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Published on: February 19, 2013
Enhancement of experimental actinomycosis in mice by Eikenella corrodens
Abstract:
The infectivity of Actinomyces israelii in a susceptible-weanling-mouse was increased by the presence of Eikenella corrodens in the inoculum. A minimal infecting dose of 1.7 X 10(7) CFU of A. israelii was required to establish chronic lesions after an intraperitoneal injection. When E. corrodens (3.8 X 10(7) CFU) was included in the inoculum, chronic lesions were established with a dose of 8.5 X 10(4) CFU of A. israelii. E. corrodens alone did not produce persistent lesions. Viable E. corrodens could be recovered from chronic mixed actinomycotic lesions in numbers that often equaled or exceeded the populations of A. israelii in the lesions. The duration of acute actinomycotic infections caused by A. viscosus was temporarily extended by the presence of E. corrodens. The cellular inflammatory response and overall morphology of mixed experimental lesions containing A. israelii and E. corrodens did not appear to be significantly different from those of pure-culture lesions containing A. israelii alone. E. corrodens cells could not be readily discerned in stained histological sections of mixed experimental lesions.
Insights
The presence of Eikenella corrodens significantly increases Actinomyces israelii infectivity in mice, reducing the required dose for chronic lesions. E. corrodens alone does not cause persistent lesions.
Area of Science:
- Microbiology
- Immunology
- Infectious Diseases
Background:
- Actinomycosis is a bacterial infection often caused by Actinomyces species.
- The role of co-infecting bacteria in modulating Actinomyces pathogenesis is not fully understood.
Purpose of the Study:
- To investigate the effect of Eikenella corrodens on the infectivity and pathogenesis of Actinomyces israelii in a mouse model.
- To determine if E. corrodens influences the course of Actinomyces viscosus infections.
Main Methods:
- Intraperitoneal injection of varying doses of Actinomyces israelii, alone and in combination with Eikenella corrodens, into susceptible weanling mice.
- Monitoring for the establishment and duration of chronic lesions.
- Recovery and quantification of bacterial populations from lesions.
- Histological examination of lesion morphology and inflammatory response.
Main Results:
- Eikenella corrodens significantly reduced the minimal infecting dose of Actinomyces israelii required to establish chronic lesions by over 2 logs.
- Viable E. corrodens was recovered from mixed lesions, often in numbers equal to or exceeding A. israelii.
- E. corrodens alone did not induce persistent lesions.
- The presence of E. corrodens temporarily extended the duration of acute Actinomyces viscosus infections.
- Histological examination revealed no significant differences in lesion morphology or inflammatory response between pure and mixed infections.
Conclusions:
- Eikenella corrodens acts as a co-infectious agent that enhances the infectivity of Actinomyces israelii.
- E. corrodens may play a role in the chronicity and persistence of actinomycotic lesions.
- Further research is needed to elucidate the mechanisms underlying this synergistic interaction.
