Sharma Manan, Dashiell Gwendolyn, Handy Eric T, East Cheryl, Reynnells Russell, White Chanelle, Nyarko Esmond, Micallef Shirley, Hashem Fawzy, Millner Patricia D
1 U.S. Department of Agriculture, Agricultural Research Service, Northeast Area, Environmental Microbial and Food Safety Laboratory, Beltsville, Maryland 20705.
2 University of Maryland Eastern Shore, Department of Agriculture, Princess Anne, Maryland 21853.
J Food Prot. 2017 Apr;80(4):668-673. doi: 10.4315/0362-028X.JFP-16-449.
Salmonella enterica associated with consumption of cucumbers ( Cucumis sativus ) has led to foodborne outbreaks in the United States. Whole and fresh-cut cucumbers are susceptible to S. enterica contamination during growing, harvesting, and postharvest handling. The application of lytic bacteriophages specific for S. enterica was evaluated to reduce Salmonella populations on cucumbers. Unwaxed cucumbers ('Lisboa' variety, or mini-cucumbers purchased at retail) were inoculated with Salmonella Newport (5 log CFU per cucumber) and were sprayed with 3.2 mL of phosphate-buffered saline (control) or 10 log PFU/ml of SalmoFresh, a Salmonella-specific bacteriophage preparation (phage), to deliver 4.76 × 10 PFU/cm. Cucumbers were stored at 10 or 22°C for 7 days. Inoculated mini-cucumbers were sliced with a sterile knife to investigate Salmonella transfer to mesocarp, and cut pieces were stored at 4°C for 2 days. Populations (log CFU per cucumber) of Salmonella Newport on phage-treated whole cucumbers were significantly (P < 0.05) smaller (2.44 ± 0.94) than on control-treated cucumbers (4.27 ± 0.37) on day 0. Populations on phage-treated cucumbers stored at 10°C were 1.72 ± 0.77 and 1.56 ± 0.46, which were significantly lower than those on control-treated cucumbers (3.20 ± 0.48 and 2.33 ± 0.25) on days 1 and 4, respectively. Between days 0 and 1, populations on control-treated cucumbers stored at 10 and 22°C declined by 1.07 and 2.47 log CFU per cucumber, respectively. At 22°C, Salmonella Newport populations declined by 2.37 log CFU per cucumber between days 0 and 1. Phage application to whole cucumbers before slicing did not reduce the transfer of Salmonella Newport to fresh-cut slices. Lytic phage application may be a potential intervention to reduce Salmonella populations on whole cucumbers.
与食用黄瓜（Cucumis sativus）相关的肠炎沙门氏菌已在美国引发食源性疾病暴发。完整的鲜切黄瓜在生长、收获及采后处理过程中易受肠炎沙门氏菌污染。评估了应用针对肠炎沙门氏菌的裂解性噬菌体来减少黄瓜上的沙门氏菌数量。将未打蜡的黄瓜（“里斯本”品种，或零售购买的迷你黄瓜）接种肠炎沙门氏菌新港菌株（每根黄瓜5 log CFU），并喷洒3.2 mL磷酸盐缓冲盐水（对照）或10 log PFU/ml的SalmoFresh（一种沙门氏菌特异性噬菌体制剂，噬菌体），以使每平方厘米黄瓜表面获得4.76×10 PFU。黄瓜在10或22°C下储存7天。对接种的迷你黄瓜用无菌刀切片，以研究沙门氏菌向中果皮的转移情况，切下的黄瓜片在4°C下储存2天。在第0天，经噬菌体处理的完整黄瓜上肠炎沙门氏菌新港菌株的数量（每根黄瓜的log CFU）显著（P<0.05）少于对照处理的黄瓜（2.44±0.94比4.27±0.37）。在10°C下储存的经噬菌体处理的黄瓜上的数量在第1天和第4天分别为1.72±0.77和1.56±0.46，显著低于对照处理的黄瓜（分别为3.20±0.48和2.33±0.25）。在第0天和第1天之间，在10°C和22°C下储存的对照处理黄瓜上的数量分别每根黄瓜下降了1.07和2.47 log CFU。在22°C下，肠炎沙门氏菌新港菌株的数量在第0天和第1天之间每根黄瓜下降了2.37 log CFU。在切片前对完整黄瓜应用噬菌体并未减少肠炎沙门氏菌新港菌株向鲜切黄瓜片的转移。应用裂解性噬菌体可能是减少完整黄瓜上沙门氏菌数量的一种潜在干预措施。
