Bacteria can utilize many different things in order to promote their transmission. Insects, water, food, coughs and sneezes, and sexual contact are just a few examples. Living organisms that transmit bacteria are called vectors, and lifeless objects are called fomites in this respect. In 2013 and 2014, as part of a series of experiments that took place in BMS1035 Practical and Biomedical Bacteriology, University of Surrey students revealed the vast numbers of bacteria that we all carry on our mobile phone. Today we release the results of a new and related study, in which our students examined the bacteria carried on money. The students brought in coins and notes and imprinted them onto bacteriological growth media, which was then incubated to determine how many bacteria grew and to reveal the spatial location of the bacteria on the currency. I should note that after careful washing and drying that the money was returned to the students.
As in our previous studies with mobile phones, we found that money, be it coins or notes, harbours very large numbers of bacteria. The difference here though is that the bacteria on mobile phones are mostly personal ones, because it’s generally only the owner that interacts with the device. Money, on the other hand, is something that we all share so it passes through many many different hands, washed and unwashed. It also gets kept in warm and moist pockets, which offer perfect conditions for bacterial growth and survival. Imagine your wallets or money kept close to your person as Pocket Petri Dishes! Consequently, the populations of bacteria on currency are much larger and more diverse, and money is far more likely to carry disease causing bacteria. The most common types found are skin bacteria but money has also been shown harbour MRSA and food poisoning bacteria in other related studies.