Metabolism of nitazoxanide in rats, pigs, and chickens: Application of liquid chromatography coupled to hybrid linear ion trap/Orbitrap mass spectrometer.

Nitazoxanide (NTZ) is a nitrothiazole benzamide compound with a broad activity spectrum against parasites, Gram-positive and Gram-negative anaerobic bacteria, and viruses. In this study, hybrid linear ion trap/Orbitrap mass spectrometer providing a high mass resolution and accuracy was used to investigate the metabolism of NTZ in rats, pigs, and chickens. The results revealed that acetylation and glucuronidation were the main metabolic pathways in rats and pigs, whereas acetylation and sulfation were the major metabolic pathways in chickens, which indicated interspecies variations in drug metabolism and elimination.

Complete nucleotide sequence of pHN7A8, an F33:A-:B- type epidemic plasmid carrying blaCTX-M-65, fosA3 and rmtB from China.

Objectives: To characterize a representative self-transmissible multidrug resistance plasmid pHN7A8 isolated from an Escherichia coli from a dog in China, classified as F33:A-:B- by replicon sequence typing and carrying the bla(TEM-1b), bla(CTX-M-65), fosA3 and rmtB genes conferring resistance to penicillins, cephalosporins, fosfomycin and aminoglycosides, respectively.

Methods: pHN7A8 was sequenced using a whole-genome shotgun approach and the sequence analysed by comparison with reference plasmids.

Results: pHN7A8 is a circular molecule of 76 878 bp.

Molecular characterization of the antimicrobial resistance of Riemerella anatipestifer isolated from ducks.

The antimicrobial susceptibility of 103 Riemerella anatipestifer isolates obtained from ducks during 2008 and 2010 in Southern China, to 23 antimicrobial agents was investigated using the agar dilution method. The MIC(50) and MIC(90) values of streptomycin, kanamycin, gentamicin, apramycin, amikacin, neomycin, nalidixic acid and sulfadimidine were high (32-≥ 128 μg/ml) among the 103 R. anatipestifer isolates.

Characterization of extended-spectrum β-lactamase genes found among Escherichia coli isolates from duck and environmental samples obtained on a duck farm.

In this study, we focused on evaluating the occurrence of extended-spectrum β-lactamase (ESBL)-producing Escherichia coli in fecal samples of healthy ducks and environmental samples from a duck farm in South China. Duck cloacal swabs and pond water samples were cultivated on MacConkey agar plates supplemented with ceftiofur. Individual colonies were examined for ESBL production.

Prevalence and characterisation of CTX-M β-lactamases amongst Escherichia coli isolates from healthy food animals in China.

The impact of extended-spectrum β-lactamase (ESBL)-producing Enterobacteriaceae of food animal origins on human health has caught considerable attention worldwide. Intestinal Escherichia coli obtained from healthy food animals (pigs, cattle and poultry) in China were tested for the presence of ESBL genes. CTX-M-producing isolates were further characterised by pulsed-field gel electrophoresis (PFGE), phylogenetic grouping, genetic environment analysis, conjugation and plasmid replicon typing.

Dissemination of the fosfomycin resistance gene fosA3 with CTX-M β-lactamase genes and rmtB carried on IncFII plasmids among Escherichia coli isolates from pets in China.

The presence and characterization of plasmid-mediated fosfomycin resistance determinants among Escherichia coli isolates collected from pets in China between 2006 and 2010 were investigated. Twenty-nine isolates (9.0%) were positive for fosA3, and all of them were CTX-M producers.

Dissemination of the rmtB gene carried on IncF and IncN plasmids among Enterobacteriaceae in a pig farm and its environment.

Objectives: To investigate the prevalence and characterization of 16S rRNA methylase-producing bacteria in a pig farm and its environment in East China.

Methods: Enterobacteriaceae isolates and metagenomic DNA from 102 pig faecal samples from a pig farm and 97 soil samples taken in or around the farm were screened for the presence of 16S rRNA methylase genes. The clonal relationships of 16S rRNA methylase-positive isolates, plasmid content and other associated resistance genes were also characterized.

F33:A-:B- and F2:A-:B- plasmids mediate dissemination of rmtB-blaCTX-M-9 group genes and rmtB-qepA in Enterobacteriaceae isolates from pets in China.

