Influence of the food matrix on dual-species biofilm of Listeria monocytogenes and Pseudomonas fluorescens

In the food industry, the formation of biofilms results in serious microbial recontamination problem. This work aimed to study Listeria sp. obtained from sliced products and food handling surfaces, for the preparation of food of animal origin to be consumed cold. Listeria monocytogenes, Listeria innocua and Listeria seeligeri were detected. In the evaluation of antibiotic susceptibility, the isolates were sensitive to ampicillin and penicillin, which were the main antibiotics used in treatment. The isolates showed the ability to form biofilm in microplate, in stainless steel and polypropylene surfaces, with a variation of sessile cells between 4.29±0.23 and 7.03±0.01 log10 CFU cm-2 in TSBYE. This ability was also observed in food matrix composed of UHT whole milk in mono-species cultivation and in associated cultivation of L. monocytogenes with Pseudomonas fluorescens. The application of sanitizers peracetic acid and sodium hypochlorite revealed efficiency in the eradication of adhered cells and biofilms formed in stainless steel surfaces. Therefore, Listeria sp. showed to be persistent and able to form biofilm in mono-species cultivation or associated with P. fluorescens, under different conditions. Taking these aspects into account, the need for proper hygiene in the food production process is highlighted in order to avoid risks to the consumers health.(AU)

Contribution of environmental factors in the formation of biofilms by Alicyclobacillus acidoterrestris on surfaces of the orange juice industry / Contribuição de fatores ambientais na formação de biofilmes por Alicyclobacillus acidoterrestris em superfícies da indústria de suco de laranja

The objective of this study was to evaluate the effect of the initial microbial load, temperature and contact time on the biofilm formation of Alicyclobacillus acidoterrestris on stainless steel and natural food-grade rubber using orange juice as culture medium. The low initial load of A. acidoterrestris (2 log CFU/mL) led to biofilm formation on the stainless steel surface after 48 h of contact at 28 ºC and after 24 h at 45 ºC, and on natural food-grade rubber surface after 48 h of contact at both temperatures. The high initial microbial load (5 log CFU/mL) led to biofilm formation on stainless steel after 4 h of contact at 28 °C and 45 °C, while biofilm was formed on natural food-grade rubber after 8 h of contact at 28 °C and 4 h at 45 °C. The microbial load also affected the presence of spores in biofilm, which was observed on both surfaces only at high initial loads of A. acidoterrestris.(AU)

O objetivo deste estudo foi avaliar o efeito da carga microbiana inicial, temperatura e tempo de contato na formação de biofilme de Alicyclobacillus acidoterrestris em aço inoxidável e borracha natural de qualidade alimentar utilizando suco de laranja como meio de cultura. A baixa carga inicial de A. acidoterrestris (2 log UFC/mL) levou à formação de biofilme na superfície do aço inoxidável após 48 h de contato a 28 ºC e após 24 h a 45 ºC, e na superfície natural de borracha de qualidade alimentar após 48 h de contato nas duas temperaturas. A alta carga microbiana inicial (5 log UFC/mL) levou à formação de biofilme em aço inoxidável após 4 h de contato a 28 °C e 45 °C, enquanto o biofilme foi formado em borracha natural de qualidade alimentar após 8 h de contato a 28 °C e 4 h a 45 °C. A carga microbiana também afetou a presença de esporos no biofilme, o que foi observado em ambas as superfícies apenas com altas cargas iniciais de A. acidoterrestris.(AU)

Single- and Multispecies Biofilms by Escherichia coli, Staphylococcus aureus, and Salmonella spp. Isolated from Raw Fish and a Fish Processing Unit / Formação de Biofilmes Mono e Multi-espécies de Escherichia coli, Staphylococcus aureus, e Salmonella spp. Isoladas de Pescado Cru e Indústria de Pescado

