 'transit biome' in Chennai, shaped by the city's coastal climate, humidity, and urban density.
• Low but widespread AMR genes, particularly for sulfonamide and rifamycin resistance, were detected in over 80% of the samples collected from high-touch surfaces.
• Nine unique core microbial species, including salt-tolerant and human-skin-associated bacteria, were found to be specific to Chennai's metro environment.
• This research is the first of its kind in the Chennai Metro and underscores the importance of routine microbial and AMR surveillance in Indian public transport.
• Globally, initiatives like the PathoMap project in New York City and the MetaSUB International Consortium have been mapping urban microbiomes since 2013.

Microbiome Study.jpg

Detailed Insights:

• The study involved swabbing 96 samples from 12 stations and trains on Chennai Metro's Blue and Green Lines, targeting surfaces like handrails and ticket kiosks.
• Whole-genome metagenomic sequencing was employed to analyze 47 quality-controlled samples, providing a direct genetic analysis of the microbial communities.
• Ticket-vending kiosks were surprisingly found to be the most microbially diverse surfaces, even more so than train handrails.
• The widespread presence of AMR genes, even at low abundance, highlights a potential public health concern regarding the spread of drug resistance.
• The findings establish a baseline 'digital signature' of Chennai's urban microbiome, which is vital for future monitoring and understanding disease transmission risks.
• The MetaSUB International Consortium aims to create global geospatial metagenomic maps and track AMR markers in urban built environments.
• Previous international studies, such as in the Beijing subway, have identified the potential for transmission of highly resistant bacteria like carbapenem-resistant Enterobacteriaceae.
• Understanding urban microbiomes is crucial for developing effective public health strategies to mitigate pathogen and antibiotic resistance gene transmission in high-density transit settings.

Scientific/Technical Concepts Involved:

• Microbiome: The collection of all microorganisms (bacteria, fungi, viruses) living in a particular environment.
• Antimicrobial Resistance (AMR): The ability of microorganisms to resist the effects of an antimicrobial drug, making infections harder to treat.
• Metagenomics: The study of genetic material recovered directly from environmental samples, without culturing individual organisms.
• Transit Biome: The unique microbial community found within a public transportation system, influenced by local environmental and human factors.