Thus, the capacity to isolate the target bacteria, as well as the influenceof matrix components, could be limiting factors for PCR reliability. Theseproblems could be overcome with procedures such as dilutions of thesample, previous isolation of the pathogens being studied, and DNAextraction protocols, as well as corrections in PCR reagent concentrations.In this experiment, when the protocols for extraction with thermaltreatment and Sephaglass were used, negative results were observed atall incubation periods tested (Table 2). Differently, the protocol forphenol-chloroform extraction supplied positive results after 24 hours ofsample’s pre-enrichment. With this protocol, the reduction of analysistime from approximately 96 hours, with microbiology method, to 48hours with PCR, appears to be the main advantage of the technique,since the detection limits of both methods (PCR and conventionalmicrobiology) were the same (Table 2 ). The specificity of PCR is anotherindication of its good applicability in diagnostic routines. However, thereare reports indicating the occurrence of false negative results whennaturally contaminated chicken meat samples are analyzed by the PCRmethod. Thus, the next stage of these experiments should include thecomparison between the PCR protocol developed in this study andmicrobiological analysis for the detection of Salmonella in naturallyinfected chicken meat samples.
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