Salmonelosis aviar en el oriente de Cuba. Eficacia de la acetamida furánica monobromada y de una mezcla probiótica para su control

Resumo

The aim of this study was the evaluation of two different strategies for the control of Salmonella infection in broiler chickens: the use of furan acetamide monobrominated and the use of a probiotic mixture of avian origin. In a first stage, the antimicrobial activity of monobrominated furan acetamide was evaluated in vitro against different field isolates of Salmonella enterica of avian origin and reference strains using a tube macrodilution and a plate microdilution tests to determine the minimum inhibitory concentration (MIC). Salmonella isolates of avian origin were recovered from poultry farms in eastern Cuba with clinical problems in which Salmonella infection was suspected. CMI values (12.5-50 µg/ mL) were similar or higher than those reported for some commonly used antibiotics which confirmed that the furan acetamide monobrominated is a bioactive substance with potent bactericidal activity against Salmonella enterica. In a second step, the research was directed towards obtaining a probiotic preparation that could be used in the control of infections caused by Salmonella enterica as well as other enteropathogens in poultry production. Lactic acid bacteria (LAB) were recovered from the intestinal contents and feces of two populations of birds with minimal use of antimicrobials, cocks bred for the production of feathers (gallos de pluma) and partridges. Potential probiotic characteristics of the isolates were estimated by determining the resistance profile against nine antibiotics, the ability to inhibit pathogenic microorganisms, the ability to decrease the pH of the medium and the tolerance to acid conditions and bile salts. Those isolates selected based on the above tests were identified by molecular techniques and included different species of Lactobacillus, L. reuteri, L. salivarius and L. mucosae, as well as an isolate identified as Enterococcus durans. Finally, in a third step, we conducted an in vivo assessment of the effectiveness of monobrominated furan acetamide and of the probiotic mixture 222 against Salmonella enterica in broiler chickens, using a model of experimental infection with an isolate of avian origin from Cuba. A total of 75 chicks were randomly divided into three experimental groups of 25 animals each. All chicks were challenged on day 4 of life by oral administration of a dose of 0.5 mL of a liquid culture with a concentration of 106 CFU/mL of an isolate of Salmonella enterica subsp. enterica serovar Enteritidis. Experimental group 1 was the control group and received no treatment. Chicks from experimental group 2 received orally a dose of 0.5 mL of a solution with a concentration of 50 mg/mL of furan acetamide monobrominated on postinoculation days 1, 2 and 3 while the animals of the experimental group 3 received orally and on days of life 1, 2 and 3, a probiotic mixture including three selected isolates of Lactobacillus, L. reuteri, L. salivarius and L. mucosae, at a dose of 0.5 mL per chick of a suspension with a concentration of 109 CFU/mL. The treatment with of furan acetamide monobrominated limited the spread of S. Enteritidis in different organs, particularly in the liver and the spleen, shortened the duration of clinical symptoms and decreased the extent and severity of lesions. Besides the animals showed better growth performance, weight gain and feed conversion. On the other hand, the administration of the probiotic mixture had a limited effect and only reduced the proportion of positive samples in the spleen, shortened the duration of the clinical symptoms in 3 days and was associated with limited improvements in production parameters in the second and third week of life.