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The molecular mechanisms of drug resistance in 19 strains of Vibrio fluvialis isolated from 1998 to 2002 in Kolkata, India, were investigated. Class 1 integrons were detected in eight strains, and four strains were found to carry SXT integrases. In the presence of carbonyl cyanide m-chlorophenylhydrazone or reserpine, all nalidixic acid-and ciprofloxacin-resistant strains became sensitive, suggesting that drug efflux plays a major role in quinolone resistance in V. fluvialis. It was further seen that strains which had MICs of >25 g/ml for nalidixic acid had a sense mutation (Ser to Ile) at position 83 of the quinolone resistance-determining region of gyrA. All except one of the integron-and SXT integrase-bearing strains belonged to the same ribotype.Vibrio fluvialis, a halophilic Vibrio species, has been associated with sporadic outbreaks of diarrhea worldwide (10, 11, 13), which is clinically very similar to cholera. It is being isolated with an increased frequency from hospitalized patients in Kolkata, India, with cholera-like illnesses (our unpublished observations). The V. fluvialis strains isolated in the past were found to be resistant to several antibiotics (13). However, there is a paucity of information on the genetic basis of drug resistance in these strains. Antibiotic resistance arises through multiple means and can be mediated by plasmids, integrons, and transposons, besides mutations in target genes and the overexpression of efflux systems (4,5,6,8). Only two reports (1, 2) have addressed this issue. In those studies, the presence of the drug cassettes aac(3)-Id and aadA7, which confer resistance to gentamicin, streptomycin, and spectinomycin, were identified in V. fluvialis, as was an SXT constin (6). In this study, we performed antibiotic susceptibility tests with 19 strains of V. fluvialis isolated from hospitalized patients in Kolkata, India, recovered from 1998 to 2002 and also analyzed their drug resistance profiles. MATERIALS AND METHODSV. fluvialis strains were isolated from patients with acute cholera-like diarrhea admitted to the Infectious Diseases Hospital, Kolkata, India, between 1998 and 2002.Bacteriology. V. fluvialis isolates were identified by using the API 20E system (bioMerieux, Marcy l'Etoile, France) and also by 16S rRNA gene sequencing.Antimicrobial susceptibility testing and MIC determination. The isolates were examined for antibiotic resistance as described previously (17). The MICs of ciprofloxacin and nalidixic acid were determined as described in the CLSI standards (7).Bacterial genomic DNA and plasmid isolation. Genomic and plasmid DNA was extracted from the isolates by a method described earlier (17), except that for plasmid isolation, 0.75 ml of culture and twice the suggested volumes of all three solutions were used.Bacterial transformation and plating on selective media. Escherichia coli JM109 electrocompetent cells, prepared according to the manufacturer's recommendations (Bio-Rad Laboratories, Richmond, Calif.), were transformed with 30 ng of plasmid preparations a...

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New magnetic iron oxide (Fe3O4)/activated charcoal (AC)/β-cyclodextrin (CD)/sodium alginate (Alg) polymer nanocomposite materials were prepared by direct mixing of the polymer matrix with the nanofillers. The obtained materials were utilized as nano-adsorbents for the elimination of methylene blue (MB), a hazardous water-soluble cationic dye, from aqueous solutions, and showed excellent regeneration capacity. The formation of the nanocomposites was followed by high-resolution transmission electron microscopy (HRTEM), scanning electron microscopy (SEM) equipped with energy dispersive X-ray spectrometry (EDX), Fourier-transform infrared spectroscopy (FTIR), vibrating sample magnetometer (VSM), X-ray diffraction (XRD) and adsorption of N2 at −196 °C. The rate of adsorption was investigated varying several factors, namely contact time, pH, amount of adsorbent and MB concentration on the adsorption process. Studies dealing with equilibrium and kinetics were carried out in batch conditions. The obtained results indicated that the removal rate of MB was 99.53% in 90 min. Langmuir’s isotherm fitted better to the equilibrium data of MB. Fe3O4/AC/CD/Alg polymer beads shows amazing adsorption capacities in the elimination of cationic dyes (2.079 mg/g for polymer gel beads and 10.63 mg g−1 for dry powder beads), in comparison to other adsorbent materials. The obtained adsorbent is spherical with hydrophobic cross-linked surface properties that enable an easy recovery without any significant weight loss of in the adsorbent used.