Abstract
Mycobacterium avium subsp. paratuberculosis (MAP) is the etiologic agent of Johne’s disease, a chronic intestinal disease of cattle and other ruminants. Diagnostic culture for MAP is typically unrewarding until latter stages of the disease. This may be a consequence of oxidative damage to dormant organisms, which results from culture. The purpose of this investigation was to determine the effect of the commercial reducing agent Oxyrase® for Broth (OB) on the recovery of dormant Mycobacterium smegmatis (MS) and MAP. Dormant organisms were inoculated into medium only or that supplemented with media containing serial dilutions of OB. Growth was monitored by optical density for up to 21 days. Treatment of MAP and MS with OB led to significant increases in recovery and growth yield. However, the concentration of OB necessary to promote recovery was dependent on the number of viable organisms present in seed cultures. Mitigating oxidative damage by using OB can facilitate the recovery of dormant mycobacteria. Whether this is a direct or indirect effect has yet to be be established.