Identification of Salmonella enteritidis isolates by polymerase chain reaction and multiplex polymerase chain reaction.

The polymerase chain reaction and the multiplex polymerase chain reaction were developed for detection of Salmonella and for identification of the serotype enteritidis. Three sets of primers were selected from different genomic sequences amplifying a 429 bp fragment specific for the genus Salmonella within a randomly cloned sequence, including a 250 bp fragment within the spv gene, and a 310 bp fragment within the sefA gene specific for Salmonella enteritidis. The polymerase chain reaction and the multiplex polymerase chain reaction were used for detecting S. enteritidis isolated from stool samples during outbreaks of foodborne gastroenteritis between 1992 and 1998 in Taiwan. The sefA gene was detected in all 27 strains of S. enteritidis by this polymerase chain reaction method. Multiplex polymerase chain reaction could detect 3 genes in all strains, but could not detect the spv gene in 2 strains. The sensitivity of the polymerase chain reaction and the multiplex polymerase chain reaction were 10(4) and 10(5) cells/mL, respectively. In double polymerase chain reaction, the sensitivity increased to 100 cells/mL. These data indicate that the specificity and sensitivity of the polymerase chain reaction and the multiplex polymerase chain reaction make them potentially valuable tools for diagnosis of S. enteritidis infection and that they may be used for the identification of S. enteritidis responsible for sporadic enteritis cases.