Frequency of fiveEscherichia Colipathotypes in Iranian adults and children with acute diarrhea
Authors: Eybpoosh Sana , Mostaan Saeid , Gouya Mohammad Mehdi , Masoumi-Asl Hossein , Owlia Parviz , Eshrati Babak , Khorasan Mohammad Reza Montazer Razavi , Bouzari Saeid 
Published: August 2019

Background

knowledge about the distribution ofEscherichia Coli(E. coli) pathotypes in Iran is limited to studies with small scale and limited scope. This nation-wide survey aims to provide a more generalizable estimate of pathogenicE. colidistribution in Iran.

Methods

During January 2013 and January 2014, stool samples were collected from 1306 acute diarrhea cases of 15 provinces. Culture-positiveE. colisamples were tested with PCR for detection of fiveE. colipathotypes (STEC, ETEC, EPEC, EAEC, and EIEC). Frequency of these pathotypes was estimated for different provinces, age groups, and months/seasons.

Results

Of 1305 diarrheal samples, 979 wereE. coli-positive (prevalence: 75.0%; 95% CI: 72.6, 77.3%). PathogenicE. coliwas detected in 659 diarrheal samples (prevalence: 50.5%; 95% CI: 47.8, 53.2%). STEC and EIEC was the most and the least frequent pathotypes (35.4% and 0.3%, respectively). ETEC (14.0%) and EPEC (13.1%) were the second and the third frequent pathotypes, respectively. EAEC was not highly prevalent (4.3%). Fars and Razavi Khorasan provinces had the highest and lowest frequencies (88.7% and 34.8%, respectively).E. colipathotypes were more frequent in warmer (i.e., spring and summer) than cooler (i.e., fall and winter) seasons. The highest frequency of pathogenicE. coliwas observed in infants and children under 5 years (73% each). There was no association between sex and pathogenicE. coliinfection.

Conclusions

DiarrheagenicE. colimay be an important cause of acute diarrhea in adults and children in Iran. STEC and ETEC seem to be widespread and show a peak in warmer seasons. This finding could impact the recommended use of STEC and ETEC vaccines during warmer seasons, especially for infants, young children and elderlies. Monitoring the rate of diarrheagenicE. coliinfection,E. coliserotypes, and their antibiotic resistance is recommended for evaluations of time-trends and effectiveness of interventions.

Author summary

Escherichia coli, also known asE. coliis a bacterium of the genusEscherichiathat is normally found in the lower intestine of human. MostE. colistrains are harmless, but some can cause infection in the gastrointestinal tract, causing diarrhea. These pathogenicE. colistrains are classified based on their mechanism of pathogenesis. In this regard, five importantE. colistrains include Shiga toxin-producingE. coli(STEC), enterotoxigenicE. coli(ETEC), enteropathogenicE. coli(EPEC), enteroaggregativeE. coli(EAEC), and enteroinvasiveE. coli(EIEC). In a national survey conducted in Jan 2013 till Jan 2014, we collected 1305 diarrheal samples from 15 (out of 31) provinces of Iran. Of these, 979 samples (75%) wereE. coli-positive in the culture test. Molecular tests showed that 659 samples were pathogenicE. coli, suggesting that 50.5% of the diarrhea cases were induced due to pathogenicE. coliinfection. The most prevalent pathogenicE. colistrains in Iran were STEC (35.4%) and ETEC (0.3%), and were more commonly detected in warmer seasons, infants, and children less than five years. So, the use of vaccines, especially for STEC and ETEC, during warmer seasons and for infants, young children and elderlies are recommended.