食品科学 ›› 2021, Vol. 42 ›› Issue (6): 291-297.doi: 10.7506/spkx1002-6630-20191128-291

• 安全检测 • 上一篇    下一篇

羊奶粉生产中金黄色葡萄球菌分离鉴定及其分子特性和耐药性检测

张鹏飞,付雪婷,赵春花,刘心雨,张杰,张萌,寇明莹,葛武鹏,王新   

  1. (西北农林科技大学食品科学与工程学院,陕西 杨凌 712100)
  • 出版日期:2021-03-25 发布日期:2021-03-29
  • 基金资助:
    国家自然科学基金面上项目(31871894;31271858);国家自然科学基金联合基金项目 (U1703119); 陕西省社会发展领域攻关项目(2018SF-110)

Isolation, Molecular Characteristics and Antimicrobial Susceptibility of Staphylococcus aureus inform the Production Chain of Goat Milk Powder

ZHANG Pengfei, FU Xueting, ZHAO Chunhua, LIU Xinyu, ZHANG Jie, ZHANG Meng, KOU Mingying, GE Wupeng, WANG Xin   

  1. (College of Food Science and Engineering, Northwest A&F University, Yangling 712100, China)
  • Online:2021-03-25 Published:2021-03-29

摘要: 为探究羊奶粉在加工过程中金黄色葡萄球菌污染的关键环节及菌株的分子特征和耐药性,对某羊奶粉加工厂不同生产环节进行样本收集,通过采用选择培养和聚合酶链式反应扩增nuc基因对金黄色葡萄球菌进行分离鉴定,然后对分离的菌株进行毒素基因(21 种)、耐药性(16 种常用抗生素)及葡萄球菌A蛋白(staphylococcal protein A,SPA)、多位点序列分型(multilocus sequence typing,MLST)和脉冲场凝胶电泳(pulsed field gel electrophpresis,PFGE)分型研究。结果表明,收集的112 份样本中有6 份样本被污染(5.4%,6/112),其中包括加工设备(2 份)、加工人员(2 份)、罐奶(1 份)和车间落地粉(1 份)。所有的分离株至少携带1 种毒素基因,其中以pvl基因的携带率最高(100.0%,6/6),其次为sea、sec、see、seh、sek和seq(50.0%,3/6),seg、sej和ser(33.3%,2/6),sed、sei、sem和seo(16.7%,1/6)。所有分离株至少耐受4 种抗生素,其中对氨苄西林、头孢哌酮、甲氧苄啶/磺胺甲恶唑和青霉素的耐药性最为普遍(100.0%,6/6),其次为红霉素和阿莫西林/克拉维酸(83.3%,5/6)、四环素(50.0%,3/6)和庆大霉素(16.7%,1/6)。此外,所有菌株对苯唑西林、头孢西丁、万古霉素、利奈唑胺等抗生素敏感。所有分离株共有4 种spa分型和3 种ST分型,其中以ST1-t127(50.0%,3/6)为主,其次为ST5-t002、ST5-t548和ST188-t189(16.7%,1/6)。对于PFGE分型,可分为3 个大簇(I、II和III簇)和4 个基因型(A、B、C和D),其中加工设备和落地粉存在相同的PFGE分型。研究结果表明在羊奶粉加工过程中存在金黄色葡萄球菌污染现象,罐奶、加工设备、加工人员和落地粉是受污染的关键环节,且在不同的加工环节中存在一定的交叉污染。虽然污染率较低,有必要对奶厂不同加工环节的污染情况进行长期调查,确认关键污染环节,可以有效控制金黄色葡萄球菌在奶粉制品中的扩散。

关键词: 羊奶粉加工厂;金黄色葡萄球菌;毒素基因;耐药性;分子分型

Abstract: To investigate the prevalence, molecular characteristics and antibiotic resistance of Staphylococcus aureus isolated from the key links in the goat milk powder processing chain, we collected samples from different production stages of a goat milk powder plant. The S. aureus isolates were identified by using selective culture as well as nuc gene amplification. Twenty-one virulence genes, 16 common antibiotics, staphylococcal protein A (SPA), multi-locus sequence typing (MLST) and pulsed field gel electrophoresis (PFGE) typing of the isolates were investigated. The results showed that among the 112 samples collected, 6 samples (5.4%) were contaminated by S. aureus, including processing equipment (2 samples), processing personnel (2 samples), tank milk (1 sample) and floor powder (1 sample). Each isolate carried at least one toxin gene, and the detection rate of the panton-valentine leukocidin (pvl) gene was the highest (100%, 6/6), followed by sea, sec, see, seh, sek and seq (50.0%, 3/6), seg, sej and ser (33.3%, 2/6) and sed, sei, sem and seo (16.7%, 1/6). All the isolates were resistant to at least four antibiotics, and the isolates were most commonly resistant to ampicillin, cefoperazone, trimethoprim/sulfamethoxazole and penicillin (100.0%, 6/6), followed by erythromycin and amoxicillin/clavulanic acid (83.3%, 5/6), tetracycline (50.0%, 3/6) and gentamycin (16.7%, 1/6). In addition, all the strains were sensitive to oxacillin, cefoxitin, vancomycin and linezolid. Four spa types and 3 ST types were detected in all the isolates, and ST1-t127 (50.0%, 3/6) was the most predominant clone, followed by ST5-t002, ST5-t548 and ST188-t189 (16.7%, 1/6). For PFGE typing, these strains could be divided into 3 large clusters (I, II and III) and 4 pulsotypes (A, B, C and D), among which the processing equipment and the floor powder shared the same PFGE typing. The results showed that there was S. aureus contaminations in the processing of goat milk powder. Moreover, the key links of contamination were tank milk, processing equipment, processing personnel and floor powder, and there were some cross-contaminations in different processing links. Although the contamination rate is relatively low, it is necessary to carry out a long-term investigation on microbial contamination in different processing links of goat milk plants. Investigation should be taken to confirm the key contamination links, which can provide us with useful information to effectively control the spread of S. aureus in goat milk powder products.

Key words: goat milk powder processing plant; Staphylococcus aureus; virulence genes; antimicrobial susceptibility; molecular typing

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