临床常见革兰阴性菌的分布动向及耐药趋势

监测革兰阴性菌的分布动向及耐药趋势,为临床合理使用抗菌药物提供依据。3年间临床分离致病菌以革兰阴性杆菌为主,革兰阴性杆菌检出率逐年下降,非发酵革兰阴性杆菌的比例逐年上升;加酶抑制剂的抗菌药物较不加酶抑制剂的抗菌药物对非发酵革兰阴性杆菌显示了不同程度的抑菌优势,肠杆菌科革兰阴性杆菌ESBLS检出率逐年增加。     

圈养林麝脓肿病病原菌分离鉴定及药敏分析

目的 确定林麝化脓性疾病的主要病原菌,寻找有效的治疗措施(药物).方法 采用3种培养基对28个人工饲养的发病林麝脓灶进行病原菌的分离培养、细菌革兰氏染色、镜检,然后对分离病原菌进行16S rRNA 基因PCR扩增及测序分析鉴定,再进一步用BIOLOG自动微生物鉴定系统对3种可疑菌进行生理生化鉴定,用昆明小鼠分组进行系列病理实验,最后用纸片扩散法测定病原菌对22种抗生素的敏感性.结果 脓灶中共分离到12种细菌,其中化脓隐秘杆菌Arcanobacterium pyogenes、绿脓杆菌Pseudomonas aeruginosa、蜡状芽孢杆菌Bacillus cereus的检出率分别为100.0%、21.4%、14.3%,其他菌的检出率较低.用BIOLOG自动微生物鉴定系统鉴定结果与16S rRNA鉴定结果完全一致;小鼠致病性实验中进行了脓液培养后注射,分离到单菌鉴定后进一步分别注射,剖检后进行接种划线鉴定并得到与注射前相同的病菌,确定了这几种菌均具有较强的致病性;药敏实验最终确定针对化脓隐秘杆菌的有效药物为环丙沙星,对这3种病菌的有效药物为克林霉素、环丙沙星.结论 初步确定林麝脓肿病主要是由于化脓隐秘杆菌原发感染,进而引起其他病菌的继发感染和混合感染,最终导致病重死亡;环丙沙星等为敏感药物.     

Preliminary report on the study of postharvest fruit rot bacteria and yeasts in Lanzhou Lily (Lilium davidii var. unicolor) in China

Fruit rot is one of the most important factors affecting the postharvest quality and shelf life of Lanzhou Lily fruits. The aims of this study were to characterize different isolates from Lanzhou Lily using morphological and molecular approaches and to test their pathogenicity in Lanzhou Lily fruit. Different isolates were collected from decayed Lanzhou Lily fruits in Lanzhou in Gansu Province in China during 2016 and 2017. In total, four isolates were obtained and identified based on their DNA sequences of the 16S rDNA and 26S rDNA genes in combination with the morphological characteristics of the cultures and sporulation. Of the four isolates, one was identified as Bacillus safensis, one was Stenotrophomonas maltophilia and the other two isolates were Metschnikowia pulcherrima. The pathogenicity tests showed that all four isolates were pathogenic in Lanzhou Lily fruit. Previously Fusarium tricinctum has been reported to be the primary cause of fruit rot in Lanzhou Lily throughout the world. Our report is the first to show results that indicate that B. safensis, S. maltophilia and M. pulcherrima are pathogenic in Lanzhou Lily in China. This is the first report on the bacteria and yeast that infect Lanzhou Lily fruits.     

革兰氏阴性菌IX型分泌系统的研究进展

IX型分泌系统(Type IX Secretion System,T9SS)是一种最新发现的存在于许多革兰氏阴性细菌中的分泌系统。T9SS参与细菌的毒力和滑行运动及复杂生物聚合物的降解过程。近年来,与T9SS相关的研究一直都是微生物学领域关注的热点。本文就T9SS的发现、组成与结构、分泌机制及调控机制等方面的研究进展进行综述,以期为进一步解析细菌的T9SS提供新的思路。     

Diseases of insects and other arthropods: results of diagnostic research over 55 years

Arthropods and especially insects are attacked by many arthropod-pathogenic organisms belonging to viruses, bacteria including rickettsiae, fungi, microsporidia, protists, and nematodes. They may cause lethal or chronic diseases. For 55 years, research on all kinds of arthropod diseases was conducted at the Institute for Biological Control, Darmstadt, formerly belonging to the Federal Biological Research Centre for Agriculture and Forestry (BBA) that became part of the newly founded Julius Kühn-Institute. Special attention is still being paid to diagnostics. During this period, about 1900 accessions comprising many thousands of dead or diseased specimens from 21 different arthropod orders were examined and the causative agents diagnosed. In the present paper, about 450 arthropod species, mainly insects, are listed together with the group and scientific name of the diagnosed arthropod pathogens and the origin (country) of the accession.     

