Occurrence of Transferable Integrons and sul and dfr Genes Among Sulfonamide-and/or Trimethoprim-Resistant Bacteria Isolated From Chilean Salmonid Farms

Domı́nguez, Mariana; Miranda, Claudio D.; Fuentes, Oliver; Fuente, Mery de la; Godoy, Félix A.; Bello-Toledo, Helia; González-Rocha, Gerardo

doi:10.3389/fmicb.2019.00748

Cited by 53 publications

(42 citation statements)

References 77 publications

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“…Common gene cassettes of integrons contain sul, dfrA, and aadA genes which confer resistance to sulfonamides, trimethoprim and streptomycin (Domingues et al, 2015). The co-transference of resistance to florfenicol and oxytetracycline with integron was also reported previously (Dominguez et al, 2019).…”

Section: Discussionsupporting

confidence: 52%

Antimicrobial Resistance in Swine Fecal Specimens Across Different Farm Management Systems

et al. 2020

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Antimicrobial use in agricultural animals is known to be associated with increases in antimicrobial resistance. Most prior studies have utilized culture and susceptibility testing of select organisms to document these phenomena. In this study we aimed to detect 66 antimicrobial resistance (AMR) genes for 10 antimicrobial agent classes directly in swine fecal samples using our previously developed antimicrobial resistance TaqMan array card (AMR-TAC) across three different swine farm management systems. This included 38 extensive antimicrobial use (both in treatment and feed), 30 limited antimicrobial use (treatment only), and 30 no antimicrobial use farms. The number of resistance genes detected in extensive antimicrobial use farms was higher than in limited and no antimicrobial use farms (28.2 genes ± 4.2 vs. 24.0 genes ± 4.1 and 22.8 genes ± 3.6, respectively, p < 0.05). A principal component analysis and hierarchical clustering of the AMR gene data showed the extensive use farm samples were disparate from the limited and no antimicrobial use farms. The prevalence of resistance genes in extensive use farms was significantly higher than the other farm categories for 18 resistance genes including bla SHV , bla CTX−M1 group, bla CTX−M9 group, bla VEB , bla CMY2−LAT, aac(6)-lb-cr, qnrB1, gyrA83L-E. coli, armA, rmtB, aac(3)-IIa, mphA, 23S rRNA 2075G-Campylobacter spp., mcr-1, catA1, floR, dfrA5-14, and dfrA17. These genotypic findings were supported by phenotypic susceptibility results on fecal E. coli isolates. To examine the timing of AMR gene abundance in swine farms, we also performed a longitudinal study in pigs. The results showed that AMR prevalence occurred both early, presumably from mothers, as well as after weaning, presumably from the environment. In summary, detection of AMR genes directly in fecal samples can be used to qualitatively and quantitatively monitor AMR in swine farms.

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Section: Discussionsupporting

confidence: 52%

Antimicrobial Resistance in Swine Fecal Specimens Across Different Farm Management Systems

et al. 2020

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“…Bacterial isolates were screened for their plasmid content, as previously described [62]. Briefly, the geneJET Plasmid miniprep kit (Thermo-Scientific, Waltham, MA, USA) was used and the obtained plasmid DNA was run on 1.5% agarose gel electrophoresis for plasmids less than 20 kb and 0.8% agarose gel for plasmids greater than 20 kb.…”

Section: Isolation Of Plasmid Dnamentioning

confidence: 99%

Live Feeds Used in the Larval Culture of Red Cusk Eel, Genypterus chilensis, Carry High Levels of Antimicrobial-Resistant Bacteria and Antibiotic-Resistance Genes (ARGs)

