Bacterias nosocomiales emergentes: Infección endovascular por Elizabethkingia meningoseptica / Emerging nosocomial bacteria: Endovascular infection by Elizabethkingia meningoseptica

Elizabethkingia meningoseptica es un bacilo gram negativo no fermentador, no móvil, y oxidasa positivo, ampliamente distribuido en la naturaleza pero poco frecuente en humanos, en quienes se considera un patógeno oportunista, actualmente denominado emergente. En el ambiente hospitalario se ha encontrado en superficies húmedas y en equipos médicos, soluciones que habitualmente se utilizan de forma intravenosa, y en medicamentos de reconstitución. Puede causar infección en personas inmunocomprometidas o con enfermedades debilitantes concomitantes. Además, posee enzimas de resistencia frente a los antibióticos prescritos usualmente contra las bacterias gram negativas. Se presenta un caso de bacteriemia por E. meningoseptica en un paciente con antecedente de enfermedad renal crónica, quien recibía tratamiento hemodíalítico 3 veces por semana, desde hace 2 años, al ingreso se documentó infección del sitio de inserción del catéter venoso central, y posteriormente se aisló en los hemocultivos periféricos el crecimiento de la bacteria E. meningoseptica, el paciente cumplió tratamiento con trimetroprim-sulfametoxazol por 14 días con adecuada evolución clínica, sin complicaciones...(AU)

Elizabethkingia meningoseptica is a non fermenter bacilli gram negative, non-mobile, and positive oxidase, widely distributed in nature but rare in humans, in whom it is considered an opportunistic pathogen, now called emerging. In the hospital environment it was found on wet surfaces and medical equipment, solutions usually used intravenously, and drug reconstitution. It can cause infection in immunocompromised or with concomitant debilitating diseases people. It also has resistance to enzymes usually prescribed antibiotics against gram negative bacteria. A case of bacteremia is presented by E. meningoseptica in a patient with a history of chronic kidney disease, who received hemodialysis 3 times a week, for 2 years, entry site infection insertion of central venous catheter was documented and later was isolated from peripheral blood cultures the growth of bacteria E. meningoseptica, the patient completed treatment with trimethoprim-sulfamethoxazole for 14 days with adequate clinical course without complications...(AU)

An optofluidic imaging system to measure the biophysical signature of single waterborne bacteria.

In this paper, for the first time, an on-chip optofluidic imaging system is innovated to measure the biophysical signatures of single waterborne bacteria, including both their refractive indices and morphologies (size and shape), based on immersion refractometry. The key features of the proposed optofluidic imaging platform include (1) multiple sites for single-bacterium trapping, which enable parallel measurements to achieve higher throughput, and (2) a chaotic micromixer, which enables efficient refractive index variation of the surrounding medium. In the experiments, the distinctive refractive index of Echerichia coli, Shigella flexneri and Vibrio cholera are measured with a high precision of 5 × 10(-3) RIU. The developed optofluidic imaging system has high potential not only for building up a database of biophysical signatures of waterborne bacteria, but also for developing single-bacterium detection in treated water that is in real-time, label-free and low cost.

Crystallization and preliminary X-ray analysis of flavocytochrome c(3), the fumarate reductase from Shewanella frigidimarina.

The fumarate reductase (flavocytochrome c(3)) from Shewanella frigidimarina (formerly S. putrefaciens) NCIMB400 has been crystallized in the space group P2(1), with cell dimensions of a = 45.447 A, b = 92.107 A, c = 78.311 A, and beta = 91.038 degrees and one molecule per asymmetric unit. A native data set has been collected to 1.8 A. The gene encoding Fcc(3) from the S. frigidimarina type strain ACAM591 has been cloned and sequenced and the protein crystallized in space group P2(1) with cell dimensions of a = 45.359 A, b = 88.051 A, c = 77.473 A, and beta = 104.499 degrees. Anomalous data have also been collected from the NCIMB400 crystal allowing the heme iron positions to be identified.

Structure of the acidic polysaccharide chain of the lipopolysaccharide of Shewanella alga 48055.

A lipopolysaccharide (LPS) with an acidic polysaccharide chain was isolated from the bacterium Shewanella alga strain 48055 and cleaved selectively at the glycosidic linkage of N-acetylneuraminic acid to give a tetrasaccharide. Studies of the tetrasaccharide and the O-deacylated LPS by 1H and 13C NMR spectroscopy, including 2D COSY, TOCSY, NOESY, rotating-frame NOE spectroscopy (ROESY), and H-detected 1H, 13C heteronuclear multiple-quantum coherence (HMQC) experiments, revealed the following structure of the polysaccharide repeating unit: -->3)-beta-D-GalpA6GroN-(1-->3)-beta-D-GlcpNAc-(1-->3)-alpha-D- GalpA6GroN- (1-->4)-alpha-Neup5Ac-(2--> where GroN is an amidically linked residue of 2-amino-1,3-propanediol (2-amino-2-deoxyglycerol). A similar structure, but with 2-acetamido-2,6-dideoxy-D-glucose instead of 2-acetamido-2-deoxy-D-glucose, has been reported previously for the polysaccharide chain of a non-O1 Vibrio cholerae H11 LPS [E. V. Vinogradov, O. Holst, J.E. Thomas-Oates, K.W. Broady, and H. Brade, Eur. J. Biochem., 210 (1992) 491-498].

