Depletion study and estimation of the withdrawal period for oxytetracycline in tilapia cultured in Brazil

Defining pharmacokinetic parameters and depletion intervals for antimicrobials used in fish represents important guidelines for future regulation by Brazilian agencies of the use of these substances in fish farming. This article presents a depletion study for oxytetracycline (OTC) in tilapias (Orechromis niloticus) farmed under tropical conditions during the winter season. High performance liquid chromatography, with fluorescence detection for the quantitation of OTC in tilapia fillets and medicated feed, was developed and validated. The depletion study with fish was carried out under monitored environmental conditions. OTC was administered in the feed for five consecutive days at daily dosages of 80 mg/kg body weight. Groups of ten fish were slaughtered at 1, 2, 3, 4, 5, 8, 10, 15, 20, and 25 days after medication. After the 8th day posttreatment, OTC concentrations in the tilapia fillets were below the limit of quantitation (13 ng/g) of the method. Linear regression of the mathematical model of data analysis presented a coefficient of 0.9962. The elimination half- life for OTC in tilapia fillet and the withdrawal period were 1.65 and 6 days, respectively, considering a percentile of 99% with 95% of confidence and a maximum residue limit of 100 ng/g. Even though the study was carried out in the winter under practical conditions where water temperature varied, the results obtained are similar to others from studies conducted under controlled temperature.FAPESP [04/07312-9]FAPESPCNPqCNP

Listeria monocytogenes, E. coli O157, Salmonella spp. e microrganismos indicadores em carcaças bovinas para exportação

Samples were collected from 100 carcasses in a slaughterhouse exporter, located within the State of São Paulo, sampled over a year through the sponge method, applied to the chest of the animal. Samples were taken at three points, denominated A, B and C, each carcass sampled at three points located in the following steps: after bleeding (A) after skinning (B) and after washing (C). Research was conducted for Listeria sp., E. coli O157, Salmonella spp. and Micro-organism (Petrifilms ® AC, EC and EB). Listeria or E. coli O157 were not isolated in any of the 300 samples. Salmonella spp. was isolated in nine, eight at point A and one at point B. For Mesophiles, scores ranged from 0 to 6.8 log UFC/cm²; for Total coliforms, 0 to 4.57 log UFC/cm² and E. coli from 0 to 4.38 log UFC/cm². With the results obtained and compared with the literature, it is concluded that the establishment in this study has both sanitary quality (due to the low prevalence of pathogens) and hygienic quality (due to the sharp decrease in the microbial load of indicators along the line.Foram colhidas amostras de 100 carcaças em um frigorífico exportador, localizado no interior do estado de São Paulo, amostradas ao longo de um ano, por meio do método de esponjas, aplicado na região do peito do animal. As amostras foram colhidas em três pontos, denominados A, B e C, sendo cada carcaça amostrada nos três pontos, localizados nas etapas: pós-sangria (A); pós-esfola (B) e pós-lavagem (C). Foram realizadas pesquisas de Listeria sp., E. coli O157, Salmonella spp. e microrganismos indicadores (Petrifilms® AC, EC e EB). Não foram isolados Listeria ou E. coli O157 em nenhuma das 300 amostras. Salmonella spp. foi isolada em nove, sendo oito no ponto A e uma no ponto B. Para mesófilos, as contagens variaram de 0 a 6,8 log UFC/cm², para coliformes totais, de 0 a 4,57 log UFC/cm², e para E. coli, de 0 a 4,38 log UFC/cm². Diante dos resultados obtidos e em comparação com a literatura, conclui-se que o estabelecimento estudado apresenta qualidade, tanto sanitária (devido às baixas prevalências dos patógenos) quanto higiênica (devido à acentuada diminuição da carga microbiana de indicadores ao longo da linha)