Hurtado

Miranda

Rojas

et al. 2020

Animals

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Simple Summary: The culture of the marine fish red cusk eel Genypterus chilensis is currently considered a priority for Chilean aquaculture but low larval survival rates have prompted the need for the continuous use of antibiotics, mainly florfenicol. In this study, the role of live prey (rotifers and the brine shrimp Artemia franciscana) used to feed fish larvae as a source of antibacterial-resistant bacteria in a commercial culture of G. chilensis was investigated. Samples of live feeds were collected during the larval growth period and their bacterial contents were determined. High levels of potentially opportunistic pathogens, such as Vibrio spp., as well as florfenicol-resistant bacteria, were detected. Sixty-five florfenicol-resistant isolates were recovered from these cultures and identified as Vibrio (81.5%) and Pseudoalteromonas (15.4%), which exhibited a high incidence of co-resistance to the antibiotics streptomycin, oxytetracycline, co-trimoxazole, and kanamycin. The majority of them carried the florfenicol-resistance encoding genes floR and fexA. The high prevalence of antibiotic-resistant bacteria and the associated genetic elements in live feed administered to reared fish larvae requires the prompt implementation of efficient management strategies to prevent future therapy failures in fish larval cultures and the spread of antibiotic-resistant bacteria to associated aquatic environments. Abstract:The culture of red cusk eel Genypterus chilensis is currently considered a priority for Chilean aquaculture but low larval survival rates have prompted the need for the continuous use of antibacterials. The main aim of this study was to evaluate the role of live feed as a source of antibacterial-resistant bacteria in a commercial culture of G. chilensis. Samples of rotifer and Artemia cultures used as live feed were collected during the larval growth period and culturable bacterial counts were performed using a spread plate method. Rotifer and Artemia cultures exhibited high levels of resistant bacteria (8.03 × 10 4 to 1.79 × 10 7 CFU/g and 1.47 × 10 6 to 3.50 × 10 8 CFU/g, respectively). Sixty-five florfenicol-resistant isolates were identified as Vibrio (81.5%) and Pseudoalteromonas (15.4%) using 16S rRNA gene sequence analysis. A high incidence of resistance to streptomycin (93.8%), oxytetracycline (89.2%), co-trimoxazole (84.6%), and kanamycin (73.8%) was exhibited by resistant isolates. A high proportion of isolates (76.9%) carried the florfenicol-resistance encoding genes floR and fexA, as well as plasmid DNA (75.0%).Animals 2020, 10, 505 2 of 23 microbiota in reared fish larvae, thus proper monitoring and management strategies for live feed cultures appear to be a priority for preventing future therapy failures in fish larval cultures.

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“…A total of 65 isolates exhibiting resistance, reduced susceptibility, or susceptibility to flumequine were included in the study. The bacterial isolates used in this study were recovered from various sources of land-based and lake-based Chilean salmonid farms, as previously described [31]. Isolates from land-based culture centers were isolated from various sources including unmedicated fish food pellets, mucus of healthy salmonid fingerlings, and water samples from fish farm influents, effluents, and fish rearing tanks.…”

Section: Bacterial Isolates and Culture Conditionsmentioning

confidence: 99%

Characterization of Mechanisms Lowering Susceptibility to Flumequine among Bacteria Isolated from Chilean Salmonid Farms

et al. 2019

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Despite their great importance for human therapy, quinolones are still used in Chilean salmon farming, with flumequine and oxolinic acid currently approved for use in this industry. The aim of this study was to improve our knowledge of the mechanisms conferring low susceptibility or resistance to quinolones among bacteria recovered from Chilean salmon farms. Sixty-five isolates exhibiting resistance, reduced susceptibility, or susceptibility to flumequine recovered from salmon farms were identified by their 16S rRNA genes, detecting a high predominance of species belonging to the Pseudomonas genus (52%). The minimum inhibitory concentrations (MIC) of flumequine in the absence and presence of the efflux pump inhibitor (EPI) Phe-Arg-β-naphthylamide and resistance patterns of isolates were determined by a microdilution broth and disk diffusion assays, respectively, observing MIC values ranging from 0.25 to >64 µg/mL and a high level of multi-resistance (96%), mostly showing resistance to florfenicol and oxytetracycline. Furthermore, mechanisms conferring low susceptibility to quinolones mediated by efflux pump activity, quinolone target mutations, or horizontally acquired resistance genes (qepA, oqxA, aac(6′)-lb-cr, qnr) were investigated. Among isolates exhibiting resistance to flumequine (≥16 µg/mL), the occurrence of chromosomal mutations in target protein GyrA appears to be unusual (three out of 15), contrasting with the high incidence of mutations in GyrB (14 out of 17). Bacterial isolates showing resistance or reduced susceptibility to quinolones mediated by efflux pumps appear to be highly prevalent (49 isolates, 75%), thus suggesting a major role of intrinsic resistance mediated by active efflux.

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Occurrence of Transferable Integrons and sul and dfr Genes Among Sulfonamide-and/or Trimethoprim-Resistant Bacteria Isolated From Chilean Salmonid Farms

Cited by 53 publications

References 77 publications

Antimicrobial Resistance in Swine Fecal Specimens Across Different Farm Management Systems

Antimicrobial Resistance in Swine Fecal Specimens Across Different Farm Management Systems

Live Feeds Used in the Larval Culture of Red Cusk Eel, Genypterus chilensis, Carry High Levels of Antimicrobial-Resistant Bacteria and Antibiotic-Resistance Genes (ARGs)

Characterization of Mechanisms Lowering Susceptibility to Flumequine among Bacteria Isolated from Chilean Salmonid Farms

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