金黄色葡萄球菌及其肠毒素等指标在发酵牛肉加工过程中变化规律的研究

作者对自然状态发酵牛肉、接种金黄色葡萄球菌的发酵牛肉和接种发酵剂(植物乳杆菌、戊糖片球菌)与金黄色葡萄球菌的发酵牛肉中金黄色葡萄球菌及其肠毒素等指标在加工过程中的变化规律做了研究。研究结果表明,自然发酵牛肉中没有金黄色葡萄球菌及其肠毒素;接种发酵剂和金黄色葡萄球菌的发酵牛肉中金黄色葡萄球菌先是上升然后快速下降,且金黄色葡萄球菌肠毒素为阴性;接种金黄色葡萄球菌的发酵牛肉中金黄色葡萄球菌及其肠毒素都显著高于接种发酵剂的发酵牛肉(P＜0.05)。由试验结果可知,发酵剂植物乳杆菌和戊糖片球菌对金黄色葡萄球菌有很强的抑制作用。     

内蒙古地区乳源金黄色葡萄球菌肠毒素基因的分布

为了了解内蒙古地区金黄色葡萄球菌肠毒素基因的分布状况,并为评估金黄色葡萄球菌肠毒素的污染风险和研制金黄色葡萄球菌疫苗提供基础资料,试验采用PCR方法,对2015年从内蒙古地区临床型奶牛乳房炎乳样中分离的121株金黄色葡萄球菌进行16种肠毒素基因的检测。结果表明:121株金黄色葡萄球菌全部携带肠毒素基因,其中携带比例较高的是sei、selm和selj基因,分别为121株(100%)、81株(66.94%)和64株(52.89%),未检测到see、selo和selp基因。携带传统肠毒素基因(sea-see)的有59株(48.76%),携带新型肠毒素基因(seg-selq)的有121株(100%)。同时携带2种及2种以上肠毒素毒基因的有118株(97.52%),组合也很复杂。说明内蒙古地区的奶牛场存在着很大的金黄色葡萄球菌安全隐患,防治较为困难。     

金黄色葡萄球菌耐药性及肠毒素分型研究

为了解从生鲜乳中分离得到的31株金黄色葡萄球菌的耐药性和肠毒素分布情况,用微量肉汤稀释法进行药敏试验,用PCR方法进行肠毒素的检测和分型。结果表明,31株金黄色葡萄球菌耐药率在50%以上的抗菌药有7种,药耐药率小于10%的有3种;敏感率大于50%的抗菌药有6种,敏感率小于10%的有5种。31株金黄色葡萄球菌毒素基因携带率为93.5%,同时携带2种及以上毒素的菌株占67.7%,有SEA基因的占38.7%,含其他传统的毒素基因类型SEB、SEC、SED和SEE基因的菌株只占40.4%,携带新发现的毒素基因SEG、SHE、SEI和SEJ的菌株占67.7%。说明本次试验中的31株金黄色葡萄球菌对6类13种抗菌药都有不同程度的耐药性,且多重耐药现象比较严重。生鲜乳中分离的金黄色葡萄球菌带毒率高,且携带新发现的肠毒素基因较多。     

金黄色葡萄球菌产肠毒素规律的初步研究

为研究金黄色葡萄球菌产毒的最佳条件和规律。依国标GB/T4789-10-2003液体透析培养法培养质控金黄色葡萄球菌,采用全自动荧光/化学发光分析仪检测金黄色葡萄球菌肠毒素,利用正交试验设计得最佳工艺,应用于质控金黄色葡萄球菌和分离菌。结果显示,质控金黄色葡萄球菌培养40 h,温度为40℃,培养室空气中氧含量为15.5%时肠毒素产量最大,单个菌落肠毒素产量为59.31 mg。表明生产工艺中产毒培养温度和振荡培养时间以及空气中氧含量对肠毒素的产量影响较大。     

乳品安全中的微生物风险评估

乳品安全日益成为社会和科学关注的焦点.本文介绍了乳品安全及微生物风险评估概念,并从影响乳品安全的危害因素出发,对乳品中的微生物危害来源及现状作了全面性综述.详细论述了国内外乳品中微生物风险评估情况和通用步骤,比较了微生物风险评估与化学危害风险评估的差异,最后对乳品微生物风险评估在中国的未来发展方向作了前瞻性展望.     

