Enterobacterial repetitive intergenic consensus typing of pathogenic Escherichia coli

Background: Escherichia coli (E. coli) is considered as an opportunistic pathogen. It is rarely detected in healthy people but occasionally discovered in medical and domestic sources. DNA typing techniques have regularly been employed to evaluate the diversity of E. coli specimens. The aim of this study was to evaluate the prevalence, genetic diversity, and antibiotic resistance of E. coli isolates responsible for infections among hospitalized patients in Baghdad, Iraq, from October 2023 to December 2023. Methods: In this cross-sectional study, 60 E. coli isolates were collected from different clinical samples including urine, wound, burn, sputum, and blood from hospitals in Baghdad, Iraq from October 2023 to December 2023. Biofilm composition was tested using Congo red agar. The genetic diversity and antibiotic resistance of the isolates were examined. API 20NE and PCR tests targeting rpsL genes were performed, followed by ERIC-PCR for DNA sequencing amplification. Results: Biofilm formation on Congo red agar showed 39 positive isolates, indicating a high potential for persistent infections, while 21 isolates showed no biofilm activity. Antibiotic susceptibility testing revealed complete resistance to tetracycline, ceftazidime, and cefepime, with 42% resistance to ceftazidime-clavulanic acid. High sensitivity was observed for norfloxacin 85% and azithromycin 90%. The ERIC-PCR analysis identified 10 DNA fragments (200–2500 bp), forming two main clusters: Cluster A (26.6%) and Cluster B (73.3%), with sub-clusters B1 and B2, suggesting clonal spread within hospitals. Conclusion: The isolates from the same hospital were often genetically linked, indicating clonal spread, while those from the same patient were usually unrelated, highlighting diverse strain types. The ERIC-PCR effectively distinguishes E. coli strains, supporting the hospital surveillance and prevention of multidrug-resistant spread.