multi-locus sequence typing

多位点序列分型
  • 文章类型: Journal Article
    隐球菌病是人类和猫的重要真菌感染,但是对从猫中分离出的菌株的分子流行病学研究是有限的。我们对14种隐球菌进行了多位点序列分型(MLST)分析和抗真菌药敏试验。日本的家猫菌株和新加坡的猫分离出的一种菌株。日本家猫的所有14株菌株均被鉴定为新生隐球菌分子型VNI。序列类型(STs)包括8例ST5,5例ST31和1例新型ST。VNIST5也是日本患者中最常见的分离菌株,而没有从日本患者中分离出VNIST31的记录。新加坡猫菌株被鉴定为C.gattiiVGIIb(子宫隐球菌),ST7.我们将这些结果与先前报道的从猫中分离的菌株进行了比较。此比较表明隐球菌属的分子类型。与猫隔离可能因国家而异。在新生梭菌的抗真菌药敏试验中,每个菌株超过了两性霉素B和5-氟胞嘧啶的流行病学临界值(ECV),而两个菌株超过了氟康唑的ECV。本研究揭示了隐球菌属的分子流行病学。从日本的隐球菌病猫中分离出来。这表明调查隐球菌属。由猫携带,与人类共享紧密的生活环境,可能有助于猫和人类的健康。
    隐球菌病是人类和猫的重要真菌病。我们对从日本的隐球菌病猫中分离出的菌株进行了基因分型。我们的发现表明,在日本感染猫和人类的最常见基因型是相同的。
    Cryptococcosis is an important fungal infection for both humans and cats, but molecular epidemiological studies on strains isolated from cats are limited. We conducted multi-locus sequence typing (MLST) analysis and antifungal susceptibility testing of 14 Cryptococcus spp. strains from domestic cats in Japan and one strain isolated from a cat in Singapore. All 14 strains from domestic cats in Japan were identified as Cryptococcus neoformans molecular type VNI. The sequence types (STs) included eight cases of ST5, five cases of ST31, and one novel ST. VNI ST5 is the most frequently isolated strain in Japanese patients as well, while there are no records of VNI ST31 being isolated from Japanese patients. The Singaporean cat strain was identified as C. gattii VGIIb (Cryptococcus deuterogattii), ST7. We compared these results with strains previously reported to have been isolated from cats. This comparison suggested that molecular types of Cryptococcus spp. isolated from cats may differ depending on the country. In the antifungal susceptibility testing of C. neoformans, one strain each exceeded the epidemiological cutoff value (ECV) for amphotericin B and 5-fluorocytosine, while two strains exceeded the ECV for fluconazole. This study reveals the molecular epidemiology of Cryptococcus spp. isolated from cats with cryptococcosis in Japan. It suggests that investigating Cryptococcus spp. carried by cats, which share close living environments with humans, may contribute to the health of both cats and human populations.
    Cryptococcosis is an important fungal disease in both humans and cats. We genotyped strains isolated from cats with cryptococcosis in Japan. Our findings revealed that the most common genotype infecting both cats and humans in Japan is identical.
