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Effect of bacterial secondary infection in an animal model of trachoma
Abstract:
In trachoma the interaction between chronic chlamydial and acute bacterial conjuntivitis has been suggested as important in determining the severity of disease and, therefore, blindness. We investigated the effect of acute conjunctival infection with each of three common human pathogens, Haemophilus influenzae, Haemophilus aegyptius , and Streptococcus pneumoniae, in a model of trachoma established in cynomolgus monkeys. Although acute conjunctivitis developed, animals with trachoma were not more susceptible to infection than other monkeys, nor did they develop more severe disease as a result of the bacterial conjunctivitis. The failure of bacterial conjunctivitis to exacerbate the experimental trachoma indicates that, in this model at least, chronically maintained chlamydial infection alone is sufficient to produce the changes characteristic of trachoma.
Insights
In trachoma, acute bacterial conjunctivitis did not worsen disease severity in a monkey model. Chronic chlamydial infection alone appears sufficient to cause trachoma-related changes.
Area of Science:
- Ophthalmology
- Infectious Diseases
- Microbiology
Background:
- Trachoma severity is potentially influenced by interactions between chronic chlamydial infection and acute bacterial conjunctivitis.
- Understanding these interactions is crucial for preventing blindness associated with trachoma.
Purpose of the Study:
- To investigate the impact of acute bacterial conjunctivitis on experimental trachoma in a cynomolgus monkey model.
- To determine if common bacterial pathogens exacerbate trachoma progression.
Main Methods:
- Cynomolgus monkeys with established trachoma were experimentally infected with Haemophilus influenzae, Haemophilus aegyptius, or Streptococcus pneumoniae.
- Disease severity and susceptibility to bacterial infection were monitored in infected and control animals.
Main Results:
- Animals with trachoma developed acute conjunctivitis following bacterial challenge.
- However, trachoma-infected monkeys did not show increased susceptibility to bacterial pathogens or more severe disease compared to controls.
- Bacterial conjunctivitis did not exacerbate the experimental trachoma.
Conclusions:
- In this primate model, chronic chlamydial infection alone is sufficient to induce trachoma-associated pathology.
- Acute bacterial conjunctivitis does not appear to worsen trachoma in this experimental setting.