Screening currency notes...bugs in your pocket

posted Sep 16, 2015, 2:41 AM by Vinod Scaria   [ updated Sep 17, 2015, 2:32 AM by SRamachandran Igib ]
Saakshi Jalali, 
Research Scholar, CSIR-IGIB.....

Currency notes are extensively exchanged among individuals in a population and have been studied for their ability to carry and transmit infectious agents. Generally microbial culture-based approaches were used to characterize organisms on currency notes. Culture-based are limited by the conditions and culturing media, which differ widely among different organisms. Previous approaches used 16S ribosomal RNA typing to examine taxonomy of the genetic material isolated. The high-throughput DNA sequencing approach offers advantages in providing additional information on the gene repertoire of organisms on the fomite. This information could provide insights into the catalog of antibiotic resistance genes harboured by these organisms. We show success of our approach by characterizing the microbes, including pathogens on currency notes and additionally provide insights into the antibiotic resistance gene repertoire of the microbes.

We obtained metagenomics sequence data using a high-throughput sequencing approach. The sequence data was computationally analyzed to characterize the genomic material.Our analysis revealed the genetic material on the Indian currency notes roughly has Eukaryotic species such as fungi (70%), bacterial populations (9%) and viruses (<1%) including genetic material of 78 pathogens on currency notes. We also identified antibiotic resistance genes for several antibiotics. Our study has the following caveats: 1) compared to the large scale of circulation of Indian currency notes, our sample size may not be sufficiently representative. 2) Presence of genetic material necessarily does not affirm to the presence of live organism although genes and DNA material are known to be exchanged between bacteria in communities. 3) We are unable at this point in time to identify the host organism harbouring the antibiotic resistance genes. Many countries have either adopted or in the process of adopting polymer or plastic currency, owing to their longer life. We should adopt hygienic practices and perhaps use plastic currency more frequently.

Jalali S, Kohli S, Latka C, Bhatia S, Vellarikal SK, Sivasubbu S, Scaria V, Ramachandran S.
Screening currency notes for microbial pathogens and antibiotic resistance genes using a shotgun metagenomic approach.
PLoS One. 2015 Jun 2;10(6):e0128711. doi: 10.1371/journal.pone.0128711. eCollection 2015