Aeromonas spp. are opportunistic pathogens related to multiple infectious diseases in ornamental fishes. In the present study, the antimicrobial susceptibility, resistance genes, and integrons of 65 goldfish-borne Aeromonas spp. were evaluated. The isolates were identified as A. hydrophila (n = 30), A. veronii (n = 32), and A. punctata (n = 3) by gyrB sequencing. The antimicrobial susceptibility testing of the isolates designated that most of the isolates were resistant to amoxicillin (100.00%), nalidixic acid (100.00%), ampicillin (98.46%), tetracycline (92.31%), rifampicin (86.15%), and cephalothin (61.54%) and each of the isolates showed multiple antimicrobial resistance phenotype (resistant to ≥3 classes of antimicrobials). PCR amplification of antimicrobial resistance genes revealed that the plasmid-mediated quinolone resistance gene, qnrS, was the most prevalent (73.85%) among the isolates. The other antimicrobial resistance genes were detected in the following proportions: qnrB (26.15%), aac(6′)-Ib-cr (4.60%), tetA (16.92%), tetE (21.54%), aac(6′)-Ib (29.23%), and aphAI-IAB (7.69%). The IntI gene was found in 64.62% isolates, and four class 1 integron gene cassette profiles (incomplete dfrA1, catB3-aadA1, dfrA1-orfC, and qacE2-orfD) were identified. These data suggest that goldfish-borne Aeromonas spp. serve as a reservoir of antimicrobial resistance genes and class 1 integrons.
L-theanine was examined for its effects on the generation of superoxide anion, lysozyme and anti-protease in the plasma of catfish (Silurus asotus) by a single intraperitoneal injection with five different concentrations (0, 3, 6, 9 and 12 mg/kg). When compared with the mock-injected group (0 mg/kg), both groups injected with 6 and 9 mg/kg were significantly enhanced in levels of superoxide anion in leukocytes, lysozyme and anti-protease in plasma. Based on the results, L-theanine is thought to function as an immunostimulant and/or immunomodulator on non-specific immune responses in catfish.
Abstract Antimicrobial resistance properties of 32 Aeromonas strains isolated from fresh scallops ( Patinopecten yessoensis (Jay)) marketed in Korea were assessed. All the Aeromonas spp., including A. salmonicida , were mesophilic and grew very well at 37°C. The isolates were tested for susceptibility to 19 antimicrobials belonging to eight antimicrobial classes. All isolates were multi-drug resistant, which means they were resistant to five or more antimicrobials. Higher resistance rates (≥ 50%) were observed for ampicillin, piperacillin, cephalothin, imipenem, meropenem, trimethoprim-sulfamethoxazole, tetracycline, oxytetracycline, and nalidixic acid while intermediate resistance was also determined. PCR assays revealed the presence of many antimicrobial resistance genes among the isolates in varying combinations. Among them, some isolates harbored higher numbers of resistant genes, e.g., A. veronii -V1 ( aac(6’)-Ib, tetE, qnrS, IntI1 ), A . salmonicida –SL10 ( IntI1, blaCTX, aac(3’)-Ib, aac(6’)-Ib, qnrS ), A. hydrophila –H13 ( IntI1, blaTEM, qnrS, aac(6’)-Ib, strA-strB ). However, neither the blaSHV , blaIMP , tetB , qnrA , qnrB , and aphAI-IAB genes nor class1 integrons were detected in any of the isolates. Discrepancies between phenotypic and genetic resistance traits were observed in some isolates. With respect to outcomes, scallops are proposed as a source of multi-drug resistant Aeromonas spp. that harbor antimicrobial resistant genes.
The present study was to investigate in vitro antimicrobial effects of propolis against six different fish bacterial pathogens, Aeromonas hydrophila, Edwardsiella tarda, Vibrio vulnificus, V. parahaemolyticus, A. salmonicida subsp. masoucida, A. salmonicida subsp. salmonicida) using minimum inhibitory concentration (MIC) and minimum bacteriocidal concentration (MBC) tests. In the results, propolis exhibited antimicrobial activity against all bacteria used in the present study, but there was no marked difference in bacterial species except Vibrio species. Collectively, propolis was thought to be an usefulness antimicrobial substance for controlling bacterial diseases in the fish industry.
