Maryn McKenna

Journalist and Author

MRSA research round-up: hospitals, vitamins, pets

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Because I’ve been so behind, there’s so much to cover! So let’s dive in:

In today’s Archives of Surgery, researchers from Seattle’s Harborview Medical Center report that one simple addition to the routine of caring for trauma patients made a significant difference to the patients’ likelihood of acquiring a hospital-associated infection: bathing them once a day with the antiseptic chlorhexidine (in an impregnated wipe). Patients who were bathed with the antiseptic wipe, compared with patients wiped down with an inert solution, had one-fourth the likelihood of developing a catheter-related bloodstream infection and one-third the likelihood of ventilator-associated MRSA pneumonia. Cite: Evans HL et al. Effect of Chlorhexidine Whole-Body Bathing on Hospital-Acquired Infections Among Trauma Patients. Arch Surg. 2010;145(3):240-246.

How important are hospital-acquired infections? Here’s a piece of research from a few weeks ago that I sadly failed to blog at the time: Just two categories of HAIs, sepsis and pneumonia, account for 48,000 deaths and $8.1 billion in health care costs in a single year. Writing in the Archives of Internal Medicine, researchers from the nonprofit project Extending the Cure analyzed 69 million hospital-discharge records issued in 40 states between 1998 and 2006. Hospital charges and number of days that patients had to stay in the hospital were 40% higher because of those infections, many of which are caused by MRSA — and all of which are completely preventable. Cite: Eber, MR et al. Clinical and Economic Outcomes Attributable to Health care-Associated Sepsis and Pneumonia. Arch Intern Med. 2010; 170(4): 347-53.

 What else could reduce the rate of MRSA infections? How about Vitamin D? South Carolina scientists analyze data from the NHANES (National Health and Nutrition Examination Survey 2001-2004), a massive database overseen by the CDC, and find an association between low blood levels of Vit. D and the likelihood of MRSA colonization. More than 28% of the population is Vitamin D deficient. MRSA colonization is increasing in the US. Can giving Vit. D decrease MRSA carriage? More research needed. Cite: Matheson EM et al. Vitamin D and methicillin-resistant Staphylococcus aureus nasal carriage. Scand J Infect Dis. 2010 Mar 8. [Epub ahead of print]

And finally: Who else carries MRSA? Some unlucky pet owners have found that animals can harbor human strains, long enough at least to pass the strain back to a human whose colonization has been cleared. So it makes sense to ask whether humans who spend time with pets are carrying the bug. Last month’s Veterinary Surgery reports that the answer is Yes. Veterinarians are carrying MRSA in very significant numbers: 17% of vets and 18% of vet technicians at an international veterinary symposium held in San Diego in 2008. Cite: Burstiner, LC et al. Methicillin-Resistant Staphylococcus aureus Colonization in Personnel Attending a Veterinary Surgery Conference. Vet Surg. 2010 Feb;39(2):150-7.

Recommending: Consumer Reports on hospital infections

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Constant readers, the magazine Consumer Reports has done an extended, state-by-state analysis of which hospitals do well, or very badly, in preventing one important category of infections: central line-associated bloodstream infections, or CLABSIs (pronounced klab-sees). It’s a comprehensive package in easily understandable language. It’s based on the state reporting data that some activists have managed to persuade states to disclose, along with another set of data that some hospitals voluntarily tender to the nonprofit firm The Leapfrog Group.

From the Consumer Reports story:

Poorly performing hospitals included some major teaching institutions. For instance, New York University Langone Medical Center in New York City reported 39 infections in 10,119 central-line days in 2008, roughly twice the national average for its mix of ICUs. The University of Virginia Medical Center in Charlottesville didn’t do much better, reporting 77 infections in 18,572 days for the 15 months ending in September 2009, also about two times the national average.

More encouragingly, nationwide, we counted 105 hospitals whose most recent public reports tallied zero central-line infections. They ranged from modest rural institutions to urban giants such as the University of Pittsburgh Medical Center Presbyterian hospital, which reported no infections among patients who were on central lines a total of 13,596 days in 2008.

It’s well worth reading, and checking to see whether a hospital you may have used, or may be considering using, is on the good list or the bad list. Take a look.

MRSA in the journal Science – spread, outbreaks and an argument for active surveillance

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I have a story tonight at CIDRAP about a paper published this evening in the journal Science. To respect fair use and make sure my colleagues get clicks, I just quote the story here — but then I want to talk about why I think it’s such an important study.

