Prevalence and characterization of Clostridium perfringens in broiler chickens and retail chicken meat in central China.

We report that Clostridium perfringens was present in 23.1% (130/562) of broiler chickens and 15.1% (38/252) of retail chicken meat samples in central China. Among 168 isolates, type A was the preponderant genotype, and 3% of isolates were positive C. perfringens enterotoxin (cpe). Among different sources, the prevalence was higher in free-range chickens compared to chickens from intensive poultry farms, but with lower proportions of antimicrobial resistance.

Molecular epidemiology, virulence determinants and antimicrobial resistance of Campylobacter spreading in retail chicken meat in Central China.

BACKGROUND: Campylobacter species are the major food-borne pathogens which could cause bacterial gastroenteritis in humans. Contaminated chicken products have been recognized as the primary vehicles of Campylobacter transmission to human beings. In this study, the prevalence of Campylobacter in retail chicken meat in Central China was investigated, and the isolates were further characterized using molecular approaches and tested for antibiotic resistance. RESULTS: A total of 302 chicken samples purchased from April 2014 to April 2015 were tested. The level of Campylobacter contamination was enumerated by most probable number-PCR (MPN-PCR). The Campylobacter positive rate was 17.2% (52/302), with bacterial count varying from 3.6 to 360 MPN/g in positive samples. A total of 52 Campylobacter strains, including 40 Campylobacter jejuni and 12 Campylobacter coli, were isolated from the positive samples. To examine the genetic diversity of the isolates, multilocus sequence typing (MLST) technology was applied, which identified 23 sequence types (STs) belonging to seven clonal complexes (CCs) and unassigned. Among them, the dominant CCs of C. jejuni included CC-353 and CC-464, and the dominant CCs of C. coli were CC-828 and CC-1150. Antibiotic resistance analysis showed that all of the isolates were resistant to norfloxacin and ciprofloxacin. 23 virulence-associated genes were tested in the isolates, which showed that the number of virulence-associated genes detected in the C. jejuni isolates ranged from 16 to 21, while in most of the C. coli isolates ranged from 12 to 16. Virulence-associated genes, flaA, flgB, flgE2, fliM, fliY and cadF were detected in all isolates. VirB11, however, was not detected in any of the isolates. CONCLUSIONS: To the best of our knowledge, this is the first report on the contamination level and molecular biological features of Campylobacter strains in retail chicken meat in Central China, which showed high genetic diversity and remarkable antibiotic resistance. This study provided scientific data for the risk assessment and evaluation of Campylobacter contamination in retail chicken products.

Genome Sequence of Avirulent Riemerella anatipestifer Strain RA-JLLY.

Riemerella anatipestifer is an important bacterial pathogen associated with epizootic infections in waterfowl and various other birds. Riemerella anatipestifer strain RA-JLLY is an avirulent strain, isolated from the brain of an old duck in Hubei province, China. Here, we report the genome sequence of this species.

Pharmacokinetics and tissue residues of hydrochloric acid albendazole sulfoxide and its metabolites in crucian carp (Carassius auratus) after oral administration.

The pharmacokinetics and residues elimination of hydrochloric acid albendazole sulfoxide (ABZSO) and its metabolites were studied in healthy crucian carp (Carassius auratus, 250 ± 30 g) kept at water temperatures of 10 °C and 25 °C. The concentrations of ABZSO and its metabolites concentration in plasma and tissues were determined using high-performance liquid chromatography (HPLC) using an ultraviolet detector. The results revealed that the plasma concentration of ABZSO in plasma was significantly higher than that of albendazole sulfone (ABZSO(2)), whereas albendazole-2-aminosulfone (ABZ-SO(2)NH(2)) was not detected. The plasma concentrations of ABZSO and its main metabolite ABZSO(2) concentration-time data were fitted using a single-compartment model at 10 °C and 25 °C. The absorption half-life (t1/2ka) of ABZSO was 3.86 h at 10 °C and 1.29 h at 25 °C, whereas the elimination half-life (t1/2ke) was 16.34 h at 10 °C and 6.72 h at 25 °C; the maximum plasma concentration (C(max)) and the time-point of maximum plasma concentration (T(p)) were calculated as 3.20 µg mL(-1) and 10.58 h at 10 °C, 4.39 µg mL(-1) and 3.80 h at 25 °C. The distribution volume (V(d)/F) of ABZSO was estimated to be 1.99 L kg(-1) at 10 °C and 1.53 L kg(-1) at 25 °C; the total body clearance (CL(b)) of ABZSO were computed as 0.08 and 0.19 L/(h kg) at 10 and 25 °C, respectively; the areas under the concentration-time curve (AUC) was 118.22 µg mL(-1)h at 10 °C and 63.12 µg mL(-1)h at 25 °C. The [Formula: see text] of ABZSO(2) was found to be 6.39 °C at 10 °C and 3.73 h at 25 °C, whereas the [Formula: see text] was 12.86 h at 10 °C and 6.56 h at 25 °C; the C(max) and T(p) of ABZSO(2) was calculated as 0.78 µg mL(-1) and 12.82 h at 10 °C, 1.03 µg mL(-1) and 7.04 h at 25 °C, respectively; the V(d)/F of ABZSO(2) were estimated to be 6.43 L kg(-1) at 10 °C and 4.61 Lkg(-1) at 25 °C; the CL(b) of ABZSO(2) were computed as 0.34 and 0.49 L/(h kg) at 10 °C and 25 °C, respectively; the AUC of ABZSO(2) were 28.86 µg mL(-1)h at 10 °C and 20.52 µg mL(-1)h at 25 °C. It was demonstrated that ABZSO(2) was the main metabolite of ABZSO. The concentrations of ABZSO and its main metabolite (ABZSO(2)) were detected in muscle, skin, liver and kidney, whereas ABZ-SO(2)NH(2) was only detected in liver and kidney. The ABZSO and it metabolite (ABZSO(2)) could still be detected at 4 d time-point after administration at both temperatures in all tissues. The results revealed that the depletion of ABZSO and its metabolite (ABZSO(2)) in crucian carp was slower with a long half-life time, especially at lower water temperature.

