Activity of rosemary (Rosmarinus officinalis - Family: Lamiaceae) essential oil compared to peracetic acid in Listeria monocytogenes biofilms

The objective of this study was to evaluate the activity of Rosmarinus officinalis essential oil (EO) compared to peracetic acid (PA) regarding formation and elimination of Listeria monocytogenes biofilms on polystyrene surface. The minimum inhibitory concentration (MIC) was determined according to standard protocol. Isolates were inoculated according to MIC standards polystyrene plate wells, which were then incubated at 37°C/96 hours for evaluation of biofilm formation. Regarding the evaluation of biofilm elimination, the biofilms were treated under MIC for 10 minutes. The MIC obtained were 2.0 and 3.0 mg mL-1 for EO and 0,015% for PA. Therefore, the results showed a reduction in the formation of biofilm with the presence of EO and PA, EO being more efficient (p < 0.05). Both compounds had a good capacity of eliminating biofilms, however the EO reduced the biofilm formation when compared to PA, highlighting its potential as an antibacterial agent and antibiofilm.(AU)

Fasciola hepatica and rumen flukes - in vitro evaluation of main commercial anthelmintics

Background: Trematode infections are of great importance as they affect the health of many species of mammals as cattle, sheep and goat. Fasciola hepatica represents the main trematode zoonosis and risks to human and cattle and paramphistomosis is one emerging parasitic diseases of ruminants widely distributed in the world. The economic expenses are incurred by the use of ineffective anthelmintics for trematode control. Besides to faecal egg count reduction test (FECRT) to determine the anthelmintic efficacy, can be used in vitro assays, by this the aim of the study was to determine the lethal doses (LD) with hatching egg test (EHT) of the main commercial anthelmintics used for the control of trematodes in cattle. Materials, Methods & Results: Liver and rumen were examined from cattle slaughtered in Tabasco, Chiapas and Campeche states from Mexico. F. hepatica eggs were recovered from gallbladder and rumen fluke eggs collected from adult parasites in saline solution. Subsequently, the hatching egg assays were performed placing 100 trematode eggs in distilled water in each one of 96 wells of polystyrene plates. After making the appropriate dilutions, several concentrations of commercial anthelmintics were evaluated, ranging from 0.04 to 80.63 mM for triclabendazole + 0.046 to 96.87 mM febendazole (TC+FBZ), from 0.04 to 91 mM for rafoxanide (RAFOX), from 0.02 to 43.74 mM for closantel (CLOS), from 0.036 to 76.18 mM for clorsulon + 0.002 to 3.31 mM ivermectin (CLORS+ IVM) and from 0.163 to 334.47 mM for nitroxynil (NITROX). A control group (water) was included in each plate. Lethal doses were obtained using the Probit procedure and analysis of the means with a one-way statistical design. Most drugs used against rumen fluke eggs presented a high LD50 and therefore were ineffective to cause egg mortality, such was the case of RAFOX that presented LD50 from 4,580 to 10,790 µg/mL (7 to 17 mM). CLOS presented the lowest LD50 (80 µg/mL or 0.12 mM) on rumen fluke eggs. TC+FBZ was found to be effective drug against the development of F. hepatica eggs in many samples. In the same way NITROX showed a low LD50 (37 to 63 µg/mL or 0.13 to 0.22 mM), but RAFOX presented a highest LD50 (1,450 µg/mL or 2.32 mM). Discussion: The present study focused on screen the ovicidal activity and determining in vitro lethal doses 50 of main commercial anthelmintics used to control F. hepatica and rumen fluke as rapid tests in a tropical region from Mexico. The FECRT is the main method to detect effectiveness of anthelmintic and other method is the coproantigen reduction test (CRT) by ELISA. Both tests require many infected animals depending the number of treatments and by this the egg hatch assay (EHA) represent a complementary diagnosis of effectiveness of anthelmintic products to compare between regions and even between farms, because few animals are required from the farm to collect trematode eggs, and it is possible to know the effectiveness against various anthelmintics at the same time. Efficacy studies on trematodes using egg hatching tests are scarce, although they have the advantage that they can be applied to both F. hepatica and rumen fluke. TC+FBZ was one of the most effective products in inhibiting the development of F. hepatica eggs. However, RAFOX showed low effectiveness against trematode eggs, with very high lethal doses. These results agree with a study that show low efficacy against the development of Paramphistomum cervi eggs and with the FECRT test reductions of 75% and 80.58% were obtained, in times from 7 to 84 days after treatment with RAFOX. NITROX and CLORS were drugs that had good efficacy on the development of F. hepatica eggs. A differential response between liver and rumen fluke was observed. The anthelmintics used against rumen fluke eggs show low ovicidal activity and in Fasciola hepatica TC+FBZ show the best activity

Antiadhesion and antibiofilm potential of Fagonia indica from Cholistan desert against clinical multidrug resistant bacteria

