Fate of Shigella sonnei on Parsley and Methods of Disinfection

Abstract

Outbreaks of shigellosis associated with chopped parsley used as a garnish for foods occurred in four states in the United States and in two Canadian provinces in 1998. This prompted a study to determine survival and growth characteristics of Shigella sonnei inoculated onto raw parsley. Two inoculum levels (∼103 and 106 CFU/g) were applied to parsley leaves, portions of which were then chopped. Inoculated whole and chopped parsley leaves were held at 4°C or 21°C for up to 14 days. Initial populations of the organism on chopped parsley receiving high or low levels of inoculum increased by approximately 3 log10 CFU/g, within 1 day at 21°C. Populations of S. sonnei on inoculated chopped or whole parsley leaves held at 4°C decreased by 2.5 to 3.0 log10 CFU/g during a 14-day storage period. The pathogen multiplied, without a lag phase, on inoculated (2.72 log10 CFU/g) chopped parsley held at 21°C, exceeding 6 log10 CFU/g within 24 h. Treatment of inoculated whole parsley leaves with vinegar containing 5.2% (vol/vol) acetic acid or 200 ppm free chlorine for 5 min at 21°C reduced the population of S. sonnei by more than 6 log10 CFU/g, whereas treatment with vinegar containing 7.6% acetic acid or 250 ppm free chlorine reduced initial populations of 7.07 and 7.26 log10 CFU/g, respectively, to undetectable levels (<0.6 log10 CFU/g). These studies revealed that S. sonnei can grow rapidly on chopped parsley held at ambient temperature and remain viable for at least 14 days at 4°C. Treatment of contaminated parsley with vinegar or chlorinated water offers a simple method to reduce markedly or eliminate the pathogen in food-service or home settings.

Foodborne outbreaks of shigellosis in the USA, 1998–2008

“…Outbreak investigations frequently implicate a particular food item, but the source of contamination is often an infected food handler. Because Shigella is easily spread and can survive in refrigerated foods, transmission is often associated with foods that are served cold or raw and require handling during preparation [23][24][25].…”

Decontamination Strategies for a Few Potentially Pathogenic and Food Spoilage Causing, Antibiotic-Resistant Bacteria Isolated From Commonly Used Food Garnishes

“…A lot of work has been done on uncooked vegetables, spices and nuts (Ali, 2014;Andleeb, 2013;Banerjee, 2004;Ghosh, 2007;Khan, 2012;Nipa, 2011;Roy, 2007;Sago, 2003;Schaffner, 1967;Shrivastava, 2014). However, not much work has been done on garnishes so far, except parsley and mint (Hsu, 2010;Naimi, 2003;Wu, 2000), even though they have been a part of our daily food. Methods to improve the microbial quality of these food garnishes have also been minimally analyzed.…”

Vinegar as an antimicrobial agent for control of Candida spp. in complete denture wearers

“…This is product is cheap, easily found in the market, and seems to have antimicrobial potential 18,26,27,30 . Estrela, et al 9 (2004) evaluated the use of vinegar as an irrigating solution and intracanal medicament in microbial elimination from dog's teeth with apical periodontitis.…”