A fourth patient linked to a mycobacterium abscessus infection at Greenville Memorial Hospital died last week, Greenville Health System officials said Monday. A total of 15 patients who underwent surgery at the hospital have tested positive since March for an infection caused by the bacteria.
The average incubation time for the slow-growing bacteria is 60 days and an average incubation period for the GHS patients who contracted the infection was 79 days, officials said.
GHS officials released preliminary results of their three-month investigation conducted with assistance from the Centers for Disease Control and Prevention (CDC) and South Carolina Department of Health and Environmental Control (DHEC), which traced the source of the infection to tap water, said Dr. Robert Mobley, GHS medical director of quality.
Mycobacterium is naturally occurring and does not usually cause problems for those who are healthy; however, those who are already sick or who undergo surgical procedures can be susceptible, Mobley said. Patients contracted the infection at their surgical sites, and many had additional health issues, GHS officials have said.
The infection control team assessed the commonalities of the cases from equipment to scrub sinks, Mobley said. “The common theme of tap water seems to be the issue.”
An ice machine that produced the ice used to cool blood during cardiac procedures tested positive for the bacteria – though the ice did not come in contact with the patients, Mobley said. The machine was removed from service and replaced, and the hospital now uses sterile water to make ice, he said.
A cardiopulmonary perfusion (heart-lung) machine used in the operating room was removed and tested during the investigation, but no problem was identified with the equipment, Mobley said.
Tap water did not come in direct contact with patients in the operating room, but is used by medical staff to scrub before donning surgical gear and disinfecting before surgery and to clean equipment before it is disinfected, Mobley said. Testing for mycobacterium is not required for hospitals. There are no standards on how to treat tap water inside a facility, Mobley said. “The water system here meets EPA standards of delivery of the water.”
Mobley said the bacteria was detected in Greenville Memorial Hospital’s internal water supply and in water supplies outside the hospital, including at the GHS downtown administrative offices, which house no treatment facilities.
According to the Environmental Protection Agency (EPA), mycobacterium are relatively resistant to standard disinfection procedures for drinking water. The agency has set a goal of eliminating all bacteria and viruses, including mycobacteria, from drinking water, but it is a non-enforceable guideline.
GHS officials said Greenville Memorial Hospital has implemented all suggestions from DHEC to help prevent the naturally occurring bacteria from gaining access to the facility. These measures include the installation of point-of-use filters, elimination of slow-flow areas in water pipes, flushing scrub sinks before their first use and increasing the frequency of the disinfection schedule for the cardioplegia machine (used to stop the heart during cardiac surgery). Mobley said the water filters are already in place.
After tracing potential exposures back at least a year, GHS has advised approximately 180 patients to notify their surgeons if they see signs of infection, Mobley said. No new cases have surfaced since early June and there has been “an interruption in the outbreak,” he said.
GHS epidemiologist Dr. Bill Kelly advised physicians to watch for new cases of mycobacterium infection over 180 days due to its slow-growing nature, Mobley said.
DHEC recommendations after site visit to GHS:
- Designate specific water source for heater/cooler machine
- Consider point-of-use bacteriologic filters at scrub sinks
- Install filter if making ice from tap water
- Future plumbing installation should avoid areas of dead legs and unused branches