Abstract High resistance to antimicrobials is associated with biofilm formation responsible for infectious microbes to withstand severe conditions. Therefore, new alternatives are necessary as biofilm inhibitors to control infections. In this study, the antimicrobial and antibiofilm activities of Fagonia indica extracts were evaluated against MDR clinical isolates. The extract exhibited its antibiofilm effect by altering adherence and disintegration of bacterial cell wall. Fagonia indica has antibacterial effect as minimum inhibitory concentration (MIC) values ranging from 125 to 500 µg mL-1 and minimum bactericidal concentration (MBC) value was 500-3000 µg mL-1 against multidrug resistant (MDR) clinical isolates. The extract exhibited its antibiofilm effect by altering adherence and disintegration of bacterial cell wall. Fagonia indica had antibacterial effect as minimum inhibitory concentration (MIC) values ranging from 125 to 500 µg mL-1 and minimum bactericidal concentration (MBC) value was 500-3000 µg mL-1 against MDR isolates. The maximum inhibitory effects of Fagonia indica chloroform extract on biofilm formation was observed on Staphylococcus aureus (71.84%) followed by Klebsiella pneumoniae (70.83%) after 48 hrs showing that inhibition is also time dependent. Our results about bacterial cell protein leakage indicated that MDR isolates treated with chloroform extract of Fagonia indica showed maximum protein leakage of K. pneumoniae (59.14 µg mL-1) followed by S. aureus (56.7 µg mL-1). Cell attachment assays indicated that chloroform extract resulted in a 43.5-53.5% inhibition of cell adherence to a polystyrene surface. Our results revealed that extracts of Fagonia indica significantly inhibited biofilm formation among MDR clinical isolates, therefore, could be applied as antimicrobial agents and cost effective biofilm inhibitor against these MDR isolates.

Resumo A alta resistência aos antimicrobianos está associada à formação de biofilme responsável por micróbios infecciosos para suportar condições severas. Portanto, novas alternativas são necessárias como inibidores de biofilme para controlar infecções. Neste estudo, as atividades antimicrobiana e antibiofilme dos extratos de Fagonia indica foram avaliadas contra isolados clínicos MDR. O extrato exibiu seu efeito antibiofilme ao alterar a aderência e a desintegração da parede celular bacteriana. Fagonia indica tem efeito antibacteriano com valores de concentração inibitória mínima (CIM) variando de 125 a 500 µg mL-1, e valor de concentração bactericida mínima (MBC) de 500-3000 µg mL-1 contra isolados clínicos multirresistentes (MDR). O extrato exibiu seu efeito antibiofilme ao alterar a aderência e a desintegração da parede celular bacteriana. Fagonia indica teve efeito antibacteriano com valores de concentração inibitória mínima (CIM) variando de 125 a 500 µg mL-1, e concentração bactericida mínima (MBC) de 500-3000 µg mL-1 contra isolados MDR. Os efeitos inibitórios máximos do extrato de clorofórmio Fagonia indica na formação de biofilme foi observada em Staphylococcus aureus (71,84%), seguido por Klebsiella pneumoniae (70,83%) após 48 horas, mostrando que a inibição também é dependente do tempo. Nossos resultados sobre extravasamento de proteínas de células bacterianas indicaram que isolados MDR tratados com extrato clorofórmico de Fagonia indica apresentaram vazamento máximo de proteínas de K. pneumoniae (59,14 µg mL-1), seguido por S. aureus (56,7 µg mL-1). Ensaios de fixação de células indicaram que o extrato de clorofórmio resultou em uma inibição de 43,5-53,5% da aderência das células a uma superfície de poliestireno. Nossos resultados revelaram que extratos de Fagonia indica inibiram significativamente a formação de biofilme entre isolados clínicos MDR, portanto, poderiam ser aplicados como agentes antimicrobianos e inibidores de biofilme de baixo custo contra esses isolados MDR.

Antiadhesion and antibiofilm potential of Fagonia indica from Cholistan desert against clinical multidrug resistant bacteria / Potencial de antiadesão e antibiofilme de Fagonia indica do deserto do Cholistão contra bactérias multirresistentes clínicas

High resistance to antimicrobials is associated with biofilm formation responsible for infectious microbes to withstand severe conditions. Therefore, new alternatives are necessary as biofilm inhibitors to control infections. In this study, the antimicrobial and antibiofilm activities of Fagonia indica extracts were evaluated against MDR clinical isolates. The extract exhibited its antibiofilm effect by altering adherence and disintegration of bacterial cell wall. Fagonia indica has antibacterial effect as minimum inhibitory concentration (MIC) values ranging from 125 to 500 µg mL-1 and minimum bactericidal concentration (MBC) value was 500-3000 µg mL-¹ against multidrug resistant (MDR) clinical isolates. The extract exhibited its antibiofilm effect by altering adherence and disintegration of bacterial cell wall. Fagonia indica had antibacterial effect as minimum inhibitory concentration (MIC) values ranging from 125 to 500 µg mL-¹ and minimum bactericidal concentration (MBC) value was 500-3000 µg mL-¹ against MDR isolates. The maximum inhibitory effects of Fagonia indica chloroform extract on biofilm formation was observed on Staphylococcus aureus (71.84%) followed by Klebsiella pneumoniae (70.83%) after 48 hrs showing that inhibition is also time dependent. Our results about bacterial cell protein leakage indicated that MDR isolates treated with chloroform extract of Fagonia indica showed maximum protein leakage of K. pneumoniae (59.14 µg mL-¹) followed by S. aureus (56.7 µg mL-1). Cell attachment assays indicated that chloroform extract resulted in a 43.5-53.5% inhibition of cell adherence to a polystyrene surface. Our results revealed that extracts of Fagonia indica significantly inhibited biofilm formation among MDR clinical isolates, therefore, could be applied as antimicrobial agents and cost effective biofilm inhibitor against these MDR isolates.

