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Objective: Safe and effective vaginally applied microbicides could help to control the continuing spread of sexually transmitted diseases., Study Design: This study used nonhuman primates to test the effects of multiple applications of nonoxynol 9, benzalkonium chloride, or a combination on vaginal flora and lower reproductive tract tissues. Fourteen monkeys (Macaca nemestrina) received daily vaginal applications of nonoxynol 9, benzalkonium chloride, or both for 3 to 4 days. Vaginal microflora and colposcopic observations were made at baseline and during and after completion of treatments. Cervical biopsy specimens were collected from a subset of animals., Results: Cervical erythema and vaginal erythema were observed in all 3 treatment groups. Cervical papillae and epithelial disruption were present in both the nonoxynol 9 and the nonoxynol 9 plus benzalkonium chloride groups. Vaginal epithelial disruption was noted in both the benzalkonium chloride and the nonoxynol 9 plus benzalkonium chloride groups. Cervical biopsy specimens from each group revealed acute inflammatory infiltrates with occasional plasma cells and lymphoid follicles. Detection of most microorganisms, including viridans streptococci, decreased in the benzalkonium chloride and the nonoxynol 9 plus benzalkonium chloride groups. Detection of Lactobacillus species decreased in the benzalkonium chloride group. All microflora levels recovered after several days without microbicide use., Conclusions: Although nonoxynol 9 is currently the only microbicide approved for use as a spermicide in the United States, its repeated use may be detrimental to the epithelial tissues of the female reproductive tract. Benzalkonium chloride, currently approved for use in other countries, not only may damage epithelial tissues but also appears to reduce the population of potentially protective Lactobacillus species in the vagina.

Background and Objectives: Nonoxynol-9, an intravaginal microbicide, is chlamydiacidal in vitro but also cytotoxic. This study examines the effects of nonoxynol-9 in vivo, using a pigtail macaque model of chlamydial cervicitis., Goals: To establish a minimum infectious dose of Chlamydia trachomatis in the macaque, and to observe the effects of a single dose of nonoxynol-9 on efficiency of chlamydial infection, vaginal microflora, and cervicovaginal irritation., Study Design: The effects of 4% nonoxynol-9, C. trachomatis (5,000 or 10,000 IFU) or both nonoxynol-9 application and chlamydial infection were studied in 17 macaques., Results: Following a single application of nonoxynol-9, chlamydial infection was prevented in 4 of 6 monkeys infected with 10,000 IFU; there was a transient decrease in anaerobic gram-negative rods (P < 0.05) and Peptostreptococci (P > 0.05), but no change in Lactobacillus. Mild cervicovaginal irritation was observed in the monkeys., Conclusions: A single dose of nonoxynol-9 causes minimal vaginal flora and epithelial irritation, and may be useful for prevention of chlamydial infection.