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Endotoxin liberation from Neisseria meningitidis isolated from carriers and clinical cases
B M Andersen1, O Solberg, K Bryn
1Department of Bacteriology, National Institute of Public Health, Oslo, Norway.
Abstract:
Endotoxin liberation was studied in a blinded material of 121 Neisseria meningitidis isolates; from nasopharynx of 58 carriers and from cerebrospinal fluid or blood of 63 cases with meningococcal disease. Endotoxin activity in culture filtrates was determined by a Limulus lysate test. Meningococci isolated from clinical cases were significantly more frequently endotoxin-liberating (E+) (84.1%) than in carriers (25.9%); p less than 0.001. Serogroupable carrier isolates had a significantly higher frequency of E+ meningococci (61.9%) than non-groupable ones (5.4%); p less than 0.002. Serogroup B case isolates, which generally had a larger amount of capsular polysaccharide than B meningococci from carriers, had a significantly higher proportion of E+ meningococci than group B from carriers; p = 0.007. All 7 serogroup C isolates were E+ (5 cases and 2 carriers). No correlation was found between endotoxin liberation and the serotype: subtype 15:P1.16, tested by a selection of monoclonal antibodies, or between endotoxin liberation and sulfonamide resistance, when carrier and case isolates were studied separately. Meningococci isolated from cases had the following mean endotoxin titres: 320.5 in the meningitis group, 408.2 in the septicaemic group, 462.1 in the septicaemic and meningitis group, and 123.7 in the group with other systemic disease. E+ meningococci were isolated from 5/6 fatal cases. Thus, endotoxin liberation from meningococci is strongly, but not completely associated with establishment of meningococcal disease and with the presence of capsular polysaccharide.
Insights
Endotoxin liberation from Neisseria meningitidis is strongly linked to meningococcal disease development. This endotoxin activity is more prevalent in clinical cases than carriers and associated with capsular polysaccharide presence.
Area of Science:
- Microbiology
- Immunology
- Infectious Diseases
Background:
- Neisseria meningitidis causes invasive meningococcal disease.
- Endotoxins are key virulence factors in Gram-negative bacteria.
- Understanding endotoxin liberation is crucial for disease pathogenesis research.
Purpose of the Study:
- To investigate endotoxin liberation in Neisseria meningitidis isolates from carriers and patients with meningococcal disease.
- To determine the association between endotoxin liberation and disease establishment.
- To explore correlations with serogroup, capsular polysaccharide, and antimicrobial resistance.
Main Methods:
- Studied 121 Neisseria meningitidis isolates (58 carriers, 63 cases).
- Assessed endotoxin activity using the Limulus lysate test.
- Correlated endotoxin liberation with clinical data, serogroup, serotype, and sulfonamide resistance.
Main Results:
- Endotoxin-liberating (E+) meningococci were significantly more frequent in clinical cases (84.1%) than carriers (25.9%).
- E+ isolates were more common in serogroupable carrier isolates and Serogroup B case isolates with higher polysaccharide content.
- All Serogroup C isolates were E+; no correlation found with serotype or sulfonamide resistance.
Conclusions:
- Endotoxin liberation is strongly associated with the establishment of meningococcal disease.
- The presence of capsular polysaccharide is also linked to increased endotoxin liberation.
- Endotoxin liberation is a significant virulence factor in Neisseria meningitidis infections.