A alta resistência aos antimicrobianos está associada à formação de biofilme responsável por micróbios infecciosos para suportar condições severas. Portanto, novas alternativas são necessárias como inibidores de biofilme para controlar infecções. Neste estudo, as atividades antimicrobiana e antibiofilme dos extratos de Fagonia indica foram avaliadas contra isolados clínicos MDR. O extrato exibiu seu efeito antibiofilme ao alterar a aderência e a desintegração da parede celular bacteriana. Fagonia indica tem efeito antibacteriano com valores de concentração inibitória mínima (CIM) variando de 125 a 500 µg mL-¹, e valor de concentração bactericida mínima (MBC) de 500-3000 µg mL-1 contra isolados clínicos multirresistentes (MDR). O extrato exibiu seu efeito antibiofilme ao alterar a aderência e a desintegração da parede celular bacteriana. Fagonia indica teve efeito antibacteriano com valores de concentração inibitória mínima (CIM) variando de 125 a 500 µg mL-¹, e concentração bactericida mínima (MBC) de 500-3000 µg mL-¹ contra isolados MDR. Os efeitos inibitórios máximos do extrato de clorofórmio Fagonia indica na formação de biofilme foi observada em Staphylococcus aureus (71,84%), seguido por Klebsiella pneumoniae (70,83%) após 48 horas, mostrando que a inibição também é dependente do tempo. Nossos resultados sobre extravasamento de proteínas de células bacterianas indicaram que isolados MDR tratados com extrato clorofórmico de Fagonia indica apresentaram vazamento máximo de proteínas de K. pneumoniae (59,14 µg mL-¹), seguido por S. aureus(56,7 µg mL-¹). Ensaios de fixação de células indicaram que o extrato de clorofórmio resultou em uma inibição de 43,5-53,5% da aderência das células a uma superfície de poliestireno. Nossos resultados revelaram que extratos de Fagonia indica inibiram [...].

Antiadhesion and antibiofilm potential of Fagonia indica from Cholistan desert against clinical multidrug resistant bacteria / Potencial de antiadesão e antibiofilme de Fagonia indica do deserto do Cholistão contra bactérias multirresistentes clínicas

High resistance to antimicrobials is associated with biofilm formation responsible for infectious microbes to withstand severe conditions. Therefore, new alternatives are necessary as biofilm inhibitors to control infections. In this study, the antimicrobial and antibiofilm activities of Fagonia indica extracts were evaluated against MDR clinical isolates. The extract exhibited its antibiofilm effect by altering adherence and disintegration of bacterial cell wall. Fagonia indica has antibacterial effect as minimum inhibitory concentration (MIC) values ranging from 125 to 500 µg mL-1 and minimum bactericidal concentration (MBC) value was 500-3000 µg mL-¹ against multidrug resistant (MDR) clinical isolates. The extract exhibited its antibiofilm effect by altering adherence and disintegration of bacterial cell wall. Fagonia indica had antibacterial effect as minimum inhibitory concentration (MIC) values ranging from 125 to 500 µg mL-¹ and minimum bactericidal concentration (MBC) value was 500-3000 µg mL-¹ against MDR isolates. The maximum inhibitory effects of Fagonia indica chloroform extract on biofilm formation was observed on Staphylococcus aureus (71.84%) followed by Klebsiella pneumoniae (70.83%) after 48 hrs showing that inhibition is also time dependent. Our results about bacterial cell protein leakage indicated that MDR isolates treated with chloroform extract of Fagonia indica showed maximum protein leakage of K. pneumoniae (59.14 µg mL-¹) followed by S. aureus (56.7 µg mL-1). Cell attachment assays indicated that chloroform extract resulted in a 43.5-53.5% inhibition of cell adherence to a polystyrene surface. Our results revealed that extracts of Fagonia indica significantly inhibited biofilm formation among MDR clinical isolates, therefore, could be applied as antimicrobial agents and cost effective biofilm inhibitor against these MDR isolates.(AU)

A alta resistência aos antimicrobianos está associada à formação de biofilme responsável por micróbios infecciosos para suportar condições severas. Portanto, novas alternativas são necessárias como inibidores de biofilme para controlar infecções. Neste estudo, as atividades antimicrobiana e antibiofilme dos extratos de Fagonia indica foram avaliadas contra isolados clínicos MDR. O extrato exibiu seu efeito antibiofilme ao alterar a aderência e a desintegração da parede celular bacteriana. Fagonia indica tem efeito antibacteriano com valores de concentração inibitória mínima (CIM) variando de 125 a 500 µg mL-¹, e valor de concentração bactericida mínima (MBC) de 500-3000 µg mL-1 contra isolados clínicos multirresistentes (MDR). O extrato exibiu seu efeito antibiofilme ao alterar a aderência e a desintegração da parede celular bacteriana. Fagonia indica teve efeito antibacteriano com valores de concentração inibitória mínima (CIM) variando de 125 a 500 µg mL-¹, e concentração bactericida mínima (MBC) de 500-3000 µg mL-¹ contra isolados MDR. Os efeitos inibitórios máximos do extrato de clorofórmio Fagonia indica na formação de biofilme foi observada em Staphylococcus aureus (71,84%), seguido por Klebsiella pneumoniae (70,83%) após 48 horas, mostrando que a inibição também é dependente do tempo. Nossos resultados sobre extravasamento de proteínas de células bacterianas indicaram que isolados MDR tratados com extrato clorofórmico de Fagonia indica apresentaram vazamento máximo de proteínas de K. pneumoniae (59,14 µg mL-¹), seguido por S. aureus(56,7 µg mL-¹). Ensaios de fixação de células indicaram que o extrato de clorofórmio resultou em uma inibição de 43,5-53,5% da aderência das células a uma superfície de poliestireno. Nossos resultados revelaram que extratos de Fagonia indica inibiram [...].(AU)

