RESUMEN
Salmonella pathogenicity relies on virulence factors many of which are clustered within the Salmonella pathogenicity islands. Salmonella also harbours mobile genetic elements such as virulence plasmids, prophage-like elements and antimicrobial resistance genes which can contribute to increase its pathogenicity. Here, we have genetically characterized a selected S. Typhimurium strain (CCRJ_26) from our previous study with Multiple Drugs Resistant profile and high-frequency PFGE clonal profile which apparently persists in the pork production centre of Rio de Janeiro State, Brazil. By whole-genome sequencing, we described the strain's genome virulent content and characterized the repertoire of bacterial plasmids, antibiotic resistance genes and prophage-like elements. Here, we have shown evidence that strain CCRJ_26 genome possible represent a virulence-associated phenotype which may be potentially virulent in human infection. SIGNIFICANCE AND IMPACT OF THE STUDY: Whole-genome sequencing technologies are still costly and remain underexplored for applied microbiology in Brazil. Hence, this genomic description of S. Typhimurium strain CCRJ_26 will provide help in future molecular epidemiological studies. The analysis described here reveals a quick and useful pipeline for bacterial virulence characterization using whole-genome sequencing approach.
Asunto(s)
Genoma Bacteriano/genética , Salmonelosis Animal/microbiología , Salmonella typhimurium/genética , Porcinos/microbiología , Animales , Antibacterianos , Brasil , Farmacorresistencia Bacteriana/genética , Islas Genómicas/genética , Humanos , Pruebas de Sensibilidad Microbiana , Plásmidos/genética , Profagos/genética , Carne Roja/microbiología , Salmonella typhimurium/clasificación , Salmonella typhimurium/aislamiento & purificación , Virulencia/genéticaRESUMEN
A enrofloxacina é um dos antimicrobianos mais utilizados na avicultura industrial, e a deposição de resíduos em produtos avícolas, como os ovos, são de grande importância para a saúde pública. Na legislação brasileira não existe padronização do período de carência para o seu uso na produção avícola e não há Limite Máximo de Resíduo (LMR) fixado para enrofloxacina em ovos. Neste estudo, foi utilizado o kit de ELISA comercial (Bioo Scientific(r)) e a LC-MS/MS na pesquisa de enrofloxacina em ovos de 30 galinhas tratadas previamente via água de bebida, com 10mg/kg de enrofloxacina, durante cinco dias. Seis ovos foram coletados diariamente e analisados durante o tratamento e após a sua suspensão, durante 15 dias. A deposição de resíduos obteve níveis máximos no quinto dia de tratamento das aves, declinando gradativamente até não ser detectada a partir do nono dia de suspensão do tratamento. Considerando como base o LMR de 100µg/kg fixado pelo Brasil para tecidos comestíveis de aves e pela União Europeia para músculo, gordura e pele, após seis dias de suspensão do tratamento, os níveis de resíduos foram inferiores a esse limite, tendo como médias 37,43µg/kg na LC-MS/MS e 14,731µg/kg no ELISA. Dentro das condições deste estudo, um período de carência de seis dias seria mais adequado para utilização dos ovos para consumo humano. Foram detectados valores de resíduos nos ovos menores no ELISA em relação à LC-MS/MS para a mesma amostra, mas os dois métodos apresentaram concordância estatística entre si. A LC-MS/MS é o teste recomendado pela legislação brasileira para a análise de resíduos em alimentos; entretanto, pelos resultados obtidos, o kit de ELISA utilizado também pode ser aplicado na detecção de resíduos de enrofloxacina em ovos, com as vantagens de rapidez e simplicidade...
Enrofloxacin is one of the most used antibiotics in the poultry industry and the deposition of residues in poultry products, such as eggs, are of great concern to public health. In Brazilian law there is no standard withdrawal period for enrofloxacin in eggs and there is no Maximum Residue Limit (MRL) established for this antimicrobial in eggs. In this study, (Bioo Scientific(r)) commercial ELISA kit and LC-MS/MS were used to investigate enrofloxacin in eggs of 30 hens pretreated via drinking water at 10mg/kg of enrofloxacin for five days. Six eggs were collected daily and analyzed during treatment and after the end of treatment, for 15 days. Residues obtained maximum levels on the fifth day of treatment, declined gradually and were no longer detected from the ninth day to the end of treatment. Based on the MRL of 100mg/kg established for edible tissues of poultry by Brazillian law and for muscle, fat and skin, by the European Union, after six days of treatment withdrawal, the residue levels were below that limit, with the average of 37.43mg/kg in LC-MS/MS and 14.731mg/kg in ELISA. Within the conditions of this study, a withdrawal period of six days would be more appropriate to use the eggs for human consumption. The values obtained by ELISA for residues in eggs were lower than those obtained in LC-MS/MS for the same sample, however both methods showed statistical agreement. LC-MS/MS is the recommended method by Brazilian legislation for analysis of residues in food, however, according to the results the ELISA kit used can also be applied to the detection of enrofloxacin residues in eggs, with the advantages of speed and simplicity...
