Susceptibilidade in vitro e eficácia da terapia com oxitetraciclina em infecções por Streptococcus agalactiae em tilápia do Nilo

• Ano de defesa: 2009
• Autor(a) principal: Faria, Flaviane Castro de
• Orientador(a): Figueiredo, Henrique César Pereira
• Banca de defesa: Costa, Geraldo Marcio da, Varaschin, Mary Suzan, Coimbra, Roney Santos
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: UNIVERSIDADE FEDERAL DE LAVRAS
• Programa de Pós-Graduação: DMV - Programa de Pós-graduação; Programa de Pós-Graduação em Ciências Veterinárias
• País: BRASIL
• Palavras-chave em Português: Streptococcus agalactiae; Oxitetraciclina; Testes de susceptibilidade; Terapia antimicrobiana; Tilápia do Nilo; Oxytetracycline; Testes of susceptibility; Antimicrobial therapy; Nile tilapia
• Área do conhecimento CNPq: CNPQ_NÃO_INFORMADO
• Link de acesso: https://repositorio.ufla.br/handle/1/2217

The aims of this work were to determine the in vitro sensitivity of different isolates of Streptococcus agalactiae to oxytetracycline (OTC) and verify the effectiveness of antibiotic therapy in the treatment of streptococcal disease in Nile tilapia (Oreochromis niloticus). To determine the diameter of the halo of inhibition and minimum inhibitory concentration (MIC) of OTC were used 29 S. agalactiae strains isolates from outbreaks of meningoencephalitis and septicemia in the Nile tilapia. The isolates were classified as sensitive (wild-type - WT) or resistant (non-wild-type - NWT) according to the frequency distributions of the values of MIC and diameter of the zone of inhibition. The strains were divided into two groups: sensitive to OTC diameter of the zone of inhibition of ³28 mm and the MIC value of <1.95 mg/mL composed of 27 isolates, and resistant to OTC, composed of only two isolated, with the diameter of the zone of inhibition equal to 12 mm and MIC value of equal to 31.25 mg/mL. The therapeutic efficiency of OTC was determined by experimental infection in Nile tilapia with S. agalactiae and treatment with OTC (medicated feed) before or after the challenge. The dose of OTC used was 100 mg per kg body weight for ten days. Three therapeutic models were tested: 1 - treatment with OTC initiated 24 hours before the challenge; 2 - treatment with OTC started 1h after the challenge and 3 - treatment with OTC started 24h after the challenge. The use of OTC in the treatment of infections by S. agalactiae in Nile tilapia was effective in reducing mortality, but it can collaborate in the maintenance of the agent in the breeding because of asymptomatic carriers.