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The exponential growth of aquaculture over the past 30 years has been accompanied by a parallel increase in the use of antimicrobials. This widespread use has had negative effects on animal, human and environmental health and affected the biodiversity of the environments where aquaculture takes place. Results showing these harmful effects have been resisted and made light of by the aquaculture industry and their scientific supporters through introduction of misunderstandings and misinterpretations of concepts developed in the evolution, genetics, and molecular epidemiology of antimicrobial resistance. We focus on a few of the most obvious scientific shortcomings and biases of two recent attempts to minimise the negative impacts of excessive antimicrobial use in Chilean salmon aquaculture on human and piscine health and on the environment. Such open debate is critical to timely implementation of effective regulation of antimicrobial usage in salmon aquaculture in Chile, if the negative local and worldwide impacts of this usage are to be avoided.

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Large amounts of antimicrobials are used in salmonid aquaculture in Chile. Most are used in marine aquaculture, but appreciable amounts are also employed in freshwater aquaculture. Much research and many publications have examined transferable antimicrobial resistance in bacteria isolated from marine salmon farms, but much less attention has been paid to this area in freshwater salmon farming. A recent paper by Domínguez et al. (2019) has as least in part remedied this situation. We now comment on some of its interpretations and have attempted to point out its areas of strength and weakness in light of the published scientific literature. Seen in this setting, the important results presented by Domínguez et al. (2019) underline the need for increased awareness of the challenge to animal and human health posed by excessive use of antimicrobials in aquaculture.

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Although public health and social medicine have a long history in Latin America going back to Co lonial times, their relevance has ebbed and flowed as a result of the development of a variety of social and political movements. The Mexican Revolution accelerated implementation of public health po licies in Mexico and resulted in the creation of the Mexican Institute of Social Security to serve the health and social security needs of the country's population. Construction of the Hospital La Raza and its embellishment by the mural paintings of Diego Rivera and David Alfaro Siqueiros correspon ded to the heyday of public health ideas in Mexico. This is clearly reflected in Rivera's mural painting from 1953, The History of Medicine in Mexico: People's Demand for Better Health. The left side of the painting, representing the history of modern medicine in Mexico, exemplifies the tensions between individuals and social groups demanding the fruits of modern medicine and public health, and en trenched bureaucracy and private interests resisting their demands. Rivera's artistry illustrates this tension by depicting urban social groups and a family with a pregnant mother and children reques ting medical attention on one side of the main panel, facing condescending physicians, bureaucrats and upper society gentlemen and ladies on the other side. The importance of social movements to the development of public health policies illustrated by Rivera in 1953 continues to be relevant in Latin America today where increasing millions still lack the benefits of health care and social security.

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Abstract: Although public health and social medicine have a long history in Latin America going back to Co lonial times, their relevance has ebbed and flowed as a result of the development of a variety of social and political movements. The Mexican Revolution accelerated implementation of public health po licies in Mexico and resulted in the creation of the Mexican Institute of Social Security to serve the health and social security needs of the country's population. Construction of the Hospital La Raza and its embellishment by the mural paintings of Diego Rivera and David Alfaro Siqueiros correspon ded to the heyday of public health ideas in Mexico. This is clearly reflected in Rivera's mural painting from 1953, The History of Medicine in Mexico: People's Demand for Better Health. The left side of the painting, representing the history of modern medicine in Mexico, exemplifies the tensions between individuals and social groups demanding the fruits of modern medicine and public health, and en trenched bureaucracy and private interests resisting their demands. Rivera's artistry illustrates this tension by depicting urban social groups and a family with a pregnant mother and children reques ting medical attention on one side of the main panel, facing condescending physicians, bureaucrats and upper society gentlemen and ladies on the other side. The importance of social movements to the development of public health policies illustrated by Rivera in 1953 continues to be relevant in Latin America today where increasing millions still lack the benefits of health care and social security.

