Lactic acid bacteria against Listeria monocytogenes

Listeria monocytogenes is a pathogenic bacterium that can contaminate food and cause public health problems due its ability to form biofilms and resistance to sanitizers, it is responsible for sanitary and economic losses in food producing establishments. The difficulties in controlling biofilms and increasing resistance to traditional antibacterial agents is motivating studies of alternative potential biological agents for the control of pathogenic biofilms, among which lactic acid bacteria (LABs) are included. The objective of this work was to evaluate the activity of LABs against Listeria monocytogenes biofilm formation on polystyrene plates, a surface commonly used in the food industry. Lyophilized commercial strains of Bifidobacterium animalis, Lactobacillus fermentum, Lactobacillus plantarum, Lactobacillus salivaris and Lactobacillus acidophilus were used. The strain of Listeria monocytogenes (L4) was isolated from polystyrene mats from a poultry slaughterhouse cutting room and demonstrated the ability to attach to microplates and resistance to sanitizers (sodium hypochlorite and hydrogen peroxide) at all times, temperatures and tested surfaces. The antimicrobial activity of LABs was evaluated by the agar diffusion method. The LABs that presented action on Listeria monocytogenes were selected for the inhibition and/or removal of biofilms in microplates, and all experiments were carried out in triplicate. Only Bifidobacterium animalis and Lactobacillus plantarum demonstrated action against Listeria monocytogenes in the agar diffusion assays and were selected for inhibition and competition assays. Furthermore, competition of LABs against Listeria monocytogenes adhesion was evaluated. There was no significant difference between LABs and L. monocytogenes, alone or in combination, at temperatures of 30ºC and 37ºC in the Listeria monocytogenes inhibition assays on polystyrene surface. The lactic acid bacteria evaluated did not demonstrate inhibition of L. monocytogenes adhesin testes with optical density visualization, however, it was possible to identify a reduction in L. monocytogenes counts with the application of Bifidobacterium animals and Lactobacillus plantarum in the testes of competition against biofilm formation. In competition tests Bifidobacterium animalis and Lactobacillus plantarum have an injunction in Listeria monocytogenes, indicating that these lactic acid bacteria can retard Listeria biofilm formation on polystyrene surfaces and thus help control the pathogen in the food industry. A potential mechanism to control biofilm adhesion and formation of pathogens for nutrients and fixation on surfaces, multiplication factors and surfaces are a challenge in controlling biofilms of pathogenic microorganisms, alternative measures to traditional methods for inactivating pathogens and biofilm formers bacteria are necessary. In this sense, lactic acid bacteria generate high levels of bacteriocin and are effective in inhibiting the biofilm of pathogenic bacteria, however, our study did not reveal this. We verified that Bifidobacterium animalis and Lactobacillus plantarum have an inhibitory action on Listeria monocytogenes, indicating that these lactic acid bacteria can be used to delay the formation of biofilms by Listeria on polystyrene surfaces, helping to control this pathogen in food industry.(AU)

Adhesion of pathogenic bacteria to polystyrene, skin and gut mucus of gilthead seabream, infectious capacity and antibiotics susceptibility / Adesão de bactérias patogênicas a poliestireno, pele e muco intestinal de gilthead seabream, capacidade infecciosa e susceptibilidade a antibióticos

Linking proprieties of adhesion, infectious capacities and antibiotic resistance of pathogen bacteria could help to treat fish diseases. Adhesions of ten fish pathogenic bacteria were tested in microtiter plates vacant, coated with skin or gut mucus, fixed with methanol, stained with 2% crystal-violet and revealed by colorimetric method. Infectious capacity was performed by exposing gilthead seabream fibroblast cell line (SAF-1) to 107 -108 CFUmL-1 of pathogen bacteria. Cell viability was measured 3h, 9h and 20 hours post-infection. The sensitivity to antibiotics was executed by disk diffusion. Data showed that all the bacteria tested adhere to polystyrene. For skin mucus, Vibrio harveyi, Vibrio alginolyticus, Halomonas venusta, and Aeromonas bivalvium were moderately adherent. Dietzia maris was strongly adherent. For gut mucus, 60% of tested bacteria were weakly adherent and 40% were non adherent. For infection, D. maris, V. harveyi and A. bivalvium decreased the cells viability to 89% after only 3h. After 20h, the viability percentage ranged between 1% and 32%. All isolates presented resistance to 1000 mg ml-1 of sulphonamide, 60% were resistant to sulfonamide and penicillin G. Present findings could be relevant in fish aquaculture and underscore the importance of the linkage between adhesion, infectious capacity, and antibiotic susceptibility of pathogen bacteria to avoid fish diseases.

