Salmonella Heidelberg Strain Responses to Essential Oil Components
<em>Salmonella</em> are one of the more prominent foodborne pathogens that represent a major health risk to humans. <em>Salmonella </em>serovar Heidelberg strains are increasingly becoming an important public health concern, since they have been identified as one of the primary <em>Salmonella </em>serovars responsible for human outbreaks. Over the years, <em>Salmonella </em>Heidelberg isolates have exhibited higher rates of resistance to multiple antimicrobial agents compared to other <em>Salmonella </em>serovars. Essential oils (EOs) have been widely used as alternatives to chemical-based antimicrobials. In the current research, five EOs were screened to determine their antimicrobial activity against 15 <em>S. </em>Heidelberg strains from different sources. Oils tested were R(+)-limonene, orange terpenes, cold compressed orange oil, trans-cinnamaldehyde and carvacrol. EOs were stabilized in nutrient broth by adding 0.15% (w/v) agar. Tube dilution assays and minimal inhibitory concentrations (MIC) were determined by observing color changes in samples during exposure to EOs. Carvacrol and <em>trans-</em>cinnamaldehyde completely inhibited the growth of <em>S.</em> Heidelberg strains, while R(+)-limonene and orange terpenes did not show any inhibitory activity against the strains tested. Cold compressed orange oil only inhibited growth of two of the strains exhibiting an MIC of 1%. All <em>S</em>. Heidelberg isolates evaluated exhibited similar responses to the respective EOs. The use of all natural antimicrobials such as specific EOs offers the potential to limit the majority of <em>S. </em>Heidelberg isolates that may occur in food production.