Direct Leishmania species typing in Old World clinical samples: evaluation of 3 sensitive methods based on the heat-shock protein 70 gene.

In the diagnosis of leishmaniasis, identification of the causative Leishmania species is relevant for treatment, prognosis, and epidemiology. Three new hsp70-based PCR variants were developed and recently validated on clinical samples from Peru, without the need for culturing. We evaluated their performance on 133 clinical samples (bone marrow, blood, buffy coat, lymph node aspirates, lesion biopsies) from 42 cutaneous and 56 visceral leishmaniasis patients and 35 negative cases, all from Old World countries (Italy, Sudan, Israel, and Tunisia). The 3 new PCRs were significantly more sensitive than those previously described for hsp70, and their respective restriction fragment analyses were more efficient for species identification. In 79% of the parasitologically confirmed positive samples, the species could be identified directly from sample DNA. This evaluation demonstrated that these new tools are globally applicable in different geographical, clinical, and sampling contexts, and they could become the reference method for identification of Leishmania species in clinical specimens.

Comparison of sxx commercially-available dna polymerases for direct ccr / Comparacao de seis polimerases de DNA disponiveis comercialmente para o PCR direto

SUMMARY The use of a “direct PCR” DNA polymerase enables PCR amplification without any prior DNA purification from blood samples due to the enzyme's resistance to inhibitors present in blood components. Such DNA polymerases are now commercially available. We compared the PCR performance of six direct PCR-type DNA polymerases (KOD FX, Mighty Amp, Hemo KlenTaq, Phusion Blood II, KAPA Blood, and BIOTAQ) in dried blood eluted from a filter paper with TE buffer. GoTaq Flexi was used as a standard DNA polymerase. PCR performance was evaluated by a nested PCR technique for detecting Plasmodium falciparum genomic DNA in the presence of the blood components. Although all six DNA polymerases showed resistance to blood components compared to the standard Taq polymerase, the KOD FX and BIOTAQ DNA polymerases were resistant to inhibitory blood components at concentrations of 40%, and their PCR performance was superior to that of other DNA polymerases. When the reaction mixture contained a mild detergent, only KOD FX DNA polymerase retained the original amount of amplified product. These results indicate that KOD FX DNA polymerase is the most resistant to inhibitory blood components and/or detergents. Thus, KOD FX DNA polymerase could be useful in serological studies to simultaneously detect antibodies and DNA in eluents for antibodies. KOD FX DNA polymerase is thus not limited to use in detecting malaria parasites, but could also be employed to detect other blood-borne pathogens. .

RESUMO O propósito deste estudo foi avaliar 6 polimerases de DNA disponíveis comercialmente que são resistentes aos inibidores do PCR para uma amplificação potencial de DNA de amostras de sangue total. O DNA genômico do parasita humano da malária, Plasmodium falciparum, foi analisado sob condições que incluíram os componentes inibidores do sangue extraído de sangue ressacado em papel de filtro. Nossos resultados sugerem que a polimerase KOD FX DNA é superior a outras polimerases. .

Molecular identification of Clostridium chauvoei from common filter paper / 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 fi lter 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 fi lter paper was tested for specifi city, sensitivity and feasibility. To test the specifi city, 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 fi lter paper. To both test, DNA extraction of impregnated ordinary fi lter 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 fi lter paper with suspension of C. cha

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 fi lter 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 fi lter paper was tested for specifi city, sensitivity and feasibility. To test the specifi city, 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 fi lter paper. To both test, DNA extraction of impregnated ordinary fi lter 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 fi lter paper with suspension of C. cha

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.

Molecular identification of Clostridium chauvoei from common filter paper / 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 fi lter 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 fi lter paper was tested for specifi city, sensitivity and feasibility. To test the specifi city, 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 fi lter paper. To both test, DNA extraction of impregnated ordinary fi lter 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 fi lter paper with suspension of C. cha

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 fi lter 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 fi lter paper was tested for specifi city, sensitivity and feasibility. To test the specifi city, 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 fi lter paper. To both test, DNA extraction of impregnated ordinary fi lter 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 fi lter paper with suspension of C. cha