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  • 文章类型: Journal Article
    这项研究旨在检测,分离并通过分子方法表征来自巴西的白耳负鼠(Didelphisalbiventris)中的复发性发热组(RFG)疏螺旋体。在2015-2018年期间,负鼠(Didelphisspp。)在圣保罗州的六个城市被捕,巴西,分子分析显示存在新型RFG疏螺旋体。在七个负鼠(Didelphisalbiventris)的血液中,142个样本负鼠中(4.9%感染率)。所有七个受感染的负鼠都来自一个地点(RibeirãoPreto市)。在随后2021年在RibeirãoPreto进行的实地研究中,有两个新的负鼠(D.albiventris)被捕获,其中一个血液中含有疏螺旋体DNA。将来自该感染负鼠的坏死组织接种到实验动物(啮齿动物和兔子)和两个大耳负鼠(Didelphisaurita)中,每天通过暗视野显微镜检查血液样本。在实验动物的血液中没有可见螺旋体。相反,接种后12至25天,在两个D.aurita负鼠的血液中可见螺旋体。来自这些负鼠的血液样品用于基于六个疏螺旋体基因座的多基因座测序分型(MLST)。从MLST基因推断的系统发育将测序的疏螺旋体基因型定位到亚非群疏螺旋体的基础上的RFG疏螺旋体进化枝,与另一个巴西分离物形成单系群,“CandidatusB.caatinga”。基于这种串联的系统发育分析,这支持新的疏螺旋体分离株对应于一个假定的新物种,我们建议命名为“CandidatusBorreliamimona”。
    This study aimed to detect, isolate and to characterize by molecular methods a relapsing fever group (RFG) Borrelia in white-eared opossums (Didelphis albiventris) from Brazil. During 2015-2018, when opossums (Didelphis spp.) were captured in six municipalities of the state of São Paulo, Brazil, molecular analyses revealed the presence of a novel RFG Borrelia sp. in the blood of seven opossums (Didelphis albiventris), out of 142 sampled opossums (4.9% infection rate). All seven infected opossums were from a single location (Ribeirão Preto municipality). In a subsequent field study in Ribeirão Preto during 2021, two new opossums (D. albiventris) were captured, of which one contained borrelial DNA in its blood. Macerated tissues from this infected opossum were inoculated into laboratory animals (rodents and rabbits) and two big-eared opossums (Didelphis aurita), which had blood samples examined daily via dark-field microscopy. No spirochetes were visualized in the blood of the laboratory animals. Contrastingly, spirochetes were visualized in the blood of the two D. aurita opossums between 12 and 25 days after inoculation. Blood samples from these opossums were used for a multi-locus sequencing typing (MLST) based on six borrelial loci. Phylogenies inferred from MLST genes positioned the sequenced Borrelia genotype into the RFG borreliae clade basally to borreliae of the Asian-African group, forming a monophyletic group with another Brazilian isolate, \"Candidatus B. caatinga\". Based on this concatenated phylogenetic analysis, which supports that the new borrelial isolate corresponds to a putative new species, we propose the name \"Candidatus Borrelia mimona\".
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  • 文章类型: Journal Article
    非囊性纤维化支气管扩张患者之间是否会发生呼吸道病原体的交叉感染存在争议。传统微生物培养的研究存在简化肺部微生物组的风险。我们证明了在28例非囊性纤维化支气管扩张患者的队列中,使用不依赖培养的多位点序列分型来筛选流感嗜血杆菌菌株类型。
    Whether cross-infection of respiratory pathogens between patients with non-cystic fibrosis bronchiectasis occurs is debated. Investigation with traditional microbiological culture risks simplifying the lung microbiome. We demonstrate the use of culture-independent Multilocus sequence typing to screen for Haemophilus influenzae strain types in a cohort of twenty-eight patients with non-cystic fibrosis bronchiectasis.
