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Lab expert says sniffling can lead to inhalation
The case of a fatal meningitis infection in a 35-year-old lab worker at Crestwood Medical Center in Huntsville, AL, began with the emergency department admission of a young girl on July 11, 2000.
Presenting with worsening cough and illness, the 12-year-old had a lumbar puncture performed to draw cerebral spinal fluid. The lab worker had not been at work the day that the patient was admitted but worked with her specimens the next day and confirmed the presence of Neisseria meningitidis, says Brian Whitley, MPH, an epidemiologist with the Alabama Department of Public Health in Montgomery.
Unaware of the danger
"It is possible he didn’t know what it was immediately," he says. "That is a point of speculation. The blood cultures are apparently done in bottles, and it is possible or maybe even likely that he worked outside a containment hood with those bottles. He opened them up, took some of the blood out, and did a gram stain on that. Apparently that is common practice throughout the U.S., so he wasn’t in any kind of violation of accepted practices. But everything else was apparently done under the hood."
A few days later on July 15, he developed general symptoms of headache, low-grade fever, and coughing. In addition, he had a pre-existing respiratory condition that caused his nose to run, Whitley explains. The laboratorian went to the hospital emergency department, where he was prescribed an antibiotic for his respiratory condition. Meningitis was not apparently suspected at that time, and he returned home.
During that night, his illness progressed to include nausea, diarrhea, pain, and lethargy. He returned to the emergency department on Sunday morning at 7 a.m.
"His vital signs had declined significantly," Whitley says. "He had a temperature of 95.6 and lowered blood pressure." At this time, the connection was apparently made between his work as a laboratorian and his worsening illness. But little could be done as his symptoms progressed rapidly. "At 9:01 a.m., they began the resuscitation efforts, and the time of death was noted at 10:02 a.m. on Sunday the 16th," Whitley says. "Three hours from the time he returned to emergency department, he was deceased."
The 12-year-old source patient eventually recovered.
Did the worker’s respiratory condition contribute to aerosol exposure? While the case is not likely to be solved in any definitive fashion, a Centers for Disease Control and Prevention laboratory expert tells Hospital Infection Control that such a condition could predispose someone to inhale infectious particles. Harvey Holmes, PhD, ran a hospital clinical lab for years before becoming chief of the diagnostic microbiology section at the CDC.
"Essentially, the only restriction I had on the bench for individuals working with meningococcus was whether they had [a runny nose]," he says. "If they had an upper respiratory infection and had a runny nose, they were not permitted to work on a Neisseria meningitidis culture. The inference was that either they would wipe their nose or they may have just been sniffling, and that in and of itself [could lead to aerosol inhalation].
The CDC is considering revising its infection control guidelines for laboratories in light of the case, particularly with regard to containing aerosols. "There are many ways one can cause aerosols in the laboratory," Holmes says. "Even just doing a gram stain and then sticking the loop’ [lab instrument] in a flame to disinfect it can create an aerosol."
CDC may go to level 3
The CDC is considering recommending use of a biosafety level 3 safety cabinet for clinical laboratories working with meningococcal specimens. Current guidelines call for biosafety 2 conditions, including use of gloves and laboratory coats and decontamination of all infectious wastes. The use of masks and face shields is less clearly defined and apparently not common practice.
"The current guidelines read so that they are very open to interpretation," says Jim Sejvar, MD, medical epidemiologist in the CDC’s meningitis and special pathogens branch. "Face masks and face shields are suggested when there is a significant risk of aerosolization.’ One of the things that we have endeavored to do is find out what those situations are."
For example, common laboratory diagnostic procedures such as subplating and "streaking" to inoculate culture medium in agar plates can create aerosols, he says. "We suspect that does represent increased risk," he says. "Streaking can certainly lead to aerosolization, and if that is not done under a biosafety hood, that could certainly lead to increased risk."
As a result of the case, the Crestwood Medical Center brought in a laboratory consultant and implemented many changes that go beyond current CDC guidelines.
"One key thing is that if you come to work and you have symptoms of cold and sniffling, then you wear a mask — all day if necessary — whenever you are working over specimens," says Suzanne Stanfield, RN, MSN, CIC, infection control coordinator, at Crestwood. In addition to immunizing workers with the meningococcal vaccine, hospital officials also decided that all procedures involving spinal fluid must be done under a laboratory hood. they also looked at traffic patterns, airflow, and the effects of opening and closing doors on laboratory hoods and safety cabinets.
"We tried to look at everything," she says. "We went to plastic covers on the computer key pads so they can be washed."