Prophylactic effects of silver nitrate and erythromycin on Chlamydia psittaci conjunctivitis

An animal model has been developed to study the effects of various prophylaxis agents on acquisition of chlamydial conjunctivitis. When Hartley strain newborn guinea pigs received ocular inoculations of Chlamydia psittaci followed by the instillation of various agents, 1% AgNO3 significantly lowered the risk of developing chlamydial conjunctivitis if it was administered within 15 min after the inoculation with C. psittaci. However, if the AgNO3 was administered at either 1 hr or 2 hr following inoculation, it did not have any prophylactic effect on the development of chlamydial conjunctivitis. Erythromycin ointment, 0.5%, was also found to prevent chlamydial conjunctivitis. The prophylactic effect was similar to placebo when the drug was given at 15 min; however, erythromycin ointment prophylaxis 1 hr or 2 hr after inoculation with C. psittaci was statistically superior to placebo.