Structure of a phosphorylated polysaccharide from Shewanella putrefaciens strain S29.

A phosphorylated polysaccharide was isolated from the aqueous layer of the phenol-water extract of a non-halophilic bacterium Shewanella putrefaciens strain S29. The glycosyl phosphate linkage in the polysaccharide was split under mild acid conditions to give, after borohydride reduction, a phosphorylated oligosaccharide-alditol. On the basis of sugar analysis and 1H, 13C and 31P NMR spectroscopy, including 2D COSY, relayed COSY, rotating-frame NOE spectroscopy (ROESY), heteronuclear 13C,1H COSY, and H-detected heteronuclear 1H,31P multiple-quantum coherence (HMQC), it was concluded that the polysaccharide is built up of tetrasaccharide-phosphate repeating units having the following structure: [sequence: see text] where QuiNAc and Qui4NAc are 2-acetamido-2,6-dideoxyglucose and 4-acetamido-4,6-dideoxyglucose, respectively.

Shewanella woodyi sp. nov., an exclusively respiratory luminous bacterium isolated from the Alboran Sea.

Thirty-four strains of nonfermentative, respiratory, luminous bacteria were isolated from samples of squid ink and seawater from depths of 200 to 300 m in the Alboran Sea. Although these strains had a few properties similar to properties of Shewanella (Alteromonas) hanedai, they did not cluster phenotypically with any previously described bacterium. The nucleotide sequence of a 740-bp segment of luxA was not homologous with other known luxA sequences but clustered with the luxA sequences of Shewanella hanedai, Vibrio logei, Vibrio fischeri, and Photobacterium species. The 16S RNA gene from two strains was sequenced and was found to be most closely related to the S. hanedai 16S RNA gene. Based on the differences observed, we describe the new isolates as members of new species, Shewanella woodyi sp. nov. Strain ATCC 51908 (= MS32) is the type strain of this new species.

Shewanella gelidimarina sp. nov. and Shewanella frigidimarina sp. nov., novel Antarctic species with the ability to produce eicosapentaenoic acid (20:5 omega 3) and grow anaerobically by dissimilatory Fe(III) reduction.

A polyphasic taxonomic study was performed to characterize dissimilatory iron-reducing strains mostly isolated from Antarctic sea ice. The strains were isolated from samples of congelated (land-fast) sea ice, grease ice, and ice algal biomass collected from the coastal areas of the Vestfold Hills in eastern Antarctica (68 degrees S 78 degrees E). The strains were facultatively anaerobic, motile, and rod shaped, were capable of anaerobic growth either by fermentation of carbohydrates or by anaerobic respiration, and utilized a variety of electron acceptors, including nitrate, ferric compounds, and trimethylamine N-oxide. A phylogenetic analysis performed with 16S rRNA sequences showed that the isolates formed two groups representing novel lineages in the genus Shewanella. The first novel group included seawater-requiring, psychrophilic, chitinolytic strains which had DNA G + C contents of 48 mol%. The members of the second strain group were psychrotrophic and did not require seawater but could tolerate up to 9% NaCl. The strains of this group were also unable to degrade polysaccharides but could utilize a number of monosaccharides and disaccharides and had G + C contents of 40 to 43 mol%. The whole-cell-derived fatty acid profiles of the sea ice isolates were found to be similar to the profiles obtained for other Shewanella species. The omega-3 polyunsaturated fatty acid eicosapentaenoic acid (EPA) (20:5 omega 3) was detected in all of the sea ice isolates at levels ranging from 2 to 16% of the total fatty acids. EPA was also found at high levels in Shewanella hanedai (19 to 22%) and Shewanella benthica (16 to 18%) but was absent in Shewanella alga and Shewanella putrefaciens. On the basis of polyphasic taxonomic data, the Antarctic iron-reducing strains are placed in two new species, Shewanella frigidimarina sp. nov. (type strain, ACAM 591) and Shewanella gelidimarina sp. nov. (type strain, ACAM 456).

Differentiation of Shewanella putrefaciens and Shewanella alga on the basis of whole-cell protein profiles, ribotyping, phenotypic characterization, and 16S rRNA gene sequence analysis.

