Objectives. In 2013, Clermont classified E. coli strains into eight phylogenetic groups using a new quadruplex PCR method. The aims of this study were to identify the phylogenetic groups of E. coli based on this method and to assess their antibiotic resistance patterns in Bushehr, Iran. Methods. In this cross-sectional study, 140 E. coli isolates were subjected to phylogenetic typing by a quadruplex PCR method. Antimicrobial susceptibility testing was performed by disk diffusion method. Results. Phylogenetic group B2 was most predominant (39.3%), followed by unknown (27.1%), E (9.3%), C and Clade I (each 6.4%), B1 (5%), F and D (each 2.9%) and A (0.7%). The most common antibiotic resistance was related to amoxicillin (82.1%), and the least to meropenem (0.7%). 82.14% of isolates were multiple drug resistant (MDR). Antibiotic resistance was mainly detected in group B2 (50%).
