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[Adhesiveness in Neisseria meningitidis. A virulence factor?]
M C Mellado1, R Rodríguez-Contreras, R López
1Departamento de Medicina Preventiva y Salud Pública, Facultad de Medicina de Granada.
Abstract:
The role of adhesivity as a factor of virulence in cases of N. meningitidis has not yet been established. Unlike other bacteria in which the presence of adhesivity reflects an enhanced virulence, a high capacity of adherence is associated with a low virulence and invasive capacity in cases of meningococcus. In order to gain more insight into the knowledge of this phenomenon we have studied the adhesivity of 109 strains of N. meningitidis to human pharyngeal epithelial cells. Twenty nine out of the 109 strains were isolated from blood or spinal fluid of patients with meningococcal infection (meningitis or septicemia), whereas the remaining 80 strains were obtained from pharyngeal smears of healthy carriers. The adhesivity was measured as the number of meningococci adhered to 50 epithelial cells according to Craven's scale. Strains of healthy carriers showed a greater adhesivity than that of patients (p less than 0.001). The relevance of the pharyngeal area in the evaluation of the adhesive capacity is in accordance with the hypothesis that meningococcal adhesivity decreases when the microorganism crosses the pharyngeal epithelium. The results would support the concept that the virulence of N. meningitidis is related to its adhesiveness.
Insights
Meningococcus adhesivity to cells is lower in patients with invasive disease than in healthy carriers. This suggests that reduced adhesiveness may correlate with increased virulence in Neisseria meningitidis infections.
Area of Science:
- Microbiology
- Infectious Diseases
- Bacteriology
Background:
- The role of bacterial adhesivity in virulence is complex and not fully understood for Neisseria meningitidis.
- In contrast to many bacteria, high adherence in N. meningitidis has been paradoxically linked to lower virulence and invasiveness.
Purpose of the Study:
- To investigate the relationship between adhesivity and virulence in Neisseria meningitidis.
- To compare the adherence capacity of N. meningitidis strains from invasive infections versus healthy carriers.
Main Methods:
- Studied adhesivity of 109 N. meningitidis strains to human pharyngeal epithelial cells.
- Compared 29 strains from patients (meningitis/septicemia) with 80 strains from healthy carriers.
- Quantified adherence using Craven's scale based on meningococci per 50 epithelial cells.
Main Results:
- Strains from healthy carriers exhibited significantly higher adhesivity compared to strains from patients (p < 0.001).
- Adhesiveness was inversely correlated with the invasive capacity of the bacteria.
- Findings support the hypothesis that adhesiveness decreases as the bacterium breaches the pharyngeal epithelium.
Conclusions:
- Bacterial adhesiveness in N. meningitidis may decrease as it transitions from carrier state to invasive disease.
- The study supports a concept where virulence of N. meningitidis is inversely related to its adhesiveness.
- Pharyngeal epithelial cell adherence is a relevant factor in understanding meningococcal pathogenesis.