The pig-tailed macaque rectal model - Microflora and chlamydial infection

Background: A topical microbicide should protect against acquisition of sex ually transmitted infection during both vaginal and rectal intercourse, The rectal microflora of the Macaca nemestrina (pig-tailed macaque) and humans were examined, as well as the histopathology of rectal tissues. In a subse t of macaques, a human rectal isolate of Chlamydia trachomatis was inoculat ed into the rectum to establish rectal chlamydial infection, Goal: To evaluate the comparability of the pig-tailed macaque rectal model with humans. Study Design: Rectal swabs were collected for microbiologic analysis to cha racterize normal microflora In pig-tailed macaques and humans. Subsequently , 10 macaques received a rectal inoculation with C trachomatis, serovar D, prepared from a clinical rectal isolate. Results: The rectal microflora of pig-tailed macaques (n = 80) were found t o be comparable with the rectal flora of humans (n = 40), The prevalence of Lactobacillus in the rectum was higher in the macaques than in humans. Col iform and Enterococcus were decreased in the macaques, as compared with tho se of humans, In 9 of 10 macaques, rectal chlamydial infection was confirme d by culture or ligase chain reaction on days 2, 7, and 14 after inoculatio n, The test results were positive for rectal chlamydial infection by ligase chain reaction only for the remaining animal on day 14 after inoculation. Conclusions: The findings demonstrate that the rectal environment of the pi g-tailed macaque is a useful model for further evaluation of newly develope d topical microbicides for rectal use. Furthermore, such products can be ev aluated for protection against rectal chlamydial infection in this model.