Blackburn C D, Davies A R
Department of Food Microbiology, Leatherhead Food Research Association, Surrey, UK.
Int J Food Microbiol. 1994 Dec;24(1-2):125-36. doi: 10.1016/0168-1605(94)90112-0.
Strains of Aeromonas spp., Salmonella enteritidis phage type 4, Salmonella typhimurium, verotoxigenic Escherichia coli O157:H7 (VTEC) and Yersinia enterocolitica resistant to streptomycin, nalidixic acid and a combination of both antibiotics were selected. When compared with the parent strains, most of the antibiotic-resistant strains had slightly slower growth rates at their optimum incubation temperature but the difference was reduced progressively when the temperature was lowered. Some antibiotic-resistant strains had considerably slower growth rates in the presence of the relevant antibiotic and these were not used further. Several agar and impedance media with added streptomycin and nalidixic acid were assessed for the enumeration of the antibiotic-resistant strains in artificially contaminated stored foods. Differential/selective media were required to enumerate low numbers of antibiotic-resistant strains in certain foods. The following agar and impedance media were selected: Aeromonas Agar (Ryan) for Aeromonas spp., Xylose Lysine Agar and Lysine Iron Cysteine Neutral Red Medium for Salmonella, Eosin Methylene Blue Agar and Coliform Medium for VTEC, and Yersinia Selective Agar without selective agents for Yersinia enterocolitica. The agar and impedance media have been used successfully to enumerate antibiotic-resistant strains inoculated into foods and stored at different temperatures.
挑选出对链霉素、萘啶酸以及这两种抗生素组合具有抗性的气单胞菌属菌株、4型肠炎沙门氏菌、鼠伤寒沙门氏菌、产志贺毒素大肠杆菌O157:H7（VTEC）和小肠结肠炎耶尔森菌。与亲本菌株相比，大多数抗生素抗性菌株在其最适培养温度下的生长速率略慢，但当温度降低时，这种差异会逐渐减小。一些抗生素抗性菌株在存在相关抗生素的情况下生长速率明显较慢，因此不再进一步使用。评估了几种添加了链霉素和萘啶酸的琼脂和阻抗培养基，用于人工污染的储存食品中抗生素抗性菌株的计数。在某些食品中，需要使用鉴别/选择性培养基来计数少量的抗生素抗性菌株。选择了以下琼脂和阻抗培养基：用于气单胞菌属的气单胞菌琼脂（Ryan）、用于沙门氏菌的木糖赖氨酸琼脂和赖氨酸铁半胱氨酸中性红培养基、用于VTEC的伊红美蓝琼脂和大肠菌群培养基，以及用于小肠结肠炎耶尔森菌的无选择性剂的耶尔森菌选择性琼脂。这些琼脂和阻抗培养基已成功用于计数接种到食品中并在不同温度下储存的抗生素抗性菌株。
