When an infectious disease clinician grew suspicious after seeing an "unusual occurrence" of patients infected with rare bacteria, a Boston hospital launched an investigation to identify the source. However, experts say this is not a unique experience, noting that "[e]very health care facility in the world will have a potential [encounter] with hospital acquired infections," Jessica Bartlett writes for the Boston Globe.

Detecting an 'unusual occurrence' of infections

In June 2018, an infectious disease clinician working with the cardiac surgery department at Brigham and Women's Hospital grew suspicious after noticing an "unusual occurrence" of several patients becoming infected with rare bacteria during the last 18 months.

After the clinician alerted the hospital's infection control department, the hospital launched "a deep dive," ultimately finding four patients infected with the same strain of a rare bacteria, called Mycobacterium abscessus (M abscessus). And while usually nonthreatening to healthy individuals, the bacteria can be problematic for vulnerable patients and can sometimes result in hospital-acquired infections, Bartlett writes.

According to Michael Klompas, the infectious disease physician and hospital epidemiologist who led the investigation, one of the initial challenges was just realizing that something was wrong since only a small number of cases had occurred months apart.

"We get these alerts from various clinicians on a regular basis, and often investigate and find nothing," Klompas said. "But this we looked at, and said this is unusual, and dove deeper."

The hospital searched its microbiology database going back to 2015, searching for patients who had tested positive for the bacteria. That search unveiled a fourth infected patient.

All four patients were men over the age of 50 who were admitted to the cardiac surgery ICU and a stepdown unit, which were located on a single floor of the hospital. Each patient became very ill and was hospitalized for a period of weeks to months.

While it was not clear what else the patients had in common, the hospital took cultures from the sinks and showers of each of the infected patients' rooms, ruling out several potential causes before identifying the culprit — ice and water machines on the cardiac floor.

Even though records indicated that the machines were properly cleaned and maintained, further testing revealed that chlorine levels in the units were undetectable — an issue caused by a commercial water purification system.

How the hospital addressed the infections

In addition to removing the affected ice and water machines and the purification system, the hospital changed its protocols for cleaning and maintaining its ice and water machines.

The hospital also started exclusively using sterile, distilled, or filtered water for both drinking and patient care with its most vulnerable patients. While tap water "is fine for you and me and whoever is healthy. Our immune systems can take care of it. But if you are vulnerable, you might not be able to," Klompas said.

On Monday, the hospital published a study in the Annals of Internal Medicine, outlining its efforts to identify a potentially deadly pathogen and sharing key insights into protocols that researchers hope other hospitals will implement.

Todd Ellerin, interim chief of medicine and head of infectious diseases at South Shore Health, said other health systems can learn lessons from the study, particularly about the need for more comprehensive surveillance of water systems. He also noted that the study serves as a critical reminder of why it is important to limit vulnerable patients' exposure to tap water.

Separately, Klompas said the outbreak serves as a warning that the national standards of monitoring water inside a hospital, which are largely focused on Legionnaire's infections, might not be strict enough.

"Turns out that things good enough to get rid of Legionella might not be good enough to get rid of mycobacteria," Klompas said. "This is a further [area of focus] for federal regulators … to reduce risk of mycobacteria."

The hospital has not detected any additional cases of hospital-acquired M abscessus as of September 2022.

'It's not a unique problem'

Ultimately, hospital-acquired infections are more common than many people realize. In Massachusetts alone, hospitals have seen several water-born bacterial pathogens in recent years.

"Every health care facility in the world will have a potential [encounter] with hospital acquired infections," Klompas said. "It's not a unique problem to us. If we pretend it doesn't exist, we will never be as successful as we can be if we confront these head on."

"You'd not be surprised if other hospitals and health systems have similar water systems in place, put in with the best of intentions," Klompas added. "You'd think putting a filter in would make the water better. Lo and behold, it has unintended consequences. That was the reason for publication."

Ellerin praised the hospital's efforts, which he described as an intricate, epidemiologic investigation, noting that many health systems fail to find the source of these outbreaks.

"There is a lot of sleuthing," said Ellerin. "The Brigham had to be like Sherlock Holmes." (Bartlett, Boston Globe, 3/6)