Uropathogen Distribution and Antimicrobial Resistance in Patients With Diabetes, Other Chronic Diseases, and No Comorbidities: A Retrospective Cohort Study

Abstract Background Diabetes mellitus and other chronic diseases are associated with urinary infection, catheterization, and other urological and healthcare exposures that may influence both uropathogen distribution and antimicrobial resistance. However, binary diabetic versus non-diabetic comparisons often combine otherwise healthy adults with patients who have substantial non-diabetic comorbidity. We compared bacterial isolates and antimicrobial resistance across three clinically distinct comorbidity groups. Methods This retrospective, laboratory-based study included 835 eligible positive bacterial urine-culture records from adults evaluated by the Departments of Internal Medicine, Urology, and Infectious Diseases at a tertiary hospital in Istanbul, Türkiye, between 1 January 2021 and 31 December 2025. Records were classified into three mutually exclusive groups: diabetes mellitus, non-diabetic chronic disease, and no documented comorbidity. Group differences in demographic characteristics, urine-collection method, uropathogen distribution, and antimicrobial resistance among Escherichia coli isolates were evaluated. Because complete culture dates and a consistently reliable anonymized patient identifier were unavailable, analyses were performed at the culture-record level. Results Among 835 eligible positive bacterial urine-culture records, 56 (6.7%) were from the diabetes group, 153 (18.3%) from the non-diabetic chronic disease group, and 626 (75.0%) from the no documented comorbidity group. Median age and the frequency of catheter-collected specimens were highest in the diabetes group (both P<0.001). Escherichia coli was the predominant organism but accounted for a lower proportion of records in the diabetes, non-diabetic chronic disease, and no documented comorbidity groups, respectively (32.1%, 41.2%, and 54.2%; P<0.001). Klebsiella spp. and Pseudomonas aeruginosa were proportionally more frequent in the diabetes group, although the between-group differences did not reach statistical significance. Among evaluable E. coli isolates, gentamicin resistance was 35.3%, 13.3%, and 8.7% across the diabetes, non-diabetic chronic disease, and no documented comorbidity groups, respectively (P=0.003). Corresponding nitrofurantoin resistance was 25.0%, 6.9%, and 5.0% (P=0.012). Resistance to ceftriaxone, fluoroquinolones, trimethoprim-sulfamethoxazole, and ertapenem was numerically higher in the diabetes group, but these differences were not statistically significant and several estimates were based on small tested denominators. Conclusions Uropathogen distribution and selected E. coli resistance patterns differed across comorbidity groups in this tertiary-care culture-record cohort. Adults with diabetes had greater representation of non-E. coli organisms and higher resistance to gentamicin and nitrofurantoin, but they were also older and more frequently catheterized. These findings support comorbidity-aware interpretation of local microbiological surveillance and individualized urological risk assessment; they do not establish diabetes as an independent cause of antimicrobial resistance.