Latex agglutination for bacterial antigens and meningococcus PCR: two useful tools in legal sudden deaths

Bacterial infections are considered to be a major cause of sudden deaths. The recognition of infections caused by Neisseria meningitidis is an essential duty of medicolegal offices due to the risk of secondary cases. Since other microorganisms, such as Haemophilus influenzae and Streptococcus pneumoniae, are also involved in infectious sudden deaths, the identification of the pathogen responsible for death is essential in order to establish a positive diagnosis while also preventing secondary meningococcal cases. However, because of the unreliability of culture methods used for autopsy specimens and the fragile nature of the microorganisms, other techniques were used. In this study, the detection of specific antigens of N. meningitidis (serogroups A, B, C, Y and W135), H. influenzae type b, S. pneumoniae and Group B Streptococcus was undertaken in 40 samples from sudden death cases in legal procedures with a latex agglutination test. In addition, a meningococcus polymerase chain reaction (PCR) assay (ctrA, crgA and siaD genes) was also used as a corroboration method for positive N. meningitidis agglutinations. Eleven cases of sudden death were confirmed to be due to meningococcus while one case was confirmed to have been caused by H. influenzae type b fulminant epiglottitis. Rapid laboratory diagnosis of meningococcal infection allowed contacts management and notification to the health authorities. From the point of view of the authors, forensic diagnosis of unascertained deaths should include latex agglutination and meningococcus PCR when a fulminant infection by N. meningitidis or H. influenzae is suspected as well as in deaths where the cause is unclear.