多药耐药菌感染重症肺炎患者预后的危险因素分析

摘要 目的：探讨多药耐药菌感染重症肺炎患者预后的危险因素。方法：选取本院2019年5月至2022年5月收治的198例重症肺炎患者,根据患者在ICU住院期间是否死亡分为存活组（121例）和死亡组（77例）。对重症肺炎患者多药耐药菌感染情况,多药耐药G⁺耐药情况,多药耐药G^-耐药情况进行分析,对影响多药耐药菌感染重症肺炎患者预后危险因素的单因素分析,将单因素分析中差异有统计学意义的变量进行多因素Logistic回归分析,筛选影响多药耐药菌感染重症肺炎患者预后的危险因素。结果：198例重症肺炎患者中,多药耐药菌感染患者60例,占比30.30 %,共分离出病原菌290株,其中多药耐药菌65株,占比22.41 %,其中占比比较高的有鲍曼不动杆菌（23.08 %）、铜绿假单胞菌（20.00 %）、金黄色葡萄球菌（20.00 %）、肠炎克雷伯菌（10.77 %）;重症肺炎患者多药耐药G⁺对青霉素、克林霉素、红霉素等具有较高的耐药性,而对万古霉素、替考拉宁、替加环素较为敏感;重症肺炎患者多重耐药G^-对多种抗菌药物均表现出耐药性,其中对头孢他啶、头孢吡肟等具有较高的耐药性;单因素分析结果显示,死亡组患者中男性、年龄≥70岁、APACHEⅡ评分≥26分、有创通气的患者占比显著高于存活组,碳青霉烯类抗生素使用的患者占比显著低于存活组（均P<0.05）,两组患者肺部基础疾病、脑血管疾病、高血压、联合使用其他抗生素的占比,以及两组患者机械通气时间比较无差异（均P>0.05）;纳入多因素非条件Logistic回归模型分析显示,男性、年龄≥70岁、APACHEⅡ评分≥26分、有创通气为多药耐药菌感染重症肺炎患者预后的危险因素（OR=1.568、1.203、2.812、1.674,均P<0.05）,而碳青霉烯类抗生素使用是多药耐药菌感染重症肺炎患者预后的保护因素（OR=0.542,P<0.05）。结论：多药耐药菌感染重症肺炎患者的主要菌株为鲍曼不动杆菌,且男性、年龄≥70岁、APACHEⅡ评分≥26分、有创通气为多药耐药菌感染重症肺炎患者预后的危险因素,而碳青霉烯类抗生素使用是多药耐药菌感染重症肺炎患者预后的保护因素。     

Algae-associated marine molluscs in the Azores

The raolluscan fauna of a special habitat, the high intertidal algal turf, was studied at four stations on the island of Sao Miguel, Azores. The number of species found ranged from 13 to 23. However, a small group of only six species (the bivalve Lasaea adansoni and the gastropods Pisinna punctulum, Omalogyra atomus, Fossarus ambiguus, Skeneopsis planorbis and Alvania postrema) accounted for more than 80% of all the specimens collected. Mollusc density reached values of 20000 specimens per 100 g algal dry weight. The abundance and number of species of molluscs was comparable with those reported for algal zones lower on the Azorean shores.
Wave exposure and seasonality effects were found to be small, presumably because of the relatively mild abiotic conditions and the protective role of the turf. The algal substrata influenced the phytal molluscan community in two ways. First, the abundance of molluscs was significantly correlated with algal dry weight. Secondly, molluscan abundance and diversity were influenced by the algal composition of the turf. A rich algal composition, with several species of branched fleshy and coralline algae, was associated with a rich molluscan fauna. The dominance of coralline algae resulted in a abundant but species-poor fauna, while an almost monospecific turf of Gigartina was poor in both species and number of molluscan fauna.     