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  • 文章类型: Journal Article
    这项研究旨在鉴定和分析从澳门到珠海旅行的旅游团中导致食物中毒的病原体。
    样本来自96例患者中的27例,以及澳门受污染食品的样本。对采集的样品进行血清学鉴定,药物敏感性分析,耐药基因鉴定,毒力因子分析,和追踪。
    26个分离株和沙拉分离株是肠炎沙门氏菌ST11。患者的分离株对青霉素AMP(氨苄西林)和喹诺酮NAL(萘啶酸)表现出明显的耐药性。在这些分离物中,21株对两种或两种以上抗生素耐药,表明多药耐药(MDR)。使用全基因组测序(WGS)对9个分离株进行了基因组特征和系统发育分析。分析表明,对AMP和NAL的抗性主要是由GryA突变D87Y(9/9,100%)引起的,β-内酰胺抗性基因blaOXA-1的存在(1/9,11.11%),blaTEM-141(1/9,11.11%),和blaTEM-1B(8/9,88.89%)。还发现从患者中分离出的菌株对喹诺酮类药物或β-内酰胺类药物有两个耐药基因(1/8,12.5%),分别。发现这些菌株具有165个毒力基因,一种粘附类毒力因子,一种入侵类毒力因子和各种致病性岛,包括SPI-1、SPI-2、SPI-3、SPI-4、SPI-5、SPI-9、SPI-10、SPI-13、SPI-14、SPI-15、SGI1、CS54_island、和C63PI-1。此外,检测到毒力质粒,包括IncFIB(s)-IncFII(s)-IncX1(55.56%),IncFIB(s)-IncFII(s)(33.33%),和IncFIB(s)-IncFII(s)-IncHI2-IncHI2A(11.11%)。PFGE(脉冲场凝胶电泳)和系统发育树分析显示,患者的沙门氏菌分离株与澳门的食物样品之间存在高度相似性。
    这项研究确定了肠道沙门氏菌ST11是食物中毒爆发的原因。研究结果强调了表型表征和下一代测序(NGS)工具在流行病学研究中的重要性,并强调了新出现的多抗生素ST11克隆对肠炎沙门氏菌的潜在风险。
    UNASSIGNED: This study was to identify and analyze the pathogen responsible for food poisoning in a tourist group traveling from Macao to Zhuhai.
    UNASSIGNED: Samples were obtained from 27 patients of 96 cases, as well as samples of contaminated food in Macau. The collected samples were subjected to serological identification, drug sensitivity analysis, drug resistance gene identification, virulence factor analysis, and tracing.
    UNASSIGNED: Twenty-six isolates and the salad isolate were S. enteritidis ST11. Isolates from patients were exhibited significant resistance to Penicillin AMP (Ampicillin) and quinolones NAL (Nalidixic acid). Among these isolates, 21 strains were resistant to two or more antibiotics, indicating the multi-drug resistance (MDR). Genomic characteristics and phylogenetic analysis were performed on 9 of the isolates using whole genome sequencing (WGS). The analysis revealed that the resistance to AMP and NAL was primarily caused by a gryA mutation D87Y (9/9, 100%), and the presence of beta-lactam resistance genes blaOXA-1 (1/9, 11.11%), blaTEM-141 (1/9, 11.11%), and blaTEM-1B (8/9, 88.89%). It was also found a strains isolated from patients had two resistance genes to quinolones or beta-lactam drugs (1/8, 12.5%), respectively. The strains were found to possess 165 virulence genes, one adherence class virulence factor, one invasion class virulence factor and various pathogenicity islands, including SPI-1, SPI-2, SPI-3, SPI-4, SPI-5, SPI-9, SPI-10, SPI-13, SPI-14, SPI-15, SGI 1, CS54_island, and C63PI-1. Additionally, the virulence plasmids were detected, including IncFIB(s)-IncFII(s)-IncX1 (55.56%), IncFIB(s)-IncFII(s) (33.33%), and IncFIB(s)-IncFII(s)-IncHI2-IncHI2A (11.11%). PFGE (Pulsed Field Gel Electrophoresis) and phylogenetic tree analysis revealed a high degree of similarity between Salmonella isolates from patients and food samples from Macao.
    UNASSIGNED: This study identified Salmonella enterica ST11 as the cause of the food poisoning outbreak. The findings highlight the importance of phenotypic characterization and next-generation sequencing (NGS) tools in epidemiological studies and emphasize the potential risk of a new emerging multi-antibiotic ST11 clone for S. enteritidis.