Antiadhesion and antibiofilm potential of Fagonia indica from Cholistan desert against clinical multidrug resistant bacteria / Potencial de antiadesão e antibiofilme de Fagonia indica do deserto do Cholistão contra bactérias multirresistentes clínicas

High resistance to antimicrobials is associated with biofilm formation responsible for infectious microbes to withstand severe conditions. Therefore, new alternatives are necessary as biofilm inhibitors to control infections. In this study, the antimicrobial and antibiofilm activities of Fagonia indica extracts were evaluated against MDR clinical isolates. The extract exhibited its antibiofilm effect by altering adherence and disintegration of bacterial cell wall. Fagonia indica has antibacterial effect as minimum inhibitory concentration (MIC) values ranging from 125 to 500 µg mL-1 and minimum bactericidal concentration (MBC) value was 500-3000 µg mL-1 against multidrug resistant (MDR) clinical isolates. The extract exhibited its antibiofilm effect by altering adherence and disintegration of bacterial cell wall. Fagonia indica had antibacterial effect as minimum inhibitory concentration (MIC) values ranging from 125 to 500 µg mL-1 and minimum bactericidal concentration (MBC) value was 500-3000 µg mL-1 against MDR isolates. The maximum inhibitory effects of Fagonia indica chloroform extract on biofilm formation was observed on Staphylococcus aureus (71.84%) followed by Klebsiella pneumoniae (70.83%) after 48 hrs showing that inhibition is also time dependent. Our results about bacterial cell protein leakage indicated that MDR isolates treated with chloroform extract of Fagonia indica showed maximum protein leakage of K. pneumoniae (59.14 µg mL-1) followed by S. aureus (56.7 µg mL-1). Cell attachment assays indicated that chloroform extract resulted in a 43.5-53.5% inhibition of cell adherence to a polystyrene surface. Our results revealed that extracts of Fagonia indica significantly inhibited biofilm formation among MDR clinical isolates, therefore, could be applied as antimicrobial agents and cost effective biofilm inhibitor against these MDR isolates.

A alta resistência aos antimicrobianos está associada à formação de biofilme responsável por micróbios infecciosos para suportar condições severas. Portanto, novas alternativas são necessárias como inibidores de biofilme para controlar infecções. Neste estudo, as atividades antimicrobiana e antibiofilme dos extratos de Fagonia indica foram avaliadas contra isolados clínicos MDR. O extrato exibiu seu efeito antibiofilme ao alterar a aderência e a desintegração da parede celular bacteriana. Fagonia indica tem efeito antibacteriano com valores de concentração inibitória mínima (CIM) variando de 125 a 500 µg mL-1, e valor de concentração bactericida mínima (MBC) de 500-3000 µg mL-1 contra isolados clínicos multirresistentes (MDR). O extrato exibiu seu efeito antibiofilme ao alterar a aderência e a desintegração da parede celular bacteriana. Fagonia indica teve efeito antibacteriano com valores de concentração inibitória mínima (CIM) variando de 125 a 500 µg mL-1, e concentração bactericida mínima (MBC) de 500-3000 µg mL-1 contra isolados MDR. Os efeitos inibitórios máximos do extrato de clorofórmio Fagonia indica na formação de biofilme foi observada em Staphylococcus aureus (71,84%), seguido por Klebsiella pneumoniae (70,83%) após 48 horas, mostrando que a inibição também é dependente do tempo. Nossos resultados sobre extravasamento de proteínas de células bacterianas indicaram que isolados MDR tratados com extrato clorofórmico de Fagonia indica apresentaram vazamento máximo de proteínas de K. pneumoniae (59,14 µg mL-1), seguido por S. aureus (56,7 µg mL-1). Ensaios de fixação de células indicaram que o extrato de clorofórmio resultou em uma inibição de 43,5-53,5% da aderência das células a uma superfície de poliestireno. Nossos resultados revelaram que extratos de Fagonia indica inibiram significativamente a formação de biofilme entre isolados clínicos MDR, portanto, poderiam ser aplicados como agentes antimicrobianos e inibidores de biofilme de baixo custo contra esses isolados MDR.

Lactic Bacterium and Bacillus Sp. Biofilms Can Decrease the Viability of Salmonella Gallinarum, Salmonella Heidelberg, Campylobacter Jejuni and Methicillin Resistant Staphylococcus Aureus on Different Substrates

ABSTRACT This study aimed to evaluate the efficacy of biofilms formed by lactic acid bacteria and Bacillus sp. (BLA) in preventing and controlling the formation of wild biofilms and/or planktonic forms of Salmonella Gallinarum (SG), Salmonella Heidelberg (SH), and methicillin-resistant Staphylococcus aureus (MRSA) on different surfaces. The SH and SG viability was evaluated in polystyrene plates, wood shavings, and soil samples. Two protocols were developed to examine the use of BLA in a preventive and control application. For analysis of Campylobacter jejuni (CJ) BLA was used only preventively in a polystyrene plate. Results showed that BLA was effective in preventing the growth of SG and SH in all matrices. The effectiveness of BLA for MRSA was lower than for SG and SH. The efficiency of BLA in preventing CJ growth seems to be related to the initial CJ contamination. BLA proves to be a potential alternative to control food-borne pathogens commonly encountered in animal production and food industry.

