Unión de los antibióticos tilosina, tilmicosina y oxitetraciclina a proteínas presentes en abejas, larvas y productos de la colmena de Apis mellifera L / Binding of tylosin, tilmicosin and oxytetracycline to proteins from honeybees, larvae and beehive products

Las abejas melíferas son afectadas por gran cantidad de enfermedades infecciosas principalmente producidas por bacterias, hongos, virus y parásitos eucariotas. Dentro de las ocasionadas por procariotas, la loque americana es una enfermedad extremadamente grave que afecta a larvas y pupas de abejas; su agente causal es la bacteria esporulada Paenibacillus larvae. La administración de antibióticos es la principal alternativa para el control de esta enfermedad en colmenares con altos niveles de infección. El objetivo del presente trabajo fue determinar, mediante un método biológico, la unión de los antibióticos tilosina, tilmicosina y oxitetraciclina a las proteínas presentes en abejas adultas, larvas menores de 72 horas, larvas mayores de 72 horas, jalea de obreras, miel y polen, con la finalidad de diseñar un modelo de ruta cinética de los antibióticos. Los límites de sensibilidad de la técnica de valoración de estos antibióticos fueron 0,05 μg/ml para tilosina y tilmicosina, y 0,01 μg/ml para oxitetraciclina. Los coeficientes de correlación fueron superiores a 0,90 y los coeficientes de variación intra e inter-ensayo inferiores al 5%. Tanto tilosina como oxitetraciclina presentaron un porcentaje de unión a proteínas de un 15% en promedio en tejidos y subproductos de la colmena, lo cual resultó inferior a lo observado con tilmicosina (29% en promedio). En conclusión, por sus características químicas, su actividad antimicrobiana y su baja tasa de unión a las abejas, larvas y subproductos de la colmena, la tilosina presenta propiedades farmacocinéticas que podrían representar una ventaja terapéutica para el tratamiento de la loque americana en colmenas.

American Foulbrood (AFB) caused by the spore-forming bacterium Paenibacillus larvae is the most serious disease of bacterial origin affecting larvae and pupae of honeybees. Antibiotics are used in many countries for the control of AFB in high incidence areas, but their misuse may lead to antibiotic resistance of bacterial strains and honey contamination. The objective of the present work was to determine, through a biological method, the protein binding of tylosin, tilmicosin and oxytetracycline to worker jelly; honey; pollen; adult bees and larvae in order to propose their kinetic routes. The sensitivity limit of the technique used was 0.05 μg/ml for tylosin and tilmicosin and 0.01 μg/ml for oxytetracycline, respectively. The method had intra and inter-assay correlation coefficients over 0.90, respectively and a coefficient variation of intra-and inter-assay for all antibiotics and processed samples under 5%. Tylosin and oxytetracycline presented lower percentages of protein binding in tissues and hive products (average 15%) in relation to those observed for tilmicosin (29%). In conclusion, tylosin is useful for AFB control in honey bee colonies due to its chemical characteristics, antimicrobial activity and levels of protein binding in bees, larvae, and beehive products.

Evaluation of cefepime kinetic variables and milk production volume in goats

Avaliaram-se as variáveis cinéticas da cefepime e a produção de leite de cabras após a administração parenteral (intravenosa e intramuscular) de cefepime, com e sem reação inflamatória na região implantada. Dez cabras em lactação, implantadas com caixas de material sem reação imunológica para colher o fluido de tecido (FT) foram usadas em dois experimentos. No primeiro a aplicação de cefepime foi feita na primeira semana após a implantação e no segundo na oitava semana. Na primeira semana após a implantação observou-se elevação dos níveis de proteína no fluido do tecido após uma simples dose de 20mg/kg de cefepime via endovenosa ou intramuscular. Amostras do sangue e do leite foram obtidas e as variáveis cinéticas foram avaliadas.

Farmacocinética de ceftazidima en neonatos / Pharmacokinetics of ceftazidime in newborn infants

A pharmacokinetic study of ceftazidime was performed in newborn children. Six premature infants with a body weight up to 2000 g and with symptoms of pneumonia (Table 1) were treated with ceftazidime (50 mg/kg body weight) by endovenous route. Plasma concentrations of the antibiotic (Fig. 1) were determined by HPLC. A kinetic behavior was described through a compartment model independent analysis. The calculated parameters were as follows: half-life (T1/2z = 4.05 +/- 0.81 h) apparent volume of distribution (Vz = 686.0 +/- 258.6 ml/kg), elimination rate constant (lambda z = 0.18 +/- 0.04h-1), area under curve (AUC = 464.4 +/- 139.1 mu gh/ml, mean residence time (MRT = 5.2 +/- 1.3 h), and total clearance (CI = 114.9 +/- 30.0 ml/h. kg) (Table 2). Good correlation was observed (r = 0.83, p < 0.05 between lambda z = and Vz). The loading and maintenance doses calculated for enterobacteria and P. aeruginosa were 15 and 13 mg/kg i.v. respectively each 12 h.