Estudar o link entre propriedades de adesão, capacidades infecciosas e resistência a antibióticos de bactérias patogênicas pode ajudar a tratar doenças de peixes. A adesão de dez bactérias patogênicas foi testada em placas de microtitulação vazias, revestidas com muco da pele ou do intestino, fixadas com metanol, coradas com 2% de violeta cristal e reveladas pelo modo colorimétrico. A capacidade infecciosa foi realizada expondo a linha celular de fibroblasto de dourada (SAF-1) a 107-108 CFUmL-1 de bactérias patogénicas. A viabilidade celular foi medida 3h, 9h e 20 horas após a infecção. A sensibilidade aos antibióticos foi executada por difusão em disco. Os dados mostram que todas as bactérias testadas aderem ao poliestireno. Para o muco cutâneo, Vibrio harveyi, Vibrio alginolyticus, Halomonas venusta e Aeromonas bivalvium foram moderadamente aderentes. Dietzia maris foi fortemente aderente. Para o muco intestinal, 60% das bactérias testadas eram fracamente aderentes e 40% não aderentes. Para infecção, D. maris, V. harveyi e A. bivalvium diminuíram a viabilidade celular para 89% após apenas 3h. Após 20h, o percentual de viabilidade variou entre 1% e 32%. Todos os isolados apresentaram resistência a 1000 mg mL-1 de sulfonamida, 60% foram resistentes à sulfonamida e à penicilina G. Os achados atuais podem ser relevantes na aqüicultura e ressaltam a importância da ligação entre adesão, capacidade infecciosa e suscetibilidade a antibióticos de bactérias patogênicas para evitar doenças em peixes.

Adhesion of pathogenic bacteria to polystyrene, skin and gut mucus of gilthead seabream, infectious capacity and antibiotics susceptibility / Adesão de bactérias patogênicas a poliestireno, pele e muco intestinal de gilthead seabream, capacidade infecciosa e susceptibilidade a antibióticos

Linking proprieties of adhesion, infectious capacities and antibiotic resistance of pathogen bacteria could help to treat fish diseases. Adhesions of ten fish pathogenic bacteria were tested in microtiter plates vacant, coated with skin or gut mucus, fixed with methanol, stained with 2% crystal-violet and revealed by colorimetric method. Infectious capacity was performed by exposing gilthead seabream fibroblast cell line (SAF-1) to 107 -108 CFUmL-1 of pathogen bacteria. Cell viability was measured 3h, 9h and 20 hours post-infection. The sensitivity to antibiotics was executed by disk diffusion. Data showed that all the bacteria tested adhere to polystyrene. For skin mucus, Vibrio harveyi, Vibrio alginolyticus, Halomonas venusta, and Aeromonas bivalvium were moderately adherent. Dietzia maris was strongly adherent. For gut mucus, 60% of tested bacteria were weakly adherent and 40% were non adherent. For infection, D. maris, V. harveyi and A. bivalvium decreased the cells viability to 89% after only 3h. After 20h, the viability percentage ranged between 1% and 32%. All isolates presented resistance to 1000 mg ml-1 of sulphonamide, 60% were resistant to sulfonamide and penicillin G. Present findings could be relevant in fish aquaculture and underscore the importance of the linkage between adhesion, infectious capacity, and antibiotic susceptibility of pathogen bacteria to avoid fish diseases.(AU)

Estudar o link entre propriedades de adesão, capacidades infecciosas e resistência a antibióticos de bactérias patogênicas pode ajudar a tratar doenças de peixes. A adesão de dez bactérias patogênicas foi testada em placas de microtitulação vazias, revestidas com muco da pele ou do intestino, fixadas com metanol, coradas com 2% de violeta cristal e reveladas pelo modo colorimétrico. A capacidade infecciosa foi realizada expondo a linha celular de fibroblasto de dourada (SAF-1) a 107-108 CFUmL-1 de bactérias patogénicas. A viabilidade celular foi medida 3h, 9h e 20 horas após a infecção. A sensibilidade aos antibióticos foi executada por difusão em disco. Os dados mostram que todas as bactérias testadas aderem ao poliestireno. Para o muco cutâneo, Vibrio harveyi, Vibrio alginolyticus, Halomonas venusta e Aeromonas bivalvium foram moderadamente aderentes. Dietzia maris foi fortemente aderente. Para o muco intestinal, 60% das bactérias testadas eram fracamente aderentes e 40% não aderentes. Para infecção, D. maris, V. harveyi e A. bivalvium diminuíram a viabilidade celular para 89% após apenas 3h. Após 20h, o percentual de viabilidade variou entre 1% e 32%. Todos os isolados apresentaram resistência a 1000 mg mL-1 de sulfonamida, 60% foram resistentes à sulfonamida e à penicilina G. Os achados atuais podem ser relevantes na aqüicultura e ressaltam a importância da ligação entre adesão, capacidade infecciosa e suscetibilidade a antibióticos de bactérias patogênicas para evitar doenças em peixes.(AU)

Biofilm formation on polystyrene under different temperatures by antibiotic resistant Enterococcus faecalis and Enterococcus faecium isolated from food

The ability of antibiotic resistant E. faecalis and E. faecium isolated from food to form biofilm at different temperatures in the absence or presence of 0.75% glucose was evaluated. A synergistic effect on biofilm at 10 °C, 28 °C, 37 °C and 45 °C and glucose was observed for E. faecalis and E. faecium.(AU)