The consumption of fish by the Brazilian population is increasing. However, fish and seafood are highly perishable and can be contaminated with several microorganisms. In addition, the possibility of biofilm formation is a greater cause for concern. In this study, biofilm formation was evaluated in single- and multispecies cultures at 25°C for incubation periods of 0, 4, 8, 24, and 48h in stainless steel coupons (size, 1.0×1.0cm) immersed in tryptic soy broth. The characteristics of the formed biofilms after sanitizing by immersing the coupons in 200ppm sodium hypochlorite solution for 10min were also evaluated under the same experimental conditions but with some modifications. Biofilm structure was evaluated using scanning electron microscopy. Analysis of single-species biofilms indicated that all bacterial strains formed biofilms at different intervals without any statistically significant difference. However, comparison of the growth of single- and multispecies cultures indicated a significantly higher biofilm formation by the pure cultures. In multispecies biofilms, compared with the other microorganisms, growth of Salmonella spp. was significantly lower for all tested incubation periods; whereas, of Staphylococcus aureus was significantly higher than that of E. coli until 8h of incubation; the differences in growth were not significantly different after this incubation period. Sanitizing with sodium hypochlorite was effective because no cell growth was observed in the coupons that were treated with 200ppm sodium hypochlorite for 10min. This study demonstrated the ability of isolated microorganisms to form biofilms, reinforcing the need for food handling establishments to adopt good manufacturing practices, developing adequate protocols for cleaning and disinfecting surfaces and equipment used in food production, maintaining and replacing equipment when necessary.

A população brasileira tem apresentado um elevado consumo de peixes, no entanto pescados são alimentos altamente perecíveis e podem ser contaminados por uma diversidade de microrganismos. A situação ainda é mais alarmante quando se trata da formação de biofilmes. Para verificação da formação de biofilme, as cepas foram testadas dentro de cultivos mono e multi-espécies a 25°C durante o tempo total de 48h, onde as análises foram realizadas no tempo 0 e nos intervalos de 4, 8, 24 e 48h em cupom de aço inoxidável medindo 1,0x1,0cm, imersos em caldo TSB (Tryptic Soy Broth).O comportamento dos biofilmes formados, diante da sanitização por imersão dos cupons em solução de hipoclorito de sódio a 200ppm por 10 minutos, também foi avaliado, nas mesmas condições citadas acima, com algumas particularidades. A avaliação estrutural foi procedida por microscopia de varredura eletrônica (MEV). Nos resultados de biofilmes mono-espécie, foi verificado que todas as cepas foram capazes de formar biofilme, nos diferentes tempos, sem diferenças estatisticamente significativas. Entretanto, comparando-se o crescimento de culturas mono e múltiplas espécies observou-se formação de biofilme, estatisticamente maior, entre as culturas puras. Nas culturas multi-espécies, Salmonella spp. apresentou crescimento, estatisticamente menor, em todos os tempos, entre os microrganismos testados, enquanto S. aureus apresentou maior crescimento que E. coli até 8 horas de incubação, deste tempo em diante a diferença não foi significativa. Quanto ao comportamento frente sanitização com hipoclorito, o sanitizante foi eficaz, uma vez que não foi observado crescimento celular nas análises dos cupons tratados com a solução de hipoclorito a 200ppm por 10 minutos.

Single- and Multispecies Biofilms by Escherichia coli, Staphylococcus aureus, and Salmonella spp. Isolated from Raw Fish and a Fish Processing Unit / Formação de Biofilmes Mono e Multi-espécies de Escherichia coli, Staphylococcus aureus, e Salmonella spp. Isoladas de Pescado Cru e Indústria de Pescado

