Spread of the serotypes and antimicrobial resistance in strains of Salmonella spp. isolated from broiler.

Serotypes and antimicrobial susceptibility of Salmonella's isolates from broiler production chain were determined. A total of 239 isolated strains from chicken, carcasses, breeding environments, and slaughter was analyzed by disk diffusion test, in the period of 2009 to 2010. For antibiotics with a high number of resistant strains, the minimal inhibitory concentration (MIC) was performed. We identified 24 serotypes, being the most frequent, Minnesota (31.4%) and Infantis (22.6%). The highest percentages of resistance were obtained for sulfonamide (42.7%), followed by tetracycline with 37.6% and amoxicillin with 27.6%. From the total, 32 resistance profiles were identified, being 60.7% of the strains were resistant to at least one antibiotic. Of these, 31.7% of the isolates showed multidrug resistance profiles belonging to serovar Minnesota, Saintpaul, and S. enterica. The highest resistance was found in isolates from slaughterhouse (66.9%) and aviary (58.7%). A large number of strains showed MIC above the maximum tested concentration for the antibiotics amoxicillin and sulfamethoxazole. The high number of Salmonella's resistant strains indicates the need for prudent use of these drugs in poultry production in order to reduce the occurrence and spread of antibiotic resistance profiles, and the risk that multiresistant strains isolated from broilers may pose a risk to human health.

PFGE characterisation and adhesion ability of Listeria monocytogenes isolates obtained from bovine carcasses and beef processing facilities.

Listeria monocytogenes is a pathogen capable of adhering to many surfaces and forming biofilms, which may explain its persistence in food processing environments. This study aimed to genetically characterise L. monocytogenes isolates obtained from bovine carcasses and beef processing facilities and to evaluate their adhesion abilities. DNA from 29 L. monocytogenes isolates was subjected to enzymatic restriction digestion (AscI and ApaI), and two clusters were identified for serotypes 4b and 1/2a, with similarities of 48% and 68%, respectively. The adhesion ability of the isolates was tested considering: inoculum concentration, culture media, carbohydrate source, NaCl concentration, incubation temperature, and pH. Each isolate was tested at 108 CFU mL⁻¹ and classified according to its adhesion ability as weak (8 isolates), moderate (17) or strong (4). The isolates showed higher adhesion capability in non-diluted culture media, media at pH 7.0, incubation at 25°C and 37 °C, and media with NaCl at 5% and 7%. No relevant differences were observed for adhesion ability with respect to the carbohydrate source. The results indicated a wide diversity of PFGE profiles of persistent L. monocytogenes isolates, without relation to their adhesion characteristics. Also, it was observed that stressing conditions did not enhance the adhesion profile of the isolates.

Antimicrobial activity of autoclaved and non autoclaved copaiba oil on Listeria monocytogenes / Atividade antimicrobiana de óleo de copaíba autoclavado e não autoclavado sobre Listeria monocytogenes

The aim of this study was to evaluate the antimicrobial effect of different copaiba oil concentrations against the growth of Listeria monocytogenes, and analyze differences in inhibition of microorganisms with autoclaved and non autoclaved oil. This study provided an agar diffusion test with six isolates of bacteria and six different concentrations of autoclaved or non autoclaved copaiba oil and a negative control. The results showed sensitivity of five L. monocytogenes isolates related to the 10 percent autoclaved solution of copaiba oil. Four strains also showed sensitivity to the 5 percent autoclaved solution and one to 2.5 percent autoclaved solution. The 10 percent non autoclaved oil solution showed growth inhibition only for two strains. These results had pointed the 10 percent autoclaved solution of copaiba oil with higher inhibition as all other solutions and concentrations tested (P<0.05). For the other concentrations of both solutions, the 5 and 2.5 percent autoclaved and 10 percent non autoclaved solutions had presented statistically equal. All other concentrations of both copaiba solutions and the negative control did not presented any bacteria inhibition. In conclusion, the results of this study suggest that the autoclaved copaiba oil may be a potential new agent source for infection control or for food preservation, inhibiting the growth of food-borne bacteria such as L. monocytogenes.

Os objetivos deste estudo foram avaliar o efeito antimicrobiano de diferentes concentrações de óleo de copaíba contra o crescimento de Listeria monocytogenes e analisar as diferenças na inibição do microorganismo com soluções do óleo autoclavadas e não autoclavadas. Para tanto, foi realizado um teste de difusão em ágar, com seis isolados do microrganismo originários de produtos cárneos, seis concentrações de ambas as soluções e um controle negativo. Os resultados mostraram sensibilidade de cinco cepas de L. monocytogenes em relação à solução 10 por cento de óleo de copaíba autoclavada. Quatro isolados também apresentaram sensibilidade para a solução de 5 por cento autoclavada e apenas um foi sensível à solução de 2,5 por cento autoclavada. A solução 10 por cento não autoclavada apresentou inibição do crescimento de apenas dois isolados. Esses resultados apontaram a solução autoclavada de 10 por cento do óleo de copaíba com maior inibição em relação a todas as outras soluções e concentrações testadas (P<0,05). As soluções 5 e 2,5 por cento autoclavadas e a solução 10 por cento não autoclavada apresentaram-se estatisticamente iguais. Todas as outras concentrações das soluções de copaíba e o controle negativo não apresentaram inibição das bactérias. Os resultados deste estudo sugerem que o óleo de copaíba autoclavado pode ser uma potencial fonte de novos agentes para o controle de infecção ou para a conservação dos alimentos, inibindo o crescimento de bactérias de origem alimentar como L. monocytogenes.