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)

Mortality of leaf-cutting ants with salicylic acid / Mortalidade de formigas-cortadeiras com ácido salicílico

Strategies for the control of leaf-cutting ants have mainly involved granular baits based on fipronil and sulfluramid as active ingredients, which are commonly coated with attractive citrus-based substances. Their constant use and the lack of alternatives in the market may favor the perception of these substances by ants, causing rejection for foraging and consequent difficulty in their control. In this respect, this study examined the mortality of leaf-cutting ants of the genera Atta and Acromyrmex subjected to direct application with dry powders, in laboratory conditions. As a preliminary treatment, a commercial antiseptic talc powder (C. A. P. T.) was used, followed by isolated treatments that corresponded to its components with potential insecticidal action, namely, salicylic acid, sulfur, boric acid, zinc oxide, in addition to an inert talc powder (Quimidrol®) as the control. For each treatment, 40 (worker) ants, whose activity was reduced due to remaining in a refrigerator prior to the treatment, were placed in transparent crystal polystyrene ('Gerbox' type) and were sprinkled with a salt shaker. The ants were kept at 25 ± 2 °C, under a 12-h photophase, and cumulative mortality was recorded every 24 h, considering dead ants as those that were unable to maintain the natural position of their body, i.e., even dying ants were considered dead when they exhibited no reaction when touched by a paintbrush. When sprinkled on ants, C. A. P. T. causes 40% mortality in both species 24 h after application. Subsequent studies of the components of this commercial product have found that when sprinkled on both Atta sexdens rubropilosa and Acromyrmex crassispinus, salicylic acid causes 100% mortality of workers in the first 24 h. This result provides a new prospect of control through a low environmental-impact product, representing an alternative for control in nests in the field that can contribute to the integrated control of ants.(AU)

As estratégias de controle de formigas-cortadeiras têm sido realizadas principalmente com iscas granuladas, à base dos princípios ativos fipronil e sulfluramida, que são comumente revestidas por substâncias atrativas cítricas. O uso constante das mesmas e a falta de alternativas no mercado podem favorecer a percepção de tais substâncias pelas formigas, causando rejeição para forrageamento e consequente dificuldade do seu controle. Neste sentido, o objetivo do trabalho foi avaliar a mortalidade de formigas-cortadeiras dos gêneros Atta e Acromyrmex, submetidas a aplicação direta com pós secos, em laboratório. Como tratamento preliminar, utilizou-se: um talco antisséptico comercial e, posteriormente seus componentes, com potencial ação inseticida, isoladamente, sendo: ácido salicílico, enxofre, ácido bórico, óxido de zinco, além de um talco inerte (Quimidrol®), como testemunha. Para cada tratamento foram utilizadas 40 formigas (operárias) acondicionadas em poliestireno cristal transparente (Tipo Gerbox), que foram polvilhadas com auxílio de um saleiro, estando com atividade reduzida, devido a permanência em geladeira, previamente ao tratamento. As formigas foram mantidas em 25 ± 2°C, fotofase de 12 horas e a mortalidade acumulada foi observada a cada 24 horas, considerando-se formigas mortas aquelas que não conseguiam manter a posição natural do corpo, ou seja, mesmo formigas moribundas foram consideradas mortas, quando não exibiam reação, ao serem tocadas por um pincel. O talco antisséptico comercial, quando polvilhado sobre as formigas, causa mortalidade de 40%, em ambas as espécies, 24 horas após as aplicações. Estudos subsequentes dos componentes do referido produto comercial detectaram que o ácido salicílico, quando polvilhado tanto para Atta sexdens rubropilosa quanto para Acromyrmex crassispinus, causa mortalidade de 100% das operárias nas primeiras 24 horas. Esse resultado abre uma nova perspectiva de controle, com produto de baixo impacto ambiental, sinalizando uma alternativa de controle em ninhos a campo, podendo contribuir para o controle integrado de formigas.(AU)

Formação de biofilmes e resistência a antimicrobianos de isolados de Salmonella spp / Biofilm formation and antimicrobial resistance of Salmonella spp. isolates

O presente estudo avaliou a presença de Salmonella spp. em 89 amostras de produtos cárneos comercializados na região sul do Rio Grande do Sul e, a partir dos isolados obtidos, foi verificada a capacidade de resistência a agentes antimicrobianos e de formação de biofilme em superfícies de poliestireno. Foi constatada a presença de Salmonella spp. em 19,1% das amostras avaliadas e, dos isolados obtidos, 40% mostraram resistência a pelo menos um dos agentes antimicrobianos testados e 33,3% manifestaram-se multirresistentes. Apenas o antimicrobiano amicacina (30 µg) foi eficaz na inibição de todos os isolados testados. Nenhum isolado mostrou-se capaz de formar biofilmes em superfícies de poliestireno.

The objective of the study was to evaluate the presence of Salmonella spp. in 89 samples of meat products marketed in southern Rio Grande do Sul and from isolates obtained was verified the ability of resistance to antimicrobials and biofilm formation on polystyrene surfaces. The presence of Salmonella spp. was found in 19.1% of the samples. Of the isolates obtained, 40% showed resistance to at least one of the tested antimicrobials and 33.3% expressed multiresistant. Only the antimicrobial amikacin (30 µg) was effective in inhibiting all isolates tested. No isolate was able to form biofilms on polystyrene surfaces.