The consumption of fish by the Brazilian population is increasing. However, fish and seafood are highly perishable and can be contaminated with several microorganisms. In addition, the possibility of biofilm formation is a greater cause for concern. In this study, biofilm formation was evaluated in single- and multispecies cultures at 25°C for incubation periods of 0, 4, 8, 24, and 48h in stainless steel coupons (size, 1.0×1.0cm) immersed in tryptic soy broth. The characteristics of the formed biofilms after sanitizing by immersing the coupons in 200ppm sodium hypochlorite solution for 10min were also evaluated under the same experimental conditions but with some modifications. Biofilm structure was evaluated using scanning electron microscopy. Analysis of single-species biofilms indicated that all bacterial strains formed biofilms at different intervals without any statistically significant difference. However, comparison of the growth of single- and multispecies cultures indicated a significantly higher biofilm formation by the pure cultures. In multispecies biofilms, compared with the other microorganisms, growth of Salmonella spp. was significantly lower for all tested incubation periods; whereas, of Staphylococcus aureus was significantly higher than that of E. coli until 8h of incubation; the differences in growth were not significantly different after this incubation period. Sanitizing with sodium hypochlorite was effective because no cell growth was observed in the coupons that were treated with 200ppm sodium hypochlorite for 10min. This study demonstrated the ability of isolated microorganisms to form biofilms, reinforcing the need for food handling establishments to adopt good manufacturing practices, developing adequate protocols for cleaning and disinfecting surfaces and equipment used in food production, maintaining and replacing equipment when necessary.(AU)

A população brasileira tem apresentado um elevado consumo de peixes, no entanto pescados são alimentos altamente perecíveis e podem ser contaminados por uma diversidade de microrganismos. A situação ainda é mais alarmante quando se trata da formação de biofilmes. Para verificação da formação de biofilme, as cepas foram testadas dentro de cultivos mono e multi-espécies a 25°C durante o tempo total de 48h, onde as análises foram realizadas no tempo 0 e nos intervalos de 4, 8, 24 e 48h em cupom de aço inoxidável medindo 1,0x1,0cm, imersos em caldo TSB (Tryptic Soy Broth).O comportamento dos biofilmes formados, diante da sanitização por imersão dos cupons em solução de hipoclorito de sódio a 200ppm por 10 minutos, também foi avaliado, nas mesmas condições citadas acima, com algumas particularidades. A avaliação estrutural foi procedida por microscopia de varredura eletrônica (MEV). Nos resultados de biofilmes mono-espécie, foi verificado que todas as cepas foram capazes de formar biofilme, nos diferentes tempos, sem diferenças estatisticamente significativas. Entretanto, comparando-se o crescimento de culturas mono e múltiplas espécies observou-se formação de biofilme, estatisticamente maior, entre as culturas puras. Nas culturas multi-espécies, Salmonella spp. apresentou crescimento, estatisticamente menor, em todos os tempos, entre os microrganismos testados, enquanto S. aureus apresentou maior crescimento que E. coli até 8 horas de incubação, deste tempo em diante a diferença não foi significativa. Quanto ao comportamento frente sanitização com hipoclorito, o sanitizante foi eficaz, uma vez que não foi observado crescimento celular nas análises dos cupons tratados com a solução de hipoclorito a 200ppm por 10 minutos.(AU)

Action of antimicrobial copper on bacteria and fungi isolated from commercial poultry hatcheries

Since 2008, when the US Environmental Protection Agency (EPA) registered copper and its alloys as an antimicrobial agent for contact surfaces, research has demonstrated their antimicrobial activity. The aim of this study was to evaluate the efficacy of antimicrobial copper against bacteria and fungi isolated from commercial poultry hatcheries in order to develop a microbiological control alternative in these environments. Samples were collected from the surfaces of hatcher baskets from two hatcheries. Mesophilic microorganisms and fungi/yeasts were isolated and standardized in concentration of 105 cells/mL. Four copper plates and four stainless steel plates were completely immersed for one minute in bacteria and fungi/yeasts solutions and left to dry for a day at room temperature. Subsequently, samples were collected from the metal plates with the aid of sterile swab and delimiter. These samples were planted onto Plate Count Agar (for mesophilic culture) and Sabouraud Dextrose Agar (for fungi and yeast culture) and incubated at 36°C for 48 hours and at 25°C for 5-7 days, respectively. After incubation, the colonies recovered from the plates were counted according to IN 62 of the Brazilian Ministry of Agriculture. Almost all contamination was eliminated from the surface of copper plates in a single day, while the stainless steel plates proved to be innocuous to the screened microorganisms. Copper, as a contact surface, proved to have important antimicrobial action on bacteria, fungi and yeasts common to hatcheries.

