Hospital surprised by outbreak after replacing sink drains in ICU
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Key takeaways:
- Hospital sinks are readily contaminated with antibiotic-resistant pathogens.
- A hospital that replaced drains in an ICU during an outbreak experienced a different outbreak afterward.
SEATTLE — A hospital replaced sink drains and traps in an ICU to stop the ongoing acquisition of multiple species of antibiotic-resistant bacteria and found — paradoxically, researchers said — that it may have caused another outbreak.
Hospital sinks have been identified as an important reservoir for antibiotic-resistant bacteria, including in ICUs. The University of Virginia Hospital, as part of an effort to mitigate ongoing infections from multiple species of bacteria producing Klebsiella pneumoniae carbapenemase (KPC), tested chemical interventions in the sinks in two ICUs — and replaced the sink drains and traps in one of them.
According to David Lehman, MD, an infectious disease fellow at the University of Virginia School of Medicine, instead of stopping the infections, replacing the sink drains and traps created a new opportunity for pathogens to take residence and infect patients.
“What we saw was an unexpected environment shift” from the presence of multiple species of KPC-producing bacteria to the environment being dominated by Serratia marcescens, Lehman said in a presentation at the Society for Healthcare Epidemiology of America Spring Conference.
“This resulted in unintended clinical consequences,” he said. “We set out to fix multispecies KPC acquisition and did not intend to set to create a clonal S. marcescens outbreak.”
The study presented by Lehman included patients who were admitted to one of two ICUs at the hospital for more than 12 hours between Dec. 1, 2010, and Jan. 31, 2016.
In January 2014, in an effort to eliminate bacterial colonization in ICU sinks, the hospital replaced sink drains and traps in one ICU and treated the sinks with chemicals to prevent recolonization. In the other ICU, they treated the existing sink drains and traps with chemicals but did not replace them. Chemical mitigation efforts continued in both units for several months but “were abandoned as recolonization was occurring regardless,” Lehman said.
The researchers found that the risk for an S. marcescens infection was nearly three times higher in the ICU with new drains and traps than in the control ICU (RR = 2.85; 95% CI, 1.24-6.58) and more than six times higher in that ICU than before the drains and traps were replaced (RR = 6.26; 95% CI, 2.59-15.1).
To control for patient-to-patient spread, the researchers also evaluated patients for MRSA acquisition during the same period and found there was no change, suggesting the difference in S. marcescens spread was related to the sinks, rather than some type of change in infectious disease prevention at the hospital, Lehman said.
“Overall, this type of intervention can lead to an unpredictable microbiologic impact,” he said, noting that replacing drains and traps actually created an environment for a new pathogen to dominate.
Sink drains and traps are “notorious for containing years of biofilm buildup that are difficult, if not impossible, to clean,” Lehman said.
“When you’re removing these [items] and the established biofilm, you’re basically creating a microbiologic vacuum, and it’s unclear what can come in,” Lehman said. “So, the lesson here is if this is something that an infection control team is considering, proceed with caution.”
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Lehman D, et al. Paradoxical consequences of wastewater interventions targeting carbapenemase-producing enterobacterales. Presented at: Society for Healthcare Epidemiology of America Spring Meeting; April 11-14, 2023; Seattle.
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