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The emergence and dissemination of antimicrobial-resistant bacteria (ARB) is currently seen as one of the major threats to human and animal public health. Veterinary use of antimicrobials in both developing and developed countries is many-fold greater than their use in human medicine and is an important determinant in selection of ARB. In light of the recently outlined National Plan Against Antimicrobial Resistance in Chile, our findings on antimicrobial use in salmon aquaculture and their impact on the environment and human health are highly relevant. Ninety-five percent of tetracyclines, phenicols and quinolones imported into Chile between 1998 and 2015 were for veterinary use, mostly in salmon aquaculture. Excessive use of antimicrobials at aquaculture sites was associated with antimicrobial residues in marine sediments 8 km distant and the presence of resistant marine bacteria harboring easily transmissible resistance genes, in mobile genetic elements, to these same antimicrobials. Moreover, quinolone and integron resistance genes in human pathogens isolated from patients in coastal regions adjacent to aquaculture sites were identical to genes isolated from regional marine bacteria, consistent with genetic communication between bacteria in these different environments. Passage of antimicrobials into the marine environment can potentially diminish environmental diversity, contaminate wild fish for human consumption, and facilitate the appearance of harmful algal blooms and resistant zoonotic and human pathogens. Our findings suggest that changes in aquaculture in Chile that prevent fish infections and decrease antimicrobial usage will prove a determining factor in preventing human and animal infections with multiply-resistant ARB in accord with the modern paradigm of One Health.

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Northern Europe at the beginning of the 16th Century was in turmoil as a result of religious and political dissention, epidemics of plague, syphilis, ergotism, and famine, and the threat of the Ottoman Empire. In Alsace, a fulcrum between Germany, France, Switzerland and the Netherlands, Grünewald painted his celebrated and complex altarpiece at Isenheim in a convent chapel of the Antonine religious order that kept a hospital for the care of patients suffering from ergotism, plague, syphilis and other illnesses. The ten paintings of this altarpiece convey a series of religious, medical and political meanings, with the scenes of the Crucifixion and the Resurrection being thought to play an integral part of the curative process. This was because patients could be soothed by comparing their suffering to that of Christ on the cross and could console themselves by the Resurrection. The portrait of Christ in the cross is astounding in its realism and naturalism. It represents, with great pathological veracity, a tortured body in agony, a break with previous traditional representations of this event. Impressive pathological detail is also given to a figure in the Temptation scene. The entire work is suffused with religious connotations provided by the composition, the forms and the richness and sophisticated use of colors. Although Grünewald's paintings are few and the facts of his personal life sparse, it is known he married a Jewish woman, supported the peasant revolts, and was probably a Lutheran in a Catholic area. While Grünewald is considered the epitome of a German artist, the universal projections of his art have influenced physicians and the artistic productions of many painters, writers, musicians and sculptors throughout the world.

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Northern Europe at the beginning of the 16th Century was in turmoil as a result of religious and political dissention, epidemics of plague, syphilis, ergotism, and famine, and the threat of the Ottoman Empire. In Alsace, a fulcrum between Germany, France, Switzerland and the Netherlands, Grünewald painted his celebrated and complex altarpiece at Isenheim in a convent chapel of the Antonine religious order that kept a hospital for the care of patients suffering from ergotism, plague, syphilis and other illnesses. The ten paintings of this altarpiece convey a series of religious, medical and political meanings, with the scenes of the Crucifixion and the Resurrection being thought to play an integral part of the curative process. This was because patients could be soothed by comparing their suffering to that of Christ on the cross and could console themselves by the Resurrection. The portrait of Christ in the cross is astounding in its realism and naturalism. It represents, with great pathological veracity, a tortured body in agony, a break with previous traditional representations of this event. Impressive pathological detail is also given to a figure in the Temptation scene. The entire work is suffused with religious connotations provided by the composition, the forms and the richness and sophisticated use of colors. Although Grünewald's paintings are few and the facts of his personal life sparse, it is known he married a Jewish woman, supported the peasant revolts, and was probably a Lutheran in a Catholic area. While Grünewald is considered the epitome of a German artist, the universal projections of his art have influenced physicians and the artistic productions of many painters, writers, musicians and sculptors throughout the world.

