Diagnosis of blackleg from cattle tissue impregnated in common filter paper / Diagnóstico de carbúnculo sintomático a partir de papel filtro comum impregnado com tecido bovino

Blackleg, an acute myonecrosis caused by Clostridium chauvoei, is usually underdiagnosed since the rapid transport of adequate samples for laboratory testing is difficult. This study tested a direct polymerase chain reaction (PCR) technique using common filter paper impregnated with cattle tissue samples obtained from animals suspected with blackleg. Twenty-five samples, belonging to eleven animals from Rio Grande do Sul State, Brazil, were analyzed. The direct PCR technique identified eight positive animals corroborating with results from microbiological culture. Skeletal muscle was the most common tissue type used in this study and when the animal was positive the pathogen was always detected in this tissue. Storage time of the impregnated filter paper at room temperature did not prove to be a limiting factor for the quality of the results indicating that this procedure can be carried out in the field and samples be sent in regular mail. Our results suggested that direct PCR of common filter paper impregnated with cattle tissue is a practical and economical alternative for the diagnosis of blackleg.

Carbúnculo sintomático, uma mionecrose aguda causada por Clostridium chauvoei, costuma ser subdiagnosticada, pois o transporte rápido de amostras adequadas para exames laboratoriais é complicado. O objetivo deste estudo foi testar a técnica de reação em cadeia da polimerase (PCR) direta, utilizando papel filtro comum impregnado com amostras de tecido bovino obtidas de animais suspeitos de carbúnculo sintomático. Foram analisadas 25 amostras, pertencentes a onze animais do estado do Rio Grande do Sul, Brasil. A técnica de PCR direta identificou oito animais positivos, corroborando com os resultados da cultura microbiológica. O músculo esquelético foi o tecido mais utilizado neste estudo e quando o animal foi positivo, o patógeno sempre foi detectado neste tecido. O tempo de armazenamento do papel filtro impregnado, à temperatura ambiente, não se mostrou um fator limitante para a qualidade dos resultados, indicando que esse procedimento pode ser realizado no local e as amostras enviadas por correio normal. Nossos resultados sugerem que a PCR direta usando papel filtro comum impregnado com tecido bovino é uma alternativa prática e econômica para o diagnóstico de carbúnculo sintomático.

Diagnosis of blackleg from cattle tissue impregnated in common filter paper / Diagnóstico de carbúnculo sintomático a partir de papel filtro comum impregnado com tecido bovino

Blackleg, an acute myonecrosis caused by Clostridium chauvoei, is usually underdiagnosed since the rapid transport of adequate samples for laboratory testing is difficult. This study tested a direct polymerase chain reaction (PCR) technique using common filter paper impregnated with cattle tissue samples obtained from animals suspected with blackleg. Twenty-five samples, belonging to eleven animals from Rio Grande do Sul State, Brazil, were analyzed. The direct PCR technique identified eight positive animals corroborating with results from microbiological culture. Skeletal muscle was the most common tissue type used in this study and when the animal was positive the pathogen was always detected in this tissue. Storage time of the impregnated filter paper at room temperature did not prove to be a limiting factor for the quality of the results indicating that this procedure can be carried out in the field and samples be sent in regular mail. Our results suggested that direct PCR of common filter paper impregnated with cattle tissue is a practical and economical alternative for the diagnosis of blackleg.(AU)

Carbúnculo sintomático, uma mionecrose aguda causada por Clostridium chauvoei, costuma ser subdiagnosticada, pois o transporte rápido de amostras adequadas para exames laboratoriais é complicado. O objetivo deste estudo foi testar a técnica de reação em cadeia da polimerase (PCR) direta, utilizando papel filtro comum impregnado com amostras de tecido bovino obtidas de animais suspeitos de carbúnculo sintomático. Foram analisadas 25 amostras, pertencentes a onze animais do estado do Rio Grande do Sul, Brasil. A técnica de PCR direta identificou oito animais positivos, corroborando com os resultados da cultura microbiológica. O músculo esquelético foi o tecido mais utilizado neste estudo e quando o animal foi positivo, o patógeno sempre foi detectado neste tecido. O tempo de armazenamento do papel filtro impregnado, à temperatura ambiente, não se mostrou um fator limitante para a qualidade dos resultados, indicando que esse procedimento pode ser realizado no local e as amostras enviadas por correio normal. Nossos resultados sugerem que a PCR direta usando papel filtro comum impregnado com tecido bovino é uma alternativa prática e econômica para o diagnóstico de carbúnculo sintomático.(AU)

Molecular identification of Clostridium chauvoei from common filter paper

Background: Blackleg is an acute and often fatal infection in bovine caused by the bacterium Clostridium chauvoei. The absence of conclusive diagnosis of blackleg usually occurs due to absence of practical and economical methods to send samples to microbiology laboratory. The goal of this work was to verify the possibility of using ordinary filter paper as a practical and economically feasible method for collecting, storing and shipping material to the laboratory to be used in a rapid and direct PCR approach to detect Clostridium chauvoei DNA. Materials, Methods & Results: The PCR technique for the diagnosis of blackleg from common filter paper was tested for specificity, sensitivity and feasibility. To test the specificity, the papers were impregnated with a suspension of the following microorganisms: C. chauvoei, C. perfringens, C. septicum, Bacillus anthracis, Staphylococcus aureus, and Escherichia coli. To test the sensitivity different concentration of C. chauvoei (ATCC 10092) were pipetted on common filter paper. To both test, DNA extraction of impregnated ordinary filter paper and their respective controls followed the method previously described and tested under different storage times (0 h, 24 h, 72 h and a week later). To test the feasibility, 12 bovine livers were collected and tissues samples were impregnate on common filter paper with suspension of C. chauvoei. The filter paper was stored for 48 h, 72 h and one week. Subsequently, a rapid and direct PCR approach to detect C. chauvoei was performed. All procedures were performed in triplicate and was performed by PCR using the same primers employed to amplify the flic gene encoding flagellin (FliC). There was no cross reaction with any tested microorganism, confirming the specificity of the flic gene previously studied. It was possible to visualize the amplification until the corresponding to 100 CFU. Specific PCR amplification products were visualized in 100% of the trials at 48 h, 70% at 72 h, and 90% within one week of storage at room temperature using direct PCR. Discussion: This report describes a rapid, highly sensitive method for the detection of C. chauvoei DNA from liver tissue bovine samples stored on filter papers. It was observed a high sensitivity and a specificity of 100%. The selection of hepatic tissue was based on previous studies that identified C. chauvoei in this tissue by PCR assays. Besides, blackleg in visceral form can be detected in hepatic tissue but does not in muscle. According to others researchers, the direct PCR procedure exhibits several advantages, such as costs and time reduction through omission of DNA extraction as well as avoid any cross contamination with other agents. However, current substances in the blood and tissues may inhibit the PCR amplification. For this reason, a methanol fixation and preheating the samples before the direct PCR assay was performed, mainly because the amplicon is relatively large (535 bp). Some authors consider the use of direct PCR from filter paper simple and inexpensive which offer a handy tool for epidemiologic studies and to clinicians, particularly in many tropical countries where collection and storage of clinical specimens for this purpose are logistically complicated. Furthermore, this procedure can simplify the material shipment for laboratory diagnosis, since it can also be transported in standard envelops by regular mail. The current results propose the use of the direct PCR from common filter paper as practical and economical alternative to diagnosis of blackleg.