Effect of bacterial secondary infection in an animal model of trachoma

Abstract

In trachoma the interaction between chronic chlamydial and acute bacterial conjunctivitis 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 conomolgus 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.