This study investigated the prevalence of 16S rRNA methylase genes in 267 Enterobacteriaceae isolates collected from pets. The rmtB gene was detected in 69 isolates, most of which were clonally unrelated. The coexistence of the rmtB gene with the bla(CTX-M-9) group genes and/or qepA within the same IncFII replicons was commonly detected.

Prevalence and dissemination of oqxAB in Escherichia coli isolates from animals, farmworkers, and the environment.

OqxAB has recently been identified as one of the mechanisms of plasmid-mediated quinolone resistance (PMQR). Compared to what is observed for other PMQR determinants, there is a paucity of data with regard to the prevalence and epidemiology of OqxAB and its contribution to resistance to different antimicrobials. In this study, the prevalence and dissemination of oqxAB and other PMQR genes in Escherichia coli isolates from animals, farmworkers, and the environment in 2002 in China were investigated.

High prevalence and widespread distribution of multi-resistant Escherichia coli isolates in pigs and poultry in China.

Escherichia coli play an important ecological role within resistant bacteria populations, and can be used as a bio-indicator of antimicrobial resistance. The aim of the present study was to use this feature of E. coli to investigate the prevalence of antimicrobial resistance and the degree of cross-species transmission of bacteria in pigs and poultry in China.

[Insertion sequence common region element: a novel gene-capturing system in bacteria--a review].

Insertion sequence common region (ISCR) elements are insertion sequences that have similarities to the IS91 family in both structure and function. ISCR elements differ from the insertion sequences by that they lack terminal inverted repeats (IRs), do not generate directly repeated sequence on insertion and are thought to be transposed by a mechanism termed rolling-circle (RC) transposition. ISCR elements, as a novel gene-capturing system, can mobilize any piece of adjacent DNA sequences.

Novel cyromazine imprinted polymer applied to the solid-phase extraction of melamine from feed and milk samples.

A water compatible molecularly imprinted polymer (MIP) using cyromazine as a mimic template, methacrylic acid as the functional polymer and ethylene glycol dimethacrylate as the cross-linker was synthesized and used to extract melamine from feed and milk samples via a molecularly imprinted solid-phase extraction (MISPE) protocol. Optimum retention of melamine on the MISPE cartridge was achieved using methanol, and the interferences in the samples were effectively washed out. The binding capacity of the polymer toward melamine was found to be about 500 microg of melamine/g of polymer.

[Effects of enrofloxacin on DNA sequence diversity of soil cultural bacterial community].

In order to understand the effects of remained enrofloxacin (ENR) in environment on the diversity of soil microbial communities, amplified ribosomal DNA restriction analysis (ARDRA) approach and genomic fingerprinting technique enterobacterial repetitive intergenic consensus sequence-polymerase chain reaction (ERIC-PCR) were used to analyze the molecular diversity of 16S rDNA from soil bacteria after ENR addition. The results showed that after the ENR addition for 35 days, the total count of soil bacteria was less than that of CK, and decreased with increasing ENR concentration. The ARDRA divided the separated soil bacteria into different operational taxonomic units (OTU) groups, and the count of group I to group VI was 15, 13, 10, 8, 6, and 6, respectively.

[Determination of clopidol residues in chicken muscle by gas chromatography-mass spectrometry].

A confirmative method to determine clopidol residues in chicken muscle by gas chromatography-mass spectrometry (GC-MS) was developed. The analyte was extracted with ace tonitrile, and then purified with an Alumina-B cartridge column. The drug was derived at 80 degrees 3 for 60 min with Sylon BFT, and more toluene was added and then applied to GC-MS.

Molecular variability of DR-1 and DR-2 within the pvpA gene in Mycoplasma gallisepticum isolates.

A total of 15 Mycoplasma gallisepticum (MG) isolates from Chinese poultry farms and three reference strains (S6, BG44T, and F36) were characterized by nested polymerase chain reaction and sequence analysis for two identical and directly repeated sequences, DR-1 and DR-2, within the putative cytadhesin pvpA gene. The molecular variation patterns of the pvpA genes among the 15 MG isolates were identical to the reference strains S6 and BG44T, that is, a 60 bp deletion in DR-1 and DR-2 and repetition of 1) a proline residue 33 times and 2) a tetrapeptide motif 10 times (Pro-Arg-Pro-X, where X is Met, Gly, Asn, or Gln for 6, 1, 1, or 2 times, respectively). However, the variation pattern is quite different from that of the vaccine strain F36, in which only the DR-1 region is retained, 24 of the 25 peptides comprising the linkage sequence between DR-1 and DR-2 are missing, and the entire DR-2 sequence is deleted.