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El aumento de la resistencia bacteriana múltiple a antimicrobianos es considerado una gran amenaza para la salud pública mundial y como generador de una importante crisis en el funcionamiento de los sistemas de salud. Esta crisis es discutida diariamente por los gobiernos y los parlamentos, las instituciones globales de salud, fundaciones benéficas y de científicos y de profesionales de la salud y también de consumidores de productos animales. En todos los países del orbe se ha identificado al uso de antimicrobianos en la crianza industrial de animales como un importante determinante en la selección de esta resistencia. Aprovechando la oportunidad que se ha planteado en Chile con el diseño del Plan Nacional Contra la Resistencia a los Antimicrobianos, hemos creído importante revisitar y actualizar sumariamente nuestros estudios sobre el uso de antimicrobianos en la acuicultura del salmón y de su potencial impacto en el ambiente y la salud humana y animal. Estos estudios indican que 95% de tres grupos de antimicrobianos importados al país, que incluyen tetraciclinas, fenicoles y quinolonas, son usados en medicina veterinaria y mayormente en la acuicultura del salmón. Nuestros estudios indican que el excesivo uso de estos antimicrobianos genera la presencia de residuos de antimicrobianos en el ambiente marino hasta 8 km de los sitios de acuicultura, los que seleccionan a bacterias con resistencia múltiple en dicho ambiente, ya que ellas contienen variados genes de resistencia a estos antimicrobianos. Estos genes de resistencia están contenidos en elementos genéticos móviles incluyendo plásmidos e integrones, los que son trasmitidos a otras bacterias permitiendo su potencial diseminación epidémica entre poblaciones bacterianas. Bacterias del ambiente marino contienen genes idénticos a los genes de resistencia a quinolonas e integrones similares a los de patógenos humanos, sugiriendo comunicación genética entre estas bacterias de diversos ambientes. Alrededor de los recintos de acuicultura, este uso exagerado de antimicrobianos contamina con ellos también a peces silvestres para consumo humano y potencialmente selecciona BRA en su carne y en los productos de acuicultura. El consumo de estos productos selecciona bacterias resistentes en el microbioma humano y facilita también el intercambio genético entre bacterias del ambiente acuático y la microbiota comensal y patógena humana. El pasaje de antimicrobianos al ambiente marino disminuye la diversidad en él, y potencialmente podría facilitar la aparición de florecimientos de algas nocivas, la infección de peces por patógenos piscícolas resistentes los antimicrobianos y la aparición de patógenos zoonóticos resistentes, incluyendo a Vibrio parahaemolyticus. Estos hallazgos sugieren que la prevención de infecciones en peces y la disminución del uso de antimicrobianos en su crianza, será en Chile un factor determinante en la prevención de infecciones humanas y animales con resistencia múltiple a los antimicrobianos, de acuerdo con el paradigma moderno e integral de Una Salud.

The emergence and dissemination of antimicrobial-resistant bacteria (ARB) is currently seen as one of the major threats to human and animal public health. Veterinary use of antimicrobials in both developing and developed countries is many-fold greater than their use in human medicine and is an important determinant in selection of ARB. In light of the recently outlined National Plan Against Antimicrobial Resistance in Chile, our findings on antimicrobial use in salmon aquaculture and their impact on the environment and human health are highly relevant. Ninety-five percent of tetracyclines, phenicols and quinolones imported into Chile between 1998 and 2015 were for veterinary use, mostly in salmon aquaculture. Excessive use of antimicrobials at aquaculture sites was associated with antimicrobial residues in marine sediments 8 km distant and the presence of resistant marine bacteria harboring easily transmissible resistance genes, in mobile genetic elements, to these same antimicrobials. Moreover, quinolone and integron resistance genes in human pathogens isolated from patients in coastal regions adjacent to aquaculture sites were identical to genes isolated from regional marine bacteria, consistent with genetic communication between bacteria in these different environments. Passage of antimicrobials into the marine environment can potentially diminish environmental diversity, contaminate wild fish for human consumption, and facilitate the appearance of harmful algal blooms and resistant zoonotic and human pathogens. Our findings suggest that changes in aquaculture in Chile that prevent fish infections and decrease antimicrobial usage will prove a determining factor in preventing human and animal infections with multiply-resistant ARB in accord with the modern paradigm of One Health.