Effects of Caenorhabditis elegans (Nematoda: Rhabditidae) on the spread of the bacterium Pseudomonas tolaasii in mushrooms (Agaricus bisporus)

The effects of mass-produced saprobic rhabditid nematodes, Caenorhabditis elegans on the spread of the bacterial blotch pathogen, Pseudomonas tolaasii , were studied in mushroom growth chambers. C. elegans significantly reduced the intensity of blotch on sporophores. Repeated isolations of the bacterial flora from the gut of C. elegans recovered from mushroom sporophores during cropping, revealed the presence of Pseudomonas fluorescens biovar reactans . All the isolates of P. fluorescens biovar reactans isolated from nematodes were antagonists of P. tolaasii .
C. elegans produced much larger populations in monoxenic cultures with P. fluorescens biovar reactans than with P. tolaasii . It is suggested that as C. elegans selects P. fluorescens biovar reactans rather than P. tolaasii as a food substrate it probably spreads the antagonist in the mushroom crop and may contribute to the control of bacterial blotch.     

Solving the problem of how to eat something as big as yourself: Diverse bacterial strategies for degrading polysaccharides

Polysaccharide digestion by bacteria is an important activity in many ecosystems, and a number of bacterial genera can perform this function. Although many papers have been published about the properties of isolated polysaccharide-degrading enzymes, relatively little is known about how intact bacteria degrade polysaccharides. This review summarizes recent findings suggesting that there are at least three different strategies. the most familiar one is the excretion of extracellular polysaccharidases, which diffuse to and degrade nearby polysaccharides. An example of this type of strategy is provided by the plant pathogen,Erwinia spp. A second strategy is to have the enzyme exposed to the extracellular medium but attached to the surface of the cell. Examples of this strategy are provided by the pullulanase system ofKlebsiella oxytoca and the cellulosomes ofClostridium thermocellum. A strategy that could be seen as a combination of the extracellular enzyme strategy and the surface organelle strategy is provided byVibrio harveyi, which attaches to its substrate, chitin, via proteins that appear to be specialized for attachment and produces extracellular enzymes that attack the chitin. A third strategy is to import the polysaccharide, as appears to be done byBacteroides spp. In this instance, the polysaccharide is bound to an outer membrane receptor, then passes into the periplasm where the degradative enzymes are located. The ecological advantages and disadvantages of these systems are discussed, and areas where further research is needed are defined.     

Construction and characterization of two rice bacterial artificial chromosome libraries from the parents of a permanent recombinant inbred mapping population

Rice is a leading grain crop and the staple food for over half of the world population. Rice is also an ideal species for genetic and biological studies of cereal crops and other monocotyledonous plants because of its small genome and well developed genetic system. To facilitate rice genome analysis leading to physical mapping, the identification of molecular markers closely linked to economic traits, and map-based cloning, we have constructed two rice bacterial artificial chromosome (BAC) libraries from the parents of a permanent mapping population (Lemont and Teqing) consisting of 400 F9 recombinant inbred lines (RILs). Lemont (japonica) and Teqing (indica) represent the two major genomes of cultivated rice, both are leading commercial varieties and widely used germplasm in rice breeding programs. The Lemont library contains 7296 clones with an average insert size of 150 kb, which represents 2.6 rice haploid genome equivalents. The Teqing library contains 14208 clones with an average insert size of 130 kb, which represents 4.4. rice haploid genome equivalents. Three single-copy DNA probes were used to screen the libraries and at least two overlapping BAC clones were isolated with each probe from each library, ranging from 45 to 260 kb in insert size. Hybridization of BAC clones with chloroplast DNA probes and fluorescent in situ hybridization using BAC DNA as probes demonstrated that both libraries contain very few clones of chloroplast DNA origin and are likely free of chimeric clones. These data indicate that both BAC libraries should be suitable for map-based cloning of rice genes and physical mapping of the rice genome.     

Cloning,expression, and crystallization of the V delta domain of a human gamma delta T-cell receptor.

