Effects of Bacillus Cereus and Its Toxins on Microorganisms from Used Mouth-guards

Abstract

Bacillus cereus, a surrogate for B. anthracis, was employed to evaluate inhibitory effects that bacteria and toxins have on oral microbial growth. Two strains (Whimpy and Arnold) helped assess the ability of B. cereus to contaminate new mouth-guards and affect the growth of microorganisms cultured from worn mouth-guards. Mouth-guards placed in B. cereus inoculated media possessed B. cereus on their surfaces and depths after boiling for 12 seconds. B. cereus was also cultured from steam while contaminated mouth-guards were boiling. Only the Arnold strain inhibited the growth of certain isolates of oral bacteria. Adding B. cereus culture filtrates decreased optical densities at 24 hours and increased midpoints of oral bacterial growth curves, suggesting B. cereus toxins cause lags in growth and decreases in stationary phase concentrations. Different strains of B. cereus have stronger inhibitory effects than others and inhibition is increased when both bacteria and toxins are present.