   A multi-national team of researchers has applied a new genomic tool to a 50-year-old bacterial foe, using minute mutations to track the spread of drug-resistant staph both across continents and within a single hospital.
   On a global scale, their sleuthing tracked the movement of one clone of methicillin-resistant Staphylococcus aureus (MRSA) back and forth across the planet, pinpointing when individual cases transported infections across national borders to spark new outbreaks. Separately, their method demonstrated that what appeared to be a hospital epidemic of MRSA was not a single outbreak, but rather a mixed event of patient-to-patient transmission of one strain that was accompanied by multiple importations from outside the hospital of similar but unrelated strains. …
   In a briefing yesterday for the press, the authors emphasized the latter finding, pointing out that the traditional infection control measures usually applied to hospital outbreaks would not curb the spread of infections that were carried in undetected from outside. Their method, they said, provides a proof of concept for using cutting-edge genomics to uncover the precise pathways by which MRSA spreads within hospitals—not only tracing its path from patient to patient, but also identifying the bug in patients whose undetected bacterial carriage could spark outbreaks but have not yet.

 If you’d like more, here’s a very good story at Scientific American, one at BBC Health and one by the Associated Press; and Science Daily‘s version.

Now, the details. This team (which has 15 members from almost as many institutions) secured two collections of MRSA isolates: 43 collected from all over the globe between 1982 and 2003, and 20 from a single hospital in Thailand, collected between October 2006 and November 2007. All of the isolates were ST239, which is a hospital-acquired strain that is particularly prevalent in Asia. They analyzed them using high-throughput sequencing, with a particular analyzer (Illumina) that could produce whole genomes of up to 96 isolates very quickly (an extraordinary advance from the weeks and months it used to take to achieve a single whole genome). Then they compared the genomes, looking for single-letter changes in the genetic code (single-nucleotide polymorphisms, SNPs or “snips,” and also insertions and deletions of nucleotides). They used those findings to construct a “family tree” of 239 that tracks very nicely with the known history of MRSA’s emergence and initial spread, and that pinpoints rare but intriguing importations of clones from certain areas into other parts of the world.

But it’s what they found in the Thai hospital isolates that is especially interesting. (Most of this is not explicit in the paper, but was related in the press briefing that Science conducted on Wednesday). The differences that can be seen in the whole-genome analysis can’t be discerned by earlier identification methods, so the isolates collected at the hospital appeared to be the same. However, they weren’t the same. Some of them were very closely related, and formed what seems to have been a chain of person-to-person transmission — a true hospital-acquired outbreak. But others of them were not so closely related, either to the outbreak or to each other. What they were, instead, were individual importations into the hospital of a hospital strain that had been acquired outside the hospital, and were carried in by staff, patients, visitors.

You can see where this is going, right? If all the cases in the hospital had represented patient to patient transmission within a known outbreak, excellent infection control might have corralled them. But some of them were not part of that outbreak, so infection control measures aimed at that outbreak would not have kept those other cases from spreading. What would have stopped them from spreading, as the authors pointed out, is detecting them at some other point in their entry into the hospital:

…”That implies you have to have a different perspective on where you are going to apply your infection-control procedures and strategies,” co-author Dr. Sharon Peacock of the University of Cambridge said during the briefing.

What that sounds like — and the authors acknowledged as much — is an argument for active detection and isolation/active surveillance and testing/search and destroy, the process of screening some percentage of patients coming into a hospital for MRSA carriage so that the bug can be detected and dealt with long before its presence triggers an outbreak. It is probably not a coincidence that the majority of the authors (including Peacock) are British, and search and destroy has recently become widely accepted in the UK; in fact, the National Health Service recently made it mandatory.

But search and destroy remains remarkably controversial here in the US, despite strong proof of concept demonstrations in healthcare institutions such as Evanston-Northwestern Healthcare, and adoption throughout the VA system. I’ll be interested to see whether this paper makes a dent in the overall resistance to search and destroy, and if not, to hear why not.

The cite is: Harris SR, Feil EJ, Holden MTG, et al. Evolution of MRSA during hospital transmission and intercontinental spread. Science 2010 Jan 22;327(5964):469-74

One surgical infection with MRSA: $61,000

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From a multi-state, public-private research team — Duke University, Wayne State University, and the Durham, NC VA — comes a precise and alarming calculation of MRSA’s costs in hospitals: For one post-surgery infection, $61,681.

