Evaluation of methanolic crude extract of Linum usitatissimum for the removal of biofilm in diabetic foot isolates / Avaliação do extrato em bruto metanólico de Linum usitatissimum para remoção de biofilmes em isolados diabéticos de pé

Linum usitatissimum L is a widely used traditionally for multiple ailments. The present research was carried out to explore the antimicrobial, and anti-biofilm activity of crude extract of Linum usitatissimum L (Lu. Cr). Phytochemical and proximate analyses were performed. The bandages of diabetic foot patients were collected from the various hospitals. The bandages were cultured to isolate the bacterial strains present on it. The disc diffusion method was used to identify the antimicrobial potential whereas the minimum inhibitory concentration of the Lu.Cr were also determined. Proximate analysis confirms moisture content 8.33%, ash content 4.33%, crude protein 21.20%, crude fat 49.2% and crude fiber 5.63%. It was revealed that Gram-positive bacteria are most prevalent among all study groups. Lu.Cr possess significant bactericidal potential against S. aureus among all other microbes. Owing to this potential, linseed coated bandages can be used alternatively for the treatment of diabetic foot.

Linum usitatissimum L é amplamente utilizado tradicionalmente para doenças múltiplas. O presente trabalho foi realizado para explorar a atividade antimicrobiana e antibiofilme do extrato bruto de Linum usitatissimum L (Lu.Cr). Foram realizadas análises fitoquímicas e aproximadas. As ataduras de pacientes diabéticos com pé foram recolhidas nos vários hospitais. As bandagens foram cultivadas para isolar as cepas bacterianas presentes nas mesmas. O método de difusão em disco foi utilizado para identificar o potencial antimicrobiano e a concentração inibitória mínima do Lu.Cr também foi determinada. A análise aproximada confirma o teor de umidade 8,33%, teor de cinzas 4,33%, proteína bruta 21,20%, gordura bruta 49,2% e fibra bruta 5,63%. Foi revelado que as bactérias Gram-positivas são mais prevalentes entre todos os grupos de estudo. Lu.Cr possui potencial bactericida significativo contra S. aureus entre todos os outros micróbios. Devido a esse potencial, as ligaduras revestidas com linhaça podem ser utilizadas alternativamente para o tratamento do pé diabético.

Evaluation of methanolic crude extract of Linum usitatissimum for the removal of biofilm in diabetic foot isolates / Avaliação do extrato em bruto metanólico de Linum usitatissimum para remoção de biofilmes em isolados diabéticos de pé

Linum usitatissimum L is a widely used traditionally for multiple ailments. The present research was carried out to explore the antimicrobial, and anti-biofilm activity of crude extract of Linum usitatissimum L (Lu. Cr). Phytochemical and proximate analyses were performed. The bandages of diabetic foot patients were collected from the various hospitals. The bandages were cultured to isolate the bacterial strains present on it. The disc diffusion method was used to identify the antimicrobial potential whereas the minimum inhibitory concentration of the Lu.Cr were also determined. Proximate analysis confirms moisture content 8.33%, ash content 4.33%, crude protein 21.20%, crude fat 49.2% and crude fiber 5.63%. It was revealed that Gram-positive bacteria are most prevalent among all study groups. Lu.Cr possess significant bactericidal potential against S. aureus among all other microbes. Owing to this potential, linseed coated bandages can be used alternatively for the treatment of diabetic foot.(AU)

Linum usitatissimum L é amplamente utilizado tradicionalmente para doenças múltiplas. O presente trabalho foi realizado para explorar a atividade antimicrobiana e antibiofilme do extrato bruto de Linum usitatissimum L (Lu.Cr). Foram realizadas análises fitoquímicas e aproximadas. As ataduras de pacientes diabéticos com pé foram recolhidas nos vários hospitais. As bandagens foram cultivadas para isolar as cepas bacterianas presentes nas mesmas. O método de difusão em disco foi utilizado para identificar o potencial antimicrobiano e a concentração inibitória mínima do Lu.Cr também foi determinada. A análise aproximada confirma o teor de umidade 8,33%, teor de cinzas 4,33%, proteína bruta 21,20%, gordura bruta 49,2% e fibra bruta 5,63%. Foi revelado que as bactérias Gram-positivas são mais prevalentes entre todos os grupos de estudo. Lu.Cr possui potencial bactericida significativo contra S. aureus entre todos os outros micróbios. Devido a esse potencial, as ligaduras revestidas com linhaça podem ser utilizadas alternativamente para o tratamento do pé diabético.(AU)

