Effect of milk on antibacterial activity of tetracycline against Escherichia coli and Staphylococcus aureus isolated from bovine mastitis
Effect of milk on antibacterial activity of tetracycline against Escherichia coli and Staphylococcus aureus isolated from bovine mastitis
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DOI：
10.1007/s00253-009-2008-6
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发表时间：
2009-08-01
影响因子：
5
通讯作者：
Tanji, Yasunori
中科院分区：
文献类型：
--
作者：
Kuang, Ying;Jia, Haoyu;Tanji, Yasunori
通过引入pH指示剂溴甲酚紫，在原料奶和MH发酵液中测定了引起乳腺炎的大肠埃希菌和金黄色葡萄球菌对两种常用抗生素四环素和青霉素G的敏感性，结果表明该方法简便、灵敏、快速。牛奶中青霉素G的最小抑菌浓度(MIC)与MH发酵液相同，而四环素在牛奶中的MIC是MH的4~32倍。透析试验证实了四环素与牛奶大分子之间的不可逆结合，这可能是由于疏水作用所致，这表明所观察到的损伤效应是由于牛奶对被测四环素的作用所致。进一步的研究发现，牛奶中四环素活性的降低很大程度上是由于牛奶中的酪蛋白，而牛奶中的其他热敏感成分也起到了一定的作用。
The susceptibility of mastitis-causing Escherichia coli and Staphylococcus aureus to two commonly used antibiotics, tetracycline and penicillin G, was tested in raw milk and in Muller-Hinton (MH) broth by introducing a pH indicator, bromocresol purple, which was shown to be a simple, sensitive, and rapid method. The minimum inhibitory concentration (MIC) of penicillin G in milk was the same as those in MH broth, whereas the MIC of tetracycline in milk was 4 to 32 times that in MH. An irreversible binding between tetracycline and large molecules of milk, which might be due to a hydrophobic interaction, was demonstrated by a dialysis test, suggesting the observed impairing effect was due to the action of milk on the tetracycline being tested. Further investigation revealed that much of the reduction of tetracycline's activity in milk was attributable to the milk protein casein, while other heat-sensitive components in milk also play some roles.