Further Experiments with B. Pertussis Filtrate

Toomey and McClelland 1 have described a substance found in cultures of veal brain broth during the growth of H. pertussis. The following is an additional report on the character of this filtrate, termed for convenience B.P.F.

The strain of B. pertussis used was number 778 of the American Type Culture Collection, originally isolated by Park. It was planted and grew luxuriantly in 50 Erlenmeyer flasks, each of which contained 50 cc. of bloodless veal brain broth medium. 1 For 50 successive days, the contents of a flask were treated each day as described previously. 1 The filtrate obtained was kept sterile by the addition of 0.2% of tricresol. The 50 specimens collected were divided into groups of 10 each.

One group of filtrates was injected intradermally into the arms and forearms of at least 6 individuals, in doses of 0.1 cc. There was no appreciable change in the toxicity of the filtrate obtained from these growths as evidenced by the reactions to skin tests until the filtrate of the twelfth day was harvested. The filtrates that were obtained after the twelfth day always gave local inflammatory reactions when injected intradermally in the skins of individuals; these reactions were still present 24 hours after the injection, although a positive reaction was sometimes obtained with those filtrates that had grown for from 8 to 12 days. The filtrates obtained after the twentieth day of growth, however, contained no greater amount of B.P.F. than those obtained from the twelfth to the twentieth day.

Cultures were taken of the growths preceding each daily filtration to make certain of purity and to note the length of time that organisms remained viable. The transplantation was made on solid veal brain agar. Beginning with the twentieth day, the transferred growth became more sparse. By the twenty-fifth day, little or none of the transplanted material had grown, and by the thirtieth day, all the organisms were dead since no further growth could be obtained on subculture. Demonstrable death of the organisms started about the twentieth day.