Formação de biofilmes e resistência a antimicrobianos de isolados de Salmonella spp. / Biofilm formation and antimicrobial resistance of Salmonella spp. isolates

O presente estudo avaliou a presença de Salmonella spp. em 89 amostras de produtos cárneos comercializados na região sul do Rio Grande do Sul e, a partir dos isolados obtidos, foi verificada a capacidade de resistência a agentes antimicrobianos e de formação de biofilme em superfícies de poliestireno. Foi constatada a presença de Salmonella spp. em 19,1% das amostras avaliadas e, dos isolados obtidos, 40% mostraram resistência a pelo menos um dos agentes antimicrobianos testados e 33,3% manifestaram-se multirresistentes. Apenas o antimicrobiano amicacina (30 µg) foi eficaz na inibição de todos os isolados testados. Nenhum isolado mostrou-se capaz de formar biofilmes em superfícies de poliestireno.(AU)

The objective of the study was to evaluate the presence of Salmonella spp. in 89 samples of meat products marketed in southern Rio Grande do Sul and from isolates obtained was verified the ability of resistance to antimicrobials and biofilm formation on polystyrene surfaces. The presence of Salmonella spp. was found in 19.1% of the samples. Of the isolates obtained, 40% showed resistance to at least one of the tested antimicrobials and 33.3% expressed multiresistant. Only the antimicrobial amikacin (30 µg) was effective in inhibiting all isolates tested. No isolate was able to form biofilms on polystyrene surfaces.(AU)

Irradiação ionizante em pós-colheita de atemoia cultivar Thompson / Ionizing irradiation in postharvest in the atemoia cultivar Thompson

O estudo da irradiação ionizante com Cobalto 60 (60Co), neste experimento, teve por objetivo avaliar sua influência no aumento de vida de prateleira para atemoia cv. Thompson. As atemoias foram irradiadas com as seguintes doses de cobalto 60 (60Co): T0= Sem irradiação (controle), T1=0,2kGy, T2=0,4kGy, T3=0,6kGy, T4=0,8kGy, T5=1,0kGy e T6= 1,2kGy sendo posteriormente embaladas em bandejas de poliestireno expandido (2 frutas/bandeja) e selados com filmes de policloreto de vinila 0,020mm; exceção feita ao tratamento controle o qual não recebeu tratamento com irradiação; para cada tratamento houve três repetições com duas frutas por repetição. As frutas que receberam os tratamentos foram armazenadas em câmara fria nas condições de 15 ± 0,2ºC e 90 ± 2% de UR. Em todos os tratamentos, foram realizadas as análises de: perda de massa fresca, sólidos solúveis (SS), acidez titulável (AT), pH, ácido ascórbico (AA), açúcares redutores, taxa respiratória. As análises de todos os tratamentos foram analisadas a cada três dias (0,3,6,9,12,15 e 18) dias de armazenamento. A irradiação foi realizada no Centro de Tecnologia das Radiações CTR IPEN/CNEN SP, situado na cidade universitária USP (Universidade de São Paulo) no irradiador multipropósito do tipo compacto onde se utiliza o Raio Gama. O experimento foi conduzido em delineamento inteiramente casualizado (D.I.C.), em esquema fatorial...

The study of ionizing irradiation with Cobalt 60 (60Co), in this experiment, aimed to evaluate its influence on the increase of shelf life for atemoia cv. Thompson. Atemias were irradiated with the following doses of cobalt 60 (60Co): T0 = No irradiation (control), T1 = 0.2kGy, T2 = 0.4kGy, T3 = 0.6kGy, T4 = 0.8kGy, T5 = 1 , 0kGy and T6 = 1,2kGy and subsequently packed in expanded polystyrene trays (2 fruits / tray) and sealed with 0.020mm polyvinyl chloride films; exception made to the control treatment which did not receive irradiation treatment; for each treatment there were three repetitions with two fruits per repetition. The fruits that received the treatments were stored in a cold chamber at 15 ± 0.2ºC and 90 ± 2% RH. In all treatments, the analyzes of: loss of fresh mass, soluble solids (SS), titratable acidity (AT), pH, ascorbic acid (AA), reducing sugars, respiratory rate were performed. The analyzes of all treatments were analyzed every three days (0,3,6,9,12,15 and 18) days of storage. The irradiation was carried out at the Radiation Technology Center - CTR IPEN / CNEN - SP, located in the university city USP (University of São Paulo) in the compact multi-purpose radiator where the Gamma Ray is used. The experiment was conducted in a completely randomized design (D.I.C.), in a factorial scheme (treatment x storage), composed of the treatments and seven storage...

Irradiação ionizante em pós-colheita de atemoia cultivar Thompson / Ionizing irradiation in postharvest in the atemoia cultivar Thompson

O estudo da irradiação ionizante com Cobalto 60 (60Co), neste experimento, teve por objetivo avaliar sua influência no aumento de vida de prateleira para atemoia cv. Thompson. As atemoias foram irradiadas com as seguintes doses de cobalto 60 (60Co): T0= Sem irradiação (controle), T1=0,2kGy, T2=0,4kGy, T3=0,6kGy, T4=0,8kGy, T5=1,0kGy e T6= 1,2kGy sendo posteriormente embaladas em bandejas de poliestireno expandido (2 frutas/bandeja) e selados com filmes de policloreto de vinila 0,020mm; exceção feita ao tratamento controle o qual não recebeu tratamento com irradiação; para cada tratamento houve três repetições com duas frutas por repetição. As frutas que receberam os tratamentos foram armazenadas em câmara fria nas condições de 15 ± 0,2ºC e 90 ± 2% de UR. Em todos os tratamentos, foram realizadas as análises de: perda de massa fresca, sólidos solúveis (SS), acidez titulável (AT), pH, ácido ascórbico (AA), açúcares redutores, taxa respiratória. As análises de todos os tratamentos foram analisadas a cada três dias (0,3,6,9,12,15 e 18) dias de armazenamento. A irradiação foi realizada no Centro de Tecnologia das Radiações CTR IPEN/CNEN SP, situado na cidade universitária USP (Universidade de São Paulo) no irradiador multipropósito do tipo compacto onde se utiliza o Raio Gama. O experimento foi conduzido em delineamento inteiramente casualizado (D.I.C.), em esquema fatorial...(AU)