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  • 文章类型: Journal Article
    我们研究了从重庆一家大型三级医院的临床标本中获得的34种替加环素-不敏感鲍曼不动杆菌(TNAB)分离株,中国。这34株菌株属于8个不同的克隆,包括ST195(35.3%)和ST208(17.7%)。EBURST分析发现,这8种ST类型属于克隆复合体92。替加环素抗性相关基因adeR,ades,adeL,adeN,rrf,rpsJ,在大多数菌株中检测到trm。TNAB菌株中抗性结瘤细胞分裂(RND)外排泵的表达水平高于参考菌株ATCC19606。58.8%的菌株在添加羰基氰3-氯苯腙(CCCP)后,替加环素的最低抑制浓度(MIC)降低。我院TNAB菌株具有高度的亲和力和耐药性。应进行定期监测,以防止TNAB流行病的爆发。
    We studied 34 isolates of Tigecycline-Non-Susceptible A. baumannii (TNAB) obtained from clinical specimens at a large tertiary care hospital in Chongqing, China. These 34 strains belonged to 8 different clones including ST195 (35.3%) and ST208 (17.7%). EBURST analysis found that these 8 ST types belonged to the Clonal Complex 92. Tigecycline resistance-associated genes adeR, adeS, adeL, adeN, rrf, rpsJ, and trm were detected in most strains. The expression level of the resistance-nodulation-cell division (RND) efflux pumps in TNAB strains was higher than the reference strain ATCC19606. 58.8% of strains had a decrease in the tigecycline minimum inhibitory concentration (MIC) after the addition of carbonyl cyanide 3-chlorophenylhydrazone (CCCP). The TNAB strains in our hospital have a high degree of affinity and antibiotic resistance. Regular surveillance should be conducted to prevent outbreaks of TNAB epidemics.
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  • 文章类型: Journal Article
    乳房链球菌是牛乳腺炎的全球特有且控制不佳的原因,影响了现代乳制品行业的可持续性。核心基因组来自579个新测序的S.uberis分离株,以及从全球11个国家分离的305个公开可用的S.uberis基因组序列,用于开发核心基因组多位点序列分型(cgMLST)方案。S.uberis核心基因组包含1475个基因,这些被用来识别1447个被筛选的基因座,这些基因座被索引到cgMLST方案中。这能够对使用的1037个(>97%)分离株中的1012个进行分型,并将相关序列分化成932个离散核心基因组序列类型(cgST)。对cgSTs的系统发育关系的分析显示,根据疾病状况或分离年份等元数据,分离株没有明确的聚类。cgST的地理聚类仅限于以英国为中心的进化枝的识别,但是来自英国分离株的cgSTs也与来自其他地理区域的cgSTs分散在整个系统发育拓扑中。cgMLST方案为详细分析这种全球重要的奶牛病原体提供了新工具。初步分析再次强调并举例说明了这种机会性病原体的全球种群的遗传多样性。
    Streptococcus uberis is a globally endemic and poorly controlled cause of bovine mastitis impacting the sustainability of the modern dairy industry. A core genome was derived from 579 newly sequenced S. uberis isolates, along with 305 publicly available genome sequences of S. uberis isolated from 11 countries around the world and used to develop a core genome multi-locus sequence typing (cgMLST) scheme. The S. uberis core genome comprised 1475 genes, and these were used to identify 1447 curated loci that were indexed into the cgMLST scheme. This was able to type 1012 of 1037 (>97  %) isolates used and differentiated the associated sequences into 932 discrete core genome sequence types (cgSTs). Analysis of the phylogenetic relationships of cgSTs revealed no clear clustering of isolates based on metadata such as disease status or year of isolation. Geographical clustering of cgSTs was limited to identification of a UK-centric clade, but cgSTs from UK isolates were also dispersed with those originating from other geographical regions across the entire phylogenetic topology. The cgMLST scheme offers a new tool for the detailed analysis of this globally important pathogen of dairy cattle. Initial analysis has re-emphasized and exemplified the genetically diverse nature of the global population of this opportunistic pathogen.
