03/22/2015 11:58 EDT | Updated 05/22/2015 05:59 EDT

MRSA Is More Widespread Than You Think


At one time or another we may be asked by a friend or a relative to invite them in for a visit. Usually, it's only "for a few days." Most adhere to their promise but some may tend to overstay their welcome and hang around for much longer than anticipated. Unless directly confronted, the visitation may turn into an unintended co-habitation requiring us to be wary of any possible consequences such as an empty fridge or a borrowed piece of clothing.

Pathogens also tend to make household visits usually leading to days or weeks of anguish. Names such as influenza, norovirus, and E. coli can come into the home and stick around, spreading from one member of a household to another. Thankfully, their stay is limited and eventually we return to normal.

But last week, a team of American researchers revealed one particular health threat with the ability to hang around a home for not just weeks, but years. It's commonly know as MRSA -- Methicillin-Resistant Staphylococcus aureus -- and it is one of the most worrisome bacteria known to public health. Not only is it resistant to many antibiotics, but it also is the cause of both persistent and in possibly deadly infections. In Canada alone, thousands of people are infected by this pathogen each year.

Because MRSA can be found in the community, the authors wanted to get an idea of how the bacterium tends to live and spread. To do this, they investigated several MRSA cases in Los Angeles and Chicago. The team asked 350 suffering from a confirmed infection for permission to sample their homes. They had no problem with the short visitation and agreed.

With consent in place, members of the group went into the homes and took samples from the nostrils, the mouth and the abdomen of the inhabitants. The swabs were taken back to the lab where they were examined for any signs of MRSA. In total, the group tested 1,162 people and found MRSA in close to half of the people tested. In terms of the number of homes, positive samples were found in 137 of the 350 visited.

But while this was sufficient to show spread like other pathogens, the group wanted to go further in depth to determine how long the bacteria may have been around. To do this, they looked at the genetic material from 146 samples taken from 21 homes. This analysis was incredibly in-depth, taking a look at every single piece of DNA to identify any changes in the genetic code. Each difference was marked, catalogued and then compared to the sequences of MRSA strains contained in historical databases.

When the work was completed, the results were shocking. Based on the analysis, the length of time MRSA lingered in a home was between two and eight years. In the process, the bacteria simply transferred within the confines of the home. Though only the individual people were tested, the authors suggested the bacteria were moving from people to pets to inanimate objects and back again.

The results of this study are shocking for two distinct reasons. The first is the incredible amount of time the bacterium can persist in a home environment. The dynamics of transfer are based on simple contact between loved ones and the objects they use on a regular basis. It would be almost impossible to get rid of the unwanted visitor without direct intervention. But even then, people have to stick to a program for up to a year before they can be MRSA-free.

But the second reason is far more distressing. The experiments reflected MRSA persistence in a rather confined area, a home. But this bacterium can be found in a number of larger places, including gyms, schools and even public institutions. If MRSA can last for up to eight years in a home, more public areas may harbour the bacterium for even longer periods of time; perhaps even permanently. Then there is the healthcare environment where MRSA has been causing troubles for decades. The premise of long-term persistence in these areas of health is not outside the realm of this study. Although no such in-depth study has been conducted in these areas, there is definitely a reason to believe it should be done.

The presence of MRSA in the community, such as the home or public places, continues to be a concern for public health officials. Although it is not a strict pathogen like flu and norovirus, the bacterium is still a problem as it can infect any break in the skin and also cause troubles in the lungs. The results of this study only highlight the need to be even more careful when we have those cuts and scrapes as well as any respiratory difficulties. Although we may not have MRSA staying in our homes, the risk of finding it elsewhere in the community suggests we should always be aware.