Polyphasic characterization of heterotrophic bacteria from shrimp farm environments to tetracyclines

• Main Author: Rafael dos Santos Rocha
• Other Authors: Regine Helena Silva dos Fernandes Vieira
• Format: Others
• Language: Portuguese
• Published: Universidade Federal do Cearà 2016
• Subjects: Carcinicultura; Antibacterianos; Vibrionaceae; Shimp farm; Antibacterial agents; ENGENHARIA DE PESCA
• Online Access: http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=16669

CoordenaÃÃo de AperfeÃoamento de Pessoal de NÃvel Superior === Antimicrobial agents of tetracycline class has been extensively used in aquaculture for disease control and growth promotion. Thus, the aim of this study was to evaluate the polyphase profile of the bacterial community in shrimp farming environment front antimicrobial classes of tetracyclines, focusing on Vibrio genus. Water and sediment samples were collected four (4) shrimp farms: two (2) in the state of Cearà and two (2) in the state of Rio Grande do Norte, of points: estuary, supply channel, pond and drainage channel. Cultivable heterotrophic bacteria (CHB), with resistance to tetracycline (CHB+TET) and oxytetracycline (CHB+OTC), total Vibrio, positive sucrose Vibrio and sucrose negative Vibrio were surveyed by Standard Plate Count method (SPC). The strains isolated from CHB, CHB+TET, CHB+OTC and Vibrio underwent phenotypic identification. The phenotypic profile of antimicrobial susceptibility of strains of Vibrio and other BHC was compared between the disk diffusion techniques and macrodilution by determining the Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) for tetracycline and oxytetracycline antimicrobials. Resistance genes tet(M), tet(S) otr(A) and otr(B) were investigated in strains characterized as phenotypically resistant. Diversity of heterotrophic bacteria is influenced by wet and rainy seasons and also by the different collection points within the shrimp farms. Overall, the CHB, CHB+TET and CHB+OTC and Vibrio counts differ between the collection seasons, with higher measurements during the rainy season to the points of pond and drainage channel. 146 strains of CHB, 57 of CHB+TET and 45 of CHB+OTC were isolated, of which the most representative genera were Vibrio and Enterobacter. A total of 100 strains of Vibrio were isolated, which V. coralliilyticus was the most representative species. Antimicrobial profile of Vibrio and other CHB differed between disk-diffusion and macrodilution techniques, being the macrodilution the most efficient in the characterization of resistance among isolates. All strains of Vibrio and other CHB, phenotypically resistant, presented the tet(M) gene as a determinant of resistance determinat, but tet(S) otr(A) and otr(B) genes were not observed. Thus, it proves that Vibrio genus is most abundant among herotrotrophic bacteria with resistance to tetracyclines, with the bacterial diversity strongly influenced by seasons. === Antimicrobianos da classe das tetraciclinas tÃm sido extensivamente usados em aquicultura para o controle de doenÃas e como promotores de crescimento. Dessa forma, foi traÃado como objetivo geral avaliar o perfil polifÃsico da comunidade bacteriana de ambiente de criaÃÃo de camarÃo frente aos antimicrobianos das classes das tetraciclinas, com enfoque no gÃnero Vibrio. Amostras de Ãgua e sedimento foram coletadas de quatro (4) fazendas de carcinicultura: duas (2) no estado do Cearà e duas (2) no estado do Rio Grande do Norte, dos pontos: estuÃrio, canal de abastecimento, viveiro e canal de drenagem. Foram pesquisadas bactÃrias heterotrÃficas cultivÃveis (BHC), com resistÃncia à tetraciclina (BHC+TET) e oxitetraciclina (BHC+OTC), Vibrio total, sacarose positivos e negativos pelo mÃtodo de Contagem PadrÃo em Placas (CPP). As cepas isoladas de BHC, BHC+TET, BHC+OTC e Vibrio foram submetidas à identificaÃÃo fenotÃpica. O perfil fenotÃpico de susceptibilidade antimicrobiana das cepas de Vibrio e demais BHC foi comparado entre as tÃcnicas de disco-difusÃo e macrodiluiÃÃo, pela determinaÃÃo da ConcentraÃÃo InibitÃria MÃnima (CIM) e ConcentraÃÃo Bactericida MÃnima (CBM) para os antimicrobianos tetraciclina e oxitetraciclina. Os genes de resistÃncia tet(M), tet(S), otr(A) e otr(B) foram pesquisados nas cepas fenotipicamente caracterizadas como resistentes. A diversidade de bactÃrias heterotrÃficas foi influenciada pelos perÃodos de estio e chuvoso e tambÃm pelos diferentes pontos de coleta dentro das fazendas de carcinicultura. No geral, as contagens de BHC, BHC+TET e BHC+OTC e Vibrio e demais BHC diferiram entre os perÃodos de coleta, com quantificaÃÃes superiores no perÃodo chuvoso para os pontos de coleta viveiro e canal de drenagem. Foram isoladas 146 cepas de BHC, 57 de BHC+TET, 25 de BHC+OTC, das quais os gÃneros mais representativos foram Vibrio e Enterobacter. Foi possÃvel o isolamento de 100 cepas de Vibrio, das quais V. coralliilyticus foi a espÃcie mais representativa. O perfil antimicrobiano diferiu entre as cepas de Vibrio e demais BHC entre as tÃcnicas de disco-difusÃo e macrodiluiÃÃo, sendo a de macrodiluiÃÃo a mais eficiente na caracterizaÃÃo de resistÃncia dentre os isolados. Todas as cepas de Vibrio e demais BHC, fenotipicamente resistentes, apresentaram o gene tet(M) como determinante de resistÃncia, no entanto os genes tet(S), otr(A) e otr(B) nÃo foram verificados. Com isso, comprovou-se que Vibrio à gÃnero mais abundante dentre as bactÃrias heterotrÃficas com resistÃncia Ãs tetraciclinas, estando a diversidade bacteriana fortemente influenciada pelos perÃodos do ano.