Isolation and Phenotypic Characterization of Lytic Bacteriophage with Activity against Pseudomonas aeruginosa

Aims: To perform the isolation and phenotypic characterization of bacteriophage with lytic activity against Pseudomonas aeruginosa. To demonstrate that this type of viral agent can be isolated from the environment and used for the biocontrol of resistant bacterial types, such as Pseudomonas aeruginosa. Study Design: This study was an experimental study. Place and Duration of Study: The study was conducted at, Bacteriology and Mycology Laboratory in the Veterinary Hospital at the School of Agricultural Sciences, Innovation and Business of the University of Passo Fundo (ESAN/UPF) and Center for Diagnosis and Research in Animal Health of the University of Passo Fundo (CDSA/UPF), between April 2022 and June 2022. Methodology: Samples of untreated water were inoculated with the host bacterium strain Pseudomonas aeruginosa ATCC 27853 in an enriched media After the incubation period in, a phage filtrate was obtained by centrifugation followed by filtration. We verified the presence of bacteriophages using spot test and we carried out its purification by the method of sterile toothpick plate transfer on bacterial overlay semi-solid agar. Amplification was performed using an SM buffer elution procedure to produce a stock of viral material. Through assays in Petri dishes with bacterial overlay, we performed titration and phenotypic characterization regarding the lysis spectrum and efficiency of phage infection in the host. Results: We managed to isolate a morphologically characterized lytic bacteriophage with approximately 1 mm of diameter, high clarity in the inhibition area, the presence of halo and well-demarcated edges. The bacteriophage, named as Pseudomonas aeruginosa Phage UPF_PaBP1, demonstrated the infection capacity of the target bacteria in all tested dilutions and a stock preparation with a titre of 6.5 x 10? PFU/ml was obtained for future use. Conclusion: The isolated phage showed strong lytic activity against the bacterial host, a finding that nourishes our expectations regarding the use of this phage as a biocontrol agent and phage therapy.

Sistema de lavagem de carcaças e controle de Salmonella spp. em abatedouros de frangos de corte / Carcass washing system and Salmonella spp. control in poultry slaughterhouses

Avaliaram-se os dados do controle e monitoramento de Salmonella em carcaças de frangos de corte, antes e após a implantação do sistema de lavagem de carcaças. Foram amostradas 2692 carcaças antes da instalação do sistema e 1940 após a instalação, totalizando 4632 amostras em cinco abatedouros sob Inspeção Federal, no sul do Brasil. Anteriormente à instalação dos lavadores, obtiveram-se 156 resultados positivos para Salmonella spp. e, após a instalação, 83 resultados positivos, com diferença significativa (P<0,05/OR 1,4) entre os resultados gerais. Em dois dos cinco abatedouros avaliados, houve redução na positividade para Salmonella spp. nas carcaças amostradas após a instalação do lavador. Entretanto, em três estabelecimentos não houve diferença significativa após a instalação desse sistema. Os resultados sugerem que o aumento da vazão da água está relacionado com a redução da contaminação, enquanto o aumento da pressão de água do sistema de lavagem não foi suficiente para reduzir o patógeno nas carcaças amostradas. Dessa forma, conclui-se que o sistema de lavagem tem vantagens do ponto de vista operacional, ao evitar os desperdícios atribuídos à prática do refile, porém não elimina o risco da presença de Salmonella na carcaça de frango.(AU)

Data of the Control and Monitoring of Salmonella in broiler carcasses were evaluated before and after the implementation of a carcass washing system. A total of 2692 carcasses prior to system installation and 1940 after installation were sampled, totaling 4632 samples in five slaughterhouses under Federal Inspection in southern Brazil. Prior to installation of the washers, 156 carcasses were positive for Salmonella spp. and after installation, 83 carcasses tested positive, with a significant difference (P <0.05/OR 1.4) on the overall results. Two of the five evaluated slaughterhouses showed a prevalence decrease of Salmonella spp. in the sampled carcasses after installing the washer. However, in three establishments, there was no significant difference after installing this system. The results suggest that the increase of the water flow is related to the reduction of the contamination, while the increase of the water pressure of the washing system was not enough to reduce the pathogen in the sampled carcasses. The results show operational results since the washing system avoids the trimming of some carcasses, but doesn't eliminate the risk of Salmonella.(AU)

Resistência antimicrobiana em Salmonella Enteritidis isoladas de amostras clínicas e ambientais de frangos de corte e matrizes pesadas / Antimicrobial resistance in Salmonella Enteritidis isolated from clinical and environmental broiler chickens and breeders broiler

The antimicrobial resistance of Salmonella Enteritidis strains isolated from clinical and environmental poultry samples in the Southern Brazil during the years of 1999, 2000 and 2001 was evaluated. Among the 79 isolated samples, 64 (81 percent) were resistant to at least one of the antimicrobial agents tested, showing 22 different resistance patterns. Tetracycline showed the highest percentage (64,5 percent) of resistance among the antimicrobial agents used. Resistance to drugs at different levels was found as the following: ampicillin (1.2 percent), kanamycin (1.2 percent), ciprofloxacin (2.5 percent), enrofloxacin (8.8 percent), gentamicin (21.5 percent), streptomycin (20.2 percent), nitrofurantoin (26.6 percent), and nalidixic acid (30.4 percent). None of the S. Enteritidis strains were resistant to chloramphenicol, norfloxacin, and polimycin B. Among the 64 S. Enteritidis strains that showed resistance, 43 (67.2 percent) were resistant to two or more antimicrobial agents. Twenty-one (32.8 percent) strains were resistant to only one of the antimicrobial agents, 14 to tetracycline, three to nalidixic acid, three to nitrofurantoin, and one to gentamycin. These antimicrobial resistance levels suggest a high occurrence of tetracycline resistant S. Enteritidis strains and resistance to two or more antimicrobial agents.