The Salmonella sp detection in feed samples is time consuming, it has five stages and requires 120 hours for final results. The use of polimerase chain reaction technique can reduce this time considerably, however it can be affected by substances from the sample. This study had the objective of comparing two methods of DNA extraction, by heating process and by phenol-chloroform in samples of 100 chicken eggs experimentally infected with a sample of Salmonella enterica sorovar typhimurium in stationary phase. After the two extraction methods a PCR was done using a pair of oligonucleotides that amplifies a fragment of 284pb in the InvA gene de Salmonella sp. Comparing the extraction methods it was noted a difference of 12% favorably to the phenol-chloroform method when the extraction was done from eggs with shell. The same method using just the egg internal part resulted in a difference of 26% with high significance (P<0.003), showing that the method used was determinant to improve the technique efficiency. However, comparing the positive percentage independent of the DNA extraction method a significant difference (P<0.047) was noted for outshell eggs. This fact suggests that for Salmonella egg analysis, only the egg internal part should be used because the shell can determine interference in technique.
Salmonella; eggs; extraction; DNA; PCR