新疆乌鲁木齐市生鲜乳中金黄色葡萄球菌污染状况及耐药性分析

为了解新疆乌鲁木齐市生鲜乳中金黄色葡萄球菌的污染及耐药情况,采集该地区生产与销售环节生鲜乳104份,利用Baird-Parker培养基平板和显色培养基,分离培养、纯化细菌;采用革兰氏染色、荧光PCR、全自动微生物鉴定系统,对可疑菌落进行鉴定。结果显示:检出金黄色葡萄球菌阳性乳35份,阳性率为33.7%;分离菌株对青霉素等15种抗生素存在不同水平的耐药性。结果表明,乌鲁木齐市生鲜乳中金黄色葡萄球菌污染与耐药情况较严重。结果提示,要加强乳品安全生产管理,规范动物饲料和兽药生产,以及动物饲养管理中抗生素的使用与添加,以保证乳品品质安全,维护公共卫生健康。     

产肠毒素金黄色葡萄球菌显色培养基的制备

为了研究一种用于分离与鉴别产肠毒素金黄色葡萄球菌的FS显色培养基,依据产肠毒素金黄色葡萄球菌特有的耐热核酸酶和凝固酶阳性的特点,设计对产肠毒素金黄色葡萄球菌选择性培养和耐热核酸酶联合测试的FS显色培养基。应用质控菌株,对其特异性和灵敏度进行检测。结果显示:FS显色培养基对产肠毒素金黄色葡萄球菌具较好的特异性和灵敏度,特征菌落出现时间缩短至12 h。FS显色培养基对产肠毒素金黄色葡萄球菌具较好的特异性和灵敏度,具有较高的应用价值。     

金黄色葡萄球菌肠毒素的研究进展

金黄色葡萄球菌(Staphylococcus aureus)是一种革兰氏阳性菌,约1/3人口携带,引起常见的严重疾病.这些疾病包括食物中毒、中毒性休克综合征和非感染性疾病,这是由金黄色葡萄球菌产生的外毒素引起.截止目前,在己发现的超过20种金黄色葡萄球菌肠毒素中,SEA和SEB是最具特色的,也被视为超抗原,由于它们能与MHCⅡ类分子结合,作用于抗原呈递细胞和刺激T细胞大群体共享可变区的T细胞受体β链.本文就肠毒素的致病性、致病机制及其检测方法进行了较为深入的阐述,期望能为临床治疗和食品监控提供一定的指导意义.当前,由于金黄色葡萄球菌多重耐药菌株的出现,因而对食品的危害变得越来越严重,必须尽量降低食品中金黄色葡萄球菌的含量,并防止其在食品之间的交叉污染.     

奶牛乳房炎病例中金黄色葡萄球菌毒素基因的检测

金黄色葡萄球菌是引起奶牛乳房炎的重要病原菌之一，其不仅给奶业生产造成严重损失，而且携带毒素基因的金黄色葡萄球菌在适当环境温度、pH、介质下可产生毒素，影响乳产品质量安全，危害人体健康。金黄色葡萄球菌常产生的、临床意义较大的毒素为肠毒素（SEs）、剥脱毒素（ETs）和中毒休克毒素-1（TSST-1）三类。国外有较多奶牛乳房炎金黄色葡萄球菌毒素基因流行情况的调查报道，国内少有这方面的研究。因此，本文就我国重要奶产地呼和浩特地区奶牛乳房炎金黄色葡萄球菌的sea、seb、sec、sed、see、eta、etb、tst等8种常见毒素基因的流行情况进行调查研究，以期为食源性疾病的监控和分子检测提供科学依据。     

生鲜牛奶中不同类型金黄色葡萄球菌污染差异性分析

[目的]了解我国部分地区生鲜牛奶中金黄色葡萄球菌肠毒素的污染状况,分析产不同类型肠毒素的金黄色葡萄球菌在不同地区的流行状况。[方法]采集三个省共6个奶牛场及挤奶站的新鲜牛奶进行金黄色葡萄球菌的分离鉴定,并对分离菌肠毒素分型。[结果]从360份生鲜牛奶中共分离到102株金黄色葡萄球菌,分离率为28.33%?;92.3%的菌株产SEA—SEJ;不同地区产各种类型肠毒素的菌株存在明显差异,湖南和内蒙分离到的产各型肠毒素菌株占比例较高。     

A Qualitative Risk Assessment Approach for Swiss Dairy Products: Opportunities and Limitations