Action of antimicrobial copper on bacteria and fungi isolated from commercial poultry hatcheries

Since 2008, when the US Environmental Protection Agency (EPA) registered copper and its alloys as an antimicrobial agent for contact surfaces, research has demonstrated their antimicrobial activity. The aim of this study was to evaluate the efficacy of antimicrobial copper against bacteria and fungi isolated from commercial poultry hatcheries in order to develop a microbiological control alternative in these environments. Samples were collected from the surfaces of hatcher baskets from two hatcheries. Mesophilic microorganisms and fungi/yeasts were isolated and standardized in concentration of 105 cells/mL. Four copper plates and four stainless steel plates were completely immersed for one minute in bacteria and fungi/yeasts solutions and left to dry for a day at room temperature. Subsequently, samples were collected from the metal plates with the aid of sterile swab and delimiter. These samples were planted onto Plate Count Agar (for mesophilic culture) and Sabouraud Dextrose Agar (for fungi and yeast culture) and incubated at 36°C for 48 hours and at 25°C for 5-7 days, respectively. After incubation, the colonies recovered from the plates were counted according to IN 62 of the Brazilian Ministry of Agriculture. Almost all contamination was eliminated from the surface of copper plates in a single day, while the stainless steel plates proved to be innocuous to the screened microorganisms. Copper, as a contact surface, proved to have important antimicrobial action on bacteria, fungi and yeasts common to hatcheries.(AU)

Sanitizer resistance of biofilm-forming Salmonellaisolated from meat products / Resistência de Salmonella formadora de biofilme isolada de produtos cárneos a sanitizantes

Este estudo avaliou a capacidade de Salmonella enterica subsp. enterica isolada de produtos cárneos formar biofilme e testou sua resistência a diferentes sanitizantes. Vinte cepas foram avaliadas quanto à capacidade de formar biofilme em placas de microtitulação. As cepas formadoras de biofilme foram testadas em superfícies de polietileno de alta densidade, aço inoxidável e vidro e tiveram a sensibilidade ao hipoclorito de sódio e ao iodo avaliada. Duas cepas de Salmonella Enteritidis isoladas de produtos de frango apresentaram capacidade de formar biofilme nas superfícies testadas. Essas cepas alcançaram maiores populações nas superfícies do que aquelas não formadoras de biofilme, e foram mais difíceis de remover ou reduzir. Devido à ação sanitizante ser menos eficiente sobre bactérias formadoras de biofilme, esses micro-organismos podem persistir no biofilme formado sobre as superfícies de equipamentos e utensílios e ocasionalmente contaminar os alimentos antes da sua expedição, aumentando dessa forma o risco de ocorrência de doenças transmitidas por alimentos.(AU)

Sanitizer resistance of biofilm-forming Salmonellaisolated from meat products / Resistência de Salmonella formadora de biofilme isolada de produtos cárneos a sanitizantes

Este estudo avaliou a capacidade de Salmonella enterica subsp. enterica isolada de produtos cárneos formar biofilme e testou sua resistência a diferentes sanitizantes. Vinte cepas foram avaliadas quanto à capacidade de formar biofilme em placas de microtitulação. As cepas formadoras de biofilme foram testadas em superfícies de polietileno de alta densidade, aço inoxidável e vidro e tiveram a sensibilidade ao hipoclorito de sódio e ao iodo avaliada. Duas cepas de Salmonella Enteritidis isoladas de produtos de frango apresentaram capacidade de formar biofilme nas superfícies testadas. Essas cepas alcançaram maiores populações nas superfícies do que aquelas não formadoras de biofilme, e foram mais difíceis de remover ou reduzir. Devido à ação sanitizante ser menos eficiente sobre bactérias formadoras de biofilme, esses micro-organismos podem persistir no biofilme formado sobre as superfícies de equipamentos e utensílios e ocasionalmente contaminar os alimentos antes da sua expedição, aumentando dessa forma o risco de ocorrência de doenças transmitidas por alimentos.(AU)

