RESUMO

The objective of this study was to assess the effect of a selective antibiotic treatment strategy based on a quick bacteriological on-farm test (Petrifilm, 3M Corp., St. Paul, MN) compared with the conventional antibiotic treatment of all cows having clinical endometritis (CE) defined by the presence of purulent vaginal discharge on both clinical cure rate and reproductive performance. The study was simultaneously conducted with dairy cows reared under a highly supplemented rotational grazing system in Argentina and in a freestall system in Slovakia. Cows having an abnormal vaginal discharge (VD, indicative of clinical endometritis) on 21 to 35 d in milk (DIM) were randomly allocated to 1 of 2 study groups: selective treatment (ST) or conventional treatment (CT). All cows in the CT group (n = 174) received a single intrauterine administration of 500 mg of cephapirin. In the ST group (n = 178), treatment decision was made according to the results of the bacteriological on-farm test. For this test, we collected intrauterine samples with the cytobrush technique and stroke the brushes onto 2 different Petrifilm plates, one for aerobic count and another for Enterobacteriaceae count, incubated the plates, and counted the number of colonies after 24 h. Positive cows (≥5 colonies in one or both plates) received a single intrauterine treatment with 500 mg of cephapirin, whereas negative cows (<5 colonies) remained untreated. Clinical cure rate was assessed by direct vaginal inspection at 14 d after treatment (VD-0). The odds for conception at first artificial insemination, artificial insemination by 80 DIM, pregnancy by 100 DIM, and for nonpregnancy by 200 DIM were estimated with mixed logistic regression models. The hazard of conception was also assessed with proportional hazard regression model. The selective antibiotic treatment strategy based on the outcome of Petrifilm test reduced the number of required treatments (57%) and maintained similar efficacy in terms of clinical cure and reproductive performance as the conventional antibiotic treatment of all endometritic cows.

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RESUMO

The present study aimed to assess the performance of alternative protocols to enumerate lactic acid bacteria (LAB) in salami. Fourteen cultures and two mixed starter cultures were plated using six protocols: 1) Petrifilm™ Aerobic Count (AC) with MRS broth and chlorophenol red (CR), incubated under aerobiosis or 2) under anaerobiosis, 3) MRS agar with CR, 4) MRS agar with bromocresol purple, 5) MRS agar at pH5.7, and 6) All Purpose Tween agar. Samples of salami were obtained and the LAB microbiota was enumerated by plating according protocols 1, 2, 3 and 5. Regression analysis showed a significant correlation between the tested protocols, based on culture counts (p<0.05). Similar results were observed for salami, and no significant differences of mean LAB counts between selected protocols (ANOVA, p>0.05). Colonies were confirmed as LAB, indicating proper selectivity of the protocols. The results showed the adequacy of Petrifilm™ AC supplemented with CR for the enumeration of LAB in salami.

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Os métodos microbiológicos alternativos apresentam vantagens sobre os ensaios convencionais, no entanto é preciso confirmar sua eficácia. O presente trabalho avaliou o sistema Petrifilm™ HS com o sistema Petrifilm™ EC, em comparação com a metodologia convencional na contagem de coliformes a 35 ºC em leite pasteurizado. Altas correlações foram encontradas entre as metodologias utilizadas para efetuar a contagem de coliformes a 35 ºC. O sistema Petrifilm™ HS para contagem de coliformes a 35 ºCem leite pasteurizado mostrou resultados satisfatórios...

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RESUMO

Monitoring the populations of probiotic strains of the species Lactobacillus casei in food is required by food industries in order to assure that a minimum concentration of these organisms will be ingested by consumers. In this context, Petrifilm™ AC plates can be used along with selective culture media to allow the enumeration of specific groups of lactic acid bacteria. The present study aimed to assess chemical substances as selective agents for Lb. casei in order to propose a selective culture medium to be used with Petrifilm™ AC plates as an alternative protocol for the enumeration of probiotic strains of this species in fermented milk. Twenty-six probiotic and starter cultures (including six strains of Lb. casei) were plated on de Man Rogosa and Sharpe (MRS) agar with distinct concentrations of nalidixic acid, bile, lithium chloride, metronidazole, sodium propionate, and vancomycin. Vancomycin at 10 mg/L demonstrated selective activity for Lb. casei. In addition, 2,3,5-triphenyltetrazolium chlorine was identified as a compound that did not inhibit Lb. casei, and Petrifilm™ AC plates used with MRS and vancomycin at 10 mg/L (MRS-V) demonstrated more colonies of this organism when incubated under anaerobic conditions than aerobic conditions. Acidophilus milk and yoghurt were prepared, added to Lb. casei strains, and stored at 4 °C. Lb. casei populations were monitored using MRS-V and MRTLV by conventional plating and associated with Petrifilm™ AC plates. All correlation indices between counts obtained by conventional plating and Petrifilm™ AC were significant (p < 0.05), but the best performance was observed for growth on MRS-V. The obtained data indicate the efficiency of using MRS-V associated with Petrifilm™ AC plates for the enumeration of Lb. casei strains in fermented milk. However, the selective potential of this culture medium must be evaluated considering the specific strains of Lb. casei and the starter cultures inoculated in the fermented milk that requires monitoring.

