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The deaths of two laboratory workers who acquired meningococcal infection from exposure to patient samples has led to a review by the Centers for Disease Control and Prevention (CDC) in Atlanta. The CDC is asking for information on cases of laboratory-acquired meningococcal infection that occurred within the past 15 years. It also will consider whether any changes are necessary in the current guidelines for handling meningococcal samples.
"Based on the data we’re getting from these cases, we’re revisiting the guidelines and seeing if any clarifications or additional recommendations need to be made," says Jim Sejvar, MD, epidemiologist in CDC’s meningitis and special pathogens branch. "Our suspicion is that a lot of cases do go unreported," Sejvar says. "Essentially, what we’re trying to do is to find all the cases we can identify and look for common threads among these cases so we can assess risk factors."
The CDC guidelines currently rate meningococcus (Neisseria meningitidis) as a biohazard level 2. Lab workers should wear gloves and lab coats and should use a biological safety cabinet when "mechanical manipulations that have high aerosol potential are performed." Workers who have a blood exposure should receive chemoprophylaxis with penicillin, and those with mucosal exposure should be treated with rifampin, according to the CDC.1
The CDC does not recommend the routine immunization of lab workers, unless they work with high concentrations or large quantities of the organism, such as in a research lab. Yet the deaths last year in Alabama and Michigan involved experienced lab workers with good technique who were performing routine tasks with patient samples. In the Alabama case, a 12-year-old girl came to a Huntsville hospital complaining of nausea, cough, headache, and high fever. She had some decreased alertness, and a physician ordered a lumbar puncture to test for meningitis.
The day after the hospital lab had taken the samples and cultured them, a laboratory worker came in to perform some additional tasks of subculturing (which he did in the containment hood) and removing additional blood samples for gram stains (done outside a hood). When the lab worker developed fever and joint aches three days later, it wasn’t immediately identified as possible meningitis. The next day, his symptoms of nausea, pain, lethargy, and weakness escalated, and his body temperature dropped. He died within hours of coming to the hospital’s emergency department. The worker, who was the laboratory safety officer, was known to be "meticulous," says state epidemiologist J.P. Lofgren, MD.
At the time he worked with the samples, he had a sinus infection, and that could be related to the transmission, explains Brian Whitley, MPH, epidemiologist with the Alabama Department of Public Health in Montgomery. "The best guess by the people in the lab was that since he had a runny nose for a while that he might have been working with the organism, gotten it on his hands, and wiped his nose. That’s purely speculative."
The Michigan case was equally startling. A longtime laboratory worker with the state’s Department of Community Health was working with ear fluid from a 19-year-old Michigan State University student who had died of toxic shock syndrome. The ear fluid contained meningococcus, although the girl did not have any symptoms of meningococcal infection. "She had excellent technique," says Geralyn Lasher, director of communications for the Michigan Department of Community Health. "She was very thorough and complete. She reported no incidents of anything out of the ordinary."
Two days after working with the sample, the lab worker developed symptoms. The next day, she went to the emergency department with labored breathing and died hours later. CDC testing confirmed that the strain that infected the Alabama and Michigan lab workers was the same as the strain of their patient samples. The Michigan Department of Community Health has since changed its procedures for its laboratory, making them more stringent than the CDC guidelines.
Meningococcus is being treated as a Level 3 organism, requiring lab work to occur under a biological containment hood with an air filter. Lab workers have been immunized, although the vaccine doesn’t cover all strains of the organism, Lasher says.
[Editor’s note: To report any known cases of laboratory-acquired meningococcal infection, contact Jim Sejvar, MD, Meningitis and Special Pathogens Branch, at (404) 639-0887 or JSejvar@cdc.gov.]
1. Takata KK, Hinton BG, Werner SB, et al. Epidemiologic Notes and reports: Laboratory-acquired meningococcemia — California and Massachusetts. MMWR 1991; 40:46-47,55.