Wow, that was quite the study published this week by U.S. researchers trying to figure out what was behind an epidemic of skin and soft-tissue MRSA infections that occurred in Manhattan and the Bronx between 2009 and 2011.
The study, published April 21 in the Proceedings of the National Academy of Sciences, is heavy on genetics and requires a subscription, however, easy to read reports can be found in Nature and by CBS.
Anyway, in the effort to come to grips with the outbreak in New York City, the study offers a number of very instructive lessons about MRSA in general.
To begin with, it’s now abundantly clear that MRSA should no longer be thought of as just a hospital-bound phenomenon – simply put, it has also taken root in our homes. Specifically, the researchers found that MRSA had become “endemic,” i.e. regularly found, in private homes, and that the home plays a critical role as “reservoirs for transmission and diversification.”
Second, we see once again the effect our increasingly mobile society has on the spread of germs and disease. Because it wasn’t the case here that a single local infection spread throughout the NY community. Instead, researchers found that the MRSA had been brought into New York on multiple occasions from California and Texas. We have previously addressed this in the context of international travel where it was said: “Disease is just a plane trip away, and an outbreak anywhere is a threat everywhere.” The present study shows us that the same phenomenon is at work within the large borders of the U.S., and, we would assume, Canada too.
Third, the study illustrates the concept of “strains” of MRSA. As we pointed out recently: “We tend to think of MRSA as a single organism that remains the same over time. But that’s far from the truth and it’s also dangerously misleading. The fact is, there are hundreds of different strains of MRSA – and counting. Which strains predominate will change over time and also over place – not just between hospitals and communities but also between countries. What’s more – and this is key – many of the newer strains are more drug resistant and virulent (toxic) than earlier strains thus making MRSA harder, or even impossible, to treat.”
In this case the focus was on just a single strain of MRSA, called USA 300. While it’s the dominant strain found in U.S. communities the authors note that it was responsible for only 75% of the infections found. Moreover, even this single strain was found to be mutating.
Fourth, the researchers linked the MRSA outbreak – and the resistance of the MRSA to drug therapy – to a time of high-frequency outpatient antibiotic use. In other words, the MRSA outbreak was associated with the overuse of antibiotics. This is a phenomenon that involves physicians willing to please patients at the expense of their health, and demanding patients who insist on getting antibiotics for non-bacterial illnesses like a viral-based cold, as we’ve pointed out before in our discussion of the over-prescription problem.
Finally, even though they found that the MRSA had been brought into New York on multiple occasions from California and Texas, the study notes how MRSA is still very much prevalent in hospitals. Therefore, the authors say, further studies are needed to evaluate how hospitals might be involved in spreading the bacteria back into the community. Which leads us directly to the questionable hospital policy of not treating patients colonized with MRSA, thus sending them home with a 15 – 33% increased risk of infection to themselves, and the risk of spreading their MRSA to others. And that is is exactly what the study found: household members spread their MRSA to the people they live with.
So, in trying to understand why there was a MRSA outbreak in New York the researchers did not uncover factors unique to that city with the possible exception of it simply being a large urban center. Therefore, with this one qualification in mind, it would seem that the answer to the question, Can there be such an outbreak anywhere, is an emphatic, Yes.