1987至1996年間。本單位之沙門氏菌研究室共分離出本土與東南亞之副傷寒A型菌(Salmonella paratyphi A)計42株，其中大部分係境外移入，此與近年來國人出國頻繁有關。本土性之副傷寒案例以往罕見，但近年來已有明顯增加之警訊。為確保國人健康及防疫追蹤調查之需求，除傳統之血清分類法外，副傷寒A型菌之分子流行病學分型值得加以探討。本研究以脈場膠電泳法應用於此菌血清型之下的分型，經由四種不同限制酵素之切割，找出最具分型性之限制酵素Avr Ⅱ，作為日後例行檢驗之參考。以AvrⅡ限制酵素之切割，可將來自本土及東南亞之42株副傷寒A型菌分成三種親族群(clones)，但其中之一親族群佔85.7%，比率高且在東南亞分布頗廣。此乃表示副傷寒A型菌在演化過程中變異性少，故基因組(genomic)DNA相似性很高。

From 1987 to 1996, forty-two isolates of Salmonella paratyphi A were collected from Taiwan, China and other Southeast Asian countries. Pulsed-field gel electrophoresis (PFGE) was used to differentiate the genomic DNA of these isolates with four different restriction enzymes, Xba I, Not I, Spe I and Avr Ⅱ. Based on the PFGE profiles obtained, Avr Ⅱ allowed the most discriminatory results among these restriction endonucleases. By Avr Ⅱ digestions, 42 isolates of S. paratyphi A were differentiated into three clones. The predominant clone accounted for 85.7% of the tested strains (36 in 42 isolates) and was found in many countries of Southeast Asia. Thus, S. paratyphi A appears to have limited genetic diversity in evolutionary process.