Skinner Brandon M, Rogers Anna T, Jacob Megan E
Department of Population Health and Pathobiology, North Carolina State University , Raleigh, North Carolina.
Foodborne Pathog Dis. 2018 Nov;15(11):718-725. doi: 10.1089/fpd.2018.2457. Epub 2018 Jul 23.
Escherichia coli O157:H7 is a human pathogen associated with gastrointestinal disease and hemolytic uremic syndrome. Direct contact with ruminants and their feces at agritourism or livestock interaction events is a known source of transmission. Footbath use is a pathogen reduction strategy that may decrease the transmission of E. coli O157:H7 at these interactions. The efficacy of chemical disinfectants in footbaths is not well reported. Our objective was to determine the susceptibility of E. coli O157:H7 toward commonly used disinfectants in vitro and within contaminated footbaths. The minimum inhibitory concentration and the minimum bactericidal concentration (MIC and MBC) and the time-to-kill were determined in vitro for seven E. coli O157:H7 strains using five disinfectant compounds (didecyldimethylammonium chloride [DDAC], glutaraldehyde, hydrogen peroxide, phenol, and sodium hypochlorite). Time-kill assays were performed within simulated footbaths at 22°C, 37°C, and 42°C with and without organic contamination using three commercial disinfectants with similar active ingredients (0.26% Clorox Bleach, 0.034% Virex II 256, and 1% Virkon S). The MBCs of disinfectants toward E. coli O157:H7 were 3.2, 625, 40, 5000, and 320 ppm of DDAC, glutaraldehyde, hydrogen peroxide, phenol, and sodium hypochlorite, respectively. At 2 × MIC, E. coli O157:H7 reached a 3 log(colony-forming unit [CFU]/mL) reduction on contact with glutaraldehyde, by 20 min with DDAC and sodium hypochlorite, and by 4 h with phenol and hydrogen peroxide. In simulated footbaths, the commercial disinfectants reduced concentrations by 3 log(CFU/mL) on contact in the absence of organic contamination, but viable E. coli O157:H7 was recovered from organically contaminated Clorox Bleach and Virex II 256 footbaths. No E. coli O157:H7 was recovered from the Virkon S footbaths after 10 min. This study highlights the ability for organic contamination to compromise the efficacy of disinfectants in footbaths and the importance of choosing an appropriate footbath disinfectant to retain the efficacy.
大肠杆菌O157:H7是一种与胃肠道疾病和溶血性尿毒症综合征相关的人类病原体。在农业旅游或家畜互动活动中直接接触反刍动物及其粪便，是已知的传播源。使用足浴是一种减少病原体的策略，可能会减少这些互动活动中大肠杆菌O157:H7的传播。关于足浴中化学消毒剂的效果，报道并不充分。我们的目的是在体外以及受污染的足浴环境中，确定大肠杆菌O157:H7对常用消毒剂的敏感性。使用五种消毒剂化合物（双癸基二甲基氯化铵[DDAC]、戊二醛、过氧化氢、苯酚和次氯酸钠），对七株大肠杆菌O157:H7菌株进行体外最小抑菌浓度和最小杀菌浓度（MIC和MBC）以及杀菌时间测定。使用三种主要成分相似的商业消毒剂（0.26%高乐氏漂白剂、0.034%维克斯II 256和1%卫可），在22°C、37°C和42°C下，在有或没有有机污染的模拟足浴环境中进行杀菌时间测定。消毒剂对大肠杆菌O157:H7的MBC分别为：DDAC 3.2 ppm、戊二醛625 ppm、过氧化氢40 ppm、苯酚5000 ppm和次氯酸钠320 ppm。在2×MIC浓度下，大肠杆菌O157:H7与戊二醛接触20分钟、与DDAC和次氯酸钠接触20分钟、与苯酚和过氧化氢接触4小时后，菌落形成单位（CFU）/毫升减少3个对数。在模拟足浴环境中，在没有有机污染的情况下，商业消毒剂接触后可使浓度降低3个对数（CFU/毫升），但在有机污染的高乐氏漂白剂和维克斯II 256足浴中仍可检测到存活的大肠杆菌O157:H7。在10分钟后，卫可足浴中未检测到大肠杆菌O157:H7。本研究强调了有机污染会损害足浴中消毒剂的效果，以及选择合适的足浴消毒剂以保持效果的重要性。