Evaluation of a real-time RT-PCR assay using minor groove binding probe for specific detection of Chinese wild-type classical swine fever virus.

A one-step real-time RT-PCR assay using a minor groove binding probe was developed for the specific detection of Chinese wild-type classical swine fever virus (CSFV). The assay detected wild-type CSFV strains representing different genotypes, but did not amplify viral RNA from the Hog Cholera Lipinized Virus (HCLV) vaccine-strain and other porcine viruses. The assay had a detection limit of 10 copies/reaction or 3.0 median tissue culture infective dose/reaction. In comparison to the sequencing nested RT-PCR assay, the sensitivity and specificity of the assay were 98.3% and 94.3%, respectively, when testing 515 veterinary samples. Wild-type CSFV RNA was detected in nasal swabs 2-4 days before detection in serum samples from pigs exposed to infection by contact, and 2-4 days prior to the onset of clinical disease. HCLV RNA remained undetectable in nasal swabs and serum samples from vaccinated pigs. In conclusion, the novel assay described in this study provides a rapid and sensitive method for differentiating between wild-type and the HCLV-strain of CSFV. It could be used for monitoring in CSF outbreak areas or as a screening method for CSFV eradication strategies.

A one-step real-time reverse transcription-polymerase chain reaction detection of classical swine fever virus using a minor groove binding probe.

The aim of this study was to develop a one-step real-time reverse transcription-polymerase chain reaction assay using the minor groove binding probe (MGB rRT-PCR) for rapid and quantitative detection of classical swine fever virus (CSFV). The method, which targets the 5'-nontranslated region (5'NTR) of the viral genome, detected all CSFV isolate tested, but not heterologous pathogens. Using an in vitro transcript of the 5'NTR as a quantitative standard for the CSFV genome copy number, the assay had a detection limit of 10 copies/reaction, and the standard curve had a linear range from 10 to 10(7) copies/reaction, with good reproducibility. As determined by an end-point dilution comparison, in most case, the sensitivity of the MGB rRT-PCR was approximately 10-fold higher than that of virus isolation and the rRT-PCR using the standard Taqman probe (standard rRT-PCR). The agreement between the MGB rRT-PCR and standard rRT-PCR, or virus isolation was 93.3% and 76.7%, respectively, when detecting 261 field samples. Due to its rapidity, high specificity and sensitivity, the MGB rRT-PCR assay provides a valuable tool for diagnosis and molecular studies of CSFV biology.

Preparation and evaluation of danofloxacin mesylate microspheres and its pharmacokinetics in pigs.

Danofloxacin mesylate gelatin microspheres (DFM-GMS) were prepared by an emulsion chemical crosslinking technique. Distribution of particle size, morphologic characteristics, drug content, and drug stability were evaluated. In-vitro study showed that the release of danofloxacin mesylate (DFM) from microspheres was much slower than from the raw material (DFM) in the release medium. Pharmacokinetic characteristics were evaluated following intramuscular injection of DFM-GMS or DFM in pigs at dosage of 2.5 mg/kg body weight. Elimination half-life (t(1/2ß)) of the drug was 24.32 h for DFM-GMS, and 6.61 h for DFM (P < 0.01). Overall, DFM-GMS could be applied as a long-acting and lung targeting dosage form of DFM for clinical application.