Synergistic antimicrobial effect of nisin and rho-cymene on Salmonella enterica serovar Typhi in vitro and on ready-to-eat food

Foods contaminated with Salmonella enterica serovar Typhi are a mojor cause of typhoid fever, leading to public health problems and economic losses worldwide. Nisin and ρ-cymene were tested in this study for their antimicrobial activity against S. Typhi at 4 °C and 37 °C. Nisin and ρ-cymene, when used separately, did not inhibit the bacterium at either temperature. A synergistic antimicrobial effect between both compounds was observed when they were used simultaneously. This synergism was greater at 37 °C than at 4 °C. The lowest concentrations of nisin and ρ-cymene required for complete inhibition of S. Typhi at 37 °C were 0.3 ppm and 1.5 ppm, respectively, and 0.3 ppm and 2.5 ppm at 4 °C. The potential of nisin and ρ-cymene to control an S. Typhi population on ready-to-eat Thai-style pork sausage was also examined. The compounds were able to eliminate the contaminating bacterium with concentrations depending on the bacterial cell number on the food.