Determination of phylogenetic groups and antibiotic resistance pattern of Enterotoxigenic Escherishia coli isolates from diarrheoic cases in Bam City by PCR

Purposes of this study were to determine the phylogenetic groups، prevalence of enterotoxigenic pathotype and antibiotic resistance of Escherichia coli (E. coli) isolates from diarrheic cases in Bam city. In this study 155 E. coli were isolated from diarrheic samples in Bam city. Phylogenetic groups of isolates and enterotoxigenic pathotype were determined by detection of chuA، yjaA، TspE4C2 and ST، LT genes respectively. One hundred fifty five examined isolates were distributed in phylogenetic groups: A (71. 60%)، B1 (3. 22%)، B2 (9. 67%) and D (15. 48%). The genes for enterotoxigenic pathotype were detected in 52 isolates (33. 54%)، which ST gene were found in 29 isolates، LT in 16 isolates and LT، ST genes in 7 isolates. Twenty nine ST gene positive isolates were distributed in three phylogenetic groups A (48. 28%)، D (41. 38%) and B2 (10. 34%). According to the antibiotic susceptibility tests maximum and minimum antibiotic resistance rate was against to trimethoprim/sulfamethoxazole (74. 19%) and ciprofloxacin and gentamycin (9. 67%). Fifteen multiple antibiotic resistance patterns were detected in four phylogenetic groups. Escherichia coli isolates from enterotoxigenic pathotype have a considerable antibiotic resistance rate in Bam city and were distributed in different phylogenetic groups. Since a considerable number of isolates were negative for LT and ST genes، it is necessary to study the other virulence genes and their phylogenetic background in E. coli isolates from diarrheic cases in Bam city.