Specific and sensitive two-step polymerase chain reaction assay for the detection ofSalmonella species

A polymerase chain reaction (PCR) assay was applied for the selective amplification of a characteristic sequence within aSalmonella-specific chromosomal fragment. A two-temperature PCR cycle enhanced both the speed and overall sensitivity of the amplification procedure. Twenty-one well-characterizedSalmonella strains and a number of non-Salmonella strains were tested. With the exception of the rarely isolatedSalmonella arizonae strain, the PCR-based approach enabled the specific identification ofSalmonella with a detection limit of 10³ organisms. In combination with a nested PCR assay, as few as ten organisms were detectable. Specificity was demonstrated as no distinct amplification products were detectable with any of the testednon-Salmonella strains. With a pre-enrichment step using paramagnetic antiSalmonella beads, an increase in sensitivity was observed in the case of clinical samples while the amplification process was not influenced.