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RESUMO

This study aimed to develop a selective culture media to enumerate bifidobacteria in fermented milk and to assess this medium when used with Petrifilm™ AC plates. For this purpose, Bifidobacterium spp., Lactobacillus spp. and Streptococcus thermophilus strains were tested to verify their fermentation patterns for different carbohydrates. All bifidobacteria strains were able to use raffinose. Based on these characteristic, a selective culture medium was proposed (Raffinose-Propionate Lithium Mupirocin, RP-MUP), used with Petrifilm™ AC plates, and was used to enumerate bifidobacteria in fermented milk. RP-MUP performance was assessed by comparing the results with this medium to reference protocols and culture media for bifidobacteria enumeration. RP-MUP, whether used or not with Petrifilm™ AC, presented similar performance to TOS-MUP (ISO 29981), with no significant differences between the mean bifidobacteria counts (p < 0.05) and with high correlation indices (r = 0.99, p < 0.05). As an advantage, reliable results were obtained after just 48 h of incubation when RP-MUP was used with Petrifilm™ AC, instead of the 72 h described in the ISO 29981 protocol.

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Rapid techniques for microbiological analysis of foods show advantages when compared with the conventional methods, as the former are easy-to-performer and no time-consuming assays in getting the results. The aim of this study was to compare the performance of the rapid techniques Petrifilm® EC and Compact dry® EC and CF with the standard method for counting the coliform group in bovine raw minced meat samples. The performances of rapid tests were compared for quantifying Escherichia coli at 35C and 45C. Simple regression analysis of data showed a strong correlation between Petrifilm® and Compact dry® for determining the number of coliforms, as well as for quantifying E. coli. However, when the results of E. coli counting at 35ºC and 45C by means of the same technique were compared, the correlation factors were lower. This analysis suggests that rapid techniques are suitable to be employed as alternative techniques for microorganisms counting in raw minced meat.

Os métodos rápidos de análise microbiológica de alimentos apresentam vantagens sobre os ensaios convencionais no que se refere à simplificação do trabalho no laboratório e à redução de tempo na obtenção de resultados. O objetivo deste estudo foi de comparar os testes rápidos Petrifilm® EC e Compact dry® EC e CF com a técnica de análise convencional realizada em placas na enumeração de coliformes totais e coliformes termotolerantes em amostras de carne moída bovina e avaliar as metodologias alternativas para quantificação de Escherichia coli nas temperaturas de 35ºC e 45ºC. A análise de regressão linear dos dados mostrou alta correlação entre as contagens de coliformes totais e coliformes termotolerantes (R2>0,9). A correlação entre as contagens de Escherichia coli em Petrifilm® e Compact dry® foi também positiva e significativa (R2>0,9). Todavia, quando foi feita a comparação entre os resultados da enumeração de E. coli a temperaturas de 35ºC e 45ºC, houve decréscimo no coeficiente de correlação em ambos os sistemas (R2 0,9). Considerando-se que os métodos rápidos e a metodologia convencional para contagem de coliformes mostraram-se equivalentes, os resultados sugerem a aplicabilidade dos sistemas Petrifilm® e Compact dry® como técnicas alternativas ao método convencional de plaqueamento.

RESUMO

A contagem de bolores e leveduras nos alimentos é indicativa de falhas higiênicas ao longo do processamento ou matérias-primas de má qualidade. Nos alimentos desidratados, os fungos xerofílicos representam os principais microrganismos responsáveis de multiplicação. Diversas técnicas e meios de cultura tem sido utilizados para a sua enumeração para alimentos com baixa atividade de água. Dez amostras de diferentes alimentos foram divididas em 5 subamostras cada, totalizando 50 amostras. Os seguintes tratamentos foram avaliados: Petrifilm (controle), Petrifilm (com dicloran) e DG-18 (controle). Os resultados da análise estatística permitem concluir que não há diferença significativa, ao nível de 5 por cento, entre os tratamentos avaliados. A ocorrência de colônias espalhadas parece não estar associada a um tipo de alimento, mas às amostras de um determinado alimento. Ao se usar altas diluições, as colônias espalhadas não estiveram comumente presentes, não afetando, portanto, a contagem no Petrifilm Bolores e Leveduras.

The yeast and mold enumeration of foods is indicative of poor hygienical conditions in the processing or raw materials of bad quality. In dehydrated foods, the xerophilic fungi are the major responsible of deterioration. Several techniques and culture media have been used for its enumeration, being agar DG-18 recommended for foods with low water activity. Ten differents food samples were divided into five subsamples, totalizing 50 samples. The following treatments were evaluaied: PetrifiIm (control), PetrifiIm (with dicloran) and DG-18 (control). The results of the statistical analysis allow to conclude that it does not have significant difference to the 5% level between the evaluated treatments. The occurrence of spread colonies, seems not to be associated to a type of food, but with samples of one determined food. When high dilutions were used, spread colonies weren't present, not affecting, therefore, the Petrifilm Yeast and Mold counts.

