 Becky Smith, MD, medical director of infection prevention at Duke University Hospital, discusses a presentation she gave at IDWeek 2019 on a case of serial transmission of NDM-1 

Interview transcript (modified slightly for readability):

 We perform routine surveillance for carbapenemase-producing organisms, or CPO, at Duke Hospital just like many infection prevention programs do. In 2017, we noticed an uptick in seeing CPO within the hospital. This particular research came out of finding something called NDM-1, which is 1 of the various molecular mechanisms for carbapenemase-in this case, it's actually a metallo-beta-lactamase gene-within a germ that is considered to be a tier 2 organism per the CDC guidance. What that means is these are either multidrug-resistant pathogens with a novel resistance mechanism, or they are not yet endemic in the area. And so the state health department and CDC recommend enhanced containment efforts to really try to contain them or stop their spread because they aren't everywhere yet, so you have an opportunity to make a difference.

In 2017, we identified a patient in our hospital who had an NDM-1 Klebsiella pneumoniae. At the time, we engaged the health department as per the CDC guidance, and we reviewed the medical record to find out [whether] this patient [had] traveled to anywhere where there was endemic NMD-1 and/or where else had they been that they could have picked this up. And as part of that investigation, we found they hadn't really been anywhere typical; they had been to an outside hospital before they had come to us.

In response to this, we performed some point-prevalence surveys where we screened everybody else on the unit. We did 2 rounds of that and did not find any other patients with the organism, and we were very relieved so we sort of put it to rest. This investigation actually took place kind of in the midst of this uptick in seeing more carbapenemase-resistant organisms. We had already been in the process of trying to augment our approach to carbapenemase-producing germs in general, and what that meant at our hospital is, in addition to the normal surveillance and reaction, we wanted to be more proactive. We had an enhanced educational series for all types of healthcare workers, patients and families on what are these germs and why is it so important that we wash our hands and wear gowns and gloves and clean the environment. We also implemented this rectal screening program for our adult ICU so that once a week everybody in the ICU has a screen just to stay ahead of it by doing active surveillance. When we found a patient, enhanced communication around the whereabouts of that patient, making sure that everybody was doing the normal horizontal infection prevention measures. So we implemented that [and] thought things were rolling along quite nicely and then fast forward to March of 2018-that first case was July of 2017. And in March, we have our first case of NDM-1 Kleb pneumo from a rectal screen. So, again, [we] launch our normal investigation. This patient had been at an outside hospital for 24 hours and they were just in our hospital for a few days and were screened as part of our normal routine. We were able to identify that this patient was in the same room as the room that the first patient was in July of ’17. And we said, “Wow, there's something going on here.”

We decided to sample the sink based on the literature that has implicated sink drains and P-traps and shower drain P-traps in being persistent point sources for carbapenemase-producing organisms. We worked very closely with Amy Mathers and the UVA lab to learn how to appropriately perform those environmental cultures and help work them up, sent off those cultures. We also actually closed the room just out of an abundance of caution and we took out the sink because, again, based on what we had known from the literature, we were really suspicious that that was a persistent source. So lo and behold, the sink drain culture from the biofilm was positive for the NDM-1 Klebsiella pneumoniae. The P-trap water was negative. We had already replaced the sink and opened the room and deep cleaned just like we normally would have in the past. Then we thought, “You know, this is a really compelling story we need to share because here we are trying to stay ahead of CRE and [we] had implemented a very robust containment bundle. And yet, we still had this event happen.”

We went back and got 1 other case that was from 2015, the only other case that had ever been in the hospital, and that had been a patient with a risk factor of having had a liver transplant in India. That case was 3 years prior to the most recent case. We included that in our samples, bundled it up, and sent them off for whole genome sequencing. And then found out that patient 1, the one from 2015, was unrelated to the second patient and the third patient and the sink, and the second patient, sink, and third patient were all closely related isolates. And so this told us, “Wow, this was the smoking gun. Thank goodness, we removed the sink early on.”

The takeaway for everyone is that 1) as we already know, bacteria are always 1 step ahead, or probably 20 steps ahead, from us. And that, despite really aggressive prevention efforts, we found that the sink had become contaminated. This really leads us to believe that better education around sinks, particularly separating clean and dirty tasks, so thinking of having in ICU rooms, or in the hospital, where these really acute patients might be that might have these organisms, really having a sink that's dedicated for hand hygiene and clean things. And then an area that's used as a drain or for things like when you're performing peri care or bathing, where you've touched the patient and then that goes in the wastewater, that's considered dirty, you don't wash your hands there.

And then really, again, doubling down on your efforts to enhance horizontal infection prevention strategies, cleaning, particularly non-dedicated patient equipment, and really performing enhanced cleaning in the environment. My thought is that for hospitals that might not routinely see patients with CRE, or NDM-1 in this case, that if you were to detect a case, perhaps prospectively sampling that sink after their stay to see-we don't know the sensitivity or specificity of that, but-as a potential prevention measure, identify if there's colonization there and mitigate it before it becomes a problem. In our case, we’ve since performed many, many cultures on patients and haven't had any additional NDM-1 so we feel that because it was just in the sink drain and not the P-trap water, that it hadn't yet gotten to plumbing that couldn't be mitigated as easily.

I think that, as everyone knows, CRE is one of the most concerning pathogens out there and I just always want to put in a plug for microbial stewardship as a way to help stop the development of multidrug-resistant organisms in general. And that, again, basic infection prevention measures can really help stop the spread as well.

The study, What's Lurking in the Drain? Serial Transmission of NDM-1 Klebsiella pneumoniae to Patients Admitted 9 months Apart to the Same ICU Room, was presented Saturday, October 5, 2019, at IDWeek 2019 in Washington, DC.