Progress to bring MRSA under control worldwide

In this Ask the Experts feature, Infectious Disease News Editorial Board member Thomas File, MD, updates readers on the status of the fight against MRSA.

How do efforts around the world differ when it comes to eliminating methicillin-resistant Staphylococcus aureus?

There is a great variation between countries regarding the burden of MRSA. In Scandinavia, for example, they have much better policies for using antibiotics. They don’t abuse them; therefore, their MRSA burden is much lower.

Here, in our country, things are different, even from state to state. There is a lot of debate over whether we should pass legislation to screen people coming into hospitals to see if people have these colonies on their skin. The Veterans Affairs hospitals already require that. It’s controversial; the question of what works to keep infection rates low and what doesn’t and whether it’s a combination of factors.

But it is interesting when you look at European nations, where some countries have infection rates of more than 50%, and then others have them as low as 5%. You ask yourself, why is that; and it’s the use of antibiotics.

Has the MRSA epidemic been brought under control?

No, but it appears to be diminishing somewhat; however, I still think it’s a big deal. In fact, when I think about the most significant emerging infections that have emerged over the last decade, in terms of the ones that have had the most impact both on practicing clinicians in the community, as well as hospital-based clinicians, I think of MRSA and Clostridium difficile.

We saw MRSA emerge over the last 15 years, but in 2005, when the CDC looked at the number of patients who had invasive disease due to MRSA and found there were something like 19,000 deaths as a result of it, that both the medical and the lay press highlighted the impact of the infection.

The study estimates a standardized incidence rate of invasive MRSA infections of 31.8 per 100,000 persons in calendar year 2005.

Of course, that created a great concern publically. So while more recent studies have shown it’s decreased, MRSA is still significant. We still have to consider it the predominant pathogen for anyone who presents in the hospital with or the community with any type of skin infection or cellulitis.

Another issue is that there are often virulence factors with MRSA, which makes infections from other sites potentially deadlier. For example, if a patient’s pneumonia is caused by this kind of bacteria, then it’s associated with a higher rate of adverse outcome.

What are the reasons for the decreased rates of infection?

There are a variety of reasons, beginning with increased awareness of how to treat it. We used to use beta-lactams, and generally, 15 years ago, these were 99% effective in the majority of the staph infections. But now, MRSA is resistant to all but one of these beta-lactams anymore — the most recently approved cephalosporin, ceftaroline, approved for MRSA skin infections. Eventually, just through selective pressure — random mutations — the disease developed resistance to these antibiotics. One of the biggest risk factors for MRSAs is prior antibiotic use.

So, over the last 5 to 10 years, we’ve moved to using microbials such as Trimetha-prin-sulfa doxycycline, particularly for outpatient infections because these agents are effective against more than 95% of the community-associated MRSA.

Probably another reason we’re seeing a reduction in infections in some areas is better hygiene, which leads to less transmission. Our patients are more aware that if they have these kinds of sores, they should use antibacterial soaps, and so on.

Does the general public seem to have a better awareness of what MRSA is and how to manage it?

Well, it’s interesting how my patients, when they are referred to me in the outpatient setting for recurring staph infections, are aware of the term MRSA but not S. aureus. I had one patient the other day come to see me because of her recurrent boils. I explained to her the culture was positive for methicillin-resistant S. aureus. She told me she was relieved to know it wasn’t MRSA. So of course, I had to explain to her it was the same thing.

Patients know it is bad, but they don’t know what the initials are for. So, education is the key. We not only have to explain what the infection is, but we have to stress the importance of strict hygiene, and to teach patients strategies to reduce it, so it is less likely to re-occur.

What are the challenges to creating international standard protocols?

There are so many variations culturally, politically and financially. Still, [the IDSA] has over the past 5 years, been encouraging collaborative guidelines between medical societies and countries, because it strengthens the credibility of all the guidelines.

Another obstacle to overcome is that some antibiotics are approved for use in some countries, but not in others. For example, fusidic acid is approved in Canada, but not in this country. There is a company now looking at a new formulation of that drug, but the problem with the drug in the past, as I understand it, is resistance.

As for politics, the only point I would make is that they can unduly influence regulations that should be left up to science. And so while politicians might have good intentions, they aren’t necessarily aware of the total implications of what they are trying to legislate. It’s important that when public health policies are generated by governments, it is on the basis of science, not political pressure.

What kind of impact do you intend IDSA’s MRSA guidelines to have?

One of the benefits of our guidelines is that as we review the evidence, we recognize where the research gaps are. For example, one of the questions we have now is to do with how to eliminate recurrent boils. We still need better data to specifically and definitively state what the best strategy is. But the primary purpose is to assist clinicians in patient care decisions and to give them guidance on how to promote optimal care for best patient outcomes. – by Whitney McKnight

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