Quantification of Salmonella by 5'-nuclease real-time polymerase chain reaction targeted to fimC gene.

A new 5'-nuclease real-time polymerase chain reaction (PCR) system for the quantification of Salmonella enterica was developed, with primers and the probe oriented to a Salmonella-specific region of the fimC gene. The PCR system was specific and sensitive, its inclusivity was 100% (determined by the analysis of 53 strains of Salmonella belonging to 38 serovars) and its exclusivity was 100% (determined by the analysis of 49 non-Salmonella strains). For quantification purposes, calibration lines were constructed for three Salmonella strains belonging to three serotypes. These calibration lines were linear (r > or = 0.99) in the range from 10(3) to 10(7 )CFU/mL and practically identical in terms of very similar slopes and x-intercepts. Escherichia coli (10(6 )CFU/mL) and Citrobacter freundii (10(6) CFU/mL) had no effect on Salmonella quantification by the system.