Center for Meat Safety & Quality, Department of Animal Sciences, Colorado State University, Fort Collins, Colorado 80523-1171, USA.
J Food Prot. 2012 Oct;75(10):1751-8. doi: 10.4315/0362-028X.JFP-12-128.
Studies were performed to determine whether lactic acid treatments used to reduce Escherichia coli O157:H7 on beef trimmings are also effective in controlling non-O157 Shiga toxin-producing E. coli (nSTEC), and multidrug-resistant and antibiotic-susceptible Salmonella. Beef trimming pieces (10 by 5 by 1 cm) were inoculated (3 log CFU/cm(2)) separately with four-strain mixtures of rifampin-resistant E. coli O157:H7, O26, O45, O103, O111, O121, and O145. Similarly, in a second study, trimmings were separately inoculated with rifampin-resistant E. coli O157:H7, and antibiotic-susceptible or multidrug-resistant (MDR and/or MDR-AmpC) Salmonella Newport and Salmonella Typhimurium. Inoculated trimmings were left untreated (control) or were immersed for 30 s in 5% lactic acid solutions (25 or 55°C). No differences (P ≥ 0.05) were obtained among surviving counts of E. coli O157:H7 and those of the tested nSTEC serogroups on lactic acid-treated (25 or 55°C) samples. Counts (3.1 to 3.3 log CFU/cm(2)) of E. coli O157:H7 and nSTEC were reduced (P < 0.05) by 0.5 to 0.9 (25°C lactic acid) and 1.0 to 1.4 (55°C lactic acid) log CFU/cm(2). Surviving counts of Salmonella on treated trimmings were not influenced by serotype or antibiotic resistance phenotype and were similar (P ≥ 0.05) or lower (P < 0.05) than surviving counts of E. coli O157:H7. Counts (3.0 to 3.3 log CFU/cm(2)) were reduced (P < 0.05) by 0.5 to 0.8 (E. coli O157:H7) and 1.3 to 1.5 (Salmonella) log CFU/cm(2) after treatment of samples with 25°C lactic acid. Corresponding reductions following treatment with lactic acid at 55°C were 1.2 to 1.5 (E. coli O157:H7) and 1.6 to 1.9 (Salmonella) log CFU/cm(2). Overall, the results indicated that lactic acid treatments used against E. coli O157:H7 on beef trimmings should be similarly or more effective against the six nSTEC serogroups and against multidrug-resistant and antibiotic-susceptible Salmonella Newport and Salmonella Typhimurium.
研究旨在确定用于减少牛肉切块中大肠杆菌 O157:H7 的乳酸处理是否也能有效控制非 O157 型志贺毒素产生大肠杆菌 (nSTEC) 和多药耐药和抗生素敏感的沙门氏菌。牛肉切块（10 厘米×5 厘米×1 厘米）分别用耐利福平的大肠杆菌 O157:H7、O26、O45、O103、O111、O121 和 O145 的四株混合菌株接种（3 对数 CFU/cm²）。同样，在第二项研究中，切块分别用耐利福平的大肠杆菌 O157:H7 和抗生素敏感或多药耐药（MDR 和/或 MDR-AmpC）沙门氏菌纽波特和沙门氏菌 Typhimurium 接种。未处理的接种切块（对照）或在 5%乳酸溶液（25 或 55°C）中浸泡 30 秒。在乳酸处理（25 或 55°C）样品上，大肠杆菌 O157:H7 和测试的 nSTEC 血清群的存活计数之间未获得差异（P≥0.05）。大肠杆菌 O157:H7 和 nSTEC 的计数（3.1 至 3.3 对数 CFU/cm²）分别减少了 0.5 至 0.9（25°C 乳酸）和 1.0 至 1.4（55°C 乳酸）对数 CFU/cm²（P<0.05）。处理切块上沙门氏菌的存活计数不受血清型或抗生素耐药表型的影响，并且相似（P≥0.05）或低于（P<0.05）大肠杆菌 O157:H7 的存活计数。用 25°C 乳酸处理样品后，计数（3.0 至 3.3 对数 CFU/cm²）减少了 0.5 至 0.8（大肠杆菌 O157:H7）和 1.3 至 1.5（沙门氏菌）对数 CFU/cm²（P<0.05）。用 55°C 乳酸处理后，相应的减少分别为 1.2 至 1.5（大肠杆菌 O157:H7）和 1.6 至 1.9（沙门氏菌）对数 CFU/cm²。总体而言，结果表明，用于牛肉切块中大肠杆菌 O157:H7 的乳酸处理方法对六种 nSTEC 血清群以及多药耐药和抗生素敏感的沙门氏菌纽波特和沙门氏菌 Typhimurium 应该同样有效或更有效。
