The vaginal microflora of pig-tailed macaques and the effects of chlorhexidine and benzalkonium on this ecosystem

Background and Objectives: To characterize normal vaginal microflora of pig-tailed macaques and to evaluate two commonly used intravaginal compounds, chlorhexidine (CHG), a vaginal antiseptic (Surgilube, E. Fougera, Melville, NY), and benzalikonium chloride (BZK) (spermicidal contraceptive) in this monkey model to assess effects on the vaginal microflora. Study Desigrl: Vaginal swabs were collected for microbiologic analysis to characterize normal flora. Subsequently, the vagina was exposed to either CHG or BZK twice at 24-hour intervals. Results: The vaginal microflora of 26 pig-tailed macaques was found to be remarkably similar to the vaginal flora of the human with respect to frequency of vaginal colonization by H2O2-producing lactobacilli, Prevotella species, and several other microorganisms. After two vaginal applications at 24-hour intervals, CHG had only small effects on the vaginal microflora of five animals. By contrast, BZK applied by the same protocol had profound adverse effects on the lactobacilli and Peptostreptococcus and more transient effects on vaginal Prevotella and viridans streptococci of six animals. Conclusions: These observations demonstrate that the vaginal microflora of the pig-tailed macaque is a useful model in which to further evaluate newly developed intravaginal contraceptives that may be microbicidal and/or virucidal before widespread intravaginal use in women.