Tap water that staff used as they prepared for surgery is believed responsible for the bacteria that infected 15 patients at Greenville Memorial Hospital, officials said Monday, adding that a fourth patient has now died.
Preliminary findings show that the infection, Mycobacterium abscessus, could not be traced to one piece of equipment or process as originally thought, officials said. But tests show that water in various locations inside the hospital contained the bacterium.
"Although we use sterile water in or near the surgical sterile field," said Dr. Robert Mobley Jr., medical director of quality at Greenville Health System, "even something as seemingly safe as pre-surgery hand washing may have contributed."
But just how the patients were infected by the tap water remains a mystery, he said.
"Short of the association with tap water, we do not have a definitive causation," he said. "CDC told us in the beginning that we may never know the exact reason for this."
The infection came to light in March, when the first patient was diagnosed after a health care provider suspected something unusual and ordered a special test, Mobley said. Another case was identified in April, he said, with the rest discovered over the next month and a half. Three of the cases date to 2013 before the outbreak was identified, he said.
While most of the patients had undergone cardiac surgery, two had abdominal surgery and one a neurological operation, officials said.
An investigation, which included the U.S. Centers for Disease Control and Prevention and the state Department of Health and Environmental Protection, involved going back through all the patients who'd undergone surgery using a particular piece of equipment.
GHS has not identified any other patients with the infection, officials said, and two of the original 15 patients remain hospitalized. Some of the surviving patients continue to receive antibiotics for their infections while others have recovered, Mobley said.
The fourth death occurred last week, he said, adding that all the patients who died had complex medical conditions. Officials said the infection may have contributed to their deaths.
Normally not harmful
Mycobacterium abscessus is not rare, according to Dr. Joe Perz, an epidemiologist with the U.S. Centers for Disease Control and Prevention.
It's typically found in soil and water, he said. But it rarely causes these infections.
"In the normal course of one's life, if you encountered Mycobacterium abscessus, perhaps you would ingest some as part of drinking water, or showering or bathing," Perz said. "And for most of us, our normal host defenses are sufficient to prevent infection.
"But some medical procedures are invasive by nature, surgery being an obvious example, but even something as obvious as injections can cross those normal barriers," he added. "So if you introduce this bacteria into that environment, there is a potential for it to get a toe-hold and grow and eventually cause harm."
CDC investigates about half a dozen cases a year, he said.
Officials said this is the first time GHS has had a mycobacterium outbreak, that there are no national standards governing hospitals screening for mycobacterium or how they should treat tap water, and no EPA regulations because it isn't normally considered harmful.
The bacterium was identified in the hospital tap water and in other GHS facilities in Greenville, including at GHS's new administrative offices on E. McBee Street, Mobley said.
"The water system has been very much involved with this and they are meeting the standards," he said, "but there is no way to sterilize water coming into a home or hospital. So we make the environment as clean as we can."
Dennis Porter, chief administrative officer for the Greenville Water System, said potable water is not sterile, but is safe to drink. Water utilities don't test for mycobacterium, he said, and shouldn't.
"For normal household use and ingestion and drinking, it's healthy and safe to drink," he said. "The water industry as a whole has been drinking the same water for a long, long time. It's nothing I feel we need to be concerned about."
And DHEC issued a statement saying the quality of Greenville's drinking water is not at issue.
"Contamination of a sterile field with non-sterile water during invasive procedures may result in an infection of this type," the statement read. "Even at high levels, ingestion of mycobacterium abscessus is not typically a risk for infection, according to the Centers for Disease Control."
And though the bacterium is in the water, a spokesperson for Bon Secours St. Francis Health System said the hospital isn't aware that it has ever identified a Mycobacterium abscessus infection in a patient.
The investigation looked at any common elements between the patients, such as procedure, operating room, surgical team, equipment and environment, Mobley said.
When common equipment — an ice machine used for heart surgery and a cardiopulmonary perfusion machine — was discovered, it was removed and the OR temporarily closed, he said. But an independent analysis showed that the equipment was not responsible, he said.
Normal disinfection and sterilization processes also were followed, he said.
But the investigators also took cultures in other areas, including scrub sinks and cleaning closets, he said, and the mycobacterium was found. Those areas were taken out of service for an extensive cleaning, he said.
"The commonality in all this which remains our only issue at this time is that the organism was found in tap water used in our OR environment for cleaning, washing hands, scrubbing and things of that sort," he said. "It does not get diretly to the patient. We use sterile fluids and instruments for that."
According to DHEC, exposure is best avoided by preventing contact of medical equipment and supplies with non-sterile water.
The agency said GHS had already instituted additional safety measures, such as keeping sterile instruments in clean areas only and away from tap water, carefully examining the water system to look for stagnant water, and keeping dressings off the operating table while the OR is being cleaned.
DHEC also recommended additional steps be taken, such as designating a specific water source for equipment, bacteriological filters at scrub sinks and for ice machines, using stronger disinfectant processes that are more effective against mycobacterium, and preventing tap water from coming into contact with medical equipment and supplies.
As a result, the hospital has installed what GHS says may be the state's first bacteriologic point-of-use water filters in a hospital OR. GHS also has eliminated slow-flow areas of internal water pipes, is flushing scrub sinks for 10 minutes each day before use, and increasing the recommended disinfectant schedule, officials said.
But despite all the precautions, Mobley said, there are no guarantees that it couldn't happen again.
"If you look around the country, other hospitals have identified outbreaks like this," Mobley said. "However, they're rare."
The investigation took so long because mycobacterium has a long incubation period — 79 days in the average patient infected at GHS, Mobley said, and because the initial cases occurred sporadically. Also, it took two more months to culture the slow-growing bacteria and subtype it.
"We acknowledge the need to provide our patients with information, but an in-depth analysis requires adequate time," he said. "It would have been inappropriate to speculate while in the very early stages of the investigation."
Officials said that communicating with patients has been an ongoing processs and that any time a surgeon suspected an infection, the patient or his family was told in person or by phone and given a contact for future concerns.
GHS also notified any patients at risk of contracting the infection, sending out 180 letters by regular and certified mail.
Although no other infected patients or areas have been identified since June 1, GHS continues to test the water and environment, and will keep monitoring the situation for four months, he said.
"The overwhelming majority of surgical patients treated at Greenville Memorial have not been affected by this rare mycobacterial infection, and we apologize for any concern that we may have caused among our patients or in the broader community," Mobley said.
"Our hope that through this process we have discovered something that will be an opportunity for other health care providers in the community and around the country to be on the alert for these unsual infections," he added. "If more stringent guidelines — or, at least a clearer understanding of the problem — can come out of this situation, then it will be good for our patients as well as the entire healthcare industry."