Genetic detection of diarrheagenic Escherichia coli isolated from children with sporadic diarrhea

Lee-Jene Teng^1,2, Po-Ren Hsueh¹, Shwu-Jen Liaw^1,2, Shen-Wu Ho^1,2, Jui-Chang Tsai^3,4
1Department of Laboratory Medicine, National Taiwan University Hospital, Taipei; ²School of Medical Technology, National Taiwan University College of Medicine, Taipei; ³Division of Neurosurgery, Department of Surgery, National Taiwan University Hospital, Taipei; and ⁴Center for Optoelectronic Biomedicine , National Taiwan University College of Medicine, Taipei, Taiwan, ROC

Received: April 6, 2004 Revised: April 28, 2004 Accepted: June 14, 2004

Corresponding author: Jui-Chang Tsai, M.D. Ph.D., Division of Neurosurgery, Department of Surgery, National Taiwan University Hospital, Rm. 824, 8F, No. 7 Chung-Shan S. Rd., Taipei, Taiwan 100, ROC. E-mail:

Escherichia coli strains are among the major bacterial causes of diarrheal illness. At least 5 categories of diarrheagenic E. coli (DEC) are recognized, namely enterotoxigenic E. coli (ETEC), enteropathogenic E. coli (EPEC), enteroinvasive E. coli (EIEC), enteroaggregative E. coli (EAEC), and enterohemorrhagic E. coli (EHEC). Due to the need for costly and labor-intensive diagnostic procedures, identification of DEC is difficult at standard laboratories. Therefore, the epidemiology of DEC infections remains obscure in Taiwan. Recently, polymerase chain reaction (PCR) or dot blot has been used for genetic detection of DEC. In this study, we analyzed 150 E. coli isolates from diarrheal stools of children under 5 years old. The PCR tests detected 5 ETEC (3.3%), 6 EPEC (4%), 4 EIEC (2.7%), and 13 EAEC (8.7%) isolates. No EHEC was detected. Dot blot and sequence analysis were used to confirm the results of PCR. The cellular fatty acid (CFA) profiles from E. coli isolates were also analyzed. Comparison of CFA composition revealed minor variation in the percentage of each fatty acid detected among DEC isolates of ETEC, EPEC, EIEC and EAEC, but did not provide enough evidence for differentiating between categories of DEC by CFA profiles alone.

Key words: Diarrhea, Escherichia coli, PCR, preschool child

J Microbiol Immunol Infect 2004;37:327-334.