Optimization of some environmental and nutritional conditions using microtiter plate for Pseudomonas aeruginosa biofilm formation

One of the most important virulence factors in Pseudomonas aeruginosa is biofilm formation, as it works as a barrier for entering antibiotics into the bacterial cell. Different environmental and nutritional conditions were used to optimize biofilm formation using microtitre plate assay by P. aeruginosa. The low nutrient level of the medium represented by tryptic soy broth (TSB) was better in biofilm formation than the high nutrient level of the medium with Luria Broth (LB). The optimized condition for biofilm production at room temperature (25 °C) is better than at host temperature (37 °C). Moreover, the staining with 0.1% crystal violet and reading the biofilm with wavelength 360 are considered essential factors in increasing the productivity of biofilm formation in P. aeruginosa. Finally, we highly recommended using these optimized microtitre plate assays to assess biofilm formation in P. aeruginosa.

Biofilm production by coagulase-negative Staphylococcus: a review / Produção de biofilme por Staphylococcus coagulase-negativo: uma revisão

This review aimed to describe the biofilm formation ability of coagulase-negative Staphylococcus, addressing its impact to the food industry. Coagulase-negative Staphylococcus have the ability to produce enterotoxins in food, making it an important line of study, as it constitutes a risk to public health. The biofilm formation by these microorganisms requires physicochemical processes, such as hydrophobic forces, which are essential for the first phase of fixing the biofilm on the surface. In industrial facilities, stainless steel equipment is the most associated with the formation of biofilms, due to the presence grooves and cracks. Many species of coagulase-negative Staphylococcus produce biofilm, but the most studied is S. epidermidis, as it is the most frequently isolated from food. Coagulase-negative Staphylococcus form biofilm on different surfaces in the food industry, and can become a source of permanent contamination, that can be present in the final product, intended for human consumption. Among other alternatives to combat the formation of biofilm in industrial food facilities, there is the implementation of Good Manufacturing Practices, which is effective in preventing bacterial adhesion, and therefore, the formation of biofilm. However, further studies are needed in order to quantify the occurrence of coagulase-negative Staphylococcus biofilms in the food industry.(AU)

Esta revisão bibliográfica teve como objetivo descrever a capacidade de formação de biofilme por Staphylococcus coagulase-negativo, relacionando seu impacto na indústria alimentícia. Os Staphylococcus coagulase-negativos possuem a capacidade de produzir enterotoxina nos alimentos, tornando-se uma importante linha de estudo, pois constitui um risco para a saúde pública. A formação do biofilme por esses micro-organismos requer processos físico-químicos, como forças hidrofóbicas, essenciais para a primeira fase de fixação do biofilme na superfície. Nas indústrias, equipamentos de aço inoxidável são os mais associados à formação de biofilmes, em decorrência de possuírem ranhuras e fendas. Muitas espécies de Staphylococcus coagulase-negativo produzem biofilme, porém, o mais estudado é o S. epidermidis, por ser o mais frequentemente isolado de alimentos. Os Staphylococcus coagulase-negativos formam biofilme em diferentes superfícies de indústrias alimentícias, podendo se tornar uma fonte de contaminação permanente, contaminando o produto final destinado ao consumo humano. Dentre outras alternativas para combater a formação do biofilme nas plantas alimentícias, a implantação das Boas Práticas de Fabricação é eficaz para prevenir a adesão bacteriana, evitando a formação do biofilme. No entanto, são necessários estudos para quantificar a ocorrência de biofilmes de Staphylococcus coagulase-negativos em indústrias alimentícias.(AU)

