2019-2020年宁夏炭疽芽胞杆菌毒力鉴定及基因分型研究

目的 了解宁夏2019-2020年分离的炭疽芽胞杆菌菌株致病力及基因分型特征,为宁夏皮肤炭疽疫情判定与分子溯源提供实验室依据。方法 收集2019-2020年宁夏各地区分离的炭疽芽胞杆菌,对其进行毒力鉴定,并运用MLVA-15和canSNP分型技术进行基因分型研究。结果 2019-2020年宁夏分离到的炭疽芽胞杆菌均为强毒株,MLVA-15分型为同一种群,canSNP分型为A.Br.001/002组。结论 2019-2020年宁夏分离到的炭疽芽胞杆菌致病力较强,且菌株呈现相同的基因分型特征,提示菌株间存在流行病学关联。此研究结果填补了宁夏炭疽芽胞杆菌实验室检测中菌株致病力及基因分型的空白。     

基于全基因组测序的甲型副伤寒沙门菌暴发疫情分离株分子特征研究

目的 分析一起甲型副伤寒暴发疫情菌株的分子分型特征,为病原菌的确定和暴发疫情的防控提供科学依据。方法 利用生化试验、血清学试验对病原菌进行鉴定,并将分离到的病原菌进行微量肉汤稀释法药物敏感性试验、PFGE分子分型分析、全基因组测序,利用全基因组数据与沙门菌MLST标准数据库比对获得序列型别(ST)、cgMLST序列号以及rMLST序列号并进行聚类分析,通过细菌基因组分析平台fIDBA分析病原菌的耐药、毒力相关基因。结果 11株沙门菌血清型均为甲型副伤寒沙门菌,具有100%相似性的PFGE带型,MLST、cgMLST、rMLST的型别均分别为ST129型、cgST-2191型、rST3678型,表明此次暴发疫情菌株从分子特征角度可诊断为同一传染源导致。对萘啶酸100%耐药,对链霉素100%中介。发现本次疫情菌株基因组均携带29种耐药基因。通过毒力因子数据库比对,均携带21类250种已知毒力基因,其中以Ⅲ型分泌系统、粘附、鞭毛等最为常见。结论 本次暴发疫情是由共同来源的、具有相同分子分型特征的甲型副伤寒沙门菌引起。在病原溯源研究中,应用全基因组数据可更精细分析菌株遗传进化特征、亲缘关系及毒力基因、耐药基因携带情况,可以作为替代PFGE、MLST的技术用于更精准的传染病分子流行病学调查分析研究。     

2006-2017年四川省临床分离猪链球菌2型的病原学特征

目的 了解四川省2006-2017年临床分离猪链球菌2型的病原学特征。方法 对2006-2017年四川省临床分离的28株猪链球菌2型进行毒力基因检测、药物敏感性分析、脉冲场凝胶电泳分析(PFGE)。结果 28株猪链球菌2型分为2种毒力基因型,1株为cps2J+/mrp-/sly+/gapdh+/ef+型别,其余均为cps2J+/mrp+/sly+/gapdh+/ef+型别;药敏检测结果显示,28株猪链球菌对第三代、第四代头孢菌素类、碳青霉烯类、青霉素、左氧氟沙星、利奈唑胺、万古霉素、氯霉素、达托霉素均敏感,对四环素均耐药。28株猪链球菌中,仅2株对克林霉素、阿奇霉素、红霉素耐药,其余均敏感。PFGE分析结果显示,28株猪链球菌呈现6种PFGE图谱,相似性为76%,其中23株是完全相同的图谱,占82.14%;2006-2007年分离的19株菌呈现完全相同的PFGE图谱,2010年后分离的9株呈现出6种PFGE图谱。结论 2006-2017年四川省临床分离猪链球菌2型流行株的毒力基因型主要为高致病性cps2J+/mrp+/sly+/gapdh+/ef+型别,对β-内酰胺类药物敏感,2006、2007年不同市区临床分离的猪链球菌2型为统一来源,2010年后分离的菌株PFGE图谱相似度较低。     

