Seafood as a Reservoir of Gram-negative Bacteria Carrying Integrons and Antimicrobial Resistance Genes in Japan

PCR and DNA sequencing were used to screen and characterize integrons and resistance genes in Gram-negative bacteria isolated from seafood products in Japan.A total of 215 Gram-negative bacteria were isolated from local and imported seafood samples collected from retail markets in Hiroshima Prefecture.Class 1 integrons containing gene cassettes encoding resistance to trimethoprim

Characterization of Class 1 Integron Gene Cassettes among Clinical Bacteria Isolated from One Large Hospital in Northern China

The class 1 integron and complex gene cassettes among different species of clinical isolates in northern China were characterized in this study. 383 clinical isolates were obtained from northern China, and class 1 integrons containing gene cassettes widely distributed among gram negative clinical isolates was observed. We find that the class 1 integron showed positive correlation with multidrug resistance phenotype of gram negative bacteria. In addition, we find that isolates belonged to one species harbored different types of gene cassette arrays, while same types of gene cassette arrays were observed in different species of isolates. The diversity of gene cassette arrays among the isolates indicated the complexity of multidrug resistance in clinical isolates in northern China.

Identification and characterization of integron mediated antibiotic resistance in pentachlorophenol degrading bacterium isolated from the chemostat

A bacterial consortium was developed by continuous enrichment of microbial population isolated from sediment core of pulp and paper mill effluent in mineral salts medium（MSM） supplemented with pentachlorophenol（PCP） as sole source of carbon and energy in the chemostat.The consortia contained three bacterial strains.They were identified as Escherichia coli,Pseudomonas aeruginosa and Acinetobacter sp.by 16S rRNA gene sequence analysis.Acinetobacter sp.readily degraded PCP through the formation of tetrachloro-p-hydroquinone（TecH）,2-chloro-1,4-benzenediol and products of ortho ring cleavage detected by gas chromatograph/mass spectrometer（GC-MS）.Out of the three acclimated PCP degrading bacterial strains only one strain,Acinetobacter sp.showed the presence of integron gene cassette as a marker of its stability and antibiotic resistance.The strain possessed a 4.17 kb amplicon with 22 ORF＇s.The plasmid isolated from the Acinetobacter sp.was subjected to shotgun cloning through restriction digestion by BamHI,HindIII and SalI,ligated to pUC19 vector and transformed into E.coli XLBlue1α,and finally selected on MSM containing PCP as sole source of carbon and energy with ampicillin as antibiotic marker.DNA sequence analysis of recombinant clones indicated homology with integron gene cassette and multiple antibiotic resistance genes.

Effects of Scutellaria Baicalensis on Activity and Biofilm Formation of Klebsiella Pneumoniae

Objective To explore the effects of Scutellaria baicalensis on activity and biofilm formation of Klebsiella pneumonia(Kp).Methods The broth and agar dilution methods were carried out to determine minimum inhibitory concentration and minimum bactericidal concentration of Scutellaria baicalensis for TW518.VITEK-32 system was used to assay TW518 susceptibility to antibiotics.Kp biofilms were formed in vitro and stained with Bac Light Live/Dead stain.The class integron geneⅠ1 m RNA expression was analyzed with RT-PCR.Results The minimum inhibitory concentration of Scutellaria baicalensis on TW518 identified as a Kp colony was 32 mg/ml,and minimum bactericidal concentration was 64 mg/ml.Scutellaria baicalensis and broad-spectrum penicillin,cephalosporin,quinolones,or beta-lactamase had synergistic bactericidal effects.Biofilm formation activity of Kp treated with Scutellaria baicalensis was significantly lower than that of the control group.And class integron geneⅠ1 m RNA expression of TW518 was significantly inhibited by Scutellaria baicalensis.Conclusions Scutellaria baicalensis has sterilization effect on Kp,and Scutellaria baicalensis could effectively inhibit Kp biofilm formation with prolonged treatment.Scutellaria baicalensis might inhibit Kp biofilm formation through down-regulating integron geneⅠ1 expression.