Avaliação da capacidade de formação de biofilmes de Bacillus cereus isolados de produtos lácteos frente a diferentes temperaturas / Evaluation of the capacity to form biofilm by Bacillus cereus isolated from dairy products at different temperatures

Bacillus cereus encontra-se entre os patógenos de maior preocupação na indústria de alimentos por sua capacidade em formar biofilmes. Como resultado, podem contaminar os alimentos que entram em contato com as superfícies, representando dessa forma um obstáculo para conservação de leite e produtos lácteos, o que coloca em risco a saúde dos consumidores. Objetivou-se avaliar a capacidade de formação de biofilmes de estirpes de B. cereus frente à diferentes temperaturas encontradas na indústria de laticínios em superfície de aço inoxidável. A capacidade de formação de biofilme foi avaliada em diferentes temperaturas (5, 15, 25 e 32 ºC) e intervalos de tempo (24, 48,72, 96 e 120h). As estirpes de B. cereus apresentaram diferenças significativas nas temperaturas avaliadas e na capacidade de adesão, onde uma das estirpes apresentou maior capacidade de se aderir. Constatou-se que altas temperaturas favoreceram o desenvolvimento do biofilme e baixas temperaturas retardaram esse processo.(AU)

Avaliação da capacidade de formação de biofilmes de Bacillus cereus isolados de produtos lácteos frente a diferentes temperaturas / Evaluation of the capacity to form biofilm by Bacillus cereus isolated from dairy products at different temperatures

Bacillus cereus encontra-se entre os patógenos de maior preocupação na indústria de alimentos por sua capacidade em formar biofilmes. Como resultado, podem contaminar os alimentos que entram em contato com as superfícies, representando dessa forma um obstáculo para conservação de leite e produtos lácteos, o que coloca em risco a saúde dos consumidores. Objetivou-se avaliar a capacidade de formação de biofilmes de estirpes de B. cereus frente à diferentes temperaturas encontradas na indústria de laticínios em superfície de aço inoxidável. A capacidade de formação de biofilme foi avaliada em diferentes temperaturas (5, 15, 25 e 32 ºC) e intervalos de tempo (24, 48,72, 96 e 120h). As estirpes de B. cereus apresentaram diferenças significativas nas temperaturas avaliadas e na capacidade de adesão, onde uma das estirpes apresentou maior capacidade de se aderir. Constatou-se que altas temperaturas favoreceram o desenvolvimento do biofilme e baixas temperaturas retardaram esse processo.

Modelagem da formação de biofilmes de Pseudomonas fluorescens e Pseudomonas aeruginosa em aço inoxidável através da metodologia de superfície de resposta / Modeling Pseudomonas luorescens and Pseudomonas aeruginosa biofilm formation on stainless steel by response surface methodology

O objetivo deste trabalho foi verificar a influência do tempo e da temperatura na formação de biofilmes de P. fluorescens e P. aeruginosa em superfície de aço inoxidável através de um delineamento composto central rotacional (DCCR). Os biofilmes foram avaliados nas temperaturas de 7; 13; 27; 41 e 47 °C e nos tempos de contato de 0; 1,2; 4; 6,8 e 8 dias. As superfícies de resposta mostraram que P. fluorescens foi capaz de formar biofilme entre 0,9 e 8 dias em temperaturas entre 9,8 e 47 °C. P. aeruginosa foi capaz de formar biofilme entre0,7 a 8 dias e entre 11 e 47 °C. É importante destacar que estas condições são frequentemente encontradas durante todo o processamento de queijo Minas frescal, comprometendo a segurança do alimento.(AU)

Modelagem da formação de biofilmes de Pseudomonas fluorescens e Pseudomonas aeruginosa em aço inoxidável através da metodologia de superfície de resposta / Modeling Pseudomonas luorescens and Pseudomonas aeruginosa biofilm formation on stainless steel by response surface methodology