The group compared the course, costs and final outcome of three matched groups of patients from one tertiary-care center and six community hospitals in one infection-control network run by Duke. The three groups were: patients with a MRSA surgical-site infection; patients with a surgical-site infection (SSI) due to MSSA, drug-sensitive staph; and surgery patients who did not experience infections, matched to the other two groups by hospital, type of procedure, and year when the procedure took place. (This same cohort has been described in an earlier prospective study that looked at risks for MRSA SSIs.) Altogether, there were 150 patients with MRSA SSIs, 128 with MSSA SSIs, and 231 uninfected surgery patients to serve as controls.

Here’s what they found. Patients with post-surgical MRSA infections:

  • stayed in the hospital 23 days longer
  • incurred an average extra cost of $61,681
  • were more likely to be readmitted to the hospital within 90 days
  • were more likely to die before 90 days had passed.

The authors write:

Our study represents the largest study to date of outcomes due to SSI due to MRSA. Our findings confirm that SSIs due to MRSA lead to significant patient suffering and provide quantitative estimates of the staggering costs of these infections. SSI due to MRSA led to a 7-fold increased risk of death, a 35-fold increased risk of hospital readmission, more than 3 weeks of additional hospitalization, and more than $60,000 of additional charges compared to uninfected controls.

For just the patients in this study, the excess costs (across 7 hospitals) totalled $19 million.

This is a highly useful study on several axes. First, remarkably, there has not been agreement over whether and how much of a problem MRSA poses in post-surgical settings, particularly when compared to drug-sensitive staph. This study provides careful, thoughtful, well-documented proof that combating MRSA infection is worthwhile. (NB, MRSA infections did not increase the risk of death relative to MSSA infections, which should remind us both of the often-forgotten virulence of MSSA, and also that MRSA’s perils can lie in extended illness and disability as much or more as in early death.) Second, by putting a very specific number on the cost of a post-surgical MRSA infection, it gives healthcare administrators a benchmark against which they can judge the cost of a prevention program. We’ve all heard complaints that prevention programs can be costly and their benefit is hard to measure in a bottom-line way. With this very specific number, that complaint should no longer be valid.

There’s a final point that is implied in the paper but not called out, so let me call it out on the authors’ behalf. These results are very likely an under-estimate of MRSA’s costs. That’s because, first, the specific procedures the patients underwent were cardiothoracic and orthopedic; those are not the surgical procedures most likely to be followed by a MRSA infection. And second, data collection for this study ceased in 2003, about a year after the first emergence of USA300 and several years before that very successful community strain began its current move into hospitals. However much MRSA was extant in 2003, there is more now.

The cite is: Anderson DJ, Kaye KS, Chen LF, Schmader KE, Choi Y, et al. 2009 Clinical and Financial Outcomes Due to Methicillin Resistant Staphylococcus aureus Surgical Site Infection: A Multi-Center Matched Outcomes Study. PLoS ONE 4(12): e8305. doi:10.1371/journal.pone.0008305

Infections rise, but hospital budgets – and infection control – shrink

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Bad news from the Association of Professionals in Infection Control and Epidemiology (APIC): In a survey of almost 2,000 of their 12,000 members, 41% say that their hospitals’ infection-prevention budgets have been cut due to the down economy.

According to the survey, conducted March 2009 and released Tuesday morning:

Three-quarters of those whose budgets were cut experienced decreases for the necessary education that trains healthcare personnel in preventing the transmission of healthcare-associated infections (HAIs) such as MRSA and C. difficile.
Half saw reductions in overall budgets for infection prevention, including money for technology, staff, education, products, equipment and updated resources.
Nearly 40 percent had layoffs or reduced hours, and a third experienced hiring freezes.

As we know here, there are (by CDC estimate) 1.7 million hospital-acquired infections and 99,000 deaths as a result of them, each year. These are numbers we are supposed to be trying to reduce. That is going to be less likely if less money flows toward what may already be an underfunded goal:

A third of survey respondents say that cuts in staffing and resources have reduced their capacity to focus on infection prevention activities.
A quarter of respondents have had to reduce surveillance activities to detect, track and monitor HAIs.

Disturbingly, at a time when electronic health records are such an important part of the health-reform debate, “Only one in five respondents have data-mining programs – electronic surveillance systems that allow infection preventionists to identify and investigate potential infections in real time.” (APIC press release)

The full report is here.

While taking a flu break, a MRSA round-up

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Constant readers, the H1N1 (Virus Formerly Known as Swine) Flu story remains a bit intense. I’ve missed a few MRSA stories over the past few days, so here is a round-up.