Biofilm formation of Shiga toxin-producing Escherichia coli O153 H25, O113 H21 and O111 H8 on the stainless steel surface and the effectiveness of sanitizer / Formação de biofilmes de Escherichia coli produtora de toxina Shiga sorotipos O153 H25, O113 H21 e O111 H8 em superfície de aço inoxidável e eficácia de sanitizante

This study aimed at evaluating the biofilm formation of Shiga toxin-producing Escherichia coli O153:H25, O113:H21 and O111:H8 (STEC non-O157), isolated from Brazilian cattle, on the stainless steel surface, and also the efficacy of different s concentrations of sodium hypochlorite for inactivating these biofilms. The ability to form biofilm was demonstrated in all of Shiga toxin-producing E. coli strains. In assessing the effectiveness of sodium hypochlorite sanitizer, a reduction to 1 log CFU/cm2 was observed in all of the evaluated strains and times. These data strengthen the relevance of the correct cleaning procedure, considering that biofilms formations might be an important source of food contamination(AU)

Neste estudo as cepas de Escherichia coli produtora de toxina Shiga (STEC) O153:H25, O113:H21 e O111:H8, isoladas de rebanhos do país, foram avaliadas quanto à capacidade de formar biofilmes em superfície de aço inoxidável utilizada na indústria de alimentos, bem como a eficácia de diferentes concentrações de hipoclorito de sódio na inativação desses biofilmes. A capacidade de formação de biofilme foi detectada em todas as cepas de E. coli produtoras de toxina Shiga. Na avaliação da eficácia do sanitizante hipoclorito de sódio, nas concentrações de 100 mg.L-1 e 200 mg.L-1, observou-se a redução a 1 log UFC/cm2 em todas as cepas e nos tempos avaliados. Estes dados reforçam a importância do correto procedimento de higienização, uma vez que biofilmes podem tornar-se importantes fontes de contaminação no ambiente de produção de alimentos(AU)

Biological activities of a mixture of biosurfactant from Bacillus subtilis and alkaline lipase from Fusarium oxysporum

In this study, we investigate the antimicrobial effects of a mixture of a biosurfactant from Bacillus subtilis and an alkaline lipase from Fusarium oxysporum (AL/BS mix) on several types of microorganisms, as well as their abilities to remove Listeria innocua ATCC 33093 biofilm from stainless steel coupons. The AL/BS mix had a surface tension of around 30 mN.m-1, indicating that the presence of alkaline lipase did not interfere in the surface activity properties of the tensoactive component. The antimicrobial activity of the AL/BS mix was determined by minimum inhibitory concentration (MIC) micro-assays. Among all the tested organisms, the presence of the mixture only affected the growth of B. subtilis CCT 2576, B. cereus ATCC 10876 and L. innocua. The most sensitive microorganism was B. cereus (MIC 0.013 mg.mL-1). In addition, the effect of the sanitizer against L. innocua attached to stainless steel coupons was determined by plate count after vortexing. The results showed that the presence of the AL/BS mix improved the removal of adhered cells relative to treatment done without the sanitizer, reducing the count of viable cells by 1.72 log CFU.cm-2. However, there was no significant difference between the sanitizers tested and an SDS detergent standard (p 0.05).

Adhesion and biocides inactivation of Salmonella on stainless steel and polyethylene