O objetivo deste trabalho foi verificar a influência do tempo e da temperatura na formação de biofilmes de P. fluorescens e P. aeruginosa em superfície de aço inoxidável através de um delineamento composto central rotacional (DCCR). Os biofilmes foram avaliados nas temperaturas de 7; 13; 27; 41 e 47 °C e nos tempos de contato de 0; 1,2; 4; 6,8 e 8 dias. As superfícies de resposta mostraram que P. fluorescens foi capaz de formar biofilme entre 0,9 e 8 dias em temperaturas entre 9,8 e 47 °C. P. aeruginosa foi capaz de formar biofilme entre0,7 a 8 dias e entre 11 e 47 °C. É importante destacar que estas condições são frequentemente encontradas durante todo o processamento de queijo Minas frescal, comprometendo a segurança do alimento.

Growth, viability and architecture of biofilms of Listeria monocytogenes formed on abiotic surfaces

The pathogenic bacterium Listeria monocytogenes can persist in food processing plants for many years, even when appropriate hygienic measures are in place, with potential for contaminating ready-to-eat products and, its ability to form biofilms on abiotic surfaces certainly contributes for the environmental persistence. In this research, L. monocytogenes was grown in biofilms up 8 days attached to stainless steel and glass surfaces, contributing for advancing the knowledge on architecture of mature biofilms, since many literature studies carried out on this topic considered only early stages of cell adhesion. In this study, biofilm populations of two strains of L. monocytogenes (serotypes 1/2a and 4b) on stainless steel coupons and glass were examined using regular fluorescence microscopy, confocal laser scanning microscopy and classic culture method. The biofilms formed were not very dense and microscopic observations revealed uneven biofilm structures, with presence of exopolymeric matrix surrounding single cells, small aggregates and microcolonies, in a honeycomb-like arrangement. Moreover, planktonic population of L. monocytogenes (present in broth media covering the abiotic surface) remained stable throughout the incubation time, which indicates an efficient dispersal mechanism, since the culture medium was replaced daily. In conclusion, even if these strains of L. monocytogenes were not able to form thick multilayer biofilms, it was noticeable their high persistence on abiotic surfaces, reinforcing the need to focus on measures to avoid biofilm formation, instead of trying to eradicate mature biofilms.(AU)

Current understanding of bacterial biofilms and latent infections: A clinical perspective / Conceitos atuais sobre biofilmes e bactérias latentes em casos clínicos de endometrite

ubfertility in the mare can be frustrating to the clinician. Recent data has suggested that bacteria ineither a biofilm or latent state may be responsible for explaining many cases of subfertility. Recent work hasidentified how the pathophysiology for these type of chronic infections in the horse and identified the bestmethods for therapy. The goal of this discussion is to explain the pathophysiology of biofilm and latentinfections and how the clinician can diagnose and treat these type of infections in clinical practice.(AU)

Current understanding of bacterial biofilms and latent infections: A clinical perspective / Conceitos atuais sobre biofilmes e bactérias latentes em casos clínicos de endometrite

ubfertility in the mare can be frustrating to the clinician. Recent data has suggested that bacteria ineither a biofilm or latent state may be responsible for explaining many cases of subfertility. Recent work hasidentified how the pathophysiology for these type of chronic infections in the horse and identified the bestmethods for therapy. The goal of this discussion is to explain the pathophysiology of biofilm and latentinfections and how the clinician can diagnose and treat these type of infections in clinical practice.

Susceptibility and resistance to antimicrobial Staphylococcus aureus under biofilm / Susceptibilidade e resistência a antimicrobianos de Staphylococcus aureus em condições de biofilme

Staphylococcus is an important agent of mastitis, especially when biofilm producers are related to a number of mechanisms of resistance to different types of infections. The objective of this research was to evaluate the susceptibility and resistance of Staphylococcus aureus strains isolates from cases of bovine mastitis and milking environment under conditions of biofilm, compared to three different concentrations in different antimicrobials. Thirty-two strains used were S. aureus that, due to the inhibition tests, minimal biofilm eradication concentration were tested using cephalexin, amoxicillin and rifampin at concentrations of 30 mg/mL, and 50 mg/mL 100 mg/mL for 12 hours, and efficiency of tests evaluated by counting the colony forming units and the microplate test. The results revealed that among the tested antibiotics cephalexin showed the best efficiency at the three concentrations tested, and rifampin and amoxicillin were more efficient at concentrations of 50 and 100 mg/mL. These data demonstrate the importance of targeted antibiotic therapy associated with the correct cleaning of milking equipment, thus, preventing the formation of biofilm, avoiding persistent microbial adhesion in equipment, and the spread of microorganisms by ascending channel teats among herd animals.(AU)

