[Development and validation of a multiplex polymerase chain reaction for molecular identification of Salmonella enterica serogroups B, C2, D and E].

INTRODUCTION

The scheme Kauffman-White (KW) for serotyping of Salmonella recognizes 46 O antigens, and 119 H antigens, thereby permitting the characterization of 2541 serotypes. The serotyping is a useful epidemiological tool in identifying circulating serotypes and to characterize outbreaks. However, the method presents technical limitations, difficulty in interpretation of results and high costs.

OBJECTIVE

A multiplex polymerase chain reaction test (M-PCR) was developed as an alternative method for the identification of serogroups B, C2, D, and E of Salmonella enterica.

MATERIALS AND METHODS

The M-PCR detected Salmonella genes rfbJ of serogroups B and C2 and wzx of serogroups D and E. To standardize the M-PCR, reference strains of Salmonella serogroups were compared. Amplification of invA gender-specific gene of Salmonella was included as internal control of amplification. To validate the test, a blind study was conducted to identify by M-PCR 400 isolates that had been previously characterized by serology.

RESULTS

The M-PCR detected Salmonella serogroups with reproducible results (Kappa index = 0.95). The sensitivity of the test was between 98% to 100% and specificity between 96% to 100%.

CONCLUSIONS

The polymorphisms in the Salmonella genes rfbJ and wzx permitted the development of a method for molecular typing of Salmonella serogroups that was sensitive, specific and reproducible.