The term "CRE" was barely a blip on most hospitals' radar before the Centers for Disease Control and Prevention highlighted the emerging infection, carbapenem-resistant enterobacteriaceae, in its "Vital Signs" report in March.
Of 3,918 acute care facilities performing surveillance for CRE, only 145 short-stay and 36 long-term hospitals had reported cases as of last June. But though the bug has been uncommon in hospital settings so far, four factors make it extremely worrisome, CDC experts say:
1. It kills half of patients whose bloodstreams become infected.
2. It is resistant to nearly all antibiotics.
3. It is increasingly seen in acute care settings.
4. It spreads quickly within and across healthcare settings through central line associated bloodstream or catheter associated urinary tract infections, especially in sicker patients. Surgery and dialysis seem to place patients at higher risk.
CRE was found in 1.2% hospitals in the country in 2001, but in 2011 and the first six months of 2012, it was in 4.6% of acute care hospitals. It is now in 18% of long-term care hospitals, and has been detected in hospitals in 42 states.
Six states: Tennessee, Oregon, Minnesota, Colorado, Wisconsin, and North Dakota, have made it reportable and others are considering it. So far, northeastern and southern states appear to have the most cases.
Now, the CDC is asking providers to be more diligent about looking for patients colonized with CRE, to segregate them and the healthcare personnel who care for them, not just from those without CRE, but from personnel who treat patients without CRE as well.
Arjun Srinivasan, MD, Associate Director for Healthcare Associated Infection Prevention Programs for the CDC, agreed to answer a few questions about what is known, and not known, about CRE.
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HLM: The latest reports on cases are from January through June of 2012. Can you expand on how CRE cases are trending today?
AS: We don't have anything more recent than what was published in Vital Signs. But certainly what that data suggests is that there is an alarming increase in the frequency with which hospitals are encountering patients, and [admitting] patients who develop infections with CRE.
HLM: With only 4.6% of hospitals reporting this, might it seem that it's not that significant? How many have you documented?
AS: We didn't publish a number of cases. We don't have numbers. We are working on getting a better sense of the burden of this, and get a number. But we think it's important for people not to dwell on the number. Is it 400 or 500 or 10,000? Whatever it is, it's too many. We need people to take action to keep it from getting larger.
HLM: What percentage of patients who have colonized CRE will develop a bloodstream infection, which you mention will be fatal in half of these patients?
AS: We don't know for sure. We know that being colonized increases the risk of a bloodstream infection.
HLM: That's odd for the CDC, which usually gets good numbers for emerging infections rather quickly.
AS: We're working on it. There are many conditions for which we have numbers, and there are many for which we don't and this is one. We're working hard to gather more information to make estimates of how many people are developing these infections in addition to knowing how many hospitals are seeing this.
HLM: Why has it been so difficult to get data? Might hospital officials and physicians be more specific on death certificates?
AS: CRE is not [nationally] a reportable disease. It's not likely that it would appear on a death certificate. It doesn't have its own diagnosis code. In studies with C. diff (Clostridium difficile) or MRSA (methicillin resistant staphylococcus aureus), we are often able to get that information from specific diagnosis codes.
HLM: What other obstacles prevent you from getting more information to bolster your call to action for hospitals and providers to look for CRE?
AS: I don't know I would say we need to bolster a call to action. The fact that these organisms are on the increase, and are incredibly difficult to treat, and are in some cases untreatable by the antibiotics we have available to us, is evidence enough that we need to take action to stop these before they become a bigger problem.
One of the things you're pointing out is that we're working hard to really change peoples' thinking of how we approach these infections. In the past, we've waited until things were a big problem, until there were lots of cases, and it was pervasive and everywhere before we really encourage[d] people to take aggressive action.
We don't think that's the right way to go. The time to take action against these types of very hard to treat resistant pathogens is when they're at what we presume is a very early stage of development, while there's still an opportunity to act aggressively to slow things down or maybe even reverse it, before we see it in more than 4% of hospitals.
HLM: What do we have in our armamentarium to treat CRE?
AS: Some isolates are susceptible to some antibiotics. But there aren't many antibiotic options and there are limitations to the agents we have available. For example, one is known to be quite a bit more toxic than other agents we would use—that's colistin—and another one has been demonstrated to not be as effective. The treatment options aren't great. Some isolates are in fact resistant to everything we might have to throw at them.
HLM: Is there something health providers need to do to prevent CRE that goes beyond standard precautions?
AS: No. The precautions we recommend for CRE are the same contact precautions. People entering the room need to wear gowns and gloves and wash their hands when they leave the room. What we're encouraging is people to look actively for it, and when you have cases of CRE in your hospital, in some cases we recommend doing screening cultures for patients who might have shared the same physical space (with an infected patient) or had the same healthcare team. Look carefully for CRE and act quickly once you find it.
HLM: But you're not suggesting screening. This is just after you see the first case, right?
AS: Right.
HLM: Can you give some background? The CDC website says that CRE was "uncommon" before 2000. What happened recently that you think has provoked transmission?
AS: That's a really good question for which we don't have a satisfying answer. We really don't know why CRE, or any bacteria for that reason, all of a sudden emerges and spreads and resistance develops quickly. The first isolate was described here at the CDC in 2001 from a single isolate in North Carolina. We heard about sporadic outbreaks in hospitals in the 2000s, and in 2009, we issued our first guidance for preventing transmission. We revised the guidelines, primarily for public health departments, in 2012. The Vital Signs issue in March is an effort to raise awareness.
HLM: Can you be more specific?
AS: There are recommendations targeted for health departments to prevent the spread by working across facility types and the continuum of care. We think public health departments can play a very important role in helping ensure better coordination and communication between healthcare facilities. The 2009 and 2012 recommendations are fundamentally the same, there's just more context.
HLM: What other messages would you like to convey to infection control teams?
AS: Antibiotic stewardship is the other big area where we have not done all we need to. We know antibiotics are overused both in hospitals and outpatient settings, and we know that's one of the factors contributing to resistance, including CRE. Most importantly, it's the factor we can control. We can't control how organisms develop resistance, but we can control how we use antibiotics.