Os Staphylococcus, principais agentes causadores da mastite, quando em biofilmes, estão relacionados a uma série de mecanismos de resistência em diferentes tipos de infecções. O presente trabalho avaliou a susceptibilidade e resistência dos Staphylococcus aureus, isolados de casos de mastite bovina e do ambiente de ordenha, em condições de biofilme, frente a três antimicrobianos distintos em diferentes concentrações. Foram utilizadas trinta e duas estirpes de S. aureus testadas frente aos testes de inibição da concentração mínima de erradicação de biofilmes, utilizando cefalexina, amoxicilina e rifampicina, nas concentrações de 30 mg/mL, 50 mg/mL e 100 mg/mL, por doze horas de contato, e a eficiência dos testes avaliada pela contagem das unidades formadoras de colônias e pelo teste de microplacas. Os resultados revelaram que, entre os antimicrobianos testados, a cefalexina foi o que apresentou melhor eficiência nas três concentrações testadas, e a rifampicina e amoxacilina tiveram maior eficiência nas concentrações de 50 e 100 mg/ mL. Esses dados demonstram a importância sobre antibioticoterapia orientada associada com a correta higienização dos equipamentos de ordenha, evitando-se, assim, a formação de biofilmes, a adesão microbiana persistente em equipamentos, e a difusão dos microrganismos pelo canal ascendente dos tetos entre os animais do rebanho.(AU)

Different methods to quantify Listeria monocytogenes biofilms cells showed different profile in their viability

Listeria monocytogenes is a foodborne pathogen able to adhere and to form biofilms in several materials commonly present in food processing plants. The aim of this study was to evaluate the resistance of Listeria monocytogenes attached to abiotic surface, after treatment with sanitizers, by culture method, microscopy and Quantitative Real Time Polymerase Chain Reaction (qPCR). Biofilms of L. monocytogenes were obtained in stainless steel coupons immersed in Brain Heart Infusion Broth, under agitation at 37 °C for 24 h. The methods selected for this study were based on plate count, microscopic count with the aid of viability dyes (CTC-DAPI), and qPCR. Results of culture method showed that peroxyacetic acid was efficient to kill sessile L. monocytogenes populations, while sodium hypochlorite was only partially effective to kill attached L. monocytogenes (p < 0.05). When, viability dyes (CTC/DAPI) combined with fluorescence microscopy and qPCR were used and lower counts were found after treatments (p < 0.05). Selective quantification of viable cells of L. monocytogenes by qPCR using EMA revelead that the pre-treatment with EMA was not appropriate since it also inhibited amplification of DNA from live cells by ca. 2 log. Thus, the use of CTC counts was the best method to count viable cells in biofilms.(AU)

Clonal profile, virulence and resistance of Staphylococcus aureus isolated from sheep milk

The objective of this study was to characterize the clonal profile, virulence factors and antimicrobial resistance, particularly oxacillin resistance, of Staphylococcus aureus isolated from sheep milk. Milk samples were collected from all teats for the California Mastitis Test (CMT), somatic cell count, identification of S. aureus, investigation in these strains of genes encoding toxins (sea, seb, sec, sed, tst), biofilm (icaA, icaC, icaD, bap), leukocidin (luk-PV) oxacillin resistance by mecA gene detection and susceptibility testing (12 antibiotics). Messenger RNA expression was evaluated by RT-PCR in isolates carrying toxin and biofilm genes. Biofilm formation was also evaluated phenotypically by adherence to polystyrene plates. The clonal profile of S. aureus was investigated by pulsed-field gel electrophoresis. A total of 473 milk samples were collected from 242 animals on three farms and 20 S. aureus strains were isolated and none carried the mecA gene. The two sec gene-positive isolates and the isolates carrying the tst and luk-PV genes were positive by RT-PCR. Staphylococcus aureus isolated from the three flocks studied showed high susceptibility to the drugs tested and none was biofilm producer, indicating that biofilm formation was not a virulence factor causing infection by these strains. The typing of 17 S. aureus isolates revealed the presence of a common clone on the three farms studied, and the presence and expression of the sec and tst genes in one strain of this clone suggest the possible acquisition of virulence genes by this clone, a fact that is important for animal health and food hygiene.(AU)

