Copper versus the gonococcus in vivo.

The bactericidal activity of copper and its salts has been generally found to be of a low order in vitro by such authorities as Porter (1946) and Sprowls and Poe (1943). At the beginning of 1973 our attention was drawn to the fact that copper salts in certain concentrations had in fact been found to be toxic to gonococci. Fiscina, Oster, Oster, and Swanson (1973), working at the Mount Sinai Medical School, New York, found that copper sulphate at a concentration of 1 x 10-6M or greater is toxic to 1 x 107to 1 x 108 gonococci per ml., 1 x 1O-5M destroying most viable organisms within approximately 30 minutes. Furthermore, they also found that a copper wire placed on gonococci plated out on agar caused inhibition of growth in a wide area around the wire. A copper loop placed on such a plate is shown in the Figure. The surrounding zone of inhibition can easily be seen. The inhibition of growth is caused by minute quantities of copper dissolved from the wire. It is of interest to note that Fiscina and her colleagues obtained little inhibition of growth of E. coli using copper salts at a concentration 10,000 times greater than that required to inhibit the gonococcus. They mention that the small amount of copper incorporated in some intrauterine contraceptive devices (IUDs) is slowly lost over a period of 2 years at the rate of about 1 ,tg. per day. Half of this soluble copper is absorbed through the uterine wall and the remainder is carried out in the uterine and cervical secretions. They calculated that the concentration of copper salts in these secretions would be at least 5 x 10-6 M., a level well within the inhibitory range for the gonococcus. At the present time all forms of treatment for gonorrhoea are therapeutic, although Singh, Cutler, and Utidjian (1972) have investigated the effect of twenty vaginal contraceptive preparations and seventeen other compounds in vitro and found that several products inhibited gonococcal growth. A suitable vaccine has yet to be produced, tested, and applied,