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An experimental mouse model to study the pathogenicity of Prevotella bivia and investigations of possible virulence
L O Egwari1, V O Rotimi, A O Coker
1Faculty of Medical Science, University of Lagos, Nigeria.
Abstract:
Induction of subcutaneous abscesses in mice was used to study the pathogenicity of Prevotella bivia both in mono-infection and in mixed cultures with Escherichia coli and Peptostreptococcus spp. Virulence factors such as coaggregation and aggregate formation of cells, haemagglutination activity and tolerance to serum bactericidal activity were investigated for their possible role in P bivia pathogenicity. Monocultures of P bivia, E coli and Peptostreptococcus spp did not induce subcutaneous abscess at concentrations as high as 10(9) colony forming units/millilitre (cfu/ml). Only E coli persisted at the infection site for up to 7 days post infection but with a marked decline in cell count (8.0 x 10(2) cfu/ml). The anaerobic organisms did not persist at the infection sites beyond the fifth day. In contrast, mixed cultures of P bivia and E coli or all three organisms potentiated for infective abscess two weeks after infection. Viable cells were recovered from abscesses in greater numbers as the infection progressed. Prevotella bivia was the predominant organism in chronic abscesses while E coli predominated in abscesses in the acute stage of the infection. Prevotella bivia lacked haemagglutination activity against human and sheep erythrocytes and showed marked susceptibility to 50 per cent human serum. These may limit its haematogenous spread. Its ability to form aggregates in molar salt solutions and coaggregate with facultative organisms may account for its persistence in pathological sites.
Insights
Mixed infections with Prevotella bivia and Escherichia coli, or all three bacteria, caused subcutaneous abscesses in mice. Prevotella bivia
Area of Science:
- Microbiology
- Pathogenesis research
- Bacterial infections
Background:
- Prevotella bivia is an anaerobic bacterium implicated in various infections.
- Understanding the pathogenicity of P. bivia, especially in polymicrobial settings, is crucial.
Purpose of the Study:
- To investigate the pathogenicity of Prevotella bivia in subcutaneous abscess formation in mice.
- To evaluate the role of specific virulence factors in P. bivia infections.
- To compare mono-infections versus mixed infections with Escherichia coli and Peptostreptococcus spp.
Main Methods:
- Induction of subcutaneous abscesses in mice using bacterial mono- and co-cultures.
- Quantification of bacterial load at infection sites over time.
- Assessment of bacterial virulence factors: coaggregation, aggregate formation, haemagglutination, and serum tolerance.
Main Results:
- Mono-infections with P. bivia, E. coli, or Peptostreptococcus spp. did not induce abscesses at high bacterial concentrations.
- Mixed cultures of P. bivia and E. coli, or all three organisms, potentiated abscess formation.
- P. bivia was predominant in chronic abscesses, while E. coli dominated acute stages.
- P. bivia showed limited haemagglutination and high susceptibility to serum, but formed aggregates and coaggregated with facultative bacteria.
Conclusions:
- P. bivia requires co-infection with facultative bacteria like E. coli to cause abscesses.
- Bacterial aggregation and co-aggregation are likely key factors for P. bivia persistence in pathological sites.
- Virulence of P. bivia in abscess formation is context-dependent, influenced by the microbial community.