Adhesion, biofilm and genotypic characteristics of antimicrobial resistant Escherichia coli isolates

Aggregative adherence to human epithelial cells, most to renal proximal tubular (HK-2) cells, and biofilm formation was identified among antimicrobial resistant Escherichia coli strains mainly isolated from bacteremia. The importance of these virulence properties contributing to host colonization and infection associated with multiresistant E. coli should not be neglected.(AU)

Sub-MIC of antibiotics induced biofilm formation of Pseudomonas aeruginosa in the presence of chlorhexidine

Public health is facing a new challenge due to the alarming increase in bacterial resistance to most of the conventional antibacterial agents. It has been found that only minor cell damage is caused when exposed to sub-lethal levels of antimicrobial. Biofilms can play an important role in producing resistance, which is developed to reservoirs of pathogens in the hospital and cannot be easily removed. The aim of this study was to test whether the sub-lethal dose of antibiotics can induce biofilm formation of P. aeruginosa following incubating in the presence and absence of chlorhexidine. Standard antibiotic-micro broth 96-flat well plates were used for determination of MIC and biofilm assay. The adherence degree of biofilm was determined by estimation of OD630 nm values using ELISA reader. The mean 22 isolates of P. aeruginosa growing in culture with presence and absence of chlorhexidine, could exhibited the significant (p < 0.001) proportion of adherence followed incubation in sub minimal inhibitory concentrations (Sub-MIC) of cefotaxim, amoxicillin, and azithromycin in comparison with control (antibiotic-free broth), while the sub-MIC of ciprofloxacin revealed significant inhibition of biofilm. Conclusion: Incubating the isolates of P. aeruginosa to sub-MIC of antibiotics exhibited induction of biofilm in the presence of chlorhexidine.(AU)

Ocorrência de genes tad associados à formação de biofilme em isolados de Pasteurella multocida de pulmões de suínos com pneumonia / Occurrence of tad genes associated with biofilm formation in isolates of Pasteurella multocida from lungs of pigs with pneumonia

Nowadays pig intensive production systems increase microbial selection pressure favoring spread of respiratory diseases. The bacteria Pasteurella multocida is associated with various respiratory diseases in pigs under farming conditions causing high economic losses. In vitro biofilm formation has been described in P. multocida which role is described in tissue colonization, enhancing resistance to host defenses and antibiotics. The aims of this study were to analyze the occurrence of P. multocida in pig pneumonia and health lung microbiota, and occurrence of tad locus genes in these isolates. Seventy isolates of P. multocida were analyzed which sixty seven were from lungs with lesion and three from healthy lungs. Serotype A occurred mainly in lung lesion (85.71%), in healthy lung, instead, only serotype D was observed. Genes tadA, tadB, tadC, tadD, tadE, tadF and tadG were present in 89.55% isolates from lesion lung. Genes tadA, tadB and tadC were present in all isolates from healthy lungs but, tadD, tadE tadF and tadG were present in 0%, 33.3%, 33,3% and 66.6%, respectively. This work associated tadD, tadE and tadF gene positive isolates of P. multocida to lung pneumonic lesions.(AU)