Switzerland implemented a risk‐based monitoring of Swiss dairy products in 2002 based on a risk assessment (RA) that considered the probability of exceeding a microbiological limit value set by law. A new RA was launched in 2007 to review and further develop the previous assessment, and to make recommendations for future risk‐based monitoring according to current risks. The resulting qualitative RA was designed to ascertain the risk to human health from the consumption of Swiss dairy products. The products and microbial hazards to be considered in the RA were determined based on a risk profile. The hazards included Campylobacter spp., Listeria monocytogenes, Salmonella spp., Shiga toxin‐producing Escherichia coli, coagulase‐positive staphylococci and Staphylococcus aureus enterotoxin. The release assessment considered the prevalence of the hazards in bulk milk samples, the influence of the process parameters on the microorganisms, and the influence of the type of dairy. The exposure assessment was linked to the production volume. An overall probability was estimated combining the probabilities of release and exposure for each combination of hazard, dairy product and type of dairy. This overall probability represents the likelihood of a product from a certain type of dairy exceeding the microbiological limit value and being passed on to the consumer. The consequences could not be fully assessed due to lack of detailed information on the number of disease cases caused by the consumption of dairy products. The results were expressed as a ranking of overall probabilities. Finally, recommendations for the design of the risk‐based monitoring programme and for filling the identified data gaps were given. The aims of this work were (i) to present the qualitative RA approach for Swiss dairy products, which could be adapted to other settings and (ii) to discuss the opportunities and limitations of the qualitative method.     

Multiplex PCR and RPLA Identification of Staphylococcus aureus enterotoxigenic strains from bulk tank milk

Enterotoxigenic Staphylococcus aureus in raw milk poses a potential health hazard to consumers, and the identification of such strains should be used as part of a risk analysis of milk and milk products. The primary purpose of this study was to investigate the occurrence of enterotoxigenic S. aureus strains in raw milk supplied for dairy processing in the Czech Republic. A further aim was to compare the production of staphylococcal enterotoxins (SEs) with the presence of the corresponding genes. This was undertaken using multiplex polymerase chain reaction (PCR) and reversed passive latex agglutination (RPLA). Out of 440 bulk tank milk samples from 298 dairy herds, 70 proved positive for S. aureus (15.9%). Staphylococcal enterotoxin genes (ses) were detected in 39 (55.7%) isolates. The genes most commonly detected were sei (38.6%), seg (31.4%) and sea (27.1%). Genes seb, seh, sed, sej and sec were observed in 10%, 4.3%, 2.9%, 2.9% and 1.4% of strains respectively. Genes see and sel did not occur. The most frequently detected genotypes were seg, sei at 11.4%; sea at 10.0%; and sea, seg, sei at 8.6%. Toxin production was observed in nine (12.9%) S. aureus isolates. Seven strains were detected as SEB- (10%) and two as SED- (2.9%) producing. A relatively high number (32%) of discrepancies between the results with multiplex PCR and RPLA assays was obtained, particularly on account of SEA. Nineteen strains were sea positive by PCR but SEA negative by RPLA, and one strain was sec positive and SEC negative. The results of both methods were identical concerning SEB and SED. It was concluded that detection of ses by PCR was a useful additional tool to support identification of enterotoxigenic strains.     

生驼乳中金黄色葡萄球菌的分离鉴定与耐药性分析

为了解生驼乳中金黄色葡萄球菌的污染状况,本文从骆驼养殖户中采集了90 份生驼乳,对其进行金黄色葡萄球菌的增菌、培养和分离,并利用全自动微生物生化鉴定仪进行鉴定,同时对分离出的阳性菌株采用纸片扩散法进行耐药性分析。生化鉴定结果表明,90 份生驼乳样本中分离出8 株金黄色葡萄球菌,分离率8.9%。耐药性分析表明,8 株阳性菌株对青霉素耐药率达75%;对氧氟沙星敏感率最高,可达100%;对头孢哌酮钠、环丙沙星敏感性较高,敏感率可达87.5%;对链霉素、卡那霉素、阿莫西林、头孢唑啉和头孢西丁,四环素、氯霉素、头孢噻肟、林可霉素、苯唑西林、庆大霉素较敏感,敏感率在37.5%~75.0%之间。本研究为对生驼乳中的金黄色葡萄球菌的污染防控提供了参考依据。     

Cattle industry and zoonotic risk

The intensive farming of dairy and beef cattle has elicited a decrease in the herds and an increase in the number of animals per herd. The high concentration of cattle and the movement of the animals among herds has led to an increase in the health risks. In this context we have to consider the role of microbial agents of zoonoses, such as bacteria, parasites, and in some cases viruses. Notably, foodstuffs, such as meat, milk and dairy products, are the main sources of zoonoses of bovine origin. In particular, raw milk must be considered at high risk for trasmission of pathogens from cattle to humans. The European Regulation concerning food safety provides specific requirements for animal products and in bovine health management. Given the direct responsibility of the producer, the adoption of a self-regulation regimen on animal health, dairy and meat products must be planned by farmers.     

