Monday August 17 2015
95% of the purses studied had bacterial consumption
"More than 90 per cent of purses have bacteria on them, and women are the worst offenders," the Mail Online reports. A study found purses could be a reservoir for bacteria, especially those made out of synthetic materials.
This study took swabs from the purses of 145 men and women from Mauritius, and tested them for bacteria in the laboratory. It found that bacteria could be grown from almost all purses (95%). The most common types of bacteria identified were Micrococcus and Staphylococcus, followed by Bacillus.
Importantly, these are usually carried harmlessly on the skin of most people. It is only in specific circumstances – for example, if the person has a weak immune system or if the skin is wounded, allowing the bacteria to enter the body – that infection may take place.
This study has many limitations. One is that it’s a small sample of purses taken from a tropical environment, and the findings may not be representative of the wider population or those from other countries.
We don’t live in a completely sterile environment and ditching the purse or excessively washing it won’t make our environment – or us – bacteria-free. This study should not be a cause for concern for people who own a purse. Remembering to regularly wash your hands, particularly before eating or handling food, is likely to be a better way to reduce our chances of germs spreading that could lead to infection.
Where did the story come from?
The study was carried out by researchers from the University of Mauritius and was published in the peer-reviewed scientific journal Advanced Biomedical Research. No sources of financial support are reported.
The Mail Online’s reporting that purses could be making us sick does not give very reliable coverage of this study or cover the important limitations. A key limitation is that the bacteria grown are naturally found on skin and in the environment, and normally pose no risk to healthy people.
The study did not examine if the bacterial contamination of an individual purse went on to have an effect on a person’s health.
They are also incorrect in saying that "women are the worst offenders" and that "bacteria growth was higher on the purses of women than on those of men". While the researchers do report that bacterial growth was higher on women’s purses, it also reports that the average number of bacterial colonies grown from men’s wallets was higher – so results do not appear to be clear-cut.
What kind of research was this?
This was a laboratory study that swabbed the purses and wallets from a sample of men and women to see what bacteria grew from them under culture (culture, in this context, means creating an environment ideal for the growth of bacteria).
The researchers say that purses are hardly ever washed and are often only thrown out when they become worn out and unusable. What is often not considered is that they could be a breeding ground for bacteria. In fact, all of the things we use in the environment around us, like mobile phones, computers, keyboards and other equipment are all likely to carry some bacteria.
What did the research involve?
The study recruited 145 adults (80 women and 65 men) from the general population in Mauritius. They answered questions on their daily life and work, materials of their purse and frequency of washing their purses.
They then had swabs taken from the outer surfaces of their purses. These were then swiped across the surface of a gel "plate" in the laboratory, to encourage any bacteria on the swabs to grow. Bacterial growth was assessed after 24 hours, by counting the number of "colonies" – small clumps of bacteria – growing on each plate.
Fewer than 20 colonies was defined as scanty growth, 20 to 50 colonies as moderate growth, and more than 50 colonies as heavy growth.
What were the basic results?
Most of the purses sampled (43%) were made of leather; the remainder were synthetic (39%) and cloth (18%). Synthetic purses were more often used by women than men. Only 2% of women (three women) reported washing their purses once a month.
Other purse habits among women were:
- 11% often placed them on kitchen tables
- 18% placed them on dining tables
- 18% allowed their children to handle them
- 82% never emptied them
- Most women kept purses in handbags, most men in trouser pockets
The majority of purses sampled (95%) showed bacterial contamination. In about three-quarters (73%) this was scanty growth; 13% showed moderate growth and 14% showed heavy growth. The average number of bacterial colonies grown from each purse was significantly higher for men’s (25 colonies) than women’s purses (19 colonies). However, bacterial growth was said to be higher on women’s than men’s purses. These results appear to conflict with each other, and it was unclear why.
In roughly half of purses, there was only a single type of bacterial growth; in the other half, there was mixed growth. The most common bacteria grown were types of Micrococcus and Staphylococcus, each accounting for around two-thirds, followed by Bacillus (14%). Micrococcus was more common on the men’s purses, while Bacillus was found only on women’s purses.
Synthetic purses showed a higher number of colonies than on leather or material purses. There were no other differences in bacterial growth by age of the purse or occupation of the person.
How did the researchers interpret the results?
The researchers say that theirs "is the first study to demonstrate that the purses of both women and men from the community could be contaminated with micro-organisms". They also say that these are "potential vectors for transmission of diseases" and that the use of synthetic purses in particular should be discouraged.
This laboratory study looked at the bacteria surrounding us in our environment, this time focusing on sampling carried out on men’s and women’s purses or wallets.
However, before jumping to the conclusion that we need to be either excessively washing our purses, or ditching them altogether and carrying money in our pockets, there are various important points to bear in mind:
- Considering that the vast majority of adults will own some form of purse or wallet, this was a very small sample of purses being tested. The characteristics found in this sample – such as bacterial levels, or purse use and washing habits – may not apply to the general population.
- This was also a specific sample of people from Mauritius. The warm, humid, tropical environment may be a different breeding ground for bacteria, compared with colder climates such as the UK.
- The study only swabbed the outside of the purse. When thinking of the possible bacterial carriage of a purse or wallet, people may think that this could come from the "unclean" coins and notes that have transferred through many hands. However, the study did not swabbed the inside of the purse, which could have given different results.
- Related to this, it is possible that the researchers could have swabbed almost any surface in the environment and found similar bacterial growth. They chose the outside of the purse. They could have swabbed handbags, keys, money, mobiles, computers, door handles – the list goes on. We don’t live in a completely sterile, bacteria-free environment and we are always surrounded by potential sources of infection. From this study, the purse shouldn’t be singled out as the thing we need to ditch to be completely safe from any bacteria.
- The researchers have called purses "potential vectors for transmission of diseases". The study does not show that purses directly have or could cause infection. One of the most common types of bacteria grown was Staphylococcus. This is normally carried harmlessly on the skin of most people. It is only in certain circumstances that it causes infection – for example, if the person has a weak immune system through other disease or illness, or if the skin is wounded, allowing the bacteria to enter the body. Similarly, the other two bacteria grown – Micrococcus and Bacillus – are both found in the natural environment and usually carry no risk to humans. As the researchers rightly say, these bacteria have been called "opportunistic" organisms, rarely causing infection in healthy people.
Being, reportedly, the first study to swab and culture bacteria from purses, this research may be of interest, but it should not be a cause for concern for people who own a purse.
Not regularly washing your hands before preparing food or after going to the toilet is probably a bigger threat to your health than having a messy purse.