小白菜表面粪大肠菌群的污染及其耐药性研究

Occurrence of Fecal Coliforms on Chinese Cabbages and Their Resistance to Antibiotics

为明确粪大肠菌群对蔬菜的污染及其耐药性,对厦门市集美区主要菜市场及超市的小白菜进行抽样调查。采用平板计数和MPN法对小白菜表面的粪大肠菌群进行计数,并通过对分离的细菌进行药敏试验,揭示粪大肠菌群对常用抗生素的耐药性。结果显示平板计数粪大肠菌群数量平均为631.3 CFU·g-1,合格率达90.9%;MPN计数平均为48.2 MPN·g-1,合格率达87.9%。清洗处理后粪大肠菌群数量从564.7 CFU·g-1降到92.5 CFU·g-1;流水浸泡10 min后,粪大肠菌群数量从564.7 CFU·g-1降到99.2 CFU·g-1。药敏试验结果表明,粪大肠菌对青霉素和四环素的耐药率达到100%,对红霉素的耐药率达到85.0%,但对庆大霉素、阿米卡星和环丙沙星没有耐药性。研究表明清洗处理显著降低粪大肠菌群的数量,粪大肠菌群对常用抗生素具有一定程度的耐药性,其耐药谱较广。

Microbial contamination of vegetables has aroused public concerns. An investigation was carried out to examine occurrence and resistance to antibiotics of fecal eoliforms on fresh Chinese cabbages collected from farmers-markets and supermarkets in Jimei district of Xiamen city, China. Fecal coliforms were quantified using both MPN （most-probable-number） and PC （plate count ） methods. Two treatments（washing or immersion in water） were used to evaluate the effect of cleaning on the abundance of fecal eoliforms. The resistance of the isolated fecal coliforms to six common antibiotics（gentamiein, amikacin, penicillin, erythromycin, tetracycline, and eiprofloxacin ） was evaluated using antimierobial susceptibility testing. The results showed that average population of fecal eoliforms from the samples was 631.3 CFU·g-1 by PC method, with qualified rate of 90.9%, whereas average population of fecal eoliforms was 48.2 MPN· g-1 by MPN method, with qualified rate of 87.9%. Washing and 10 min immersion reduced the number of fecal coliform bacteria to 93 CFU ·g-1 and 99 CFU·g-1 from 565 CFU· g-1, respectively. The resistance the fecal eoliforms to antibiotics was tetracycline （100%）, penicillin （100%）, and erythromyein （ 85% ）. However, the eoliforms had no resistance to gentamicin, amikacin, and eiprofloxacin. Our results suggest that cleaning treatments can significantly reduee the number of fecal eoliforms and the fecal coliforms have resistance to common antibiotics.