Os atuais sistemas de criação intensiva de suínos aumentam a pressão de seleção microbiana propiciando a disseminação de doenças respiratórias. A bactéria Pasteurella multocida é associada a diversas patologias respiratórias em animais submetidos a esse tipo de criação, causando grandes perdas econômicas. A formação de biofilme foi descrita in vitro em P. multocida e fatores analisados indicaram a facilitação na colonização dos tecidos, aumentando a resistência às defesas do hospedeiro e aos antibióticos. Os objetivos deste trabalho foram analisar a ocorrência de P. multocida em pneumonias de suínos e na microbiota de pulmões sem lesão e a ocorrência dos genes do lócus tad nestes isolados. Foram analisados 70 isolados de P. multocida de pulmões, sendo sessenta e sete com lesão e três sem lesão. Isolados do sorotipo A ocorreram principalmente em pulmões com lesões (85,71%), enquanto em pulmões sem lesão observou-se somente o sorotipo D. Os genes tadA, tadB, tadC, tadD, tadE tadF e tadG estavam presentes em 89,55% dos isolados de pulmões com lesões. Os genes tadA, tadB e tadC estavam presentes em todos os isolados de pulmões sem lesão, porém os genes tadD, tadE, tadF e tadG estavam presentes em 0%, 33,3%, 33,3% e 66,6%, dos isolados sem lesão, respectivamente. Neste trabalho observou-se a associação da ocorrência dos genes tadD, tadE e tadF em isolados de P. multocida e a presença de lesões em pulmões.(AU)

Microbiological aspects of the biofilm on wooden utensils used to make a Brazilian artisanal cheese

The artisanal Minas cheese is produced from raw cow's milk and wooden utensils were employed in its manufacture, which were replaced by other materials at the request of local laws. This substitution caused changes in the traditional characteristics of cheese. Due to the absence of scientific studies indicating the microbial composition of biofilms formed on wooden forms, tables and shelves used in these cheese production, the present work evaluated the counts of Staphylococcus aureus, Escherichia coli, coliforms at 32 °C, yeasts, presumptive mesophilic Lactobacillus spp. and Lactococcus spp. in these biofilms, milk, whey endogenous culture and ripened cheese in two traditional regions: Serro and Serra da Canastra. Also, we checked for the presence of Salmonella sp. and Listeria monocytogenes in the ripened cheeses. The ultra structure of the biofilms was also assessed. Counts above legislation (> 2 log cfu/mL) for the pathogens evaluated were found in milk samples from both regions. Only one shelf and one form from Serro were above limits proposed (5 cfu/cm² for S. aureus and E. coli and 25 cfu/cm² for coliforms) in this study for contaminants evaluated. In Canastra, few utensils presented safe counting of pathogens. There was no Salmonella sp. and Listeria monocytogenes in the cheeses after ripening. Thus, the quality of the cheese is related to improving the microbiological quality of milk, implementation and maintenance of good manufacturing practices, correct cleaning of wooden utensils, and not its replacement.

Virulence factors and biofilm production by isolates of Bacteroides fragilis recovered from dog intestinal tracts

Bacteroides fragilis colonizes dog guts both as a commensal and as an opportunistic pathogen. This study aims to evaluate virulence factors of 13 B. fragilis strains isolated from dog intestinal tracts and their ability for biofilm formation. Capsules were detected in all the evaluated strains. A total of 61.5% of all strains were biofilm producers. These attributes most likely play an important role in B. fragilis persistent colonization in the gut.

Lack of AHL-based quorum sensing in Pseudomonas fluorescens isolated from milk

Numerous bacteria coordinate gene expression in response to small signalling molecules in many cases known as acylhomoserine lactones (AHLs), which accumulate as a function of cell density in a process known as quorum sensing. This work aimed to determine if phenotypes that are important to define microbial activity in foods such as biofilm formation, swarming motility and proteolytic activity of two Pseudomonas fluorescens strains, isolated from refrigerated raw milk, are influenced by AHL molecules. The tested P. fluorescens strains did not produce AHL molecules in none of the evaluated media. We found that biofilm formation was dependent on the culture media, but it was not influenced by AHLs. Our results indicate that biofilm formation, swarming motility and proteolytic activity of the tested P. fluorescens strains are not regulated by acyl-homoserine lactones. It is likely that AHL-dependent quorum sensing system is absent from these strains.