Background: The O-antigen is one of the uropathogenic Escherichia coli (UPEC) virulence factors used as a biomarker to classify E. coli strains. Objectives: In this study, the relationship between antibiotic resistance patterns and O-serogroups was investigated in UPEC strains isolated from patients with urinary tract infections (UTIs) in southern Iraq. Methods: A total of 100 UPEC isolates from the urine specimens of patients with UTIs within the age range of 4 months to 78 years in various southern Iraqi hospitals were collected (May 2017 to January 2018) and confirmed using biochemical tests (e.g., Analytical Profile Index 20E). Antibiotic susceptibility tests were performed using the disk diffusion method according to the Clinical and Laboratory Standards Institute guidelines. The multiple polymerase chain reaction technique was applied to investigate the prevalence of O-serogroups. Results: The most frequent serogroups in the E. coli isolates were O8 (27.7%) and O25 (24.4%); however, serogroup O83 was not observed in the samples. Serogroups O75, O6, O16, and O18 had the lowest frequency (1.1%) among the examined isolates. Furthermore, 10% of the isolates did not belong to any of the examined serogroups. The phenotypic tests showed that the highest and the lowest resistance belonged to piperacillin (92%) and imipenem (5%), respectively. Serogroups O4 and O21 showed the highest drug resistance; nevertheless, serogroups O75, O18, and O1 showed the lowest drug resistance. Additionally, 94% of the isolates were resistant to three or more classes of antibiotics. Conclusions: According to the results, UPEC isolates showed high resistance to common antibiotics; however, they were sensitive to imipenem and amikacin. Serogroups O8 and O25 were the most common among UPEC isolates. Moreover, O4 and O21 showed the highest drug resistance. There was a direct relationship between antimicrobial resistance and O-serogroups in UPEC isolates

Keywords