Mobilization of Tn1721-like structure harboring blaCTX-M-27 between P1-like bacteriophage in Salmonella and plasmids in Escherichia coli in China

The aim of this study was to explore the characteristics of blaCTX-M-27 carriage and mobilization in Salmonella and Escherichia coli isolates from food-producing animals in China. A total of 2280 E. coli and 229 Salmonella isolates collected from food animals from June 2003 to September 2014 were screened for the presence of blaCTX-M-27 gene. The blaCTX-M-27-positive isolates were typed and plasmid DNA sequenced to determine the genetic context of blaCTX-M-27 and plasmid types present. Bacterial fitness was evaluated by growth curve and plasmid stability in vitro. CTX-M-27-positive E. coli (18, 0.79 %) and Salmonella (34, 14.85 %) were detected. PFGE profiles of CTX-M-27-positive strains revealed a wide variety of genotypes and S. Indiana was the most prevalent serotype. Replicon typing, S1-PFGE and hybridization of CTX-M-27-carrying plasmids confirmed that blaCTX-M-27 gene was located on IncFII (12/18), IncN (4/18), and non-typeable (2/18) plasmids in E. coli and on P1-like bacteriophage (21/34), IncP (4/34), IncFIB (4/34), IncN (2/34), IncHI2 (2/34), and IncA/C (1/34) plasmids in Salmonella. Comparison and analysis of gene context of blaCTX-M-27 in P1-like bacteriophage and plasmids revealed they shared the same structure and contained an identical genetic context with the Tn1721-like structure ΔISEcp1B-blaCTX-M-27-IS903D-iroN-Δmap-Tn1721. In addition, plasmid stability tests indicated that the blaCTX-M-27 P1-like bacteriophage were more stable than plasmids in the absence of cefotaxime selective pressure. These results demonstrate that Tn1721-like transposons harboring CTX-M-27 could be mobilized between different plasmids in E. coli and P1-like bacteriophage disseminated among Salmonella

Transmission of plasmid-borne and chromosomal blaCTX-M-64 among Escherichia coli and Salmonella isolates from food-producing animals via ISEcp1-mediated transposition

Objectives: To clarify the transmission mechanism of the blaCTX-M-64 gene between Escherichia coli and Salmonella isolates from food animals. Methods: A total of 329 E. coli and 60 Salmonella isolates collected from food animals in 2016 were screened for the presence of blaCTX-M-64 genes. The blaCTX-M-64-positive isolates were typed and plasmid and chromosome DNA was sequenced to determine the genetic context of blaCTX-M-64 and the plasmid types present. Results: The blaCTX-M-64 gene was identified in only three E. coli isolates but was the predominant gene in the Salmonella isolates (n = 9). These 12 CTX-M-64-positive isolates were all resistant to ampicillin, cefotaxime, ceftiofur, ceftriaxone, ceftazidime and florfenicol and 9 were resistant to ciprofloxacin. The blaCTX-M-64 gene was located on transferable IncI2 plasmids and an IncHI2 plasmid in three E. coli and one Salmonella isolate, respectively. The remaining eight Salmonella isolates contained blaCTX-M-64 integrated into the chromosome. Different genetic contexts of blaCTX-M-64 genes were found among the 12 isolates: ISEcp1-blaCTX-M-64-orf477-A/C on IncI2 plasmids of 3 E. coli isolates; DISEcp1-blaCTX-M-64-orf477-A/C in the chromosome of 1 Salmonella isolate; and ISEcp1-blaCTX-M-64-orf477 on the IncHI2 plasmid and chromosome of 8 Salmonella isolates. Conclusions: To the best of our knowledge, this is the first report of chromosomally encoded CTX-M-64 in Salmonella isolates. ISEcp1-mediated transposition is likely to be responsible for the spread of blaCTX-M-64 between different plasmids and chromosomes in Enterobacteriaceae especially E. coli and Salmonella

A simulation study on the measurement of D0-D0bar mixing parameter y at BES-III

We established a method on measuring the \dzdzb mixing parameter $y$ for BESIII experiment at the BEPCII $e^+e^-$ collider. In this method, the doubly tagged $\psi(3770) \to D^0 \overline{D^0}$ events, with one $D$ decays to CP-eigenstates and the other $D$ decays semileptonically, are used to reconstruct the signals. Since this analysis requires good $e/\pi$ separation, a likelihood approach, which combines the $dE/dx$, time of flight and the electromagnetic shower detectors information, is used for particle identification. We estimate the sensitivity of the measurement of $y$ to be 0.007 based on a $20fb^{-1}$ fully simulated MC sample.Comment: 6 pages, 7 figure