Assuntos

RESUMO

A contagem de bolores e leveduras nos alimentos é indicativa de falhas higiênicas ao longo do processamento ou matérias-primas de má qualidade. Nos alimentos desidratados, os fungos xerofílicos representam os principais microrganismos responsáveis de multiplicação. Diversas técnicas e meios de cultura tem sido utilizados para a sua enumeração para alimentos com baixa atividade de água. Dez amostras de diferentes alimentos foram divididas em 5 subamostras cada, totalizando 50 amostras. Os seguintes tratamentos foram avaliados: Petrifilm (controle), Petrifilm (com dicloran) e DG-18 (controle). Os resultados da análise estatística permitem concluir que não há diferença significativa, ao nível de 5 por cento, entre os tratamentos avaliados. A ocorrência de colônias espalhadas parece não estar associada a um tipo de alimento, mas às amostras de um determinado alimento. Ao se usar altas diluições, as colônias espalhadas não estiveram comumente presentes, não afetando, portanto, a contagem no Petrifilm Bolores e Leveduras.(AU)

The yeast and mold enumeration of foods is indicative of poor hygienical conditions in the processing or raw materials of bad quality. In dehydrated foods, the xerophilic fungi are the major responsible of deterioration. Several techniques and culture media have been used for its enumeration, being agar DG-18 recommended for foods with low water activity. Ten differents food samples were divided into five subsamples, totalizing 50 samples. The following treatments were evaluaied: PetrifiIm (control), PetrifiIm (with dicloran) and DG-18 (control). The results of the statistical analysis allow to conclude that it does not have significant difference to the 5% level between the evaluated treatments. The occurrence of spread colonies, seems not to be associated to a type of food, but with samples of one determined food. When high dilutions were used, spread colonies weren't present, not affecting, therefore, the Petrifilm Yeast and Mold counts. (AU)

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RESUMO

Alternative techniques to agar plating methods for enumerating of bacteria and fungi counting have been developed, in order to get faster and simpler techniques without producing any effect on analytical sensibility and precision. The objective of the present study was evaluate the performance of Petrifilm® AC for enumeration of bacteria and of Petrifilm® YM for enumeration of yeasts and molds in ninety samples of herbal drugs, by comparing the enumeration obtained from both Petrifilm® systems, and that one achieved from conventional agar plating methods. Correlation coefficients of 0,9833 and 0,9231 were observed for enumeration of bacteria and fungi respectively. The results suggest that Petrifilm® is suitable as an alternative technique to conventional methods for microorganisms counting.

Técnicas alternativas aos métodos de plaqueamento em ágar para enumeração de bactérias e fungos têm sido desenvolvidas, buscando-se rapidez e simplicidade, mas sem comprometimento da sensibilidade e exatidão. O objetivo deste estudo foi investigar a eficácia e aplicabilidade de Petrifilm®AC para a enumeração de bactérias e de Petrifilm® YM para enumeração de bolores e leveduras em 90 amostras de drogas vegetais, comparando-se as contagens obtidas com a utilização dos sistemas Petrifilm® com àquelas obtidas com as técnicas de semeadura em profundidade em meios de cultura. Os coeficientes de correlação obtidos foram 0,9833 e 0,9231 para as contagens de bactérias e fungos, respectivamente. As contagens obtidas não mostraram diferenças significativas entre os métodos empregados. Os resultados sugerem a aplicabilidade do sistema Petrifilm® como alternativa ao método convencional de plaqueamento.

RESUMO

Petrifilm™ EC and HS were compared to the MPN method to determine their efficacy to enumerate total coliforms and E. coli in 145 samples of water (76 water in natura, 69 drinking water). For water in natura, Petrifilm™ HS and EC showed good correlation with MPN method. In chlorinated water ( 20 col/100 mL and negatives) the agreement was low. For E.coli enumeration, Petrifilm™ EC showed a good correlation with MPN method. The results indicated that Petrifilm™ EC and HS are accurate to enumerate coliforms and E. coli in water when the expected counts are higher than 20/100 mL.

Petrifilm™ EC e HS foram comparados ao método do Número Mais Provável (NMP) para determinar sua eficiência na enumeração de coliformes totais e E. coli em 145 amostras de água (76 de água in natura e 69 de água de abastecimento). Em água in natura, Petrifilm™ HS e EC mostraram boa correlação com o método de NMP. Em água clorada ( 20 col/100 mL e negativas) a concordância foi baixa. Para enumeração de E. coli, Petrifilm™ EC mostrou boa correlação com o método de NMP. Os resultados indicaram que Petrifilm™ EC e HS podem ser usados com segurança para enumeração de coliformes totais e E. coli em água, desde que as contagens esperadas sejam maiores que 20/100 mL.