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Central China has been reported to be one of the most important endemic areas of zoonotic infection by spotted fever group rickettsiae (SFGR), severe fever with thrombocytopenia syndrome virus (SFTSV) and hantaan virus (HTNV). Due to similar clinical symptoms, it is challenging to make a definite diagnosis rapidly and accurately in the absence of microbiological tests. In the present study, an all-in-one real-time PCR assay was developed for the simultaneous detection of nucleic acids from SFGR, SFTSV and HTNV. Three linear standard curves for determining SFGR-ompA, SFTSV-L and HTNV-L were obtained within the range of 101-106 copies/µL, with the PCR amplification efficiencies ranging from 93.46% to 96.88% and the regression coefficients R2 of >0.99. The detection limit was 1.108 copies/µL for SFGR-ompA, 1.075 copies/µL for SFTSV-L and 1.006 copies/µL for HTNV-L, respectively. Both the within-run and within-laboratory coefficients of variation on the cycle threshold (Ct) values were within the range of 0.53%-2.15%. It was also found there was no statistical difference in the Ct values between single template and multiple templates (PSFGR-ompA = 0.186, PSFTSV-L = 0.612, PHTNV-L = 0.298). The sensitivity, specificity, positive and negative predictive value were all 100% for determining SFGR-ompA and SFTSV-L, 97%, 100%, 100% and 99.6% for HTNV-L, respectively. Therefore, the all-in-one real-time PCR assay appears to be a reliable, sensitive, rapid, high-throughput and low cost-effective method to diagnose the zoonotic infection by SFGR, SFTSV and HTNV.
Assuntos
Vírus Hantaan , Phlebovirus , Reação em Cadeia da Polimerase em Tempo Real , Sensibilidade e Especificidade , Febre Grave com Síndrome de Trombocitopenia , China/epidemiologia , Vírus Hantaan/genética , Vírus Hantaan/isolamento & purificação , Reação em Cadeia da Polimerase em Tempo Real/métodos , Phlebovirus/genética , Phlebovirus/isolamento & purificação , Humanos , Febre Grave com Síndrome de Trombocitopenia/diagnóstico , Rickettsia/isolamento & purificação , Rickettsia/genética , Rickettsiose do Grupo da Febre Maculosa/diagnóstico , AnimaisRESUMO
OBJECTIVES: The aim of this study was to investigate the clinical and molecular characteristics of Klebsiella pneumoniae infection from a tertiary general hospital in Wuhan, China. METHODS: From December 2019 to August 2022, 311 non-duplicate isolates of K. pneumoniae were collected from a tertiary hospital in Wuhan. These comprised 140 carbapenem-resistant K. pneumoniae (CRKP) isolates and 171 carbapenem-susceptible K. pneumoniae (CSKP) isolates. The clinical characteristics of patients with K. pneumoniae infection were retrospectively collected. Polymerase chain reaction (PCR) assays were used to identify the main carbapenem resistance genes, virulence genes and multi-locus sequence typing (MLST) profiles of the isolates, and the Galleria mellonella infection model was used to determine their virulence phenotypes. RESULTS: Independent risk factors for CRKP infection were hypertension, neurological disorders, being admitted to the intensive care unit (ICU) and prior use of antibiotics. Patient with CRKP infection had higher mortality than those with CSKP infection (23.6% vs 14.0%, P < 0.05). One hundred and two sequence types (STs) were identified among the K. pneumoniae isolates, and the most prevalent ST type was ST11 (112/311, 36.0%). All of the ST11 isolates were CRKP. Among the 112 ST11 isolates, 105 (93.8%) harboured the carbapenem resistance gene blaKPC-2 (ST11-KPC-2), and of these isolates, 78 (74.3%, 78/105) contained all of the four virulence genes, namely rmpA, rmpA2, iroN and iucA, suggesting that these genes were widespread among the isolates responsible for K. pneumoniae infections. CONCLUSION: In this study, ST11-KPC-2 was responsible for most of the K. pneumoniae infection cases. Carbapenem resistance rather than the co-occurrence of the virulence genes rmpA, rmpA2, iroN and iucA was associated with K. pneumoniae infection-related mortality during hospitalisation. Furthermore, a high proportion of ST11-KPC-2 isolates carried all of the four virulence genes.
