Molecular evidence to suggest pigeon‐type Chlamydia psittaci in association with an equine foal loss

Chlamydia psittaci is an important avian pathogen with spillover from infected wild and domesticated birds also posing a risk to human health. We recently reported a case of C. psittaci equine placentitis associated with further spillover to humans. Molecular typing of this case revealed it belonged to the 6BC clade of C. psittaci , a globally distributed highly virulent set of strains, typically linked to infection spillover from parrots. Equine chlamydiosis associated with C. psittaci infection has previously been reported elsewhere in countries where parrots are not endemic, however, raising questions over the identity of infecting C. psittaci strains and the potential infection reservoirs. In this study, we describe the detection and molecular characterization of C. psittaci in a case of equine abortion in southern Queensland. Equine placenta and fresh liver and lung tissue from the necropsied foetus were positive by C. psittaci ‐specific qPCR . Chlamydia psittaci ‐specific multilocus sequence typing and omp A genotyping were used to further characterize the detected equine strains and an additional strain obtained from a dove from a different geographic region presenting with psittacosis. Molecular typing of this case revealed that the infecting equine strains were closely related to the C0sittaci detected in dove, all belonging to an evolutionary lineage of C. psittaci strains typically associated with infections of pigeons globally. This finding suggests a broader diversity of C. psittaci strains may be detected in horses and in association with reproductive loss, highlighting the need for an expansion of surveillance studies globally to understand the epidemiology of equine chlamydiosis and the associated zoonotic risk.     

Increasing trend in invasive non-typeable Haemophilus influenzae disease and molecular characterization of the isolates,Italy, 2012–2016

Routine immunization of infants with conjugate vaccines against Haemophilus influenzae type b (Hib) has greatly reduced the incidence of invasive Hib disease; however changes in the epidemiology of H. influenzae disease have occurred. We describe the epidemiology of invasive H. influenzae disease and the characterization of isolates collected in Italy between 2012 and 2016.Trends in the overall incidence of invasive H. influenzae disease were calculated. Isolates were characterized by PCR capsular genotyping, antimicrobial susceptibility testing, ampicillin resistance-associated gene sequencing and MLST. Trends in incidence by serotype and serotype-specific distribution were estimated using multiple imputation of missing data.The overall incidence of invasive H. influenzae disease increased 22.5% yearly (from 0.11/100,000 in 2012 to 0.24/100,000 in 2016). Most cases (82.0%) were due to non-typeable H. influenzae (NTHi). An increasing trend in NTHi disease burden was estimated; the highest rise was among infants <12 months (40.8% annual increase). Invasive Hib disease showed a fluctuating trend with a clear increase in 2016, while we found an increasing trend for disease due to non-Hib capsulated serotypes in the elderly (32.9% annual increase). Ampicillin resistance mediated by either β-lactamase or altered penicillin-binding proteins 3 (PBP3) increased. In spite of genetic diversity of NTHi, sequence types (STs) associated with ampicillin resistance status were identified (ST103/ST106 linked to β-lactamase production and ST14 linked to a specific PBP3 substitution pattern). The increasing trend in invasive NTHi disease in infants is of concern underlying the need for the development of a future vaccine against NTHi.     

重症监护室耐碳青霉烯类肺炎克雷伯菌的耐药机制和同源性分析

目的探讨安徽医科大学第一附属医院4个重症监护室(ICU)中耐碳青霉烯类肺炎克雷伯菌(CRKP)的耐药机制和流行状况,为医院感染控制提供依据。方法收集4个ICU病房中CRKP菌株39株,采用纸片扩散法和Vitek 2 Compact仪器法测定临床常见抗菌药物的敏感性,用Carba NP试验对碳青霉烯酶进行筛选,同时对超广谱β-内酰胺酶(ESBLs)、头孢菌素酶(AmpC酶)、碳青霉烯酶基因进行PCR扩增和序列分析,用基质辅助激光解吸电离飞行质谱(MALDI-TOF MS)技术及多位点序列分型(MLST)进行同源性分析。结果 PCR检测基因型显示36株CRKP以产KPC-2型酶为主,部分菌株同时拥有ESBL和AmpC耐药基因。MALDI-TOF MS将39株CRKP分为3大簇,MLST结果显示35株菌均为ST11型,ST379、ST751、ST307、ST490各有1株,经eBURST在线软件分析ST11与ST379、ST751的亲缘关系较近,来源于同一克隆株。结论 4个ICU病房中CRKP以产KPC-2型酶为主,是CRKP对碳青霉烯类抗菌药物耐药的主要机制。37株CRKP高度同源,提示不同ICU病房间应进一步加强感染控制。     

乌鲁木齐地区MRSA的分子分型及耐药性研究

目的：研究乌鲁木齐地区耐甲氧西林金黄色葡萄球菌（MRSA）的分子分型及其耐药情况。方法：收集金黄色葡萄球菌163株,PCR方法扩增mecA及pvl基因,检测MRSA及pvl检出率,用SCCmec、spa、MLST等方法对MRSA进行分型,VITEK2进行药敏测定。结果：MRSA检出率39.3%,pvl阳性率45.3%,HA-MRSA为87.5%,CA-MRSA为10.9%,未定型MRSA1株。有SCCmec型5种、spa型12种及ST型6种,其中HA-MRSA以ST239-MRSA-Ⅲ-t030、ST239-MRSA-Ⅲ-t037和ST5-MRSA-Ⅱ-t002为主,CA-MRSA以ST59-MRSA-Ⅳ-t437为主,耐药结果显示未发现耐万古霉素、替考拉宁、利奈唑胺等MRSA。结论：乌鲁木齐地区MRSA较低,以HA-MRSA为主,MRSA的多种药物敏感性呈下降趋势,值得重视。     

