市售乳酸菌制品中乳酸菌耐药基因分析

Analysis on Antimicrobial Resistance Genes in Commercial Lactobacil us Products

对市售乳酸菌制品中所添加的乳酸菌菌株及其耐药基因展开调查与分析。随机选取77批市售乳酸菌制品,对其所含菌种进行分离培养及活菌计数,并用基因特异性PCR的方法对该菌是否携带内酰胺酶基因(bla Z)等耐药基因进行分析。22批样品中的乳酸菌有内酰胺酶基因bla Z基因检出,样品检出率为28.57%。通过菌落PCR分析表明, 47株菌携带bla Z,检出率为7.29%。对阳性菌进行进一步基因型分析表明, 3株菌(6.38%)含有三重耐药基因(bla Z、tet M、aph3-Ⅲa), 20株菌(42.55%)含有双重耐药基因(bla Z和tet M,或bla Z和aph3-Ⅲa)。经过基质辅助激光解析电离飞行时间质谱(MALDI-TOF MS)鉴定,含有双重耐药基因最多的是嗜热链球菌(58.33%),其次是副干酪乳杆菌(16.67%)和动物双歧杆菌(12.5%)。含有三重耐药基因的3株菌分别是嗜热链球菌、鼠李糖乳杆菌和动物双歧杆菌。乳酸菌携带一种内酰胺酶耐药基因的同时携带更多耐药基因的现象已成为安全隐患,加强食用菌株的安全性评价对保证食品安全具有重要意义。

To investigate the lactic acid bacteria strains in commercial lactobacillus products and to analysis antimicrobial resistance genes carried by those strains, a total of 77 commercial lactobacillus products were randomly taken and sampled for viable counting. Gene specific PCR was used for screening of antimicrobial resistance genes, including lactamase gene bla Z.We found that 22 products(28.57%) were detected to carry antimicrobial resistance gene bla Z. Through colony PCR of plated lactic acid bacteria, a total of 47 strains(7.29%) were detected to harbor gene bla Z. For further genotyping, twentystrains of them were detected to be dual-antimicrobial resistance gene strains(carring genes bla Z and tet M, or, bla Z and aph3-Ⅲa).Three of them were triple-antimicrobial resistance gene strains(carring genes bla Z, tet M and aph3-Ⅲa). After identification bymatrix-assisted laser desorption/ionization time-of-flight mass spectrometry(MALDI-TOF MS), 58.33% of the dualantimicrobial resistance gene strains were Streptococcus thermophilus, followed by Lactobacillus paracasei(16.67%) and Bifidobacterium animalis(12.5%). Three triple-antimicrobial resistance gene strains were identified to be Streptococcus thermophilus, Lactobacillus rhamnosus and Bifidobacterium animalis. The phenomenon that lactic acid bacteria in commercial lactobacillus products carrying lactamase gene bla Z and even more antimicrobial resistance genes had become a potential safety hazard. Strengthening the safety evaluation of edible strains was of great significance to ensure food safety.