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Antimicrobials are heavily used in Chilean salmon aquaculture. We previously found significant differences in antimicrobial-resistant bacteria between sediments from an aquaculture and a non-aquaculture site. We now show that levels of antimicrobial resistance genes (ARG) are significantly higher in antimicrobial-selected marine bacteria than in unselected bacteria from these sites. While ARG in tetracycline- and florfenicol-selected bacteria from aquaculture and non-aquaculture sites were equally frequent, there were significantly more plasmid-mediated quinolone resistance genes per bacterium and significantly higher numbers of qnrB genes in quinolone-selected bacteria from the aquaculture site. Quinolone-resistant urinary Escherichia coli from patients in the Chilean aquacultural region were significantly enriched for qnrB (including a novel qnrB gene), qnrS, qnrA and aac(6')-1b, compared with isolates from New York City. Sequences of qnrA1, qnrB1 and qnrS1 in quinolone-resistant Chilean E. coli and Chilean marine bacteria were identical, suggesting horizontal gene transfer between antimicrobial-resistant marine bacteria and human pathogens.

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Borrelia chilensis strain VA1 is a recently described South American member of the Borrelia burgdorferi sensu lato complex from Chile. Whole-genome sequencing analysis determined its linear chromosome and plasmids lp54 and cp26, confirmed its membership in the Lyme borreliosis group, and will open new research avenues regarding its pathogenic potential.

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Marine bacteria from aquaculture areas with industrial use of quinolones have the potential to pass quinolone resistance genes to animal and human pathogens. The VPA0095 gene, related to the quinolone resistance determinant qnrA, from clinical isolates of epidemic Vibrio parahaemolyticus conferred reduced susceptibility to quinolone after cloning into Escherichia coli K-12 either when acting alone or synergistically with DNA gyrase mutations. In addition, a plasmid-mediated quinolone resistance gene from marine bacteria, aac(6')-Ib-cr, was identical to aac(6')-Ib-cr from urinary tract isolates of E. coli, suggesting a recent flow of this gene between these bacteria isolated from different environments. aac(6')-Ib-cr from E. coli also conferred reduced susceptibility to quinolone and kanamycin when cloned into E. coli K-12.

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Borrelia burgdorferi sensu lato (s.l.), transmitted by Ixodes spp. ticks, is the causative agent of Lyme disease. Although Ixodes spp. ticks are distributed in both Northern and Southern Hemispheres, evidence for the presence of B. burgdorferi s.l. in South America apart from Uruguay is lacking. We now report the presence of culturable spirochetes with flat-wave morphology and borrelial DNA in endemic Ixodes stilesi ticks collected in Chile from environmental vegetation and long-tailed rice rats (Oligoryzomys longicaudatus). Cultured spirochetes and borrelial DNA in ticks were characterized by multilocus sequence typing and by sequencing five other loci (16S and 23S ribosomal genes, 5S-23S intergenic spacer, flaB, ospC). Phylogenetic analysis placed this spirochete as a new genospecies within the Lyme borreliosis group. Its plasmid profile determined by polymerase chain reaction and pulsed-field gel electrophoresis differed from that of B. burgdorferi B31A3. We propose naming this new South American member of the Lyme borreliosis group B. chilensis VA1 in honor of its country of origin.

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Antimicrobials used in salmon aquaculture pass into the marine environment. This could have negative impacts on marine environmental biodiversity, and on terrestrial animal and human health as a result of selection for bacteria containing antimicrobial resistance genes. We therefore measured the numbers of culturable bacteria and antimicrobial-resistant bacteria in marine sediments in the Calbuco Archipelago, Chile, over 12-month period at a salmon aquaculture site approximately 20 m from a salmon farm and at a control site 8 km distant without observable aquaculture activities. Three antimicrobials extensively used in Chilean salmon aquaculture (oxytetracycline, oxolinic acid, and florfenicol) were studied. Although none of these antimicrobials was detected in sediments from either site, traces of flumequine, a fluoroquinolone antimicrobial also widely used in Chile, were present in sediments from both sites during this period. There were significant increases in bacterial numbers and antimicrobial-resistant fractions to oxytetracycline, oxolinic acid, and florfenicol in sediments from the aquaculture site compared to those from the control site. Interestingly, there were similar numbers of presumably plasmid-mediated resistance genes for oxytetracycline, oxolinic acid and florfenicol in unselected marine bacteria isolated from both aquaculture and control sites. These preliminary findings in one location may suggest that the current use of large amounts of antimicrobials in Chilean aquaculture has the potential to select for antimicrobial-resistant bacteria in marine sediments.

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