MLSTest: Novel software for multi-locus sequence data analysis in eukaryotic organisms

Multi-locus sequence typing (MLST) is a frequently used genotyping method whose goal is the unambiguous assignment of microorganisms to genetic clusters. MLST typically involves analysis of DNA sequence results generated from several house-keeping gene loci. MLST remains the gold standard for molecular typing of many bacterial pathogens. Eukaryotic pathogens have also been the subject of MLST, however, few tools are available to deal with diploid sequence data. Here we present novel software for MLST data analysis tailored towards diploid Eukaryotes: MLSTest. This software meets various methods used in MLST and introduces some novel methodologies for the evaluation of the data set. In addition to construction of allelic profiles and basic clustering analysis, the MLSTest looks for network structures that suggest genetic exchange in BURST graphs. Additionally, it uses several simple methods for tree construction with the advantage of managing heterozygous or three-state sites. Additionally, the software analyses whether concatenation of fragments from different genes is suitable for the data set using different tests (bionj-incongruence length difference test, Templeton test). It evaluates how the incongruence is distributed across the tree using a variation of the localized incongruence length difference test based on a modified neighbour joining algorithm. We tested the last method in simulated datasets. We showed that is conservative (adequate type I error rate) and moderately to highly powerful as well as useful to localize incongruences in two bacterial and two eukaryotic MLST datasets. MLSTest was also designed for developing MLST schemes. It thus has tools to optimize locus combinations and to reduce the number of targets required for typing. MLSTest also analyses whether the discriminatory power of the typing scheme is increased by including more loci. We evaluated the software over simulated and real datasets from bacterial and eukaryotic microorganisms. The software is freely available at http://www.ipe.unsa.edu.ar/software.     

Characterization of size, structure and purity of serogroup X Neisseria meningitidis polysaccharide, and development of an assay for quantification of human antibodies

Serogroup X Neisseria meningitidis (MenX) has recently emerged as a cause of localized disease outbreaks in sub-Saharan Africa. In order to prepare for vaccine development, MenX polysaccharide (MenX PS) was purified by standard methods and analyzed for identity and structure by NMR spectroscopy. This study presents the first full assignment of the structure of the MenX PS using (13)C, (1)H and (31)P NMR spectroscopy and total correlation spectroscopy (TOCSY) and (1)H-(13)C heteronuclear single quantum coherence (HSQC). Molecular size distribution analysis using HPLC-SEC with multi-angle laser light scattering (MALLS) found the single peak of MenX PS to have a weight-average molar mass of 247,000g/mol, slightly higher than a reference preparation of purified serogroup C meningococcal polysaccharide. MenX PS tended to be more thermostable than serogroup A PS. A method for the quantification of MenX PS was developed by use of high performance anion exchange chromatography with pulsed amperometric detection (HPAEC-PAD). A novel and specific ELISA assay for quantification of human anti-MenX PS IgG based on covalent linkage of the MenX PS to functionally modified microtitre plates was developed and found valid for the assessment of the specific antibody concentrations produced in response to MenX vaccination or natural infection. The current work thus provides the necessary background for the development of a MenX PS-based vaccine to prevent meningococcal infection caused by bacteria bearing this capsule.     

血流感染中大肠埃希菌的药物敏感性、耐药基因及同源性分析

摘要：目的 分析血流感染中大肠埃希菌的药物敏感性、耐药基因分布及菌株间的同源性特征,为控制医院内感染,指导 临床合理用药提供依据。方法 连续收集2019年10月至2020年9月山西省人民医院住院患者血培养中的大肠埃希菌,用基质辅 助激光解析电离飞行时间质谱仪进行菌种鉴定,用VITEK-2进行药敏试验,PCR方法检测超广谱β-内酰胺酶(ESBLs)耐药基因, 采用多位点序列分型(Multilocus Sequence Typing,MLST)对菌株进行同源性分析。结果 76株大肠埃希菌对氨苄西林的耐药率 最高,达到90.7%,其次是环丙沙星、头孢唑林、左氧氟沙星和头孢曲松,耐药率分别为69.7%、65.7%、63.1%和56.5%。对哌 拉西林/他唑巴坦、厄他培南、亚胺培南、阿米卡星和替加环素全部敏感。产ESBLs大肠埃希菌的检出率为56.5%。共检出blaTEM, blaCTX-M和blaOXA-1 3种ESBLs基因,其中blaCTX-M为主要基因型。最常见的ST型为ST131(19.7%,15/76)、ST69(15.7%,12/76)和 ST38(7.8%,6/76)。结论 本院大肠埃希菌对大多数常用抗生素具有耐药性,治疗大肠埃希菌引起的血流感染,可经验性选择 碳青霉烯类、哌拉西林/他唑巴坦、阿米卡星和替加环素。我院主要流行的ESBLs基因型为blaCTX-M型,同源性分析表明,菌株间 存在遗传多样性。     

动物源金黄色葡萄球菌的流行特点及耐药机制研究进展

摘要：金黄色葡萄球菌是一种重要的人畜共患的条件性致病菌,可引起人和动物的多种感染性疾病。随着抗生素在临床的 广泛使用,金黄色葡萄球菌的耐药情况日益严重。动物源耐药金黄色葡萄球菌可传播给与动物密切接触者,也可通过食品链在 消费者中传播,进而可能在人群中扩散,从而增加了耐药性散播的风险。因此,有必要对动物源金黄色葡萄球菌的流行特征以 及耐药机制进行研究。本文就近几年动物源金黄色葡萄球菌在我国的流行特点及耐药机制做一综述,旨在为动物源金黄色葡萄 球菌的耐药性监测及感染治疗提供参考。