Phenotypic and Molecular Detection for Antibiotic Resistance of <i>Enterobacter cloacae</i> Isolated from Urinary Tract Infections

Introduction: Enterobacter cloacae has emerged as a significant pathogen in urinary tract infections, particularly in hospitals under antibiotic pressure, resulting in rapid development of resistance. The number of mechanisms, including β-lactamase production, aminoglycoside-modifying enzymes, efflux systems, and plasmid-mediated determinants used by the organism, made successful treatment difficult. Phenotypic resistance interpretation and the detection of widely used genetic markers are key components that drive therapy and contain the transmission of MDR strains. Methods: A total of 100 urine samples were obtained from patients with UTI at three hospitals in Babylon province from November 2024 to January 2025. Isolates were confirmed as E. cloacae by routine culture and biochemical tests. Susceptibility to antimicrobial agents was determined by the CLSI disc diffusion method. All isolates were tested for AcrAB, blaTEM, strA, and tetA using molecular detection assays, whereas 16S rRNA gene sequencing was performed to validate species identification and assess genetic diversity among isolates. Results: The isolates exhibited high-level resistance to amoxicillin-clavulanate (100%), ceftazidime (100%), and tetracycline (90%). Resistance to ampicillin, clarithromycin, erythromycin, and streptomycin was also higher. Gentamicin and ciprofloxacin demonstrated moderate activity, whereas levofloxacin and high-level streptomycin were most potent. The most common were AcrAB (80%), tetA (70%), blaTEM (40%), and strA (30%). Sequencing validated the correct assignment and identified single-nucleotide variants, indicating micro-variation. Conclusion: The study revealed an alarming level of multidrug resistance among E. cloacae isolates in Babylon province. To prevent further dissemination of resistant strains, antimicrobial stewardship should be reinforced and routine molecular surveillance established.