1426. Laboratory Gram Stain Misidentifications of Neisseria meningitidis and Impact on Public Health Response to Meningococcal Disease
Session: Poster Abstract Session: Public Health
Friday, October 28, 2016
Room: Poster Hall
  • Datta1426_IDWeek2016.pdf (957.1 kB)
  • Background:  Invasive meningococcal disease (IMD) caused by Neisseria meningitidis, a Gram-negative diplococci, can quickly lead to death or significant sequelae in survivors. N. meningitidis transmission occurs by person-to-person contact and secondary cases can occur. Public health response to IMD cases includes identifying close contacts and administering post-exposure prophylaxis as soon as possible. Identification of Gram-negative diplococci provides initial evidence for an IMD diagnosis. California laboratories are required to immediately notify public health authorities about suspect IMD cases so public health control measures can be implemented. However, Gram stain interpretation is subjective and the accuracy of results may be affected by laboratorian training and experience. We determined the number of Gram stain misidentifications among confirmed IMD cases and assessed the impact of misidentification on public health response to these cases. 

    Methods:  Gram stain results for IMD cases reported to California Department of Public Health during January 2013 through February 2015 were reviewed. Gram stain results were classified as misidentified when Gram-negative diplococci were not initially identified and the result was subsequently corrected. The impact of Gram stain misidentifications on public health response to IMD cases was assessed by calculating the amount of time that elapsed between issuance of incorrect and corrected Gram stain reports. 

    Results:  Gram stain results for 162 IMD cases were reviewed. Blood specimens were available for all cases; cerebrospinal fluid (CSF) specimens were available for 101 (62%) cases. 13% of cases had at least one misidentified Gram stain result. 11% of blood specimens and 4% of CSF specimens were misidentified. The median delay in reporting suspect IMD cases to public health due to incorrect initial results was 20 hours.

    Conclusion: Initial misidentification of N. meningitidis Gram stains can occur and results in delayed reporting of IMD cases to public health. Delayed reporting leads to a delay in identification of contacts and administration of post-exposure prophylaxis. Misidentification could result in exposure of laboratorians to N. meningitidis. The risk of developing IMD is highest 1-3 days after exposure and a delay in reporting is of concern.  

    Shrimati Datta, PhD, MPH, Anthony Moore, BA, Jennifer Zipprich, MS, PhD, Kathleen Winter, MPH, PhD and Kathleen Harriman, PhD, MPH, RN, Immunization Branch, California Department of Public Health, Richmond, CA


    S. Datta, None

    A. Moore, None

    J. Zipprich, None

    K. Winter, None

    K. Harriman, None

    See more of: Public Health
    See more of: Poster Abstract Session

    Findings in the abstracts are embargoed until 12:01 a.m. CDT, Wednesday Oct. 26th with the exception of research findings presented at the IDWeek press conferences.