Bacteremia in an immunocompromised patient caused by a commensal Neisseria meningitidis strain harboring the capsule null locus (cnl)

Abstract

We recently described the capsule null locus (cnl) of constitutively unencapsulated Neisseria meningitidis clonal lineages. cnl meningococci were recovered from healthy carriers at high frequency. We here report on the first case of invasive disease caused by cnl meningococci in a severely immunosuppressed patient with chronic graft-versus-host disease after allogeneic peripheral blood stem cell transplantation. The sequence type 845 strain was extensively typed and, furthermore, shown to be sensitive to serum bactericidal activity.

FIG. 1.

Serum killing assay with NHS. NHS was applied to meningococci for 30 min in various concentrations. The serogroup B strain MC58 and its unencapsulated derivative MC58 siaD mut. were used as controls in addition to the test strain DE9536. Strains were tested after growth without or with an exogenous supply of CMP-NANA. The bactericidal assays were performed two (in the case of MC58) or three (in the case of DE9536) times. Mean values of log₁₀ CFU per milliliter are shown. Vertical bars represent the standard errors of the means, which were calculated for values derived from DE9536. The limit of detection was 1.