The adhesion of Salmonella (S.) strains to stainless steel and polyethylene and their inactivation by biocides used in food industry was investigated. Coupons of stainless steel and polyethylene were immersed in bacterial suspensions of S. Enteritidis, S. Typhimurium, and S. Bredeney during 15, 30, and 60 minutes, and submitted to different concentrations of peracetic acid (PAA), sodium hypochlorite (NaOCl), and quaternary ammonium (Quat) sanitizers. Hydrophobicity of the surfaces was evaluated by contact angle measurements using the sessile drop method and bacterial adhesion was accompanied through bacterial counts and scanning electron microscopy (SEM). Results indicated that the three serovars of Salmonella presented similar adhesion to both materials (5.0 to 6.5 log cfu cm-2). The time of exposure did not influence the counts of adhered cells on both surfaces, however SEM revealed larger clusters of S. Enteritidis on both materials, not found for the other serovars. S. Enteritidis presented lower sessile drop angle on polyethylene, indicating hydrophilic properties of this material. The biocides were not able to inactivate all the microorganisms adhered on both surfaces. At least 1 log cfu cm-2 of all serovars tested remained viable after the exposure to different biocide concentrations. In general, higher counts of survivors were observed on polyethylene disinfected with different concentrations of biocides. S. Bredeney e S. Typhimurium were more resistant than S. Enteritidis to PAA, whilst S. Enteritidis presented smaller reduction rates to NaOCl. This last biocide was able to reduce Salmonella counts in approximately 3.0 to 4.0 log cm-2. When adhered to polyethylene, the serovars S. Typhimurium and S. Enteritidis were more resistant to Quat than S. Bredeney in all concentrations tested, and the numbers of S. Enteritidis remained almost unaltered. On stainless steel disinfected by Quat, S. Bredeney presented higher numbers of survivors.

Formation of biofilms by Staphylococcus aureus on stainless steel and glass surfaces and its resistance to some selected chemical sanitizers

The objectives of this work were to verify the capability of Staphylococcus aureus of forming bio-film on stainless steel and glass surfaces; to evaluate the efficiency of sodium dichloroisocyanurate, hydrogen peroxide and peracetic acid in inactivating Staphylococcus aureus cells adhered onto these surfaces; and to visualize biofilm development by scanning electron microscopy before and after sanitizer treatment. The surfaces studied consisted of 10x20mm chips immersed in Petri dishes containing BHI broth inoculated with S. aureus ATCC 25923. Biofilm formation was observed after 15-day incubation, when the cells were removed using the swab technique, followed by Baird Parker agar plating. Also, the efficiency of the chemical sanitizers on the chip surfaces was tested and the non-removed cells were counted on the Baird-Parker agar. After biofilm formation and use of sanitizers, the chips were respectively observed by scanning electronic microscopy following a pre-existing protocol. The obtained results showed biofilm formation on both surfaces, with bacterial count in the order of 10(7) CFU/cm² on and 10(8) CFU/cm² on stainless steel and glass surfaces, respectively. Peracetic acid was the most efficient in removing adhered cells, presenting 5.26 and 4.5 decimal reduction for adhered cells on stainless steel and glass surfaces, respectively.

Os objetivos deste trabalho foram verificar a capacidade de Staphylococcus aureus formar biofilme nas superfícies de aço inoxidável e vidro, avaliar a eficiência do dicloroisocianurato de sódio, peróxido de hidrogênio e ácido peracético na inativação de células de S. aureus aderidas e visualização por microscopia eletrônica de varredura, o desenvolvimento antes e depois do tratamento das superfícies com os sanificantes. As superfícies foram cupons 10x200mm imersos em placas de Petri contendo caldo BHI inoculado com cultura de Staphylococcus aureus ATCC 25923. A formação de biofilme foi observada após 15 dias de incubação, quando as células foram removidas pela técnica do suabe, seguiram-se diluições seriadas e plaqueamento em ágar Baird Parker. Testou-se a eficiência dos sanificantes nas superfícies dos cupons e as células não removidas foram enumeradas no ágar Baird Parker. Os cupons após formação do biofilme e cupons sanificados foram observados pela microscopia eletrônica de varredura seguindo um protocolo. Os resultados obtidos indicaram a formação de biofilme em ambas superfícies, com contagens bacterianas na ordem de 10(7) UFC/cm² e 10(8) UFC/cm² nas superfícies de aço inoxidável e vidro, respectivamente. Dentre os sanificantes estudados o ácido peracético apresentou uma eficiência maior na remoção das células aderidas, apresentado redução decimal de 5,26 e 4,5 para as células aderidas na superfície de vidro e aço inoxidável.

