Ralstonia mannitolilytica-Induced Septicemia and Homology Analysis in Infected Patients: 3 Case Reports.

BACKGROUND: Ralstonia mannitolilytica is an emerging opportunistic pathogen. Hospital outbreaks of Ralstonia spp. are mainly associated with contaminated treatment water or auxiliary instruments. OBJECTIVES: In this report, we summarize the clinical infection characteristics of R. mannitolilytica, the drug-susceptibility testing of the bacterial strains, and the results of related infection investigations. PATIENTS AND METHODS: We retrospectively analyzed the clinical information of 3 patients with R. mannitolilytica. RESULTS: The patients' primary-onset symptoms were chills and fever. The disease progressed rapidly and septic shock symptoms developed. Laboratory tests indicated progressively decreased white blood cells and platelets, as well as significant increases in certain inflammation indicators. The effect of treatment with Tazocin was good. The growth period of R. mannitolilytica in sterile distilled water was > 6 months. The pulsed-field gel electrophoresis (PFGE) results revealed that the infectious strains from these 3 patients were not the same clonal strain. This bacterium was not detected in the nosocomial infection samples. CONCLUSIONS: Our results suggest that R. mannitolilytica-induced septicemia had an acute disease onset and rapid progression. The preferred empirical antibiotic was Tazocin. In these 3 cases, the R. mannitolilytica-induced septicemia was not due to clonal transmission.

Improvements on high-precision measurement of bromine isotope ratios by multicollector inductively coupled plasma mass spectrometry.

A new, feasible procedure for high-precision bromine isotope analysis using multicollector inductively coupled plasma mass spectrometry (MC-ICP-MS) is described. With a combination of HR mass resolution mode and accurate optimization of the Zoom Optics parameters (Focus Quad: -1.30; Zoom Quad: 0.00), the challenging problem of the isobaric interferences ((40)Ar(38)ArH(+) and (40)Ar(40)ArH(+)) in the measurement of bromine isotopes ((79)Br(+), (81)Br(+)) has been effectively solved. The external reproducibility of the measured (81)Br/(79)Br ratios in the selected standard reference materials ranged from ±0.03‰ to ±0.14‰, which is superior to or equivalent to the best results from previous contributions. The effect of counter cations on the Br(+) signal intensity and the instrumental-induced mass bias was evaluated as the loss of HBr aerosol in nebulizer and potential diffusive isotope fractionations.

An improved procedure for separation/purification of boron from complex matrices and high-precision measurement of boron isotopes by positive thermal ionization and multicollector inductively coupled plasma mass spectrometry.

In order to eliminate boron loss and potential isotopic fractionation during chemical pretreatment of natural samples with complex matrices, a three-column ion-exchange separation/purification procedure has been modified, which ensures more than 98% recovery of boron from each step for a wide range of sample matrices, and is applicable for boron isotope analysis by both TIMS and MC-ICP-MS. The PTIMS-Cs2BO2(+)-static double collection method was developed, ensuring simultaneous collection of (133)Cs2(11)B(16)O2(+)(m/z 309) and (133)Cs2(10)B(16)O2(+) (m/z 308) ions in adjacent H3-H4 Faraday cups with typical zoom optics parameters (Focus Quad: 15 V, Dispersion Quad: -85 V). The external reproducibilities of the measured (11)B/(10)B ratios of the NIST 951 boron standard solutions of 1000 ng, 100 ng and 10 ng of boron by PTIMS method are ±0.06‰, ±0.16‰ and ±0.25‰, respectively, which indicates excellent precision can be achieved for boron isotope measurement at nanogram level boron in natural samples. An on-peak zero blank correction procedure was employed to correct the residual boron signals effect in MC-ICP-MS, which gives consistent δ(11)B values with a mean of 39.66±0.35‰ for seawater in the whole range of boron content from 5 ppb to 200 ppb, ensuring accurate boron isotope analysis in few ppb boron. With the improved protocol, consistent results between TIMS and MC-ICP-MS data were obtained in typical geological materials within a wide span of δ(11)B values ranging from -25‰ to +40‰.