T-lymphocytes recognize a wide variety of antigens through highly diverse cell-surface glycoproteins known as T-cell receptors (TCRs). These disulfide-linked heterodimers are composed of alpha and beta or gamma and delta polypeptide chains consisting of variable (V) and constant (C) domains non-covalently associated with at least four invariant chains to form the TCR-CD3 complex. It is well established that alpha beta TCRs recognize antigen in the form of peptides bound to molecules of the major histocompatibility complex (MHC); furthermore, information on the three-dimensional structure of alpha beta TCRs has recently become available through X-ray crystallography. In contrast, the antigen specificity of gamma delta TCRs is much less well understood and their three-dimensional structure is unknown. We have cloned the delta chain of a human TCR specific for the MHC class I HLA-A2 molecule and expressed the V domain as a secreted protein in the periplasmic space of Escherichia coli. Following affinity purification using a nickel chelate adsorbent, the recombinant V delta domain was crystallized in a form suitable for X-ray diffraction analysis. The crystals are orthorhombic, space group P2(1)2(1)2 with unit cell dimensions a = 69.9, b = 49.0, c = 61.6 A. and diffract to beyond 2.3 A resolution. The ability of a V delta domain produced in bacteria to form well-ordered crystals strongly suggests that the periplasmic space can provide a suitable environment for the correct in vivo folding of gamma delta TCRs.     

Cellular responses to enteropathogenicEscherichia coli infection

EnteropathogenicEscherichia coli (EPEC), first described in the 1940's and 1950's, remain an important cause of severe infantile diarrhoea in many parts of the developing world. EPEC do not produce enterotoxins and are not invasive; instead their virulence depends upon exploitation of host cell signalling pathways and the host cell cytoskeleton both as a means of colonizing mucosal surfaces of the small intestine and causing diarrhoea. Following initial mucosal attachment, EPEC secrete signalling proteins and expresss a surface adhesin, intimin, to produce attaching & effacing lesions in the enterocyte brush border membrane characterised by localised destruction of brush border microvilli, intimate bacterial adhesion and cytoskeletal reorganisation and accretion beneath attached bacteria. The pathophysiology of EPEC diarrhoea is also complex and probably results from a combination of epithelial cell responses including both electrolyte secretion and structural damage.     

Seleno-lactobacillus

Lactic acid bacteria are nonpathogenic bacteria commonly used in food processing. An evaluation was made of the capacity to concentrate selenium in species of Lactobacillus. A selenium concentration of 1 μg/mL in the culture medium yielded in a bacterial content of 400 μg/g dry biomass. Dialysis and TCA precipitation experiments of a native intracellular extract proved that at least 80% of the total selenium is associated with organic molecules. Seleno-cysteine was identified as the only seleno-amino acid present in the intracellular selenoproteins. This study shows that species of the lactic acid bacteria are able to concentrate selenium intracellular as seleno-cysteine, which could be applied in supplementation studies.     

Yeast communities as descriptors of habitat use by the Drosophila fasciola subgroup (repleta group) in Atlantic rain forests

Yeast communities associated with four species of the Drosophila fasciola subgroup (repleta group) in tropical rain forests were surveyed in an abandoned orchard, and rain forest sites of Rio de Janeiro and Ilha Grande, State of Rio de Janeiro, Brazil. Adult flies of Drosophila carolinae, Drosophila coroica, Drosophila fascioloides and Drosophila onca frequently carried Candida colliculosa, Geotrichum sp, Kloeckera apiculata and a Pichia membranaefaciens-like species. The most frequent yeasts in the crop of flies included Candida collicullosa, C. krusei, Pichia kluyveri and a P. membranaefaciens-like species. The physiological abilities and species composition of these yeast communities differed from those of other forest-inhabiting Drosophila. The narrow feeding niches of the fasciola subgroup suggested the use of only part of the substrates available to the flies as food in the forest environment, as noted previously for cactophilic Drosophila serido (mulleri subgroup of the repleta group) in a sand dune ecosystem. The cactophilic yeasts that were isolated have not been previously found in forests. The fasciola subgroup probably used epiphytic cactus substrates as breeding and feeding sites in the forest. The physiological profile of yeasts associated with the fasciola flies was broader than that of yeasts associated with the cactophilic Drosophila serido, suggesting that the fasciola subgroup represents an older lineage from which the South American repleta species evolved.