Behind the screens

As the fight against hospital-acquired MRSA continues in earnest, hospitals are sifting through a myriad of different screening techniques to find a best fit – and for NorthShore HealthSystems, they could be that one step closer to doing so.

The battle against infection is an on-going struggle of one-upmanship - especially when it comes to hospital-acquired infections (HAIs). The point at which you think you've harnessed a specific bacteria's tolerance levels is usually the point at which you realize how far away you are from doing precisely that - and the cyclical nature of infection prevention continues. So what's left in the armory when it comes to dealing with HAIs for hospitals in the US, especially when it comes to MRSA?

Well, according to Lance Peterson, Director of Clinical Microbiology and the Infectious Diseases Research Division at NorthShore University HealthSystem, the answer comes down to active surveillance. And, being the first US-based hospital to do so - starting back in 2005 - both the hospital and Peterson have a solid track record in screening for MRSA, with a staggering 70 percent reduction in all disease infections in the last five years. The real question that needs answering, as Peterson asserts, is finding out if you can have the same impact by doing less.

"When we first started, we could have captured about 80 percent of our patients with MRSA by screening half of the admission instead of all of them," begins Peterson. "But the consensus was that would be more work for the nurses as they would have had to ask a series of questions, so it was just operationally easier to screen everybody, which is really how we got into active surveillance. We added the equivalent of one-and-a-half people to the laboratory to do the testing as they were doing roughly 200 tests per day, with the hospital system consisting of three hospitals and about 750 acute-care beds at that time."

And while universal screening is the preferred choice for hospitals, financial and staffing issues often mean that it's not a viable option. So, to get the ball rolling, Peterson often suggests a procedure called 'point prevalence' to hospitals looking to advance their MRSA screening techniques. In essence, the procedure involves culturing every patient's nose in the hospital, either over a day or a week, to see what percentage of patients occupying the hospital are harboring MRSA in their nose - which is exactly how NorthShore started its surveillance.

"We did that in 2004 and found that 8.5 percent of our patients had MRSA in their nose. The previous public note had been out of Atlanta based on 1999 data, and about 2.7 percent of their admission had MRSA. Clearly, in the big cities in the US, the disease had tripled between 1999 and 2004, so that was what pushed us into doing something. If you conduct point prevalence and find that you maybe have one percent of patients with MRSA in their nose, there's probably no point in doing anything. However, if you're over about five percent, then it's likely that you have an issue you need to deal with. If you're between one and five percent, then you have to look at the cost benefit of it all."

An uphill battle

The drive in increase between 1999 and 2004 that Peterson notes comes down to nothing more than the very nature of bacteria and their ability, every once in a while, to produce a strain that becomes efficient at surviving within its relative environment - becoming adept at being adherent to patients and healthcare workers and allowing them to spread with ease: the unavoidable bane of infection control departments across the country.

"There's been some elegant work done in England showing that, of the 20 lineages of regular Staph Aureus that circulate the world, only about six of them are able to tolerate the genetics to make the Methicillin resistant," continues Peterson. "There are a few clones of MRSA that are just very good at spreading. For example, when an epidemic strain finally made its way down to Australia, within three years it had taken over between 30 and 70 percent of the ICU MRSA disease. These bit clones, once embedded in a population, spread extremely well."

And once spread, the battle changes from prevention to treatment. While standard protocol changes between hospitals, the fact that they exist and are being implemented is enough to prove that a proactive approach is being taken towards combating MRSA. At NorthShore, the procedure is deliberately simple: when a new room is prepared, a nasal swab with directions is put on the bedside for the nurse to come in and use on a new patient. That nasal swab is taken and sent directly to the lab for testing. It really is as basic as that - but it works.

"We happen to use a rapid molecular test to get a fast turnaround time. If it's positive, the technologists in the lab enter the electronic medical record and order an isolation cart directly to the patient's room. At the same time, they also put on our 'problem list' that the patient has a multi-drug resistant organism. At that point, once the physician has seen it, they order mupirocin decolonization for the patient."

Indeed, the rapid molecular test used by Peterson and his team at NorthShore makes life exponentially easier when preparing a specimen. He notes that in previous years, using their own tests developed in the laboratory, it used to take twice the amount of time when compared with today's results. There are chromogenic agar tests available on the market, but their current sensitivity is about 20 percent less than the PCR, unless you consider enrichment steps - in which case you're looking at a three-day turnaround period.

The next step after getting disease and colonization down, is looking at ways to cut back on some of the screening - but, as Peterson affirms, "I'm not sure we can." The hope is that eventually NorthShore and the US in general can reach the standards of the Dutch, who are streets ahead of the game when it comes to MRSA screening. "Instead of having 50 percent of their Staph Aureus being MRSA, they have about one to two percent," continues Peterson. "They have a good understanding of who the people are that are at risk for carrying it, so they don't need to test everybody anymore. Instead, they only test people coming from high-risk countries or from other hospitals."

