Comparison of methods for differentiation of Salmonella enterica serovar Enteritidis phage type 4 isolates.

OBJECTIVE

To compare molecular typing methods for the differentiation of Salmonella enterica serovar Enteritidis phage type (PT) 4 isolates that allowed for the determination of their genetic relatedness.

SAMPLE POPULATION

27 Salmonella Enteritidis PT 4 strains isolated in the United States and Europe.

PROCEDURE

Several molecular typing methods were performed to assess their ability to genetically differentiate among Salmonella Enteritidis PT 4 isolates. Results of pulse-field gel electrophoresis (PFGE), repetitive polymerase chain reaction (PCR) assay, 16S rRNA gene sequencing, random amplification of polymorphic DNA (RAPD), PCR-restriction fragment length polymorphism of 16S rRNA, and antimicrobial susceptibility were evaluated.

RESULTS

Compared with results for other techniques, results for the RAPD typing method with the RAPD1 primer reveal that it was the most discriminatory fingerprinting technique, and it allowed us to cluster Salmonella Enteritidis PT 4 isolates on the basis of their genetic similarity.

CONCLUSIONS AND CLINICAL RELEVANCE

This study revealed the value of RAPD with the RAPD1 primer as a tool for epidemiologic investigations of Salmonella Enteritidis PT 4. It can be used in conjunction with PFGE and phage typing to determine the genetic relatedness of Salmonella Enteritidis isolates involved in outbreaks of disease. A reliable and highly discriminatory method for epidemiologic investigations is critical to allow investigators to identify the source of infections and consequently prevent the spread of Salmonella Enteritidis PT 4.