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.

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.

[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.

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.

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.

Tissue pharmacokinetics of florfenicol in pigs experimentally infected with Actinobacillus pleuropneumoniae.

Unlabelled: The aim of this study has been to determine the tissue pharmacokinetic parameters of florfenicol in the pigs experimentally infected with Actinobacillus pleuropneumoniae. 21 crossed-bred (Duroc x Landrace x Yorkshire) local species of pigs were infected experimentally with Actinobacillus pleuropneumoniae serotype 1 and confirmed as typical sub-acute pleuropneumonia. A single dose of 20 mg/kg body weight of florfenicol, a novel animal-using antibiotic, was administrated intramuscularly in the pigs and then samples of blood, lung, trachea with bronchi, liver, kidney and muscle were taken at scheduled time points.