First, though, if you’re curious about what the swine flu reaction says about our ability to handle a pandemic, you might take a look at this story I wrote Friday at CIDRAP. Quick version: Over-reaction on the part of the “worried well” — and people seeking testing and not knowing where to get it — put ERs into meltdown nationwide. If we were facing a virus that was not only fast-spreading but virulent, we could be in serious trouble.

On to MRSA:

  • Therapy animals as a vector: In a letter to the Journal of Hospital Infection, Drs. J. Scott Weese and Sandra L. Lefebvre of the Ontario Veterinary College at the University of Guelph report on two therapy dogs that became transiently colonized with C. difficile (on its paw pads) and MRSA (on its coat; found on the hands of its handler) after visiting health care facilities, demonstrating how easily bacteria can move in and out of hospitals. Constant readers will recognize Weese’s name: He is one of the most important investigators of MRSA in food animals and pets, and among other things has written infection-control guidelines for therapy animals.
  • In the Canadan Medical Association Journal, Drs. Anne G. Matlow and Shaun K. Morris of the University of Toronto and the Hospital for Sick Children caution that while hospitals may be getting better at infection control, there is not yet as much attention to it as there should be in ambulatory-care settings: urgent care centers, surgery centers and doctors’ offices. They offer a checklist of the minimal things that a physician practice should do.
  • And in the UK, Baroness Masham of Ilton, a member of the House of Lords, offers her online notes on serious infections with community MRSA, which the Brits are calling PVL-MRSA in recognition of the toxin that the strain produces. The notes are in advance of a series of questions that she intends to pose to government ministers during a Question Time on Wednesday.

More soon.

MRSA in a hospital nursery

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Via the Boston Globe and the blog of the hospital’s CEO comes work of an ongoing outbreak of community-associated MRSA in the newborn nursery at Beth Israel Deaconess Medical Center in Boston:

…between last November and March, BIDMC experienced several occurrences or “clusters” of methicillin-resistant Staphylococcus aureus, or MRSA, infections that have affected some of our patients (19 newborns and 18 mothers) days to weeks after discharge from our obstetrics and newborn services. These infections have been, for the most part, superficial skin infections and breast infections. It is important to note that no babies in our Neonatal Intensive Care Unit have been affected. (Paul Levy, president and CEO, BIDMC)

The paper and the blog post report that the Massachusetts Department of Public Health (DPH), the Boston Public Health Commission (BPHC), and the federal Centers for Medicare and Medicaid Services (CMS) are all investigating, and the Centers for Disease Control and Prevention (CDC) has sent epidemiologists to sort out transmission. Levy, the CEO, admits on his blog that in sorting out this outbreak, the hospital has found its staff’s infection-control procedures to be not-adequate.

By sheer chance, this occurs as I am writing a chapter on just this phenomenon of the blurring of the MRSA epidemics of hospital-acquired and community-associated staph. As constant readers know, the original MRSA strains arose in hospitals in the 1960s (1961 in the UK, 1968 in the US), and the separate community strain was first noticed in the 1990s. (Though there are intriguing hints about earlier cases that a few smart physicians noticed and no one else took seriously.)

But for about 5 years now, the community strain has been moving into hospitals and causing outbreaks there, particularly in mothers and newborns: first in New York City, and then in Houston, and now quite widely. The Globe article references some others.

Why this is important: Because CA-MRSA and HA-MRSA are different, and not just because they originally occurred in different settings or had different resistance profiles. CA-MRSA (which is a term that is obviously becoming much less useful than it once was) also appears, in newer research, to colonize the body in different ways — not just the nostrils, but also the armpit, groin, and genitals, possibly including vaginal colonization. So there may be an additional risk of transmission from mother to child during birth that has not been anticipated — or from mother to child to health care worker to another child to that child’s mother.

Now, mind you: Good infection control ought to anticipate all those posibilities, because good infection control does the right thing every time. But as we’re finding out, very few institutions manage to train their staff in such a way that they do the right thing every time or close to it (Novant Health Care, creators of the Soapacabana video, seem to have managed it, and won a major award for it). Most health care workers, even very well-intentioned ones, find themselves in time crunches or responding to unexpected emergencies, and make risk-based judgments about what they must do, and what they can afford to let slide.

If CA-MRSA is becoming a hospital organism, and its unique risks of colonization are not recognized by the hospital staff, then their judgments of relative risk will be off — and what would have been a relatively safe risk to take in one instance becomes a significantly unsafe risk in another.