Virulence and transferability of resistance determinants in a novel Klebsiella pneumoniae sequence type 1137 in China.

A study was designed to characterize three carbapenemase-producing Klebsiella pneumoniae isolated from pediatric patients in China. Molecular characterization was done using polymerase chain reaction and sequencing for blaVIM, blaNDM, blaIMP, blaKPC, blaCTX-Ms, blaOXAs, blaTEMs, and blaSHV; plasmid-mediated quinolone resistance determinants; aminoglycoside resistance determinants; multilocus sequencing typing; plasmid replicon typing; addiction; and virulence factors. Kp32 belonged to the newly described sequence type 1137, were positive for aac(6')-Ib-suzhou, qnrA1, qnrB4, qnrS1, aac(6')-Ib, rmtB, armA, blaSHV-12, blaCTX-M-15, blaKPC-2, and blaIMP-4; contained IncA/C plasmids that tested positive for K1 capsular antigens, the ccdAB (coupled cell division locus) addiction system and the wabG, ureA, rmpA, magA, allS, fimH, and the aerobactin virulence factors. However, the others belonged to clone ST11, and were positive for aac(6')-Ib-cr, qnrB4, blaCTX-M-14, blaSHV-11, aac(6')-Ib, rmtB, and blaKPC-2; contained IncFIA plasmids that tested positive for K2 capsular antigens, the vagCD addiction system and the uge, wabG, ureA, kfuBC, rpmA, and fimH virulence factors. ST1137 had more virulence factors than the comparative strains ST11. The blaKPC-2 gene was located on the IncFIA and IncA/C replicon groups of plasmids. An analysis of the genetic environment of blaKPC-2 gene has demonstrated that the blaKPC-2 gene was always associated with one of the Tn4401 isoforms (a or b). Our study suggested that K. pneumoniae carbapenemases being found in virulent K. pneumoniae should be emphasized, as this will eventually become a global health threat.

Efflux system overexpression and decreased OprD contribute to the carbapenem resistance among extended-spectrum beta-lactamase-producing Pseudomonas aeruginosa isolates from a Chinese university hospital.

The aim of this study was to investigate, for the first time, the combinations of carbapenem resistance mechanisms in clinical isolates of extended-spectrum beta-lactamase (ESBL)-producing Pseudomonas aeruginosa in a Chinese hospital. Pulsed-field gel electrophoresis revealed the presence of eight clonal types among the 15 ESBL producers. Multilocus sequence typing of two isolates harboured blaIMP-1 identified the clonal strain as ST325. All these genes were found either alone or simultaneously in the strains in the following five different arrangements:; ; ; ; . Regarding mutation-driven resistance, all, but four of the isolates had a relevant decrease of oprD expression. In addition, 73.3% of the isolates overexpressed mexB, 40% mexD, and 33.3% mexY. A specific combination of overexpressed mexB or mexY and alteration in loop L710 of OprD were significantly associated with meropenem resistance. In conclusion, combination of several mutation-driven mechanisms leading to OprD inactivation and overexpression of efflux systems was the main carbapenem resistance mechanism among the ESBL-producing P. aeruginosa isolates, but acquisition of a transferable resistance determinant such as metallo-ß-lactamase could be problematic in clinical settings in China.

Acquisition of carbapenem resistance in multiresistant Klebsiella pneumoniae isolates of sequence type 11 at a university hospital in China.

Four closely related KPC-producing Klebsiella pneumoniae strains, which were isolated from the patients with neonatal sepsis, harbored bla(CTX-M-14), bla(TEM-1), bla(CTX-M-15), bla(SHV-11),bla(SHV-12), class 1 integron, qnrS1, acc(6')-Ib-cr, and rmtB genes. Multilocus sequence typing experiments showed that all isolates but Kp122 were proven to share the same sequence type (ST), ST11. These isolates have not yet been previously reported in a university-affiliated children's hospital or in the city of Wenzhou.

Molecular characterization of the bla(KPC-2) gene in clinical isolates of carbapenem-resistant Klebsiella pneumoniae from the pediatric wards of a Chinese hospital.