Seventy-six presumed Shewanella putrefaciens isolates from fish, oil drillings, and clinical specimens, the type strain of Shewanella putrefaciens (ATCC 8071), the type strain of Shewanella alga (IAM 14159), and the type strain of Shewanella hanedai (ATCC 33224) were compared by several typing methods. Numerical analysis of sodium dodecyl sulfate-polyacrylamide gel electrophoresis of whole-cell protein and ribotyping patterns showed that the strains were separated into two distinct clusters with 56% +/- 10% and 40% +/- 14% similarity for whole-cell protein profiling and ribotyping, respectively. One cluster consisted of 26 isolates with 52 to 55 mol% G + C and included 15 human isolates, mostly clinical specimens, 8 isolates from marine waters, and the type strain of S. alga. This homogeneous cluster of mesophilic, halotolerant strains was by all analyses identical to the recently defined species S. alga (U. Simidu et al., Int. J. Syst. Bacteriol, 40:331-336, 1990). Fifty-two typically psychrotolerant strains formed the other, more heterogeneous major cluster, with 43 to 47 mol% G + C. The type strain of S. putrefaciens was included in this group. The two groups were confirmed by 16S rRNA gene sequence analysis. It is concluded that the isolates must be considered two different species, S. alga and S. putrefaciens, and that most mesophilic isolates formerly identified as S. putrefaciens belong to S. alga. The ecological role and potential pathogenicity of S. alga can be evaluated only if the organism is correctly identified.

Outer membrane cytochromes of Shewanella putrefaciens MR-1: spectral analysis, and purification of the 83-kDa c-type cytochrome.

The metal-reducing bacterium Shewanella putrefaciens MR-1 is known to localize a majority of its membrane-bound cytochromes to its outer membrane when grown under anaerobic conditions. In this study, pyridine hemochrome spectra confirmed that these outer membrane cytochromes are c-type, and electrophoretic data demonstrated the presence of four distinct outer membrane cytochromes, with apparent molecular masses of 150, 83, 65, and 53 kDa. Fourth-order derivative analysis of 77 K spectra of the outer membrane revealed four spectrally distinct c-type hemes, with peaks at 545.4, 548.0, 550.6, and 552.6 nm. Outer membrane cytochromes in the reduced state were rapidly re-oxidized by oxidized iron and manganese, which have previously been shown to serve as electron acceptors for anaerobic respiration in this bacterium. The 83-kDa outer membrane cytochrome was purified and a specific polyclonal antibody was generated against this protein. Western blot analysis demonstrated that the vast majority of this protein was localized to the outer membrane and an intermediate density membrane fraction of similar composition. Its levels, but not its subcellular distribution, were somewhat influenced by the electron acceptor used to support anaerobic growth, with levels higher in fumarate-grown cells relative to iron(III)- or trimethylamine N-oxide-grown cells. Its specific content in cells grown under aerobic conditions was only 14% of that of fumarate-grown cells, suggesting that a switch to anaerobic conditions significantly increases the de novo synthesis of this outer membrane cytochrome.

Structure and properties of novel inclusions in Shewanella putrefaciens.

Cytoplasmic inclusions surrounded by a bilayer membrane were seen in thin sections. negatively stained and freeze-fractured preparations of Shewanella putrefaciens. Cells harvested from the late exponential and early stationary phase showed a higher number of these vesicles than bacteria isolated from early exponential or late stationary phase. Chemical dyes for polyphosphate or poly-beta-hydroxybutyrate did not stain the material enclosed within these vesicles. Elemental analysis of the material indicated that the content was organic in nature and might be a protein. HPLC analysis of the material showed that it was probably not a carbon source, nor an electron acceptor used by S. putrefaciens.

Analysis of polar lipids from some representative enterobacteria, Plesiomonas and Acinetobacter by fast atom bombardment-mass spectrometry.

Fast atom bombardment-mass spectrometry (FAB-MS) was used to analyse lipid extracts of bacteria to assess its usefulness for analysing anionic phospholipids of potential chemotaxonomic value. The following micro-organisms were tested: Acinetobacter calcoaceticus, Acinetobacter sp., Citrobacter freundii, Enterobacter cloacae (2 strains), Escherichia coli (3 strains), Hafnia alvei, Klebsiella oxytoca, Klebsiella pneumoniae, Morganella morganii, Plesiomonas shigelloides, Proteus mirabilis (3 strains), Serratia liquefaciens and Serratia marcescens. Negative-ion spectra provide data for twenty-seven major carboxylate anions (m/z 209-325) and for thirty-seven major phospholipid anions (m/z 645-774). Generally, the largest carboxylate peaks were due to 16:1, 16:0, cyc17 and 18:1 while the largest phospholipid anion peaks were due to PE(32:1), PE(33:1), PE(34:1), PE(34:2), PG(30:2), PG(31:2), PG(32:2), PG(34:1) and PS(33:0). However, quantitative differences were observed. For example, Acinetobacter lacked PE (33:1) but had exceptionally high peaks at m/z 748, PS(33:0), and m/z 281, octadecanoate. Unknown 'carboxylate' peaks were detected at m/z 254, 256, 261, 268, 282 and 301. In some cases, unknown peaks appeared to constitute possible homologous series being separated by delta m/z of 14(identical to methylene). For chemotaxonomic purposes, the complexity of the data required numerical analysis. Using the Pearson coefficient of linear correlation, as a measure of association, it was possible to compare all strains analysed. Typical results for strain comparisons were as follows: Ent. cloacae vs Ent. cloacae, r = 0.90 (Ent. cloacae vs Ac. calcoaceticus, r = 0.46). Thus FAB-MS represents an excellent means of obtaining large quantities of data on polar lipids of a range of bacterial isolates, which may be suitable for chemotaxonomic purposes.