Measurements of the observed cross sections for e+e−→e^+e^-\to exclusive light hadrons containing π0π0\pi^0\pi^0 at s=3.773\sqrt s= 3.773, 3.650 and 3.6648 GeV

By analyzing the data sets of 17.3, 6.5 and 1.0 pb$^{-1}$ taken, respectively, at $\sqrt s= 3.773$, 3.650 and 3.6648 GeV with the BES-II detector at the BEPC collider, we measure the observed cross sections for $e^+e^-\to \pi^+\pi^-\pi^0\pi^0$, $K^+K^-\pi^0\pi^0$, $2(\pi^+\pi^-\pi^0)$, $K^+K^-\pi^+\pi^-\pi^0\pi^0$ and $3(\pi^+\pi^-)\pi^0\pi^0$ at the three energy points. Based on these cross sections we set the upper limits on the observed cross sections and the branching fractions for $\psi(3770)$ decay into these final states at 90% C.L..Comment: 7 pages, 2 figure

Partial wave analysis of J/\psi \to \gamma \phi \phi

Using $5.8 \times 10^7 J/\psi$ events collected in the BESII detector, the radiative decay $J/\psi \to \gamma \phi \phi \to \gamma K^+ K^- K^0_S K^0_L$ is studied. The $\phi\phi$ invariant mass distribution exhibits a near-threshold enhancement that peaks around 2.24 GeV/$c^{2}$. A partial wave analysis shows that the structure is dominated by a $0^{-+}$ state ($\eta(2225)$) with a mass of $2.24^{+0.03}_{-0.02}{}^{+0.03}_{-0.02}$ GeV/$c^{2}$ and a width of $0.19 \pm 0.03^{+0.06}_{-0.04}$ GeV/$c^{2}$. The product branching fraction is: $Br(J/\psi \to \gamma \eta(2225))\cdot Br(\eta(2225)\to \phi\phi) = (4.4 \pm 0.4 \pm 0.8)\times 10^{-4}$.Comment: 11 pages, 4 figures. corrected proof for journa

Direct Measurements of Absolute Branching Fractions for D0 and D+ Inclusive Semimuonic Decays

By analyzing about 33 $\rm pb^{-1}$ data sample collected at and around 3.773 GeV with the BES-II detector at the BEPC collider, we directly measure the branching fractions for the neutral and charged $D$ inclusive semimuonic decays to be $BF(D^0 \to \mu^+ X) =(6.8\pm 1.5\pm 0.7)$ and $BF(D^+ \to \mu^+ X) =(17.6 \pm 2.7 \pm 1.8)$, and determine the ratio of the two branching fractions to be $\frac{BF(D^+ \to \mu^+ X)}{BF(D^0 \to \mu^+ X)}=2.59\pm 0.70 \pm 0.25$

Measurements of the observed cross sections for exclusive light hadron production in e^+e^- annihilation at \sqrt{s}= 3.773 and 3.650 GeV

By analyzing the data sets of 17.3 pb$^{-1}$ taken at $\sqrt{s}=3.773$ GeV and 6.5 pb$^{-1}$ taken at $\sqrt{s}=3.650$ GeV with the BESII detector at the BEPC collider, we have measured the observed cross sections for 12 exclusive light hadron final states produced in $e^+e^-$ annihilation at the two energy points. We have also set the upper limits on the observed cross sections and the branching fractions for $\psi(3770)$ decay to these final states at 90% C.L.Comment: 8 pages, 5 figur

Search for the Rare Decays J/Psi --> Ds- e+ nu_e, J/Psi --> D- e+ nu_e, and J/Psi --> D0bar e+ e-

We report on a search for the decays J/Psi --> Ds- e+ nu_e + c.c., J/Psi --> D- e+ nu_e + c.c., and J/Psi --> D0bar e+ e- + c.c. in a sample of 5.8 * 10^7 J/Psi events collected with the BESII detector at the BEPC. No excess of signal above background is observed, and 90% confidence level upper limits on the branching fractions are set: B(J/Psi --> Ds- e+ nu_e + c.c.)<4.8*10^-5, B(J/Psi --> D- e+ nu_e + c.c.) D0bar e+ e- + c.c.)<1.1*10^-5Comment: 10 pages, 4 figure