Digital morphometric analysis of the aortic wall in pigs following implantation of dacron-covered stents versus non-covered stents

PURPOSE: To evaluate, by digital morphometry, the intimal thickening after the placement of two different kinds of stents: polyester covered stainless steel stents (Dacron) and non-covered stents implanted in young pigs' infrarenal aortas. METHODS: The experiment was carried out on two separate groups of pigs. Eight polyester-covered stainless steel stents (Dacron) and eight stainless steel stents (30-mm long, 8-mm diameter) were deployed through extraperitoneal approach in the normal infrarenal aorta of 16 normolipemic pigs. To allow the passage of the delivery system, a small arteriotomy was performed (phase I). After four weeks, the aorta with the stent was removed en bloc. (phase II). The values of the hematimetric and lipid analysis did not show any changes that could influence the study. Tissue samples of the fixing sites (proximal and distal) of the stents were taken. Microscope slices were prepared and submitted to Verhoeff's hematoxilin and eosin techniques and sent to morphometric analysis. RESULTS: The intima immediately proximal to the device was thicker in the group of covered stents with marginal significance (p=0.054). The distal intimal layer (p=0.185), proximal medial layer of the proximal portion (p=0.141) and distal portion (p=0.375) did not present statistical difference between the two groups. CONCLUSIONS: Patency was 100% in both groups of these normolipemic pigs. After four weeks the intimal layer immediately proximal to the covered stents was ticker when compared to uncovered stents, but this had a borderline significance. The intimal layer distal to covered stents and the media proximal or distal to the devices had similar morphometric features when covered and uncovered stents where compared.

OBJETIVO: Avaliar através de morfometria digital o espessamento intimal após o implante de dois tipos de stents de aço inoxidável, um recoberto com poliéster (dacron) e outro não recoberto, implantados na aorta infra-renal de suínos jovens. MÉTODOS: O experimento foi realizado em dois grupos (stents não revestidos e revestidos com dacron) e duas fases (I e II). Oito stents recobertos com dacron e oito stents de aço inoxidável (30mm de extensão e 8 mm de diâmetro), não revestidos, foram implantados através de abordagem retroperitoneal na aorta infrarenal normal de 16 suínos normolipêmicos. Para a passagem do sistema de implante, foi necessário uma pequena arteriotomia na aorta distal (fase I). Após quatro semanas, a aorta com os stents foram removidas em monoblocos (fase II). Os valores de hematimetria e do lipidograma foram coletados nas duas fases e não apresentaram alterações que pudessem influenciar o estudo. Amostras de tecido dos sítios de fixação (proximal e distal) dos stents foram retiradas, confeccionadas lâminas, que foram coradas pelas técnicas de hematoxilina e eosina e de Verhoeff e enviadas para análise morfométrica digital. RESULTADOS: A camada íntima proximal ao stent apresentou maior espessamento intimal no grupo de stents recobertos, mas com significância limítrofe(p=0.054). A camada íntima distal(p=0.185), a camada média das regiões proximal(p=0.141) e da porção distal (p=0.375) ao stent não apresentaram diferença entre os grupos. CONCLUSÕES: Os dois tipos de stents apresentaram 100% de perviedade, boa biocompatibilidade e boa incorporação a parede aórtica de suínos normolipêmicos. A camada íntima proximal do grupo de stents revestidos com dacron apresentou maior espessamentodo que os stents não revestidos, mas com significância estatísitica limítrofe.

Placas de aço inoxidável 316L aplicadas no reparo de fratura experimental diafisária do rádio e ulna de cães / Reparing radial and ulnar diaphysial experimental fracture of dogs employing stainless steel plates 316L