Assuntos
Infecções por Klebsiella , beta-Lactamases , Humanos , Tipagem de Sequências Multilocus , beta-Lactamases/genética , Klebsiella pneumoniae , Centros de Atenção Terciária , Hospitais Gerais , Estudos Retrospectivos , Infecções por Klebsiella/microbiologia , Carbapenêmicos/farmacologia , Antibacterianos/farmacologia , Antibacterianos/uso terapêutico , China/epidemiologia , FerroRESUMO
1T-TiSe_{2} is one of the most studied charge density wave (CDW) systems, not only because of its peculiar properties related to the CDW transition, but also due to its status as a promising candidate of exciton insulator signaled by the proposed plasmon softening at the CDW wave vector. Using high-resolution electron energy loss spectroscopy, we report a systematic study of the temperature-dependent plasmon behaviors of 1T-TiSe_{2}. We unambiguously resolve the plasmon from phonon modes, revealing the existence of Landau damping to the plasmon at finite momentums, which does not support the plasmon softening picture for exciton condensation. Moreover, we discover that the plasmon lifetime at zero momentum responds dramatically to the band gap evolution associated with the CDW transition. The interband transitions near the Fermi energy in the normal phase are demonstrated to serve as a strong damping channel of plasmons, while such a channel in the CDW phase is suppressed due to the CDW gap opening, which results in the dramatic tunability of the plasmon in semimetals or small-gap semiconductors.
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The destructive interference of wavefunctions in a kagome lattice can give rise to topological flat bands (TFBs) with a highly degenerate state of electrons. Recently, TFBs have been observed in several kagome metals, including Fe3Sn2, FeSn, CoSn, and YMn6Sn6. Nonetheless, kagome materials that are both exfoliable and semiconducting are lacking, which seriously hinders their device applications. Herein, we show that Nb3Cl8, which hosts a breathing kagome lattice, is gapped out because of the absence of inversion symmetry, while the TFBs survive because of the protection of the mirror reflection symmetry. By angle-resolved photoemission spectroscopy measurements and first-principles calculations, we directly observe the TFBs and a moderate band gap in Nb3Cl8. By mechanical exfoliation, we successfully obtain monolayer Nb3Cl8, which is stable under ambient conditions. In addition, our calculations show that monolayer Nb3Cl8 has a magnetic ground state, thus providing opportunities to study the interplay among geometry, topology, and magnetism.
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Single crystals of PrFe2Ga8were successfully grown by using Ga self-flux. PrFe2Ga8crystallizes in the CaCo2Al8-type orthorhombic structure with the space groupPbam(no. 55). By combining the results from the magnetic-susceptibility, specific-heat, and resistivity measurements, we show that PrFe2Ga8exhibits a magnetic order at 14 K. ForH//c, the antiferromagnetic order can be suppressed by magnetic fields. However, the magnetic order is robust against magnetic fields forHâ¥c. Our results provide basic physical properties of PrFe2Ga8and will help to further understand the magnetism in this system.
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The coexistence of ferroelectricity and metallicity seems paradoxical, since the itinerant electrons in metals should screen the long-range dipole interactions necessary for dipole ordering. The recent discovery of the polar metal LiOsO3 was therefore surprising [as discussed earlier in Y. Shi et al., Nat. Mater. 2013, 12, 1024]. It is thought that the coordination preferences of the Li play a key role in stabilizing the LiOsO3 polar metal phase, but an investigation from the combined viewpoints of core-state specificity and symmetry has yet to be done. Here, we apply the novel technique of extreme ultraviolet second harmonic generation (XUV-SHG) and find a sensitivity to the broken inversion symmetry in the polar metal phase of LiOsO3 with an enhanced feature above the Li K-edge that reflects the degree of Li atom displacement as corroborated by density functional theory calculations. These results pave the way for time-resolved probing of symmetry-breaking structural phase transitions on femtosecond time scales with element specificity.
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Microscopia de Geração do Segundo Harmônico , Metais , Análise EspectralRESUMO
Topological crystalline insulators (TCIs) are insulating electronic states with nontrivial topology protected by crystalline symmetries. Recently, theory has proposed new classes of TCIs protected by rotation symmetries [Formula: see text], which have surface rotation anomaly evading the fermion doubling theorem, i.e., n instead of 2n Dirac cones on the surface preserving the rotation symmetry. Here, we report the first realization of the [Formula: see text] rotation anomaly in a binary compound SrPb. Our first-principles calculations reveal two massless Dirac fermions protected by the combination of time-reversal symmetry [Formula: see text] and [Formula: see text] on the (010) surface. Using angle-resolved photoemission spectroscopy, we identify two Dirac surface states inside the bulk band gap of SrPb, confirming the [Formula: see text] rotation anomaly in the new classes of TCIs. The findings enrich the classification of topological phases, which pave the way for exploring exotic behavior of the new classes of TCIs.