Isolation and Diagnosis of Bacteria Causing Urinary Tract Infections in Diabetic Patients

Abstract

Background: Urinary tract infections (UTIs) are important bacterial infections in diabetic patients because diabetes mellitus may promote bacterial growth and recurrent infection. This study aimed to isolate and identify bacterial species associated with UTIs in diabetic patients and to evaluate the susceptibility of the isolates to selected antibiotics. Methods: The study was conducted in the laboratories of the College of Medical Technologies, Department of Medical Laboratory Analysis, Al-Islamic University, Najaf, Iraq, from December 2024 to March 2025. A total of 31 midstream urine samples were collected from diabetic patients diagnosed with UTIs by specialist physicians at Al-Sadr Teaching Hospital, Najaf. Samples were processed by centrifugation and cultured on MacConkey agar, Mannitol Salt Agar and blood agar. Isolates were identified using colony morphology, Gram staining and standard biochemical tests. Antibiotic susceptibility testing was performed by the Kirby-Bauer disk diffusion method using amikacin, gentamicin, amoxicillin/clavulanic acid, clindamycin and erythromycin. Results: Twenty-three bacterial isolates were recovered. Gram-negative bacteria accounted for 16 isolates (69.57%), whereas Gram-positive bacteria accounted for 7 isolates (30.43%). The identified species were Escherichia coli (7 isolates; 30.4%), Staphylococcus aureus (6 isolates; 26.1%), Pseudomonas aeruginosa (4 isolates; 17.4%), Proteus spp. (3 isolates; 13.0%) and Staphylococcus saprophyticus (3 isolates; 13.0%). Among Escherichia coli isolates, the highest susceptibility was observed to amikacin (85.71%), followed by gentamicin (71.43%), while complete resistance was recorded to amoxicillin/clavulanic acid. Conclusion: The findings indicate that Gram-negative bacteria, particularly Escherichia coli, were the predominant bacterial pathogens in diabetic patients with UTIs in this study. Routine bacterial identification and susceptibility testing remain important for guiding appropriate antimicrobial selection.