Juan Mo

Molecular characterization of extended-spectrum β-lactamase-producing Escherichia coli isolates from chickens in Henan Province, China

Extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli has spread rapidly worldwide and poses a serious threat to human and animal health. This study collected 51 non-replicate E. coli isolates from 14 different chicken farms in Henan Province in China from December 2007 to August 2008. The prevalence of ESBL-producing E. coli, molecular characterization of the ESBL-related bla genes, including bla(TEM), bla(SHV) and bla(CTX-M), and the susceptibilities of these bacteria to various antimicrobial agents were determined. Thirty-one of the 51 isolates were positive for an ESBL phenotype and 29 of these isolates carried one or more bla genes. Twenty-two isolates harboured bla(TEM) genes and 15 isolates carried bla(CTX-M) genes (one CTX-M-14, three CTX-M-24 and 11 CTX-M-65). One isolate carried bla(TEM)(-57); the remaining bla(TEM) isolates carried bla(TEM-1) with one silent nucleotide base variation (T18C). We believe that this is the first study to report TEM-57 in E. coli isolates. All isolates harbouring bla(CTX-M-24) and bla(CTX-M-14) and five of the bla(CTX-M-65) isolates also harboured the bla(TEM-1) gene. To our knowledge, this study is the first to describe detection of CTX-M-65-producing E. coli isolated from chickens. None of the isolates contained the bla(SHV) gene. Conjugation experiments demonstrated that bla(CTX-M) and bla(TEM) genes could be transferred to E. coli DH5 alpha. The results indicate that ESBL frequency has reached an alarming level in chicken isolates in China, with TEM-1 and CTX-M-65 enzymes being the two predominant beta-lactamases detected.

[μ-Bis(5,7-dimethyl-1,8-naphthyridin-2-yl)diazene]bis­[difluoridoboron(III)]

In the title compound, C20H18B2F4N6, the bis(5,7-dimethyl-1,8-naphthyridin-2-yl)diazene molecule is bisected by a symmetry centre midway between the central N atoms of the diazene group. Each of the symmetry-related halves of the molecule binds to a B atom through an N,N′-bite. Two terminal F ions complete the distorted BN2F2 tetrahedral geometry around each B atom. The BF2 plane is almost perpendicular to the boron–naphthyridine ring plane, with a dihedral angle of 87.8 (2)°. The main interactions in the crystal structure are some C—H⋯F hydrogen bonds and π–π contacts between 1,8-naphthyridine rings [centroid–centroid distance = 4.005 (1) Å].

{μ-N-[(Diphenyl­phosphino)meth­yl]pyridin-2-amine-κ2N1:P}bis­{[2-(2,2′-bipyridin-6-yl)phenyl-κ3N,N′,C1]platinum(II)} bis­(perchlorate)

The title compound, [Pt2(C16H11N2)2(C18H17N2P)](ClO4)2, contains two PtII atoms, bridged by an N-[(diphenylphosphino)methyl]pyridin-2-amine (dppmp) ligand. One Pt atom is coordinated by one P atom from the dppmp ligand, and one C atom and two N atoms from a 6-phenyl-2,2′-bipyridine (pbpy) ligand in a square-planar geometry. The other Pt atom is coordinated by one N atom from the dppmp ligand, and one C atom and two N atoms from another pbpy ligand in a square-planar geometry. There are intramolecular π–π interactions between the pbpy ligands, with a centroid–centroid distance of 3.62 (1) Å between two pyridyl rings. The oxygen atoms of both perchlorate anions are disordered, each over two different positions [occupanicies 0.49 (3)/0.51 (3) and 0.48 (2)/0.52 (2)].

(μ-Diphenyl­phosphanido-κ2P:P′)bis­[2,2′-(pyridine-2,6-diyl)diphenyl-κ3C1,N,C1′)gold(III)] perchlorate acetonitrile solvate

The title complex, [Au2(C17H11N)2(C12H10P)]ClO4·C2H3N, contains two AuIII atoms bridged by a diphenylphosphanide ligand. Each Au atom is in a square-planar environment coordinated by diphenylphosphanide and 2,6-diphenylpyridine ligands. There are weak π–π stacking interactions between neighbouring molecules (the interplanar separations between two neighbouring dpp units are 3.40 and 3.57 Å). The intramolecular Au⋯Au separation is 3.788 (5) Å. The crystal structure shows weak intermolecular C—H⋯O and C—H⋯N hydrogen bonds involving an O atom of the perchlorate counter-ion and the N atom of the acetonitrile solvent molecule, respectively.

2,2'-Dimethyl-7,7'-(methyl-enediimino)di-1,8-naphthyridin-1-ium bis-(perchlorate).

In the title salt, C19H20N6 2+·2ClO4 −, the two planar 1,8-naphthyridine systems are linked by a methylenediamine group with a dihedral angle of 60.6 (1)° between the two systems. The crystal structure involves extensive N—H⋯O and C—H⋯O hydrogen bonding.

2,2′,4,4′-Tetra­methyl-7,7′-diazenediylbis(1,8-naphthyridin-1-ium) bis­(perchlorate)

In the title salt, C20H20N6 2+·2ClO4 −, the cation is disposed about a center of symmetry at the mid-point of the N=N bond. The 1,8-naphthyridine systems are planar and the ten atoms have a mean deviation of 0.01 Å from the least-squares plane. The two planar 1,8-naphthyridine units are parallel but extend in opposite directions from the diazene bridge. The 1,8-naphthyridine aminium groups interact with perchlorate O atoms through N—H⋯O hydrogen bonds.

catena-Poly[[copper(I)-bis[μ-bis(di­phenyl­phos­phino)methane-κ2P:P′]-copper(I)-μ-2,2′-bipyridine-κ2N:N′] bis(tetra­fluorido­borate) dichloromethane 2.5-solvate]. Corrigendum

The title complex, {[Cu2(C10H8N2)(C25H22P2)2](BF4)2·2.5CH2Cl2}n, contains chains of CuI centres bridged alternately by two (diphenylphosphino)methane (dppm) and 4,4′-bipyridine (bpy) ligands. Each CuI atom is coordinated by one N atom of 4,4′-bipyridine (bpy) and two P atoms of two (diphenylphosphino)methane (dppm) ligand, and has a trigonal-planar coordination geometry. There is an inversion centre midway between each pair of adjacent Cu atoms. The distance of two CuI atoms separated by two (diphenylphosphino)methane bridging ligands is 3.732 (3) Å, and 4,4′-bipyridine 11.138 (5) Å.

Hexa-μ2-acetato-1:2κ4O:O′;1:2κ2O:O;2:3κ4O:O′;2:3κ2O:O-bis­(2-amino-7-chloro-5-methyl-1,8-naphthyridine)-1κN1,3κN1-trizinc(II)

The title complex, [Zn3(C2H3O2)6(C9H8ClN3)2], contains three ZnII atoms bridged by six acetate ligands. The central ZnII ion, located on an inversion centre, is surrounded by six O atoms from acetate ligands in a distorted octahedral geometry [Zn—O = 1.9588 (12)–2.1237 (12) Å]. The terminal ZnII ions are coordinated by one N atom of 2-amino-7-chloro-5-methyl-1,8-naphthyridine and three O atoms of three acetate ligands in a distorted tetrahedral geometry. The separation between the central and terminal ZnII ions is 3.245 (3) Å.