Ontario ICPs battle epidemic MRSA strain
It wasn’t there, and then it was there’
Infection control professionals in Ontario, Canada, are locked in an all-out effort to eradicate an epidemic strain of methicillin-resistant Staphylococcus aureus (MRSA) as besieged hospitals in the province continue to screen incoming patients and implement isolation and decolonization protocols.
In unofficial totals for 1998 (the most recent data available), some 8,000 patients in the pro vince screened positive for MRSA, including some 950 who had clinical infection. The total is up from a reported 6,866 Ontario patients who were colonized or infected with MRSA in 1997, a 61% increase over 1996 and a 12-fold increase over the province’s rates in the early 1990s. Officials estimate that 85% to 90% of all the MRSA in the province is from a single strain, which is being called the Ontario epidemic clone and CMRSA-1. In a reaction that underscores how dramatic the increase has been in the last few years, Ontario ICPs are somewhat encouraged that the increase from 1997 to 1998 was only in the 14% range.
Screening pays off
"We were more than quadrupling from year to year," says Karen Green, RN, CIC, infection control coordinator at Mount Sinai Hospital in Toronto. "Last year, we had a marginal increase, so the curve is starting to diminish. There is reason to believe that the aggressive measures we are taking are starting to pay off. Most of the cases we are picking up are through [admission] screening. If we weren’t doing screening and implementing precautions, our ratio of clinical cases may in fact be much higher."
Indeed, while some United States hospitals have reluctantly accepted an endemic level of MRSA and few screen patients on admission, Canadian ICPs are hopeful that a united effort by all health facilities can eradicate the pathogen.
"This is not an endemic organism; this is an epidemic organism," Green says. "If you can get it out, you should be able to get rid of it. I continually have these discussions with my colleagues around the world. When you can give me a definition of endemic which is not measured by your inability to put resources into [eradication], then we will talk about endemic vs. epidemic. But telling me you have too many cases to do anything about it does not [mean] it is endemic."
The model for a successful widespread eradication of MRSA is Denmark, where epidemic strains have been eliminated by a nationwide effort, Green notes. (See Hospital Infection Control, May 1999, pp. 65-66.) "We think that we can be as successful as Denmark was in eradicating this bug," Green says. "It just means everybody has to work really hard at it. You can’t do it by two or three hospitals being aggressive when you have a province-wide epidemic."
Strain likely in U.S. as well
The Ontario epidemic strain is almost certainly in U.S. hospitals as well, as the first case in Ontario is thought to have originated in a patient transferred from the U.S. in 1995, she says. However, in the absence of aggressive screening measures for colonization, the pathogen would not likely stand out from the many strains in circulation in the United States, she adds.
"You just wouldn’t notice it as much because you have so many other strains and [ICPs] don’t necessarily look in the same way," she says. "We had the luxury of having next to none, and then seeing this kind of really strange thing unfold very quickly."
Indeed, the spread of the organism has been particularly dramatic because health care facilities in the province had virtually no MRSA when it first appeared. The rapid spread across Ontario has been documented through surveys of laboratories and ICPs. In the most recent results from February 1998, 114 (84%) of the 136 labs responding (99 hospital-based, 25 private, and 12 public health) reported the identification of at least one MRSA patient.1
An initial problem was that not all laboratory testing kits picked up the strain, resulting in false-negative results and false positives for coagulase-negative staphylococcus, explains Barbara Willey, ART, a laboratorian in the infection control and methods development department at Mount Sinai. Lab problems were further complicated by the fact that Ontario laboratorians were not used to seeing MRSA and had a low index of suspicion for the pathogen, Willey notes. Suspicions have certainly been raised now, and new lab kits and more extensive retesting protocols have assured that few isolates are being missed.
"The organism masqueraded as a coag-negative, and it still does to an extent," Willey says. "The problem wasn’t necessarily recognized early enough. [And] there wasn’t enough buy-in initially to the fact that you actually had to control it because there had never been a situation before where a strain moved so quickly. Because this strain covered the province. It wasn’t there, and then it was there."
Labs scramble to keep up
In a finding that U.S. counterparts can empa thize with, Willey says lab identification efforts may also be hampered by health care restructuring and budget cuts that have made it difficult for lab workers to keep up with the massive screening effort. "There is more work because there is more and more screening," she says. "We used to run like one, two, or three MRSAs a year. MRSA used to be an event. Now it is like one to three a week."
Although it is labor-intensive, the screening effort triggers a series of infection control and decolonization measures that are the best hope to bring the pathogen to bay. The screening effort by many ICPs in Ontario includes getting cultures on admission from any patient who is being transferred directly from another facility, has had an overnight admission to any health care facility in the preceding six months, or was previously known to be colonized or infected with an antibiotic-resistant organism. Canadian health officials recommended swabbing multiple sites, including the nares, open wounds/drain age sites, and perineum or rectum. Following such recommendations will allow the identification of more than 93% of patients colonized with MRSA, officials estimate.
Patients who test positive on admission are placed in isolation precautions, with workers donning barrier protection similar to contact precautions for antibiotic-resistant pathogens in the United States. Patients are placed in a single room if possible and in cohorts if necessary, Green says. "We also do contact tracing, so when we identify a case [after admission], we do a series of screens on the roommate to make sure that they haven’t picked it up," she adds.
Most of the cases identified represent MRSA colonization, and a decolonization protocol that includes mupirocin ointment in the nares and chlorhexidine baths or showers is implemented to prevent subsequent transmission and possible clinical infections. "There is no question that when you identify a colonized patient at admission as opposed to a week or two into their hospitalization that your rates of transmission are much lower," Green says, estimating that colonization is being cleared in about 60% of cases. "You’ll get an initial good response, but then as you follow them over time, there is a percentage that will reacquire or recolonize," she says.
A voice in the wilderness
Though noting that some U.S. hospitals are beginning to successfully screen on admission for MRSA and vancomycin-resistant enterococci, Green says it has been an uphill fight to justify the practice. (See HIC, March 1999, p. 36.)
"Sometimes we feel like the lone voice in the wilderness because it is not just convincing colleagues south of the border," she says. "It is has been a lot of work with the rest of the country. [Canadian ICPs] that aren’t dealing with this particular strain fail to appreciate it. They just [wonder] how we can be that aggressive? But when you go from two cases a year to suddenly 50 to 70, that is mammoth change in how you approach everything."
Reference
1. Green K, McGeer A, Fleming CA. MRSA and VRE in Ontario —an update. Laboratory Proficiency Testing Program Newsletter 1998; 240:1-3.
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