Removing masks tied to TB in coroner's office

Autopsy workers found at most risk of infection

Ongoing tuberculosis transmission in a Los Angeles coroner's office was linked to workers removing high particulate efficiency air (HEPA) respirators during autopsies to communicate, reports an investigator at the Centers for Disease Control and Prevention in Atlanta.

The investigation also underscored that autopsy workers may be at substantial risk of tuberculosis infection, and should always wear respirators when opening bodies that may contain potentially infective TB bacilli. Failure to keep the masks in place was the major infection control breach identified in an ongoing outbreak that included two active cases of tuberculosis and 10 tuberculin skin-test conversions among employees at the coroner's office in 1995, reports Eric Mouzin MD, MPH, a CDC Epidemic Intelligence Service officer.

"The main point was that people who had highly effective HEPA filter masks were not able to wear them consistently because of the difficulty they experienced communicating," he tells the Consultant. "These people usually have either medical students, residents, police officers or criminalists to talk to while they are working. They were removing [masks] often to talk."

Difficulty breathing and communicating with the HEPA mask has been widely cited by the medical community, and federal regulators last year approved less restrictive and expensive N95 masks for TB. In light of the outbreak, however, the L.A. coroner's office was considering going to powered air purifying respirators (PAPR), which allow communication but provide maximum protection by enclosing the mouth and nose in a facepiece, Mouzin said. The coroners office plans to use PAPRs for autopsy technicians and N95 masks for others like police investigators that may enter the room only peripherally and for a short time.

Such measures are warranted because in reviewing medical records of employees at the facility Mouzin found a strikingly high TB skin test conversion rate over the prior 10 years.

"We found that there was an extremely high risk for skin test conversion among autopsy room workers -- 81% had converted at 10 years," he says. "Even among non-autopsy workers, we found a rate of skin test conversion of 24% in 10 years. Some of the non-autopsy workers like criminalists and investigators went to the autopsy room occasionally to check on their investigations."

Noting that the employee testing program was poor, Mouzin says pre-employment screening was documented for only 74 (40%) of 184 employees and for 30 (65%) of 46 autopsy room workers. On average, employees received a skin test every 3.3 years, rather than annually as recommended for such settings. Skin test compliance is now required at the facility, and workers are being screened every three to six months to ensure no other conversions or active cases are uncovered. Autopsy workers should treat all cadavers as potentially infective, especially in areas like LA where the prevalence of TB is high, he adds. *