河南省某一淡水养殖环节中非O1/O139群霍乱弧菌毒力基因及分子分型分析

目的 了解河南省淡水养殖环节中非O1/O139群霍乱弧菌毒力基因分布及分子分型情况。方法 对河南省淡水养殖环节中50株非O1/O139群霍乱弧菌和3株病人来源菌株进行全基因测序,利用PubMLST-Vc数据库分析其序列分型(ST),利用最小生成树关系图分析进化关系,通过VFDB数据库获得其毒力基因分布。结果 来源于淡水养殖环节和来源于病人的非O1/O139群霍乱弧菌53株菌株均具有黏附、趋化运动、抗吞噬、毒素及酶类等功能的8类毒力相关因子基因,缺失辅助定植、毒素共调、分泌等功能的毒力相关因子基因和副霍乱肠毒素等4个毒素基因。部分毒力相关因子或部分菌株的毒力相关因子毒力基因不全。与3株来源于病人的菌株相比,二者毒力因子基因携带情况相近,除MSHA Ⅳ型菌毛毒力因子mshA基因、荚膜多糖wbuB基因、wbfY基因、rmlB基因、血红素受体hutA基因及Ⅲ型分泌系统vscC2和vcrD2基因外,部分菌株二者携带相同的毒力因子基因。53株非O1/O139群霍乱弧菌分属19个ST型,ST4和ST5是优势ST型,养殖环节来源的菌株与病人来源的菌株分属不同的ST型。19个ST型等位基因位点变异差异数在1~7个,其中分离自淡水养殖环节的非O1/O139群霍乱弧菌菌株17个ST型等位基因位点变异差异数在1~7个,病人来源的非O1/O139群霍乱弧菌菌株2个ST型与分离自淡水养殖环节的非O1/O139群霍乱弧菌菌株ST1、ST2、ST6和ST10属同一簇,与ST1有6个等位基因位点存在差异。结论 河南省淡水养殖环节非O1/O139群霍乱弧菌菌株MLST分型多样化,携带多种毒力相关因子,不同来源菌株携带的毒力基因相同,虽然分属不同的ST型,但还是存在食品安全风险,提醒有关部门采取措施进行防控。     

The role of rosetting in the multiplication of Plasmodium falciparum: rosette formation neither enhances nor targets parasite invasion into uninfected red cells

The effect of rosette formation on the multiplication in vitro of Plasmodium falciparum was studied in order to establish whether rosetting acts as a major virulence factor in the pathogenesis of severe malaria by facilitating invasion of uninfected red cells. Invasion rates for rosetting (R⁺) and non-rosetting (R⁻) parasites selected from the same clone, PA1, of P. falciparum were similar over a range of starting parasite concentrations when assayed in both static cultures and conditions of shear stress comparable with microvascular flow. However, incubation of both R⁺ and R⁻ parasites under simulated conditions of flow led to decreased invasion and fewer multiply-infected red cells as we have previously observed. Studies using fluorescently labelled red cells or reticulocytes demonstrated that rosetting did not alter the rates of invasion or target merozoites into the uninfected cells comprising a rosette. Preferential invasion of reticulocytes occurred regardless of rosetting or conditions of flow. Although the role of rosetting in the pathogenesis of malaria might relate to microvascular obstruction or perhaps the restriction of phagocytosis, our data suggest that rosetting does not play a role in the invasion or targeting of parasites into uninfected cells, eliminating this mechanism to explain the association of virulence with the rosetting parasite phenotype.     

Identification of Culturable and Nonculturable Microorganisms,Lipopolysaccharides, and Lipoteichoic Acids From Root Canals of Teeth With Endodontic Failure

AimTo elucidate the presence of apical periodontitis in the root canal of teeth with secondary/persistent infection, including composition of microbiota, levels of endotoxins and lipoteichoic acid (LTA), and clinical implications of these findings.MethodSamples were collected from root canals of 50 patients who needed endodontic retreatment and had radiographic evidence of apical periodontitis. Microorganisms were identified by using the culture technique and biochemical tests. Nested–polymerase chain reaction (nested-PCR) was used to identify 17 species of specific bacteria. Lipopolysaccharides (LPS) and LTAs were quantified by using, respectively, limulus amebocyte lysate and enzyme-linked immunosorbent assay tests.ResultsBacteria were detected in all samples by culture and molecular methods. A total of 154 gram-positive strains, of 188 strains isolated, were found in the root canals by culture. Enterococcus faecalis and Gemella morbillorum were the most prevalent species identified by the biochemical tests, whereas molecular analyses (nested-PCR) showed a high frequency of P. gingivalis, E. faecalis, and Fusobacterium nucleatum. LPS and LTA were detected in all samples, with mean values being 3.52 EU/mL and 597.83 pg/mL, respectively. Significant statistical correlations were found between levels of LTA and clinical features.ConclusionDespite the prevalence of gram-positives, the microbiota present in secondary/persistent infections showed a large variety of species. Within this diversity, associations were found between specific bacteria and clinical features. In addition, higher levels of LTA were statistically associated with larger periapical radiolucent areas, but no correlation between this feature and LPS was found.     