乳房炎源生鲜乳中病原微生物的污染现状及防控措施

主要介绍了乳房炎患病牛乳中病原微生物污染情况、耐药情况及防控措施。总结出乳房炎患病牛乳中的病原微生物种类较多, 主要有大肠杆菌、金黄色葡萄球菌、链球菌和克雷伯菌, 不同地区乳房炎乳样中的病原微生物不同, 产生的耐药性和耐药基因存在差异。旨在为减少因滥用和乱用抗生素导致药物残留和耐药性产生、降低乳房炎患病牛乳中病原微生物的污染以及科学、合理用药提供参考。     

Cattle industry and zoonotic risk

The intensive farming of dairy and beef cattle has elicited a decrease in the herds and an increase in the number of animals per herd. The high concentration of cattle and the movement of the animals among herds has led to an increase in the health risks. In this context we have to consider the role of microbial agents of zoonoses, such as bacteria, parasites, and in some cases viruses. Notably, foodstuffs, such as meat, milk and dairy products, are the main sources of zoonoses of bovine origin. In particular, raw milk must be considered at high risk for trasmission of pathogens from cattle to humans. The European Regulation concerning food safety provides specific requirements for animal products and in bovine health management. Given the direct responsibility of the producer, the adoption of a self-regulation regimen on animal health, dairy and meat products must be planned by farmers.     

湖南省奶牛源金黄色葡萄球菌分离鉴定与耐药性分析

为了掌握湖南省内奶牛源金黄色葡萄球菌的耐药情况,指导临床合理用药,抽取牛乳样品,通过对细菌的分离培养和纯化,采用基质辅助激光电离飞行时间质谱仪和全自动生化鉴定仪进行鉴定,并对分离菌株进行18种抗菌药物耐药性检测,结合耐药表型和mecA基因检测判定MRSA菌株。结果显示,2020-2021年从湖南地区257份牛乳样品中分离出金黄色葡萄球菌39株,89.74%的临床分离菌株表现为不同程度耐药,其中对青霉素耐药最为严重,耐药率达82.05%;对红霉素、克林霉素、替米考星、庆大霉素、头孢西丁耐药率在20%～35%之间;对多西环素及万古霉素绝对敏感,耐药率为0。38.46%分离菌株表现为多重耐药,以7重耐药最多。鉴定出19株MRSA,其中包含15株OS-MRSA和4株OR-MRSA。本研究可为湖南省内奶牛企业制定合理用药措施提供依据。     

Microbiological quality of goat's milk obtained under different production systems

In order to determine the safety of milk produced by smallholder dairy goat farms, a farm-based research study was conducted on commercial dairy goat farms to compare the microbiological quality of milk produced using 3 different types of dairy goat production systems (intensive, semi-intensive and extensive). A survey of dairy goat farms in and around Pretoria carried out by means of a questionnaire revealed that most of the smallholder dairy goat farms surveyed used an extensive type of production system. The method of milking varied with the type of production system, i.e. machine milking; bucket system machine milking and hand-milking, respectively. Udder half milk samples (n=270) were analysed, of which 31.1% were infected with bacteria. The lowest intra-mammary infection was found amongst goats in the herd under the extensive system (13.3%), compared with 43.3% and 36.7% infection rates under the intensive and semi-intensive production systems, respectively. Staphylococcus intermedius (coagulase positive), Staphylococcus epidermidis and Staphylococcus simulans (both coagulase negative), were the most common cause of intramammary infection with a prevalence of 85.7% of the infected udder halves. The remaining 14.3% of the infection was due to Staphylococcus aureus. Bacteriology of bulk milk samples on the other hand, showed that raw milk obtained by the bucket system milking machine had the lowest total bacterial count (16,450 colony forming units (CFU)/ml) compared to that by pipeline milking machine (36,300 CFU/ml) or hand-milking (48,000 CFU/ml). No significant relationship was found between the somatic cell counts (SCC) and presence of bacterial infection in goat milk In comparison with the herds under the other 2 production systems, it was shown that dairy goat farming under the extensive production system, where hand-milking was used, can be adequate for the production of safe raw goat milk.     

乳品中硫氰酸盐的来源及其风险分析

硫氰酸盐曾作为生鲜奶的保鲜剂被广泛使用,但因其毒性,已被我国列为乳及乳制品中的非法添加物质.鉴于硫氰酸盐的毒性作用,我们对市售乳品的硫氰酸盐含量进行风险监测,并对乳品中硫氰酸盐可能对人类健康造成的危害进行风险分析,结果发现852个监测样品中的硫氰酸含量均小于10mg/kg,其中25.9％样品的硫氰酸根含量低于1 mg/kg,仅有6.24％的样品含量在5～10mg/kg之间.由此,我们分析了乳品中硫氰酸盐的可能来源,认为852个市售乳制品中的硫氰酸盐主要来源于动物生鲜乳的自身本底,系非法添加的可能性极低.