The bacteria living on our hands
Published: 20 Apr 2018
Some bacteria that contaminate our hands when handling various objects we regularly come into contact with can cause diseases including pneumonia and gastrointestinal illnesses similar to viruses such as norovirus, a common cause of “stomach flu”.
In an experiment supervised by Assistant Professor Chris Sham from the Department of Microbiology and Immunology at NUS Medicine, he examined the bacteria that contaminate our hands after coming into contact with items such as mobile phones, trolley handles and pantry sponges.
The experiment compared control plates that had prints of hands that were thoroughly washed with agar plates imprinted by hands that had come into contact with the objects. Not only did the control plates exhibit drastically less bacteria, but staphylococcus aureus, a pathogen that can cause serious infections was also found on plates that were imprinted by hands after handling mobile phones or trolley handles. Individual colonies of bacteria also appeared to have fused when examining the bacteria transferred from pantry sponges, becoming what Asst Prof Sham termed as confluent growth and suggested that such sponges may not be as clean as people expected.
Assistant Professor Natasha Bagdasarian from the Department of Medicine at NUS Medicine also cited a study that discovered enterococci, a type of faecal bacteria that is found on hands that touched handrails, door handles and seats in public areas such as museums and public transportation.
Washing our hands well and applying skin disinfectants can effectively eliminate the bacteria that are potentially harmful, but Asst Prof Sham explained that it is impossible to make oneself completely sterile.
“You can wash your hands 500 times but because the environment is filled with bacteria, you are bound to pick it up somewhere,” he said. Instead, he advised for people to control the kind of bacteria they come into contact with, noting that that not all bacteria is bad for humans.
“For example, some of your gut microbes produce vitamins that you cannot produce. Some of them also help to maintain your immune system,” Asst Prof Sham added. Bacteria are usually either transient or resident, and the latter ones are always present on human skin, often harmless and working to keep other bacteria at bay.
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