The study of ionizing irradiation with Cobalt 60 (60Co), in this experiment, aimed to evaluate its influence on the increase of shelf life for atemoia cv. Thompson. Atemias were irradiated with the following doses of cobalt 60 (60Co): T0 = No irradiation (control), T1 = 0.2kGy, T2 = 0.4kGy, T3 = 0.6kGy, T4 = 0.8kGy, T5 = 1 , 0kGy and T6 = 1,2kGy and subsequently packed in expanded polystyrene trays (2 fruits / tray) and sealed with 0.020mm polyvinyl chloride films; exception made to the control treatment which did not receive irradiation treatment; for each treatment there were three repetitions with two fruits per repetition. The fruits that received the treatments were stored in a cold chamber at 15 ± 0.2ºC and 90 ± 2% RH. In all treatments, the analyzes of: loss of fresh mass, soluble solids (SS), titratable acidity (AT), pH, ascorbic acid (AA), reducing sugars, respiratory rate were performed. The analyzes of all treatments were analyzed every three days (0,3,6,9,12,15 and 18) days of storage. The irradiation was carried out at the Radiation Technology Center - CTR IPEN / CNEN - SP, located in the university city USP (University of São Paulo) in the compact multi-purpose radiator where the Gamma Ray is used. The experiment was conducted in a completely randomized design (D.I.C.), in a factorial scheme (treatment x storage), composed of the treatments and seven storage...(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)

Radiação ultravioleta (uv-c) na qualidade pós-colheita de frutos de lichia ‘bengal’ / Ultraviolet radiation (uv-c) in post-harvest quality of lichia 'bengal' fruit

Objetivou-se avaliar a influência da radiação (UV-C) na conservação de lichias da cv. Bengal frigoarmazenadas. Os frutos foram submetidos a exposição da luz ultravioleta em equipamento IRINOX (UV-C com λ= 254 nm), acondicionados em bandeja de poliestireno expandido sem recobrimento e armazenados em câmara fria (5±0,5 ºC e 90±5 % de UR) por quinze dias. As análises foram realizadas a cada três dias e avaliados: perda de massa, atividade respiratória, pH, sólidos solúveis, acidez titulável, índice de maturação e ácido ascórbico. O experimento foi conduzido em delineamento inteiramente casualizado, em esquema fatorial e os dados foram submetidos à análise de variância e regressão polinomial (p < 0,05). A radiação UV não foi efetiva para diminuição de perda de massa. Os tratamentos de 20 e 30 minutos de exposição à radiação UV-C foram eficazes na manutenção da concentração de ácido ascórbico.

The objective of this study was to evaluate the influence of radiation (UV-C) on the conservation of litchi of cv. 'Bengal' refrigerated storage. The fruits were submitted to ultraviolet light exposure in IRINOX equipment (UV-C with λ = 254 nm), packaged in expanded polystyrene tray without overlay and stored in a cold room (5 ± 0.5 ºC and 90 ± 5% UR) for fifteen days. The analyzes were performed every three days and evaluated: loss of mass, respiratory activity, pH, soluble solids, titratable acidity, maturation index and ascorbic acid. The experiment was conducted in a completely randomized design in a factorial scheme and the data were submitted to analysis of variance and polynomial regression (p <0.05). UV radiation was not effective in reducing mass loss. The treatments of 20 and 30 minutes exposure to UV-C radiation were effective in maintaining ascorbic acid concentration.

Radiação ultravioleta (uv-c) na qualidade pós-colheita de frutos de lichia ‘bengal / Ultraviolet radiation (uv-c) in post-harvest quality of lichia 'bengal' fruit

Objetivou-se avaliar a influência da radiação (UV-C) na conservação de lichias da cv. Bengal frigoarmazenadas. Os frutos foram submetidos a exposição da luz ultravioleta em equipamento IRINOX (UV-C com λ= 254 nm), acondicionados em bandeja de poliestireno expandido sem recobrimento e armazenados em câmara fria (5±0,5 ºC e 90±5 % de UR) por quinze dias. As análises foram realizadas a cada três dias e avaliados: perda de massa, atividade respiratória, pH, sólidos solúveis, acidez titulável, índice de maturação e ácido ascórbico. O experimento foi conduzido em delineamento inteiramente casualizado, em esquema fatorial e os dados foram submetidos à análise de variância e regressão polinomial (p < 0,05). A radiação UV não foi efetiva para diminuição de perda de massa. Os tratamentos de 20 e 30 minutos de exposição à radiação UV-C foram eficazes na manutenção da concentração de ácido ascórbico.(AU)

The objective of this study was to evaluate the influence of radiation (UV-C) on the conservation of litchi of cv. 'Bengal' refrigerated storage. The fruits were submitted to ultraviolet light exposure in IRINOX equipment (UV-C with λ = 254 nm), packaged in expanded polystyrene tray without overlay and stored in a cold room (5 ± 0.5 ºC and 90 ± 5% UR) for fifteen days. The analyzes were performed every three days and evaluated: loss of mass, respiratory activity, pH, soluble solids, titratable acidity, maturation index and ascorbic acid. The experiment was conducted in a completely randomized design in a factorial scheme and the data were submitted to analysis of variance and polynomial regression (p <0.05). UV radiation was not effective in reducing mass loss. The treatments of 20 and 30 minutes exposure to UV-C radiation were effective in maintaining ascorbic acid concentration.(AU)

