NUTRITIONAL STUDIES OF A VIRULENT STRAIN OF HAEMOPHILUS DUCREYI

Abstract

A virulent strain of H. ducreyi grew well in a medium containing any 1 of several peptones dissolved in physiological saline to which a small amount of rabbit serum was added. Limited growth was obtained with a number of amino acids, inorganic nitrogen compounds and acid-hydrolyzed caseins. A mixture of vitamins and minerals did not enhance growth but biotin alone had a stimulatory effect in some media. Although H. ducreyi can be adapted to grow in the presence of minute quantities of blood, it will not grow in a medium from which blood in some form is entirely eliminated. The essential growth factors in serum are stable at 100[degree]C, are diffusible through agar and are not identifiable as X and V factors. They are found in the residue and dialyzate of rabbit serum, neither fraction being able to support growth alone. Commercially prepared bovine albumin can replace the serum residue and "Sims serum ultrafiltrate" or "supplement B" can be substituted for the dialyzate.