Moving on to the subject of the re-screening of patients re-entering the hospital, it would seem that the Dutch have that down too. Where NorthShore - and the US as a generalization - retest patients every time they cross the threshold of the hospital, the Dutch have progressed what Peterson refers to as a 'bank' filled with patients who proved negative at the screening stage. Once they enter the bank, they are exempt from screening again. Currently, NorthShore is looking at a similar potential in which, dependent on a patient's data, after a year or so they won't need to be screened again upon re-entry. Although it's only a potential solution, Peterson believes it could be one of many routes to cutting back on screening.

"We have a long list of things to look at," explains Peterson, "and this is just one that we haven't got around to look at yet - but it is important to look at. Certainly, I don't think you could make any conclusions on just screening someone once. About 20 to 25 percent of our patients get readmitted - and now we've screened close to 30,000 people - so there's a large data set we can look at to assess the potential that if you've been screened twice and been negative, what's the possibility of you screening positive later in your life."

Community-associated MRSA

Unfortunately, part of the problem is that there is an overlap of traditional MRSA and community-associated MRSA (CA-MRSA) in the large majority of hospitals, heaving up the difficulty levels in producing a standardized test to function across the board. Specific to NorthShore, Peterson cites that their CA-MRSA levels have been holding steady at around the 20 percent mark for the last three years, which would suggest that they're certainly on the right track when it comes to screening.

"The CA-MRSA primarily causes skin and soft tissue infections that look like spider bites and things like that, so people don't often get admitted to the hospital. But we find that about the same percentage of those people are nasally positive like the non-community-associated patients. If someone comes in with an infection, they have a good 30 to 40 percent chance of not being nasally positive, but you pick them up by the infection culture.

"In my opinion, one of the advantages that CA-MRSA might have is the fact that it's ability to adhere to skin, meaning that you don't need to become nasally colonized first. If someone has CA-MRSA and they touch your hand or generally comes into physical contact with you in terms of getting near a wound, then you could become infected - you certainly don't need to be nasally colonized."

The reality of the situation, irrespective of nation or quality of healthcare infrastructure, is that while HAIs in general - and MRSA specifically - can be monitored and prevented to a certain degree, attempting to reach a complete 'zero point' is at best a stretch of the imagination, and at worst a critical misuse of finances and time. Fortunately for NorthShore, this is something Peterson is all too aware of.

"Our healthcare system is a little bit like the trusts in the UK," says Peterson, "in as much as we negotiate with our insurers. We have four hospitals with patients who keep coming back to us, so it's almost like a small county healthcare system. Our goal, over the next few years, is to be able to define some of the answers to questions that have already been raised, such as ' If we've tested somebody twice or three times and they're negative, can we take them off the list of needing to be tested?

"We're also looking at new ways of handling MRSA form an infection control standpoint. Maybe all we need to do is decolonize patients and not even put them into isolation. That would actually make life a lot easier as it costs $300 a day for us to put somebody into isolation. Regardless, there are plenty of additional strategies that still need studying to figure out what the easiest approach to handling MRSA in the long term really is. It took the Dutch and the Swedish between 10 and 20 years to get to the low levels they are at now, so it needs to be a long-term proposition to effectively deal with MRSA."

And while long-term propositions are definitely a step in the right direction, the recent wave of EMR overhauls sweeping the US could play a major part in speeding up that process, specifically in the tracking and identification arenas. Peterson explains that NorthShore's four hospitals are all on EMRs already, for both inpatients and outpatients, so tracking the relative data is already ingrained into the institute's psyche.

"We're able to look at data sets of several hundred thousand patients or a million patients, rather than just a few hundred. Moving forward, there is little doubt that the EMR is going to be tremendously helpful. The Veterans Administration Healthcare System has about between 150 and 160 hospitals for which they do all their own MRSA admission screening. They recently reported their results on their first 21 months, in which they tested 1.3 million patients and noted a significant reduction in MRSA throughout their US healthcare system. Once that gets published, that'll be a huge body of evidence showing that all admission screening helps exponentially. It's going to be tremendously helpful - we've just got to wait for the right minds in technology to help get us there."

Prevent the spread

Once MRSA has reached a patient and they are considered 'positively infected', there are a few of standard practices to ensure damage limitation - both for the patient and the remainder of the hospital population.

Scrub away. Scrupulous hand washing by hospital staff before and after contact with patients is the single most effective infection control measure and should be applied without fail.

Isolation. MRSA-infected patients should be physically isolated in a single room that is regularly damp-dusted and kept away from non-infected patients.

Take note.  Patients' notes should be clearly labeled 'MRSA' for any future admittance into hospital. It is also important to notify the patient's local GP that the patient is MRSA positive.

A new start. When the patient is eventually discharged from hospital, their room should be comprehensively cleaned of all linen and other clinical waste, and disposed of in specialist bags.