Use of Polymerase Chain Reaction (PCR) Method for the Rapid Identification of Salmonella typhi

PEY-RU LIU, TIEN-KUEI WANG*, CHIEN-KU LIN**, TZU-MING PANG* AND HAU-YANG TSEN

Department of Food Science, National Chung-Hsing University, Taichung, Taiwan, R.O.C.
*National Institute of Preventive Medicine, Department of Health, Executive Yuan, Taipei, Taiwan, R.O.C. **Department of Food Nutrition, Hung-Kuang Institute of Nursing and Medical Technology, Shalu, Taiwan, R.O.C.

ABSTRACT

   In order to evaluate the applicability for using the polymerase chain reaction (PCR) method to replace the conventional biotyping and serotyping method for identification of Salmonella typhi isolated from suspected typhoid patients, PCR primers derived from the H1-d gene coding for S. typhi flagellin were used for the identification of S. typhi strains obtained from the Institute of Preventive Medicine, Taipei, Taiwan. All 50S. typhi isolates were capable of generating positive reactions. In addition , Salmonella isolates other than S. typhi and non-Salmonella isolates including strains of Enterobacteriaceae did not yield positive reaction. Study on the detection sensitivity for this PCR system shows that when single PCR running was performed, the minimal cell number required to give a positive reaction was 104 . However , when double PCR running was performed, the detection sensitivity increased to 100 CFU. Therefore, these preliminary data indicates that PCR is a rapid and reliable method that can be used for the identification of S. typhi responsible for sporadic typhoid cases.

Key words : Polymerase chain reaction, Salmonella typhi