Vulvovaginal candidiasis: Epidemiology,microbiology and risk factors

Abstract

Vulvovaginal candidiasis (VVC) is an infection caused by Candida species that affects millions of women every year. Although Candida albicans is the main cause of VVC, the identification of non-Candida albicans Candida (NCAC) species, especially Candida glabrata, as the cause of this infection, appears to be increasing. The development of VVC is usually attributed to the disturbance of the balance between Candida vaginal colonization and host environment by physiological or nonphysiological changes. Several host-related and behavioral risk factors have been proposed as predisposing factors for VVC. Host-related factors include pregnancy, hormone replacement, uncontrolled diabetes, immunosuppression, antibiotics, glucocorticoids use and genetic predispositions. Behavioral risk factors include use of oral contraceptives, intrauterine device, spermicides and condoms and some habits of hygiene, clothing and sexual practices. Despite a growing list of recognized risk factors, much remains to be elucidated as the role of host versus microorganisms, in inducing VVC and its recurrence. Thus, this review provides information about the current state of knowledge on the risk factors that predispose to VVC, also including a revision of the epidemiology and microbiology of VVC, as well as of Candida virulence factors associated with vaginal pathogenicity.     

Drug-resistant microorganisms with a higher fitness – can medicines boost pathogens?

Drug-resistant microorganisms (DRMs) are generally thought to suffer from a fitness cost associated with their drug-resistant trait, inflicting them a disadvantage when the drug pressure reduces. However, Leishmania resistant to pentavalent antimonies shows traits of a higher fitness compared to its sensitive counterparts. This is likely due the combination of an intracellular pathogen and a drug that targets the parasite’s general defense mechanisms while at the same time stimulating the host’s immune system, resulting in a DRM that is better adapted to withstand the host’s immune response. This review aims to highlight how this fitter DRM has emerged and how it might affect the control of leishmaniasis. However, this unprecedented example of fitter antimony-resistant Leishmania donovani is also of significance for the control of other microorganisms, warranting more caution when applying or designing drugs that attack their general defense mechanisms or interact with the host’s immune system.     

Escherichia coli clonal group A causing bacteraemia of urinary tract origin

Escherichia coli clonal group A (CgA) causes disease in humans. This is the first study investigating the prevalence of CgA among E. coli from non-urine, extraintestinal infections in a northern European country. E. coli blood (n = 196) and paired urine (n = 195) isolates from the same patients with bacteraemia of urinary tract origin were analysed. The isolates were collected from January 2003 through May 2005 at four hospitals in Copenhagen, Denmark. Pulsed-field gel electrophoresis (PFGE) patterns, antimicrobial resistance and patient characteristics were determined for all CgA isolates; presence of virulence-associated genes (VAGs) and serotypes were determined for the blood CgA isolates. Thirty blood isolates (15%) belonged to CgA. CgA blood isolates were associated with female patients and sulfamethoxazole-trimethoprim resistance and they harboured a distinctive VAG profile. The blood and urine isolates from each pair were found to be related in 26 of 27 CgA blood/urine pairs, confirming a urinary tract origin of infection. Furthermore, a relationship between the PFGE patterns of CgA blood/urine isolates and CgA isolates from UTI patients in general practice and a CgA isolate from a community-dwelling human reported previously, was found, suggesting a community origin of CgA. The finding of CgA strains in 15% of the E. coli bloodstream infections with a urinary tract origin in Denmark suggests that CgA constitutes an important clonal lineage among extraintestinal pathogenic E. coli. A reservoir of this pathogenic E. coli group in the community causing not only UTI but also more severe infections such as bacteraemia has implications for public health.     

Distribution of phylogenetic groups,sequence type ST131, and virulence-associated traits among Escherichia coli isolates from men with pyelonephritis or cystitis and healthy controls

Urinary tract infections (UTI), which are mostly caused by Escherichia coli, are an important public health problem worldwide. Although men experience diverse UTI syndromes, there have been relatively few molecular-epidemiological studies of UTI pathogenesis in men. We studied the distribution of 22 E. coli virulence factor (VF) genes, major phylogenetic groups, sequence type ST131, and UTI-associated O antigens among 101 pyelonephritis, 153 cystitis and 135 fecal healthy control E. coli isolates from men aged 30–70 years in a regional area of NSW, Australia. Overall, the studied traits exhibited a prevalence gradient across these groups, highest in pyelonephritis, intermediate in cystitis, and lowest among fecal isolates. Differences in virulence gene prevalence between cystitis and pyelonephritis isolates were limited to eight genes. The UTI-associated O antigens were also distributed widely, but types O6, O25 and O75 were significantly associated with pyelonephritis. The ST131 clonal group, which accounted for 13% of isolates overall (22% of group B2 isolates), likewise exhibited a significant descending prevalence gradient from pyelonephritis (36%), through cystitis (8%), to fecal (0%) isolates. These findings contribute to better understanding of the pathogenesis of UTIs in men and identify specific VF genes and O types, and a prominent clonal group (ST131), as being important in UTI pathogenesis in this population.