Location: Food and Feed Safety ResearchTitle: Methylsulfonylmethane exhibits bacteriostatic inhibition of Escherichia coli, and Salmonella enterica Kinshasa, in vitro
Submitted to: Journal of Applied Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/4/2019
Publication Date: 12/1/2019
Citation: Poole, T.L., Benjamin, R., Genovese, K.J., Nisbet, D.J. 2019. Methylsulfonylmethane exhibits bacteriostatic inhibition of Escherichia coli, and Salmonella enterica Kinshasa, in vitro. Journal of Applied Microbiology. 127(6):1677-1685. https://doi.org/10.1111/jam.14446.
Interpretive Summary: Bacteria that cause disease (pathogens) in humans and animals have produced a public health crisis because diseases once believed to be largely eradicated are reappearing. Many public health officials blame the food animal industry for the emergence of pathogenic bacteria and downplay the role of human medicine. Poultry and livestock producers have long been under pressure to limit the presence of pathogenic bacteria that are often present on retail meat products. However, with the emergence of multi-drug resistant pathogens, there are new pressures to limit the use of antimicrobial agents for treatment of food animals. There is evidence that reduction in antibiotic use alone is not sufficient to reduce antimicrobial-resistant bacterial populations. The limitation of antimicrobial use poses an additional dilemma for producers for the maintenance of food animals and preventing the presence of pathogens on retail meat. There is an effort to find alternatives to antimicrobials that will enhance growth and health of food animals. Methylsulfonylmethane (MSM), a substance approved for use in humans, horses, and dogs to reduce inflammation caused by arthritis, has been shown in these studies to inhibit growth of some bacteria. This study further characterized the type of bacterial inhibition MSM elicited on Escherichia coli and Salmonella Kinshasa bacteria.
Technical Abstract: Methylsulfonylmethane (MSM) is a dietary supplement with anti–inflammatory properties used for the treatment of osteoarthritis. The objective of this study was to evaluate antibacterial properties of MSM on Multiple–Drug Resistant (MDR) Escherichia coli (MDRE21) and MDR Salmonella enterica serovar Kinshasa (SK132). Bacterial proliferation was measured spectrophotometrically during log phase growth in Brain Heart Infusion Broth (BHIB) with 0, 3, 5, 7, 10, 12, and 16% MSM. Subsequent enumeration studies in the presence of MSM included: doubling time analysis, mechanism of inhibition determination, and a long–term viability study with exposure to 10% MSM. Absorbance data indicated a dose–dependent inhibition of both MDRE21 and SK132 from 3 to 16% MSM. MDRE21 doubling time analysis revealed that MDRE21 grown in 0–7% MSM were not significantly different (32-35 minutes); however at 10, 12, 16% MSM, the times ranged from 7.3, 4.8, and 6.8 h, respectively. Doubling times for SK132 exposed to 0, 3, and 5% MSM did not differ significantly, but at 7 and 10% MSM they were significantly higher at 1.55 and 4.94 h, respectively. At 12 and 16% MSM exposure, there was a decline in viable cells. To assess the mechanism of inhibition, cultures were grown overnight in BHIB with 0, 3, 5, 7, 10, 12, and 16% MSM and then enumerated on unmedicated BHI agar (BHIA) or with an equivalent percent of MSM as the BHIB. There was no growth of MDRE21 or SK132 on BHIA that contained 10, 12, or 16% MSM. Both strains enumerated on unmedicated BHIA from BHIB with 10, 12, or 16% MSM at were able to partially recover. It was believed this was indicative of a bacteriostatic mechanism of inhibition by MSM on both strains. The long–term viability studies illustrated that neither MDRE21 nor SK132 could be rescued from 10% MSM after five or six days, respectively. In conclusion, MSM exerted a bacteriostatic mechanism of inhibition on the E. coli and Salmonella strains used in these experiments. A dietary supplement such as MSM that displays antibacterial activity may prove useful during pre–harvest or post–harvest animal production.