The present study was conducted to confirm the presence of Klebsiella pneumoniae carbapenemase (KPC)-producing K. pneumoniae associated with a nosocomial outbreak in a Chinese pediatric hospital. From July 2009 to January 2011, 124 nonduplicated K. pneumoniae isolates were collected from specimens from patients of pediatric units in the hospital. Twelve of the 124 isolates possessed the bla(KPC-2) gene and showed 7 different pulsed-field gel electrophoresis (PFGE) patterns. Meanwhile, 16S rRNA methylase, acc(6')-Ib-cr, and several types of ß-lactamases were also produced by the majority of the KPC-producing isolates. Class 1 integron-encoded intI1 integrase gene was subsequently found in all strains, and amplification, sequencing, and comparison of DNA between 5' conserved segment and 3' conserved segment region showed the presence of several known antibiotic resistance gene cassettes of various sizes. The conjugation and plasmid-curing experiments indicated some KPC-2-encoding genes were transmissible. In addition, conjugal cotransfer of multidrug-resistant phenotypes with KPC-positive phenotypes was observed in KPC-producing strains. Restriction endonuclease analysis and DNA hybridization with a KPC-specific probe showed that the bla(KPC-2) gene was carried by plasmid DNA from K. pneumoniae of PFGE pattern B. The overall results indicate that the emergence and outbreak of KPC-producing K. pneumoniae in our pediatric wards occurred in conjunction with plasmids coharboring 16S rRNA methylase and extended-spectrum ß-lactamases.

Emission mechanism of polyatomic ions Cs2Cl+ and Cs2BO2(+) in thermal ionization mass spectrometry with various carbon materials.

The emission behavior of polyatomic ions Cs(2)Cl(+) and Cs(2)BO(2)(+) in the presence of various carbon materials (Graphite, Carbon, SWNTs, and Fullerenes) in the ionization source of thermal ionization mass spectrometry (TIMS) has been investigated. The emission capacity of various carbon materials are remarkably different as evidenced by the obvious discrepancy in signal intensity of polyatomic ions and accuracy/precision of boron and chlorine isotopic composition determined using Cs(2)Cl(+)-graphite-PTIMS/Cs(2)BO(2)(+)-graphite-PTIMS methods. Combined with morphology and microstructure properties of four selected carbon materials, it could be concluded that the emission behavior of the polyatomic ions strongly depends on the microstructure of the carbon materials used. A surface-induced collision mechanism for formation of such kinds of polyatomic ions in the ionization source of TIMS has been proposed based on the optimized configuration of Cs(2)BO(2)(+) and Cs(2)Cl(+) ions in the gas phase using a molecular dynamics method. The combination of the geometry of the selected carbon materials with the configuration of two polyatomic ions explains the structure effect of carbon materials on the emission behavior of polyatomic ions, where graphite samples with perfect parallels and equidistant layers ensure the capacity of emission to the maximum extent, and fullerenes worsen the emission of polyatomic ions by blocking their pathway.

Early Cambrian ocean anoxia in South China.

The cause of the most marked changes in the evolution of life, which define the first-order stratigraphic boundary between the Precambrian and the Phanerozoic eon, remains enigmatic and a highly topical subject of debate. A global ocean anoxic event, triggered by large-scale hydrogen sulphide (H(2)S) release to surface waters, has been suggested by Wille et al., on the basis of two data sets from South China and Oman, to explain the fundamental biological changes across the Precambrian/Cambrian (PC/C) boundary. Here we report a new precise SHRIMP U-Pb zircon age of 532.3 +/- 0.7 million years (Myr) ago (Fig. 1) for a volcanic ash bed in the critical unit that reflects the ocean anoxic event, the lowermost black shale sequence of the Niutitang Formation in the Guizhou Province, South China. This age is significantly younger than the precise PC/C boundary age of 542.0 +/- 0.3 Myr ago, approximately 10 Myr younger than the extinction of the Ediacaran fauna, and thus challenging the view of a major ocean anoxic event having been responsible for the major changes in the direction of evolution at the PC/C boundary.