Perfil de resistência à antimicrobianos de Aeromonas sp. e Streptococcus sp. isolados de tilápia-do-Nilo e detecção dos genes envolvidos na resistência à tetraciclina
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Data
2016-06-30
Autores
Gozi, Katia Suemi [UNESP]
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Editor
Universidade Estadual Paulista (Unesp)
Resumo
A intensificação na criação de tilápia tem aumentado gradativamente o número de enfermidades bacterianas nos peixes, com destaque para o Streptococcus sp. e Aeromonas sp., que provocam um número elevado de morbidade e mortalidade nos peixes. Quando surtos de bacterioses ocorrem, um grande número de antimicrobianos é utilizado, muitas vezes de forma indiscriminada e sem critérios, causando danos à saúde dos peixes, meio ambiente e consumidor. O aparecimento de cepas bacterianas resistentes a uma ou mais drogas, incluindo à oxitetraciclina, já se tornou a maior ameaça à saúde pública da atualidade, e a Organização Mundial de Saúde, já há algum tempo, tenta regulamentar o uso não terapêutico destas substâncias. Assim, este estudo teve como objetivo elucidar o perfil de resistência da Aeromonas sp. e do Streptococcus sp. aos dois antimicrobianos legalizados para uso na piscicultura brasileira (florfenicol e oxitetraciclina) e detectar os genes envolvidos na resistência à tetraciclina. Para tanto, foram utilizadas 108 bactérias, isoladas de tilápia-do-Nilo com sinais clínicos característicos de aeromonose ou estreptococose, as quais foram submetidas ao teste de susceptibilidade aos antimicrobianos oxitetraciclina e florfenicol, através da concentração mínima inibitória (MIC) pelo método da microdiluição e identificadas como cepas sensíveis ou resistentes. Também foi verificado a presença dos genes de resistência (tetA, tetE, tetL e tetM) à oxitetraciclina através da PCR. No resultado da MIC para os antimicrobianos analisados, pode-se observar uma variação da oxitetraciclina para as cepas de Aeromonasentre 0,06 – 32 µg/mL e de 0,125 a 1 µg/mL para o florfenicol. Para o Streptococcus, a variação ocorreu de 0,2 a 1µg/mL para oxitetraciclina e de 1 a 0,125 µg/mL para o florfenicol. Nas amostras não-selvagens de Aeromonas, foi detectado o gene tetA nas três espécies de identificadas neste estudo. Para as amostras não-selvagens de Streptococcus o gene tetL foi detectado em 6 das 9 cepas estudadas. Este trabalho evidencia a problemática do uso indiscriminado de antimicrobianos na aquicultura, que pode trazer sérias consequências para o meio ambiente e ao homem.
The tilapia production has gradually increased the number of fish bacterial diseases, especially for Streptococcussp. and Aeromonassp. which cause a high number of morbidity and mortality in fish. When bacterial diseases outbreaks occur, a large number of antimicrobials are used, often indiscriminate causing damage to fish health, environment and consumer. The appearance of resistant bacterial strains to one or more drugs, including oxytetracycline, has become the greatest threat to public health today, and the World Health Organization, since some time ago, tried to regulate the non-therapeutic use of these substances. This study aimed to elucidate the resistance profile of Aeromonas sp. and Streptococcus sp. to two antimicrobials florfenicol and oxytetracycline, legalized for the Brazilian fish production and to detect genes involved in resistance to tetracycline. Therefore, we used 108 bacteria isolated from Nile tilapia with clinical characteristic signs of Aeromonas or Streptococcus infection, which were submitted to the susceptibility test to oxytetracycline and florfenicol antimicrobial by minimum inhibitory concentration (MIC) using the microdilution method and identified as wild or non-wild strains. It was alsofound the presence of resistance genes (tetA, tetE, tetL and tet M) oxytetracycline by PCR analysis. As a result of MIC for the antimicrobial agents tested, one variation of oxytetracycline for Aeromonas between 0,06 to 32 µg/ml and 0,125 to 1 µg/mL to f lorfenicol. For Streptococcus, the variation was from 0,2 to 1 µg/ml for oxytetracycline and 0,125 to 1 µg/ml for florfenicol. In non-wild strains of Aeromonas, tetA gene was detected in all three species identified in this study. For Streptococcusnon-wild strains, the tetL gene was detected in 6 of the 9 strains studied. This study highlights the problem of the indiscriminate use of antimicrobialsin aquaculture, which can have serious consequences for the environment and man.
The tilapia production has gradually increased the number of fish bacterial diseases, especially for Streptococcussp. and Aeromonassp. which cause a high number of morbidity and mortality in fish. When bacterial diseases outbreaks occur, a large number of antimicrobials are used, often indiscriminate causing damage to fish health, environment and consumer. The appearance of resistant bacterial strains to one or more drugs, including oxytetracycline, has become the greatest threat to public health today, and the World Health Organization, since some time ago, tried to regulate the non-therapeutic use of these substances. This study aimed to elucidate the resistance profile of Aeromonas sp. and Streptococcus sp. to two antimicrobials florfenicol and oxytetracycline, legalized for the Brazilian fish production and to detect genes involved in resistance to tetracycline. Therefore, we used 108 bacteria isolated from Nile tilapia with clinical characteristic signs of Aeromonas or Streptococcus infection, which were submitted to the susceptibility test to oxytetracycline and florfenicol antimicrobial by minimum inhibitory concentration (MIC) using the microdilution method and identified as wild or non-wild strains. It was alsofound the presence of resistance genes (tetA, tetE, tetL and tet M) oxytetracycline by PCR analysis. As a result of MIC for the antimicrobial agents tested, one variation of oxytetracycline for Aeromonas between 0,06 to 32 µg/ml and 0,125 to 1 µg/mL to f lorfenicol. For Streptococcus, the variation was from 0,2 to 1 µg/ml for oxytetracycline and 0,125 to 1 µg/ml for florfenicol. In non-wild strains of Aeromonas, tetA gene was detected in all three species identified in this study. For Streptococcusnon-wild strains, the tetL gene was detected in 6 of the 9 strains studied. This study highlights the problem of the indiscriminate use of antimicrobialsin aquaculture, which can have serious consequences for the environment and man.
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Palavras-chave
Antimicrobiano, Resistência, Bactéria, Peixe, Antimicrobial, Resistance, Bacteria, Fish