A patient who contracted a rare bacterial infection during surgery at a South Carolina hospital died last week, bringing the total deaths to four since the outbreak was first suspected in May, a hospital spokeswoman said on Tuesday.
The four dead are among 15 patients infected by Mycobacterium abscessus during surgery at Greenville Memorial Hospital, spokeswoman Sandy Dees said.
Hospital officials cited tap water as the likely origin of the bacteria.
"Although we use sterile water in or near the surgical sterile field, even something as seemingly safe as pre-surgery hand washing may have contributed," said Dr. Robert Mobley Jr., the hospital's medical director of quality. "At this time, we have not been able to find any single cause or process as the trigger for the outbreak."
Mycobacterium abscessus is commonly found in soil, water anddust, but rarely causes infection in healthy people, hospital officials said.
Infection is usually caused by injections of contaminated substances or through invasive medical procedures using contaminated equipment or material, according to the U.S. Centers for Disease Control and Prevention.
Mycobacterium abscessus associated with healthcare can cause infections of the skin and soft tissues under the skin or lung infections in people with chronic lung diseases, the CDC said.
The first patient tested positive for the infection in March, and two of the infected surgical patients remained hospitalized, Dees said. All the infected patients had serious underlying medical conditions, she said.
After an investigation assisted by the CDC and South Carolina's health agency, the hospital has started new operating room procedures, including filtering water and flushing scrub sinks, Dees said.