Although Neisseria meningitidis is commonly isolated in clinical laboratories, laboratory-acquired infection is rare (1). This report describes two fatal cases of meningococcal infection in laboratory workers; both of these cases probably were laboratory acquired.

Case 1. On March 8, 1988, a clinical laboratory bacteriologist in California became ill with influenza-like symptoms and nausea. During the next 24 hours, she developed fever, myalgias, arthralgias, diarrhea, skin lesions, and confusion. Her husband informed ambulance personnel that she had had a mishap in the laboratory approximately 1 week earlier with a type of organism that causes meningitis.

When hospitalized at 10 p.m. on March 9, she was hypotensive with numerous petechial and purpuric lesions on her face, neck, trunk, and extremities; she died 6 hours later. The final autopsy diagnosis was "clinical acute intractable shock, consistent with acute meningococcemia." Blood cultures and cerebrospinal fluid studies were negative. Serum was positive by a bivalent (groups C and W135) latex agglutination test for N. meningitidis. A throat culture grew N. meningitidis.

No mishap had been reported at the hospital laboratory where the patient worked, nor could the patient's co-workers recall any episode; no additional information regarding a mishap could be discovered. During the previous 3 months, the patient worked with only one known N. meningitidis isolate, which was obtained from the blood of a patient with acute meningitis and cultured by the affected laboratory worker 5-6 days before onset of her symptoms. Both the workplace isolate and the laboratory worker's nasopharyngeal isolate were identified as N. meningitidis serogroup C by the Microbial Diseases Laboratory of the California Department of Health Services.

CDC performed isoenzyme testing on the laboratory worker's nasopharyngeal isolate, the workplace isolate, and 14 other unrelated but recently isolated group C strains from throughout northern California. The isoenzyme type of the laboratory worker's isolate and the workplace isolate were identical and rare. They differed from the 14 northern California isolates (p less than 0.01, Fisher's exact test) and from a collection of 256 group C meningococci isolated between 1986 and 1989 (p less than 0.01, Fisher's exact test).

Case 2. On the morning of September 6, 1988, a microbiology technician at a teaching hospital in Massachusetts presented to the hospital's employee health clinic with a history of several days of rhinorrhea, sore throat, and myalgias. She was sent home at 1 p.m. with a diagnosis of viral syndrome. Twelve hours later, she presented to the emergency room semiresponsive, hypotensive, dyspneic, and with petechial and purpuric skin lesions. A gram stain of the buffy coat of her blood showed gram negative diplococci. Despite antibiotic therapy, she died 6 hours later. Blood cultures grew N. meningitidis group B.

For several days before her hospitalization the patient had been working in the bacteriology laboratory at the teaching hospital despite her upper respiratory infection symptoms. The laboratory had not isolated N. meningitidis during the 3 weeks before the patient's illness. On September 3 and 4, the patient worked in the bacteriology laboratory of another hospital. She had been observed using gloves to subculture an N. meningitidis isolate, and she had extensive rhinorrhea.

Both the workplace isolate and the patient's blood culture isolate were identified as N. meningitidis serogroup B. Isoenzyme testing performed by CDC on the patient's blood isolate, the workplace isolate, and nine other unrelated but recently isolated group B strains from Massachusetts demonstrated that the isoenzyme pattern of the patient and workplace isolate were identical. They differed from the nine other Massachusetts group B isolates (p less than 0.02, Fisher's exact test). Reported by: KK Takata, BG Hinton, MD, Sacramento County Health Dept; SB Werner, MD, Infectious Disease Br, Preventive Medical Svcs Div; GW Rutherford, MD, State Epidemiologist, California Dept of Health Svcs. SM Lett, MD, Bur of Communicable Disease Control, Center for Disease Control, Massachusetts Dept of Public Health. Biosafety Br, Office of Health and Safety; Meningitis and Special Pathogens Br, Div of Bacterial and Mycotic Diseases, Center for Infectious Diseases, CDC.

Editorial Note

Editorial Note: Laboratory-acquired infection with N. meningitidis is rare. Three previous case reports describe infections in persons working in research laboratories who handled meningococcal organisms frequently and in large volumes (1,2); two of these occurred before the availability of effective vaccines and antibiotic therapy.

Although N. meningitidis was never isolated from the blood of the laboratory worker in California, other evidence supports the conclusion that she had laboratory-acquired meningococcal infection. The worker in Massachusetts may have been at increased risk for meningococcal infection; several studies suggest that concurrent viral infection increases the risk of developing invasive meningococcal infection (3-5).

These cases represent the first reports of meningococcal infection acquired in the clinical laboratory setting. Although laboratory workers frequently handle specimens and cultures containing meningococci, the laboratory workers probably are not at increased risk of infection when standard microbiologic practices are followed.

Meningococci may be present in specimens of pharyngeal exudates, cerebrospinal fluid, blood, and saliva. Laboratory workers may be exposed to organisms by inoculation, ingestion, and droplet or aerosol exposure of the mucous membranes. Guidelines for laboratory workers who handle meningococci include use of protective gloves and laboratory coats and decontamination of all infectious wastes (6). A class II biological safety cabinet should be used when mechanical manipulations that have high aerosol potential are performed. Work involving high concentrations or large quantities of organisms should be performed in a biosafety level 3 laboratory; laboratory workers in this setting should be immunized with the tetravalent meningococcal polysaccharide vaccine that includes serogroups A, C, Y, and W135 but does not include serogroup B, currently the most common serogroup in the United States. In the event of any incident or exposure involving meningococci, workers should seek prompt medical attention. Persons with percutaneous exposure to meningococci should receive chemoprophylaxis with penicillin; those with mucosal exposure should be treated with rifampin (7).

References

1. Pike RM. Laboratory-associated infections: incidence, fatalities, causes, and prevention. Annu Rev Microbiol 1979;33:41-66.

2. Bhatti AR, DiNinno VL, Ashton FE, White LA. A laboratory-acquired infection with Neisseria meningitidis. J Infect 1982;4:247-52.

3. Young LS, LaForce FM, Head JJ, Feeley JC, Bennett JV. A simultaneous outbreak of meningococcal and influenza infections. N Engl J Med 1972;287:5-9.

4. Krasinski K, Nelson JD, Butler S, Luby JP, Kusmiesz H. Possible association of mycoplasma and viral respiratory infections with bacterial meningitis. Am J Epidemiol 1987;125:499-508.

5. Moore PS, Hierholzer J, Dewitt W, et al. Respiratory viruses and mycoplasma as cofactors for epidemic group A meningococcal meningitis. JAMA 1990;264:1271-5.

6. CDC/National Institutes of Health. Biosafety in microbiological and biomedical laboratories. 2nd ed. Atlanta: US Department of Health and Human Services, Public Health Service, CDC, 1988; DHHS publication no. (CDC)88-8395.

7. ACIP. Meningococcal vaccines. MMWR 1985;34:255-9.

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