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Volume 50, Number 1, February 2017

Prevalence and characterization of enterotoxigenic Bacteroides fragilis and toxigenic Clostridium difficile in a Taipei emergency department 

Dar-Der Ji, I-Hsiu Huang, Chao-Chih Lai, Fang-Tzy Wu, Donald Dah-Shyong Jiang, Bing-Mu Hsu, Wei-Chen Lin


Corresponding author:

Wei-Chen Lin, Corresponding author. Department of Parasitology, National Cheng Kung University, Number 1, University Road, Tainan City 701, Taiwan, ROC. 


Background and purpose: 

Enterotoxigenic Bacteroides fragilis (ETBF) and toxin-encoding Clostridium difficile (TXCD) are associated with gastroenteritis. Routine anaerobic blood culture for recovery of these anaerobic pathogens is not used for the detection of their toxins, especially for toxin-variant TXCD. The aim of this study was to investigate the prevalence and risk factors of the genotypes of these anaerobes in patients with acute diarrheal illnesses. 



The data and samples of 513 patients with gastroenteritis were collected in a Taipei emergency department from March 1, 2006 to December 31, 2009. Nonenterotoxigenic B. fragilis (NTBF) and ETBF and the toxin genotypes of TXCD were detected by molecular methods. 



The prevalence rates of NTBF, ETBF, and TXCD infections were 33.14%, 1.56%, and 2.34%, respectively. ETBF infections often occurred in the elderly (average age = 67.13 years) and during the cold, dry winters. TXCD infections were widely distributed in age and often occurred in the warm, wet springs and summers. The symptoms of ETBF-infected patients were significantly more severe than those of NTBF-infected patients. 



This study identified and analyzed the prevalence, risk factors, and clinical presentations of these anaerobic infections. Future epidemiologic and clinical studies are needed to understand the role of ETBF and TXCD in human gastroenteritis. 


Key words:

acute diarrheal illnesses, enterotoxigenic Bacteroides fragilis, toxigenic Clostridium difficile, toxin genotypes