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  • 文章类型: Journal Article
    新生隐球菌和gattii隐球菌引起隐球菌病,感染多种物种的全身性真菌病。最近的分子生物学研究允许对这些物种进行基因分型,提供有关其致病性和感染途径的更详细信息。考拉(Phascolarctoscinereus)经常被隐球菌属定殖。,但是分子流行病学研究尚未在日本进行。这里,我们对隐球菌进行了多位点序列分型(MLST)分析。从日本七个公园中保存的所有考拉获得的定殖分离株。在检查的46只考拉中,10例(22%)对C.gattii呈阳性,3例(6.5%)对新型C.所有C.gattii分离株都属于分子型VGI,并且是序列型(ST)51或新型ST,所有新生梭菌分离株都属于分子型VNI和ST23。尽管考拉经常在公园之间移动,STs是相对特定于公园的,这表明饲养谷仓的地板是感染源,可能充当水库。MLST分析证实了加蒂梭菌被运输,已建立,并由考拉在C.gattii最初不存在的地区传播。MLST分析被认为可用于评估致病性和追踪隐球菌属的传播途径。由考拉携带。重要意义这是对隐球菌属进行多位点序列分型分析的第一项研究。由日本的圈养考拉携带。隐球菌病仍然是全球高致死率的人类真菌感染,圈养的考拉被认为携带高比例的隐球菌属。通过这项研究,隐球菌属的分子类型和传播途径。考拉携带的考拉已经被阐明,揭示了围栏地板作为水库的潜在作用。已经证实加蒂隐球菌,这在日本不是地方病,已经通过考拉建立起来,并正在传播给日本的新个体。这项研究被认为为考拉保护提供了有价值的见解,并有助于隐球菌病的一种健康方法,人畜共患感染.
    Cryptococcus neoformans and Cryptococcus gattii cause cryptococcosis, a systemic mycosis that infects a wide range of species. Recent molecular biological investigations have allowed for the genotyping of these species, providing more detailed information on their pathogenicity and infection routes. Koalas (Phascolarctos cinereus) are frequently colonized by Cryptococcus spp., but molecular epidemiological studies have yet to be conducted in Japan. Here, we conducted multi-locus sequence typing (MLST) analysis on Cryptococcus spp. colonization isolates obtained from all koalas kept in seven parks across Japan. Out of 46 koalas examined, 10 (22%) were positive for C. gattii and 3 (6.5%) were positive for C. neoformans. All C. gattii isolates belonged to molecular type VGI and were either sequence type (ST) 51 or a novel ST, and all C. neoformans isolates belonged to molecular type VNI and ST23. Despite the frequent movement of koalas between parks, the STs were relatively park-specific, suggesting that the floor of the rearing barns is a source of infection and may act as a reservoir. MLST analysis confirmed that C. gattii was transported, established, and spread by koalas in areas where C. gattii was not originally present. MLST analysis is considered useful in assessing the pathogenicity and tracing the transmission routes of Cryptococcus spp. carried by koalas.IMPORTANCEThis is the first study to conduct a multi-locus sequence typing analysis on Cryptococcus spp. carried by captive koalas in Japan. Cryptococcosis remains a globally high-fatality fungal infection in humans, and captive koalas are known to carry a high percentage of Cryptococcus spp. Through this research, the molecular types and transmission routes of Cryptococcus spp. carried by koalas have been elucidated, revealing the potential role of enclosure flooring as a reservoir. It has been confirmed that Cryptococcus gattii, which is not endemic in Japan, has become established through koalas and is spreading to new individuals in Japan. This study is believed to provide valuable insights into koala conservation and contribute to the One Health approach for Cryptococcosis, a zoonotic infection.
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  • 文章类型: Journal Article
    本研究旨在使用多位点序列分型方案(MLST)研究108个地理和时间上不同的人型支原体菌株的遗传多样性。我们从PubMLST数据库中提取了87个菌株的MLST数据,并从GenBank数据库中提供的21个完整的人型支原体基因组中检索了MLST基因序列。MLST方案确定了65种序列类型(ST),分为5个克隆复合物(CC)和47个单例。系统发育分析表明,大多数人源分离株根据其起源国进行聚类,显示出国家的一些显著的特异性趋势。尽管检测到重组,这并不足以改变人源的克隆种群结构。总之,MLST方案提供了有关人源M.hominis国际菌株的系统发育学的有见地的数据,根据分离的起源,争论遗传上可分化的STs的存在。
    This study aimed to investigate the genetic diversity of 108 geographically and temporally diverse strains of Mycoplasma hominis using a multi-locus sequence typing scheme (MLST). We extracted MLST data of 87 strains from PubMLST database and retrieved MLST gene sequences from 21 complete genomes of M. hominis available in GenBank database. MLST scheme identified 65 Sequence types (STs), which were grouped into five clonal complexes (CC) and 47 singletons. Phylogenetic analysis revealed that the majority of M. hominis isolates were clustered according to their country of origin, showing some significant specificity trends for the nation. Although recombination was detected, it was not significant enough to alter the clonal population structure of M. hominis. In sum, MLST scheme provides insightful data on the phylogenetics of international strains of M. hominis, arguing for the existence of genetically differentiable STs according to their origin of isolation.
