Prevalence and clinical course in invasive infections with meningococcal endotoxin variants

PLoS One. 2012;7(11):e49295. doi: 10.1371/journal.pone.0049295. Epub 2012 Nov 29.

Abstract

Background: Meningococci produce a penta-acylated instead of hexa-acylated lipid A when their lpxL1 gene is inactivated. Meningococcal strains with such lipid A endotoxin variants have been found previously in adult meningitis patients, where they caused less blood coagulopathy because of decreased TLR4 activation.

Methods: A cohort of 448 isolates from patients with invasive meningococcal disease in the Netherlands were screened for the ability to induce IL-6 in monocytic cell Mono Mac 6 cells. The lpxL1 gene was sequenced of isolates, which show poor capacity to induce IL-6.. Clinical characteristics of patients were retrieved from hospital records.

Results: Of 448 patients, 29 (6.5%) were infected with meningococci expressing a lipid A variant strain. Lipid A variation was not associated with a specific serogroup or genotype. Infections with lipid A variants were associated with older age (19.3 vs. 5.9 (median) years, p = 0.007) and higher prevalence of underlying comorbidities (39% vs. 17%; p = 0.004) compared to wild-type strains. Patients infected with lipid A variant strains had less severe infections like meningitis or shock (OR 0.23; 95%CI 0.09-0.58) and were less often admitted to intensive care (OR 0.21; 95%CI 0.07-0.60) compared to wild-type strains, independent of age, underlying comorbidities or strain characteristics.

Conclusions: In adults with meningococcal disease lipid A variation is rather common. Infection with penta-acylated lipid A variant meningococci is associated with a less severe disease course.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acyltransferases / genetics
  • Adolescent
  • Adult
  • Age Factors
  • Bacterial Proteins / genetics
  • Child
  • Child, Preschool
  • Humans
  • Infant
  • Infant, Newborn
  • Lipid A / genetics*
  • Lipid A / metabolism
  • Meningococcal Infections / diagnosis
  • Meningococcal Infections / epidemiology*
  • Middle Aged
  • Mutation
  • Neisseria meningitidis / classification
  • Neisseria meningitidis / genetics*
  • Neisseria meningitidis / metabolism
  • Prevalence
  • Serotyping
  • Young Adult

Substances

  • Bacterial Proteins
  • Lipid A
  • Acyltransferases
  • LpxL protein, bacteria

Grant support

National Institute for Public Health and the Environment, Bilthoven. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.