O objetivo do presente trabalho foi o de estudar a resistência à corrosão em placas de aço inoxidável 3l6L, com diferentes tipos de acabamento e tratamento superficial, e a possível interferência dessa reação corrosiva na consolidação óssea. Utilizaram-se placas semi-acabadas, polidas, tratadas com jatos de microesferas de vidro e passivadas, as quais foram aplicadas na epífise distal do rádio de cães. Foram utilizados 12 animais, divididos em dois grupos, nos quais, após osteotomia bilateral do rádio e ulna, foram realizadas osteossínteses do rádio, totalizando 24 procedimentos. Avaliou-se a evolução clínica e radiográfica das regiões que receberam os implantes aos 30, 60, 90, 180, 240 e 360 dias. Os animais do grupo 1 (GI) foram sacrificados aos 180 dias e os do GII aos 360 dias para estudo histológico e de microscopia eletrônica de varredura do local da osteotomia sob a região dos implantes metálicos e para estudo da resistência à corrosão no organismo, pelos implantes metálicos, por meio de análises química e metalográfica (microscopia óptica e eletrônica de varredura e espectroscopia de espalhamento de energia por raios X). Os animais recuperaram a função dos membros operados 24 horas após a cirurgia. Radiograficamente, verificou-se a consolidação óssea em todos os animais. Macro e microscopicamente não foram observados sinais de corrosão nos implantes metálicos, exceto em uma placa passivada, aplicada no rádio esquerdo de um animal, na qual a corrosão foi detectada pela microscopia óptica e eletrônica de varredura. Este estudo permite concluir que as placas de aço inoxidável 3l6L, independente do acabamento superficial a que foram submetidas, não sofreram corrosão ou reações adversas e foram efetivas no tratamento das fraturas experimentais do rádio e ulna de cães (AU)

A long-term study was carried out for evaluating 316L stainless steel plates with different types of finish used in the repair of experimetnal radial and ulnar dyaphisial fractures in dogs and the possible interference of this reaction in bone consolidation. Semi-finished, polished, blasted with glass microbeads and passivated plates were applied to the distal epiphysis of the radius of anesthetized dogs. Twelve animals were divided into two groups, GI (six dogs) and GII (six dogs), which underwent osteosynthesis (OS) in both bones, after bilateral radial and ulnar osteotomy, totaling 24 procedures. The clinical and radiographic evolution of the regions that received the implant was studied at 30, 60, 90, 180, 240 and 360 days after OS. The animals from GI were killed at 180 days and those from GII at 360 days for histopathological analysis of the bones at the implant region (optical and electronic-scanning microscopy) and to study corrosion on the metallic implants, through chemical and metallographic analysis (optical and eletronic-scanning microscopy and scattered-energy spectroscopy). Limb function was recovered 24h after surgery. Upon X-ray examination, bone consolidation was observed in all animals. Both in macroscopic and microscopically, no signs of metallic corrosion were observed, except for one passivated plate implanted in one animal of GII, in which the phenomenon was observed through optical and electronic-scanning microscopy. This study allows to conclude that 316L stainless steel plates, regardless of the surface treatment, did not undergo corrosion or adverse reactions and were effective in the treatment of experimental radial and ulnar fractures in dogs.(AU)

Action of peracetic acid on Escherichia coli and Staphylococcus aureus in suspension or settled on stainless steel surfaces

The efficiency of a commercial peracetic acid sanitizer on destruction of Staphylococcus aureus and Escherichia coli was evaluated using two distinct methods. The first method is the AOAC suspension test and the second is a method proposed by one of the authors in which the microbial cells are settled on a stainless steel surface and then treated with the sanitizer. The results showed that when in suspension S. aureus was more resistant to the sanitizer than E. coli. When S. aureus was settled on the stainless steel surface, the contact time between the sanitizer and the microorganisms to attain a 6.5 log reduction in the number of viable cells was three times greater than when the cells were in suspension.

A eficiência de um sanificante comercial à base de ácido peracético na destruição de Staphylococcus aureus e Escherichia coli foi avaliada apregando-se dois métodos distintos. O primeiro corresponde ao método da suspensão da AOAC e o segundo ao método desenvolvido por um dos autores, no qual a eficiência de sanificantes é avaliada em culturas microbianas aplicadas à uma superfície de aço inoxidável com o mesmo grau de acabamento das superfícies encontradas nas indústrias de alimentos. Os resultados indicaram que S. aureus foi mais resistente ao sanificante que E. coli, quando em suspensão. Quando S. aureus encontrava-se sedimentando sobre uma superfície de aço inoxidável, o tempo de contato entre sanificante e microrganismos para reduzir a população 6,5 ciclos logaritmos foi 3 vezes maior do que quando esses microrganismos estavam em suspensão.