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  • 文章类型: Journal Article
    目标:产气荚膜梭菌(C.产气荚膜)是一种重要的机会性病原体。这项研究旨在检查腹泻和食物中毒患者产气荚膜梭菌的发生,并比较其与同一城市家禽零售市场和家禽养殖场中发现的菌株的遗传相似性(泰安,中国)。
    方法:C.从30个人类粪便样品中分离出产气荚膜,并使用多重PCR进行基因分型。使用Kirby-Bauer圆盘扩散法进行抗菌敏感性试验。通过多位点序列分型(MLST)和系统发育分析分析了遗传关系。
    结果:产气荚膜梭菌阳性率为96.67%。在阳性样本中,91.67%的食物中毒患者粪便样本中含有产气荚膜梭菌F型菌株,而只有16.67%的腹泻病例样本含有F型。药敏试验显示,大多数分离株表现出广谱抗菌耐药性。在经过药物敏感性测试的57个分离株中,89.47%对至少三种抗生素表现出耐药性。MLST结果表明,来自同一宿主和环境的菌株倾向于更密切相关。然而,与食物中毒和腹泻相关的某些菌株与零售市场中的某些菌株具有相同的ST和CC。还发现这些菌株在系统发育上与某些零售市场菌株相似,提示对人类健康的潜在风险。
    结论:因此,加强家禽零售市场的管理以减轻这些相关风险至关重要。
    OBJECTIVE: Clostridium perfringens (C. perfringens) is a significant opportunistic pathogen. This study aims to examine the occurrence of C. perfringens in patients with diarrhoea and food poisoning and compare the genetic similarities with strains found in poultry retail markets and poultry farms in the same city (Tai\'an, China).
    METHODS: Clostridium perfringens was isolated from 30 human faecal samples and genotyped using multiplex PCR. The antimicrobial susceptibility test was conducted using the Kirby-Bauer disk diffusion method. Genetic relationships were analysed through Multi-locus sequence typing (MLST) and Phylogenetic analysis.
    RESULTS: The positive rate of C. perfringens was found to be 96.67%. Among the positive samples, 91.67% of the faecal samples from patients with food poisoning contained type F strains of C. perfringens, while only 16.67% of the samples from diarrhoea cases contained type F. The drug susceptibility test revealed that the majority of isolates displayed broad-spectrum antimicrobial resistance. Out of the 57 isolates tested for drug susceptibility, 89.47% demonstrated resistance to at least three antibiotics. The MLST results indicated that strains originating from the same host and environment tended to be more closely related. However, certain strains associated with food poisoning and diarrhoea in patients shared the same ST and CC as some strains found in the retail market. These strains were also found to be phylogenetically similar to some retail market strains, suggesting potential risks to human health.
    CONCLUSIONS: Therefore, it is crucial to enhance the management of poultry retail markets in order to mitigate these associated risks.