Biofilm formation by Salmonella Enteritidis at different incubation temperatures

Background: The genus Salmonella, associated with poultry products, is considered the leading cause of foodborne outbreaks in humans in many countries. In Brazil, Salmonella Enteritidis (SE) is the serovar remains as one most frequentlyisolated from humans, and it is also a major serovar found in animals, food, animal feed, and environmental samples, despiteall the efforts to control this pathogen. Also, the bacterium is able to form biofilms on different surfaces, protecting cellsfrom both cleaning and sanitizing procedures in the food industries. This study aimed to verify the ability of SalmonellaEnteritidis isolates to form biofilm on polystyrene at different incubation temperatures.Materials, Methods & Results: A total of 171 SE samples were isolated from foodborne outbreaks (foods and stool cultures) and poultry products between 2003 and 2010. The biofilm-forming ability of samples was measured at four differenttemperatures (3°C, 9ºC, 25ºC, and 36ºC), for 24 h, simulating temperatures usually found in poultry slaughterhouses. Later,200 μL of each bacterial suspension was inoculated, in triplicate, onto 96-well, flat-bottomed sterile polystyrene microtiterplates, washed, after that, the biofilm was fixed with methanol. The plates were dried at ambient temperature, stained with2% Hucker’s crystal violet. Afterwards, absorbance was read using an ELISA plate reader and the optical density (OD)of each isolate was obtained by the arithmetic mean of the absorbance of three wells and this value was compared withthe mean absorbance of negative controls (ODnc). The following classification was used for the determination of biofilmformation: no biofilm production, weak biofilm production, moderate biofilm production and strong biofilm production.Results demonstrated all isolates from stool cultures and foods involved in foodborne outbreaks, at least one of the fourtemperatures tested, were able to form biofilm...

Biofilm formation by Salmonella Enteritidis at different incubation temperatures

Background: The genus Salmonella, associated with poultry products, is considered the leading cause of foodborne outbreaks in humans in many countries. In Brazil, Salmonella Enteritidis (SE) is the serovar remains as one most frequentlyisolated from humans, and it is also a major serovar found in animals, food, animal feed, and environmental samples, despiteall the efforts to control this pathogen. Also, the bacterium is able to form biofilms on different surfaces, protecting cellsfrom both cleaning and sanitizing procedures in the food industries. This study aimed to verify the ability of SalmonellaEnteritidis isolates to form biofilm on polystyrene at different incubation temperatures.Materials, Methods & Results: A total of 171 SE samples were isolated from foodborne outbreaks (foods and stool cultures) and poultry products between 2003 and 2010. The biofilm-forming ability of samples was measured at four differenttemperatures (3°C, 9ºC, 25ºC, and 36ºC), for 24 h, simulating temperatures usually found in poultry slaughterhouses. Later,200 μL of each bacterial suspension was inoculated, in triplicate, onto 96-well, flat-bottomed sterile polystyrene microtiterplates, washed, after that, the biofilm was fixed with methanol. The plates were dried at ambient temperature, stained with2% Huckers crystal violet. Afterwards, absorbance was read using an ELISA plate reader and the optical density (OD)of each isolate was obtained by the arithmetic mean of the absorbance of three wells and this value was compared withthe mean absorbance of negative controls (ODnc). The following classification was used for the determination of biofilmformation: no biofilm production, weak biofilm production, moderate biofilm production and strong biofilm production.Results demonstrated all isolates from stool cultures and foods involved in foodborne outbreaks, at least one of the fourtemperatures tested, were able to form biofilm...(AU)

Biofilm formation by Prototheca zopfii isolated from clinical and subclinical bovine mastitis in distinct growth conditions under different dyes / Formação de biofilme por Prototheca zopfii isolados de mastite bovina clínica e subclínica em distintas condições de crescimento sob diferentes corantes

Prototheca spp. have been reported as an emergent environmental mastitis pathogen in several countries. Biofilm formation is a significant factor associated with different degrees of virulence developed by many microorganisms, including Prototheca spp. The present study aimed to compare two growth conditions and two staining dyes to determine which combination was more appropriate to evaluate qualitatively and quantitatively the production of biofilm by P. zopfii. Biofilm formation was evaluated in polystyrene microplates under static and dynamic growth conditions and staining with crystal violet or cotton blue dye. All P. zopfii isolates from cows with mastitis were classified as biofilm-producers in all growth conditions and staining. The cotton blue dye proved to be more appropriate method to classify the intensity of P. zopfii biofilm production.(AU)

Prototheca spp. tem sido relatado como um patógeno ambiental causador de mastite bovina em vários países. A formação de biofilme é um fator associado a diferentes graus de virulência desenvolvidos por muitos microrganismos, incluindo Prototheca zopfii. O presente estudo teve como objetivo comparar duas condições de crescimento e dois corantes para determinar a combinação mais adequada para avaliar qualitativa e quantitativamente a produção de biofilme por P. zopfii. A formação de biofilme foi avaliada em microplacas de poliestireno sob condições estáticas e dinâmicas de crescimento e coloração com cristal violeta ou azul de algodão. Todos os isolados de P. zopfii de vacas com mastite foram caracterizados como produtores de biofilme, independentemente das condições de crescimento e coloração. O corante azul de algodão demonstrou ser o método mais adequado para classificar a intensidade de produção de biofilme de P. zopfii.(AU)