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Interaction of insulin with Burkholderia pseudomallei may be caused by a preservative
1Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand. fnajs@diamond.mahidol.ac.th
Aim:
To re-examine the previously reported in vitro interaction of insulin with Burkholderia pseudomallei, in the light of a suggestion that the interaction may have resulted from the presence of the preservative m-cresol in commercial preparations.
Methods:
Broth culture studies of B pseudomallei were performed with and without the addition of m-cresol and various preparations of insulin.
Results:
Growth of B pseudomallei was inhibited by m-cresol at the concentrations found in pharmaceutical insulin preparations, and by the insulin preparation Humulin R, but not by pure insulin.
Conclusions:
The results of previous experiments may have been confounded by the presence of the preservative m-cresol.
Insights
The preservative m-cresol, not pure insulin, inhibited Burkholderia pseudomallei growth in vitro. Previous findings on insulin-B. pseudomallei interactions may be due to this common preservative.
Area of Science:
- Microbiology
- Pharmacology
Background:
- Previous in vitro studies reported an interaction between insulin and Burkholderia pseudomallei.
- A potential confounding factor suggested was the presence of m-cresol, a preservative in commercial insulin preparations.
Purpose of the Study:
- To investigate the in vitro interaction between insulin and Burkholderia pseudomallei.
- To determine if m-cresol, a preservative in insulin, is responsible for previously observed interactions.
Main Methods:
- Broth culture studies were conducted using Burkholderia pseudomallei.
- Cultures were treated with and without m-cresol and various insulin preparations, including pure insulin and commercial formulations.
Main Results:
- m-Cresol inhibited the growth of Burkholderia pseudomallei at concentrations found in pharmaceutical insulin.
- The commercial insulin preparation Humulin R also inhibited bacterial growth.
- Pure insulin did not demonstrate inhibitory effects on Burkholderia pseudomallei growth.
Conclusions:
- The preservative m-cresol likely explains the previously reported in vitro interaction between insulin and Burkholderia pseudomallei.
- Results from prior experiments investigating insulin-B. pseudomallei interactions may have been confounded by the presence of m-cresol.