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  • 文章类型: Journal Article
    单核细胞增生李斯特菌是李斯特菌病的病原体,一种对全球公共卫生构成威胁的食源性疾病。在屠宰过程中,鸡肉对单核细胞增生李斯特菌污染的敏感性更高。这种病原体在屠宰场环境中的持续存在使得肉制品受到反复污染。这项研究旨在确定屠宰场内单核细胞增生李斯特菌污染的来源和传播途径,该屠宰场连续三年(2019-2021年)被检测到。此外,通过调查设施内的微生物组,确定了导致鸡肉加工线污染的环境因素。2019年至2021年收集的样本进行了文化依赖性分析,以评估患病率,血清型,和单核细胞增生李斯特菌的多位点序列分型(MLST)。此外,通过实时定量聚合酶链反应(qPCR)和16SrRNA基因扩增子测序,对2021年收集的标本进行了培养无关性分析,以确定污染源并表征屠宰场内整个微生物群落.单核细胞增生李斯特菌只从干净的区域分离,最后的屠宰阶段。从最终car体中分离出的大多数菌株显示出与冷水中分离出的菌株相同的遗传簇,并被分配给MLST谱ST3。不依赖培养的qPCR证实了所有样品中的单核细胞增生李斯特菌污染,不包括烫伤后的尸体,预洗后的内脏尸体,和出血区域。因此,与依赖培养的方法相比,qPCR能够更全面地鉴定单核细胞增生李斯特菌的污染点。此外,16SrRNA基因扩增子测序表明,具有单核细胞增生李斯特菌样属性的耐霉菌和腐败相关细菌在清洁区和浸泡冷水中的生存力增强。基于宏基因组学的来源跟踪分析进一步表明,束缚和冷水代表了不同屠宰场区域之间交叉污染的主要来源,而清洁区的分级和包装工作站和冷却水被认为是影响最终car体污染的关键来源。总的来说,这些发现表明,通过培养依赖性和非依赖性方法,单核细胞增生李斯特菌沿屠宰线传播,污染屠宰场.此外,通过调查设施内屠宰线上微生物群落和细菌流动的变化,可以有效追踪影响car体污染的来源。
    Listeria monocytogenes is the etiologic agent of listeriosis, a foodborne disease that poses a threat to public health globally. Chicken meat exhibits heightened susceptibility to L. monocytogenes contamination during butchery. The persistence of this pathogen in the slaughterhouse environment enables recurring contamination of meat products. This study aimed at identifying the sources and transmission routes of L. monocytogenes contamination within an abattoir where it was consistently detected for three consecutive years (2019-2021). Furthermore, the environmental factors aiding contamination along chicken processing lines were determined by surveying the microbiome within the facility. Samples collected in 2019 to 2021 were subjected to culture-dependent analysis to assess the prevalence, serotypes, and multi-locus sequence typing (MLST) of L. monocytogenes. Additionally, the specimens collected in 2021 underwent culture-independent analysis via real-time quantitative polymerase chain reaction (qPCR) and 16S rRNA gene amplicon sequencing to identify the contamination sources and characterize the entire microbial community within the slaughterhouse. L. monocytogenes was isolated only from the clean zone, where the final slaughtering stage occurs. Most strains isolated from the final carcasses showed the same genetic cluster as the isolate in the chilling water and were assigned to MLST profile ST3. Culture-independent qPCR confirmed L. monocytogenes contamination in all samples, excluding post-scalding carcasses, prewashed post-evisceration carcasses, and the bleeding areas. Consequently, qPCR enabled more comprehensive identification of L. monocytogenes contamination points than culture-dependent approaches. Moreover, 16S rRNA gene amplicon sequencing demonstrated that psychro-tolerant and spoilage-related bacteria with L. monocytogenes-like attributes exhibited enhanced viability in the clean zone and immersion-chilling water. Metagenomics-based source tracking analysis further revealed that the shackles and chilling waters represent predominant sources of cross-contamination between different slaughterhouse zones, whereas the grading and packaging workstations and chilling water in the clean zone were deemed crucial sources affecting final carcass contamination. Collectively, these findings demonstrate through culture-dependent and -independent methods that L. monocytogenes spreads along the slaughter line, contaminating the slaughterhouse. Moreover, by investigating changes in microbial community and bacterial flow along the slaughter line within the facility, the sources influencing carcass contamination can be effectively traced.
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