Pneumococcal Colonization and Virulence Factors Identified Via Experimental Evolution in Infection Models

Streptococcus pneumoniae is a commensal of the human nasopharynx and a major cause of respiratory and invasive disease. We examined adaptation and evolution of pneumococcus, within nasopharynx and lungs, in an experimental system where the selective pressures associated with transmission were removed. This was achieved by serial passage of pneumococci, separately, in mouse models of nasopharyngeal carriage or pneumonia. Passaged pneumococci became more effective colonizers of the respiratory tract and we observed several examples of potential parallel evolution. The cell wall-modifying glycosyltransferase LafA was under strong selection during lung passage, whereas the surface expressed pneumococcal vaccine antigen gene pvaA and the glycerol-3-phosphate dehydrogenase gene gpsA were frequent targets of mutation in nasopharynx-passaged pneumococci. These mutations were not identified in pneumococci that were separately evolved by serial passage on laboratory agar. We focused on gpsA, in which the same single nucleotide polymorphism arose in two independently evolved nasopharynx-passaged lineages. We describe a new role for this gene in nasopharyngeal carriage and show that the identified single nucleotide change confers resistance to oxidative stress and enhanced nasopharyngeal colonization potential. We demonstrate that polymorphisms in gpsA arise and are retained during human colonization. These findings highlight how within-host environmental conditions can determine trajectories of bacterial evolution. Relative invasiveness or attack rate of pneumococcal lineages may be defined by genes that make niche-specific contributions to bacterial fitness. Experimental evolution in animal infection models is a powerful tool to investigate the relative roles played by pathogen virulence and colonization factors within different host niches.     

Temperature and seedling age affect susceptibility of perennial ryegrass seedlings to pathogenic fungi

Summary Effects of temperature and seedling age on survival of perennial ryegrass (Lolium perenne L.) seedlings grown on sand-wheat wholemeal cultures of different isolates ofFusarium spp. (9 isolates),Pythium spp. (9 isolates), andChaetomium spp. (1 isolate) are reported. Some isolates were virulent over the whole range of temperatures tested (7.5–27.5°C). The virulence of others depended on temperature. Most isolates were less virulent at intermediate temperatures (12.5–22.5°C) than at higher or lower temperatures. At 25°C ryegrass seedlings were susceptible to fungal attack for only a limited period after germination commenced. This period differed for different fungi, but for most isolates tested, seedlings were resistant after 2–3 days.     

Enhanced microbial safety of channel catfish (Ictalurus punctatus) fillet using recently invented medium molecular weight water-soluble chitosan coating

Chitosan with higher molecular weight exhibited higher antimicrobial efficacy against foodborne pathogens. However, the poor water solubility of higher or medium molecular weight chitosan limits its applications. To overcome the challenge, our research team searched for simple preparation procedure for fast-dissolving medium molecular weight chitosan in water. Throughout the process, we were able to obtain a higher concentration of medium molecular weight water-soluble (MMWWS) chitosan (400 kDa). The MMWWS chitosan showed physicochemical properties that are suitable for edible coating. Antibacterial activities of 400-kDa chitosan coating prepared in acetic acid (1% v/v) or aspartic acid (1% or 3% w/v) were examined. The surface of catfish cubes was inoculated with six foodborne pathogens and then coated with chitosan solutions. The survival of each pathogen was evaluated during shelf life storage. Compared with the control, 3% w/v chitosan coating in aspartic acid solution exhibited the most effective antibacterial activities among other coating treatments, completely inhibiting Vibrio parahaemolyticus on the surface of catfish. The study suggested that chitosan dissolved in aspartic acid has the potential for use as an alternative antimicrobial coating for catfish fillet.