We examined the effects of a single intraperitoneal injection of four different concentrations (0, 50, 100, 150, 200 mg/kg) of chitosan oligosaccharide on superoxide anion, plasma lysozyme and anti-protease in catfsh (Silurus asotus). The groups injected with 100 and 150 mg/kg chitosan had signifcantly enhanced superoxide anion levels in leukocytes, plasma lysozyme and anti-protease compared to the mock-injected group (0 mg/kg). Based on these results, chitosan oligosaccharide is thought to stimulate and/or modulate the non-specifc immune response in catfsh. Key words: Anti-protease, Chitosan oligosaccharide, Catfsh (Silurus asotus), Lysozyme, Superoxide anion
Abstract We report the prevalence and characterization of Vibrio spp. isolated from marketed Yesso scallop ( Patinopecten yessoensis ) in Korea. A total of 30 isolates including, V. parahaemolyticus ( n = 2), V. alginolyticus ( n = 9), V. fluvialis ( n = 7), V. diabolicus ( n = 7), V. anguillarum ( n = 4) and V. aestuarianus ( n = 1) were isolated and identified. The phenotypic pathogenicity tests demonstrated that, 18 (60%), 21 (70%), 18 (60%), 7 (23%), 22 (73%), 21 (70%), 9 (30%), and 11 (33%) of the isolates were positive for DNase, protease, gelatinase, lipase, phospho‐lipase, amylase, slime production, and haemolysis, respectively. PCR assays revealed the prevalence of toxR, tlh, VAC, vfh, hupO, and VPI genes among the isolates with varying combinations. A close genetic affinity among V. alginolyticus and V. diabolicus strains was observed. Also the virulence genes specific to one Vibrio species were detected among other species as well. In addition, 29/30 (97%) isolates were multidrug resistant, while higher resistance rates were shown for ampicillin, colistin, vancomycin, and cephalothin. The results imply that the scallops in Korean markets harbor Vibrio spp., which are potentially virulent and multidrug resistant, thus their public health implications should not be underrated. Practical applications For many decades, vibrios are known for its importance in seafoodborne illnesses. Yesso scallop is the most popular and extensively cultured scallop variety in Korea. Therefore, we sought to assess the marketed fresh Yesso scallops for the prevalence and molecular characterization of Vibrio species. A total of 30 strains were isolated and identified by a series of biochemical tests, subsequent gyrB gene sequencing and phylogenetic analyses. Six Vibrio spp. were identified with V. alginolyticus as the most prevalent. Interestingly, V. alginolyticus was genetically similar to V. diabolicus . Besides, the virulence genes specific to V. alginolyticus and V. parahaemolyticus were observed in other species as well. It suggests that the detection of the species‐specific genes does not ensure the correct identification of pathogenic vibrios. Further, the occurrence of V. parahaemolyticus ‐specific virulence genes in other Vibrio spp. potentially complicates the correct tracking of V. parahaemolyticus infections. In addition, 73% of these Vibrio spp. isolates showed multiple antibiotic resistance (MAR) indices higher than 0.2, which signifies their high risk of infection. Collectively, these results provide important evidence that not only the well‐known pathogenic vibrios like V. parahaemolyticus , but also other Vibrio spp. can act alike because of their similar characteristics.
The current study was aimed to investigate the prevalence of ureC, rsbA, zapA and mrpA virulence genes using polymerase chain reaction (PCR) in Proteus spp. isolated from 5 commercially popular species of pet turtles and comparison of the mrpA gene sequences of Proteus mirabilis isolates with human clinical isolates. A total of 24 isolates in pet turtles were identified, comprised of P. mirabilis (15), Proteus vulgaris (7) and Proteus hauseri (2). The prevalence of ureC, rsbA, zapA and mrpA genes among all identified Proteus spp. isolates were 91.7%, 50%, 45.8% and 45.8%, respectively. The average percentage similarities of mrpA gene sequence of pet turtle P. mirabilis isolates to human urinary and respiratory isolates were 96.35% and 94.85%, respectively. The prevalence of virulence genes and high similarity of mrpA gene sequences between pet turtles and human P. mirabilis isolates revealed that though pet turtles are healthy, these animals may pose a potential risk of urinary and respiratory infections to humans.
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