In early 2014, clinicians at Duke noticed an increase in the number of patients who had positive respiratory cultures for a species of NTM called Mycobacterium abscessus and decided to investigate. “When you have an increase in cultures that are positive for NTM, you often think about water colonization. So before completing the investigation, we switched over to a protocol where, for these high-risk patients, we used sterile water instead of tap water for a number of patient care activities,” said infectious diseases subspecialist Arthur W. Baker, MD, MPH.
The multidisciplinary investigation found that while some biofilms of water sources at the existing hospital were positive for NTM, the clone of M. abscessus that was isolated from clinical specimens matched that isolated from one particular area of the hospital: a new addition that included 160 ICU and intermediate beds and provided early postoperative care for all lung transplant recipients. “Those cultures were performed from this new hospital addition that opened for patient care [in late July 2013], when we started seeing these positive cultures,” said Dr. Baker. A later field investigation identified several factors that may have contributed to increased concentrations of M. abscessus within the addition's water distribution system, including low-flow rates and low residual disinfectant levels, according to results published in April 2017 by Clinical Infectious Diseases.
How it works
The hospital, which uses the municipal water supply, implemented water engineering-related interventions in the new addition, as well as targeted tap water avoidance. The tap water avoidance protocol was implemented in high-risk units in late May 2014. “The protocol was unit-wide in those four units, and then the protocol extended to certain high-risk patients, regardless of where they were in the hospital,” Dr. Baker said. As part of the protocol, all patients in three ICUs and one intermediate unit in the new addition received sterile water for consumption and patient care activities. Ice was also avoided on these units.
“Routine nursing activities, such as rinsing of suction catheters, irrigation of gastric tubes (such as nasal gastric tube or gastrostomy tubes), toothbrushing, dental care, and even showering and bathing would all be activities where . . . we used sterile water instead to decrease that exposure across the board,” he said.
The protocol was successful on two fronts. First, it mitigated the outbreak and quickly decreased the respiratory isolation of M. abscessus in high-risk patients back to baseline levels, according to the Clinical Infectious Diseases study. Second, a study published online on Aug. 23 by the same journal found that the protocol was also successful in decreasing isolation of not only M. abscessus but also other species of NTM that are commonly present in hospital tap water.
“I think the second success that this more recent paper highlights is that tap water avoidance can not only be successful in an outbreak setting for an outbreak organism, but it can also decrease respiratory isolation of other NTM at the same time,” said Dr. Baker, an assistant professor of medicine at Duke University School of Medicine in Durham, N.C.
Since tap water is part of routine inpatient care, it was challenging to revamp all of the protocols and to educate all of the people who might directly or indirectly provide tap water to patients, Dr. Baker said. “This is not only the nursing staff or physicians who are looking after patients, but it's giving that education and protocol advice to speech therapists, patients themselves, family members, etc.”
In addition, it's expensive to use sterile water for routine care for a large number of patients over time. “That has to figure into [the] hospital budget and making sure that you have a supply of sterile water that you need to comply with this protocol, which requires a fair amount of sterile water,” he said. “However, we thought that that expense was clearly worthwhile, given the decrease in respiratory isolation of NTM that we saw in our patients.”
One lesson of the outbreak experience is that clinicians need to be mindful of NTM as a potential health care-associated infection, particularly in critically ill or immunosuppressed patients, Dr. Baker said. “I think it's important to think about your patient population and consider policies such as ours for tap water avoidance in order to decrease the risk of colonization and infection from NTM.”
Words of wisdom
Tap water avoidance protocols are not common in U.S. hospitals, and the decision to use them will vary based upon a hospital's local epidemiology, water supply, and types of patients, Dr. Baker said. “Based on those factors, hospitals should consider whether such a tap water avoidance protocol is appropriate.”
The protocol remains in place, and next steps involve continued surveillance for waterborne organisms and ongoing education for current staff and new hires. “We also assess protocol compliance to make sure that as a team we are all compliant with this protocol over time, and we perform careful NTM clinical surveillance . . . in combination with a careful hospital-wide water management plan,” Dr. Baker said.