Interaction of insulin with Burkholderia pseudomallei may be caused by a preservative

Aim-To re-examine the previously reported in vitro interaction of insulin w ith Burkholderia pseudomallei, in the light of a suggestion that the intera ction may have resulted from the presence of the preservative nz-cresol in commercial preparations. Methods-Broth culture studies of B pseudomallei were performed with and wit hout the addition of m-cresol and various preparations of insulin. Results-Growth of B pseudomallei was inhibited by m-cresol ar: the concentr ations found in pharmaceutical insulin preparations, and by the insulin pre paration Humulin R, but not by pure insulin. Conclusions-The results of previous experiments may have been confounded by the presence of the preservative nz-cresol.