[Determination of eleven steroid hormones in animal muscle tissues and eggs using ultra-performance liquid chromatography-tandem mass spectrometry].

A credible method was developed for the simultaneous determination of eleven steroid hormone residues in animal muscle tissues and eggs based on ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). The eleven steroid hormones were testosterone, methyltestosterone, trenbolone, boldenone, nandrolone, methandienone, stanozolol, progesterone, nadrolone propionate, testosterone propionate and nadrolone phenylpropionate. The samples were extracted with tert-butyl methyl ether at alkaline pH and then cleaned up by freezing-lipid filtration.

High prevalence of plasmid-mediated quinolone resistance determinants qnr, aac(6')-Ib-cr, and qepA among ceftiofur-resistant Enterobacteriaceae isolates from companion and food-producing animals.

Three kinds of plasmid-mediated quinolone resistance (PMQR) determinants have been discovered and have been shown to be widely distributed among clinical isolates: qnr genes, aac(6')-Ib-cr, and qepA. Few data on the prevalence of these determinants in strains from animals are available. The presence of PMQR genes in isolates from animals was determined by PCR amplification and DNA sequencing.

Emergence of RmtB methylase-producing Escherichia coli and Enterobacter cloacae isolates from pigs in China.

Objectives: To investigate the occurrence of 16S rRNA methylases conferring high-level resistance to aminoglycosides in Enterobacteriaceae isolated from two pig farms in China.

Methods: Enterobacteriaceae isolated from 151 pig rectal swab samples and 9 environmental samples were screened for the presence of the rmtA, rmtB, armA and rmtC genes by PCR and sequencing. Conjugation experiments were carried out to study the transferability of the 16S rRNA methylase genes.

Detection and characterisation of CTX-M and CMY-2 beta-lactamases among Escherichia coli isolates from farm animals in Guangdong Province of China.

The objective of this study was to characterise the beta-lactamase genes of cephalosporin-resistant Escherichia coli isolated from farm animals in Guangdong Province of China. Of 592 E. coli isolates recovered from farm animals from 2003-2005, 50 (8.

Crystallization and preliminary crystallographic analysis of transgelin.

Transgelin was solubly expressed in E. coli. Crystals of transgelin have been grown at 291K using sodium formate or PEG-4000 as precipitants.

Crystallization and preliminary crystallographic analysis of allograft inflammatory factor 1.

Allograft inflammatory factor-1 (AIF-1) is a 17-kDa IFN-gamma inducible Ca2+-binding EF-hand protein involved in immune dysfunction and smooth muscle cell activation. AIF-1 was solubly expressed in E. coli and purified.

[Hydrolysis characteristics of enrofloxacin].

By the method of high-performance liquid chromatography (HPLC), this paper studied the hydrolysis characteristics of enrofloxacin under conditions of different pH, light, and microorganism to assess its ecological risk. The results showed that no ciprofloxacin was found in the hydrolyzed products of enrofloxacin. Under the conditions of 50 degrees C and pH 1 - 10, the hydrolyzation rate of enrofloxacin was less than 10% within 5 days.

Study of danofloxacin depletion in eggs of laying hens after oral administration.

Danofloxacin was administered to 15 laying hens via drinking water for 12 days. Egg white and yolk from each egg were separated and danofloxacin residues were analysed by a high performance liquid chromatography method with fluorescence detection. Danofloxacin was detectable on the first day in egg white and on the second day in egg yolk after the beginning of administration, and higher danofloxacin residues accumulated in egg yolk than in egg white.

Multiresidue determination of eleven quinolones in milk by liquid chromatography with fluorescence detection.

A liquid chromatographic method with fluorescence detection was developed for simultaneous determination of norfloxacin, ofloxacin, ciprofloxacin, pefloxacin, lomefloxacin, danofloxacin, enrofloxacin, sarafloxacin, difloxacin, oxolinic acid, and flumequine in milk The samples were extracted with 10% trichloroacetic acid/acetonitrile (9 + 1, v/v) and cleaned by Strata-X reversed-phase solid-phase extraction cartridges. The 11 quinolones were separated on a reversed-phase C18 column (Hypersil BDS-C18) with mobile phase gradient elution and detected with fluorescence by means of a wavelength program. The recoveries for milk fortified with the 11 quinolones at 3 levels were 69-88% with acceptable relative standard deviations of <9% (intraday) and <14% (interday).