NutriClay Zn Potentiates Both Zinc Oxide and Antioxidant Supplements, Inhibiting Multidrug‐Resistant Salmonella and Anaerobic Clostridium

ABSTRACT Salmonella and Clostridium represent foodborne pathogens that infect livestock, as well as cause gastroenteritis in humans consuming tainted pork and poultry products. Free chemical zinc oxide (ZnO), at doses much higher than nutritional zinc requirements, has been routinely added to livestock feed in order to suppress infections and promote animal growth; however, unabsorbed zinc (excreted in feces) may accumulate in the environment and/or foster antimicrobial resistant (AMR) strains of bacteria. Here, NutriClay Zn is described as an analog of montmorillonite clay (MMT) that suppresses growth of multidrug‐resistant Salmonella enterica and single‐drug resistant Clostridium perfringens . Zinc amended to the interlayer of MMT was found to be the active constituent of NutriClay Zn , and release of zinc from NutriClay Zn was quantified by inductively coupled plasma mass spectrometry. Two‐log growth suppression of Salmonella enterica by NutriClay Zn was significantly ( p < 0.05) better than the mere one‐log inhibition by concurrent equimolar (1.4 mM) free chemical ZnO positive controls. Moreover, the magnitude of NutriClay Zn efficacy was significantly ( p < 0.05) enhanced by subtherapeutic doses of antioxidants, while NutriClay Zn administered alone prevented growth of Clostridium perfringens . These findings suggest that NutriClay Zn could be developed as an alternative to free chemical ZnO for control of enterotoxigenic AMR bacteria that threaten the safety of key dietary protein sources for humans.