That’s all speculation, of course: I’m not reporting on Beth Israel and have no inside knowledge of their outbreak. But it does describe a phenomenon that has been occurring in other medical centers, and it underlines one of the risks attendant on these epidemics blurring. When CA-MRSA moves into a hospital, the MRSA ecology changes, and the risks of transmission change. It is essential that staff training keep up with that, or additional mistakes will be made.

MRSA research at Society for Healthcare Epidemiology of America meeting

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As promised, a round-up of some of the research presented at the annual meeting of the Society for Healthcare Epidemiology of America (SHEA), held last weekend in San Diego. (Disclosure: I was on the faculty for the meeting; in exchange for co-hosting a session, SHEA will be reimbursing me for airfare and hotel. I wasn’t otherwise paid, though.) There were 143 presentations on MRSA; here are a few.

I’m going to put in links to the online abstracts — I have SHEA’s permission to do this — but I can’t guarantee how long they will stay up. For those outside the science world, what happens at these meetings is that research is presented, in slide/PowerPoint sessions or in a poster, as a preliminary step to getting it published in a journal. Once a journal expresses interest, a cone of silence descends, the researchers are asked not to discuss the research until the paper is printed, and the abstract will probably be taken offline.

So, efforts to control hospital MRSA are showing some success:

  • Invasive hospital-onset MRSA infections declined 16% from 2005 to 2007, and hospital-associated community-onset infections went down almost 9% — probably, though not provably, because of in-hospital prevention campaigns. (A. Kallen et al.)
  • MRSA control in a small ICU (22 beds) leads to MRSA reductions throughout a 270-bed Montana community hospital. (P.J. Chang et al.)

But those efforts face some complexities:

  • Swabbing the nose and culturing the swab, the classic test to check for MRSA colonization, misses 30% of positive patients because they are colonized in the groin or armpit. (C. Crnich et al.)
  • If a hospital does not use AST (active surveillance and testing, or “search and destroy”) it may seriously underestimate its MRSA incidence, though it may be able to detect general trends. (P.J. Chang et al.)
  • But medical centers of similar size and situation that did v. did not use AST achieved similar reductions in hospital infections. (K. Kirkland et al.)

Community strains are moving into hospitals:

  • Most of the cases of MRSA colonization identified in a Delaware healthcare system were found so soon after admission that they must have begun out in the community and were not due to hospital transmission. (K. Riches et al.)
  • The proportion of MRSA bloodstream infections caused by community strains (proven microbioogically) doubled at Chicago’s main public hospital between 2000 and 2007. (K. Popovich et al.)
  • One out of every 7 ICU cases of MRSA in Atlanta’s major public hospital involved a community strain. (H. Blumberg et al.)
  • The number of MRSA infections brought to a Chicago-area ER increased 566% between 2002 and 2007, and was seasonally clustered (D. Buchapalli et al.)

And at the same time, hospital strains are moving out into the community:

  • Hospital-associated community-onset cases accounted for 58% of all invasive MRSA in the US between 2005 and 2007, with patients undergoing dialysis or those who have been in long-term care the most vulnerable. (J. Duffy et al.)

Resistant bacteria on health care workers’ phones

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Here’s some of the news that I mentioned Friday – no, I’m not hoarding, I’m just desperately behind on some writing (and falling further down the curve all the time, but thanks for the concern).

A team from Ondokuz Mayis University in Turkey, publishing in the open-access journal Annals of Clinical Microbiology and Antimicrobials, looked beyond the concern over health care workers’ hands being clean, and decided to interrogate what those workers hold in their possibly-not-clean hands. They swabbed and tested the hands of 200 health care workers (“15 senior, 79 assistant doctors, 38 nurses and 68 healthcare staff “), and 200 phones. Their results:

  • 94.5% of phones colonized with bacteria
  • 49% of the phones grew one bacteria
  • 34% grew two species, 11.5% three or more

The language in the paper is a bit difficult, but if I’m reading it right, the colonization rates look like this:

  • 50 of the phone and 53 health care workes carried S. aureus (approximately 25%)
  • 52% of the S. aureus strains on phones were MRSA
  • 37.7% of the S. aureus strains on hands were MRSA.

Other organisms on the phones and the hands were other staph species, coliform, enterococci, moulds and yeasts.

