The in vitro activity of nonoxynol-9 against four serotypes (C, D, H, and K) of Chlamydwa trachomatis was investigated. A constant inoculum of each serotype was exposed to serial twofold dilutions (1:100 to 1:800) of Koromex, Conceptrol, or reference preparations (not containing nonoxynol-9) for 4 and 24 h at 37°C. The mixtures of nonoxynal-9 or nonnonoxynol preparations and control inocula were dispensed into triplicate wells containing McCoy cell monolayers. After incubation at 37C, the monolayers were fixed and stained with idoine and examined for evidence of infection with C. trachomatis. All nonoxynol-9-containing preparations showed marked antichlamydial activity as judged by percent reduction of glycogen-containing intracytoplasmic inclusions. The reference preparations, which did not contain nonoxynol-9, were markedly less active when tested in this in vitro system. Nonoxynol-9 (N-9), a membrane-active detergent, is the active ingredient in numerous commercially available intravaginal contraceptive foams, inserts, and jellies. Previous studies have shown that this compound is active in vitro against many pathogens causing sexually transmitted diseases. However, the activity of N-9 against Chlamydia trachomatis has not been well studied. In this study, we investigated the in vitro activity of N-9 against C. trachomatis by using two commercially available spermicides, both containing N-9, and reference preparations not containing N-9.MATERIALS AND METHODS Microorganisms. Four strains of C. trachomatis, serotypes C, D, H, and K, were tested. All strains were provided by E. R. Alexander, Atlanta, Ga., and were selected because they are representative of the strains commonly associated with urethritis in men and cervicitis in women.Contraceptives. The contraceptive products used in this study were the commercial preparations Conceptrol (Ortho Pharmaceutical Laboratories, Raritan, N.J.), containing 4% N-9, and Koromex (Youngs Drug Products, Piscataway, N.J.), containing 2% N-9. Although each contained N-9 as the spermicidal agent, the contraceptives differed slightly with regard to other constituents. Reference formulations of each product were provided by the manufacturers and were identical to the commercial formulations except for the absence of N-9. (1:10 to 1:2,560) were prepared in cell culture media. These dilutions were then dispensed into 96-well microtiter plates that contained McCoy cell monolayers and were incubated for 48 h at 37°C. Cellular toxicity was assessed by two methods: (i) visual determination of the condition of the monolayer under x100 magnification and (ii) the ability of the cells to exclude trypan blue.The antichlamydial activity of N-9 was assayed by the inoculation of serial twofold dilutions (1:100 to 1:800) of spermicide (N-9) or reference (non-N-9) preparations, mixed with a constant inoculum of each of four strains of C. trachomatis, into McCoy cell monolayers. Each of these mixtures and controls of cell culture media and inocula of the four strains had been incubated at 37°C ...
