Distribution of Enterotoxigenic Escherichia coli among E. coli isolates from diarrheal samples referred to educational hospitals in Tehran-Iran

Enterotoxigenic Escherichia coli (ETEC) is the most important bacterial cause of watery traveler's diarrhea in developing countries. Watery diarrhea is can cause serious life-threatening dehydration. ETEC was caused diarrhea by the secretion of two heat-labile enterotoxins (LTs) and the heat-stable enterotoxins (STs) which increase intestinal secretion. Routine laboratory methods are not appropriate to detect ETEC and other diarrheagenic E. coli pathotypes. The molecular techniques such as PCR are rapid and accurate methods that have been developed for detection of ETEC. We were recognized ETEC by PCR on lt and st genes from E. coli isolates from patients with diarrhea collected from selected Tehran educational hospitals. The E. coli isolates were collected from total 140 patients with diarrhea and 110 patients without diarrhea using culture and IMViC test. DNA was extracted by boiling method and the presence of the uidA, lt and st genes was detected by PCR. Among 140 E. coli isolates from diarrheal stools 5 (3.6%) isolates were positive for, just lt gene, 3 (2.1%) co-amplified for both lt/st and 1 (0.7%) was positive for just the st gene which were considered as ETEC. In the E. coli isolates from non-diarrheal control samples just one (0.9%) isolate was positive for both lt and st genes. The results showed that the ETEC as a significant cause of diarrhea, usually ignored by laboratories using traditional methods. Sometimes the ETEC causes severe diarrhea and can threaten for patient's life. Thus a rapid diagnostic test such as PCR can be very helpful in the treatment of patients.