The health care workers were certainly not infection-control outlaws: They washed their hands regularly. But only 10% of them had ever thought to clean their phones — which are held by the mouth and nose, a prime site for staph colonization, and go with them everywhere in the hospital, including to the OR and the ICU. (The paper doesn’t make clear whether the phones in question are hospital-supplied, with potentially many users, or personal, with one user, but going from hospital to home and back again.)

So: We’ve talked in the past about the many challenges of infection control in hospitals — all the many, tiny details in multi-person, highly technological health care that can trip up even well-intended infection control. (Remember the sinks?) Here’s just one more example of the unfathomable complexity of the journey of attempting to get to zero in healthcare-associated infections — a place, of course, where we all want to be.

The cite is: Ulger, F., Esen, S., Dilek, A. et al. Are we aware how contaminated our mobile phones are with nosocomial pathogens? Annals of Clinical Microbiology and Antimicrobials 2009, 8:7doi:10.1186/1476-0711-8-7

MRSA reductions in ICUs – good news, but qualified

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Constant readers, you will no doubt have seen the overnight news about a paper by CDC authors in the Journal of the American Medical Association, reporting a significant decline in catheter-associated bloodstream infections (known by the uncatchy acronym CLABSIs, and yes, people pronounce it “klab-seez”) in intensive care units.

Our results show that the 6 most common adult ICU types reporting central line–associated BSIs to the CDC, which together account for 96% of all reported MRSA central line–associated BSIs among studied ICU types, have experienced declines of 50% or more in the incidence of MRSA central line–associated BSI since 2001. This means that the risk of primary MRSA bloodstream infections among patients with central lines in these ICUs has substantially decreased in recent years.

First, let’s stipulate that any reduction in healthcare-associated infections is good, good news.

Having said that, let’s drill down into the paper a bit. Because in some of the coverage last night and this morning, this paper is being represented as “Hooray, the MRSA problem is over,” and that’s an over-reaction. Here are some reasons why.

The data come from several overlapping CDC databases: the National Nosocomial Infections Surveillance system (NNIS) and the National Healthcare Safety Network (NHSN). The NNIS existed from 1970 to 2004; there was a data gap in 2005, and the NHSN sprang up in 2006. There were 300 hospitals in 37 states reporting to the NNIS when it shut down, and in 2007 there were 518 reporting to the NHSN, many of which joined that year as a result of new mandatory HAI reporting in New York, Colorado and South Carolina. Participation in either database was/is voluntary.

The CDC analysis abstracts data from the reports to those systems for the years 1997-2007. But, as you can guess from those numbers above, the data does not cover all 7,500 US hospitals; and because it is more weighted to certain states, it does not represent a nationally representative sample. In addition, hospitals came into the system(s) during the study, and also dropped out; an accompanying editorial estimates that only 6% of the 599 hospitals in the study reported data for all 11 years.

Second, it’s important to note that all CLABSIs went down: MRSA infections, drug-sensitive staph (MSSA) and other organisms. So something is going on — but it is not MRSA-specific. Optimistic interpretation: Enhanced infection control in hospitals is suppressing all HAIs. Pessimistic interpretation: Enhanced scrutiny, in the states that account for the most additional hospitals, is negatively affecting HAI reporting. Can we distinguish which? Probably not. On the one hand, CLABSIs started trending down in 2001, before the earliest mandatory reporting legislation became effective. On the other hand, the study doesn’t/can’t associate declines in CLABSIs with any specific interventions — so it is not possible to know from this study whether one particular strategy was responsible for this decline.

Third, to put the study focus in context, MRSA accounts for only about 7% of CLABSIs; according to the paper, it is not those infections’ most common causative organism. And CLABSIs do not account for the largest proportion of MRSA HAIs; according to a 2007 paper, they fall third on the list behind nosocomial pneumonia and septicemia.

Fourth, since it is abstracted from a hospitals data base, this study doesn’t address community MRSA infections — and there are some scientists in the family of MRSA researchers who would insist that it is the increasing prevalence of community infection that is the true driver of the MRSA epidemic.

So: Decreased MRSA HAIs, good news. Reasons, unfortunately unclear. Significance, possibly less than the headlines this morning maintain. But whatever it is that those hospitals were doing, let us hope they keep doing it.

The cite is: Burton, DC, Edwards, JR, Horan, TC et al. Methicillin-resistant Staphylococcus aureus Central Line-Associated Bloodstream Infections in US Intensive Care Units, 1997-2007. JAMA. 2009. 301(7): 727-36.
The accompanying editorial is: Climo, MW. Decreasing MRSA Infections: An End Met by Unclear Means. JAMA. 2009. 301(7)772-3.