Immune and Microbial Characterization in Patients with Urinary Tract Infections
Abstract
Urinary tract infections (UTIs) constitute a significant global public health burden. Epidemiological and immunological data specific to UTIs in Iraqi Kurdistan remain scarce. This cross-sectional study investigated common UTI-causing microbial agents and the associated systemic immune responses among hospitalized patients in Erbil city from June 2024 to January 2026. A total of 420 culture-positive urine specimens were collected from inpatients at Rzgary Teaching Hospital. Pathogen identification was performed using standard biochemical and microbiological methods. Serum immunological parameters, including immunoglobulins (IgG, IgM, IgA) and pro-inflammatory cytokines (TNF-α and TNF-β), were quantified by enzyme-linked immunosorbent assay (ELISA). The study population showed pronounced female predominance (65%, n=273) compared to males (35%, n=147). Escherichia coli emerged as the most prevalent pathogen (74%, n=311), followed by Proteus spp. (13.8%, n=58), Staphylococcus aureus (5.5%, n=23), Pseudomonas aeruginosa (3.3%, n=14), Klebsiella spp. (1.9%, n=8), and Enterococcus spp. (1.4%, n=6). A control group of 105 sex- and age-matched healthy volunteers was included for comparison. Immunological profiling revealed significantly elevated IgG (5.82 vs. 1.25 IU/mL, p<0.001) and IgA (11.40 vs. 2.86 IU/mL, p<0.001) in patients relative to controls; IgM levels were markedly reduced (4.95 vs. 13.89 IU/mL, p<0.001). Pro-inflammatory cytokines were substantially elevated, with TNF-α at 165.2 pg/mL (vs. 10.5 pg/mL in controls, p<0.001) and TNF-β at 148.5 pg/mL (vs. 14.8 pg/mL, p<0.001). These findings confirm E. coli as the predominant uropathogen in Erbil and demonstrate a robust systemic immune response. The immunoglobulin profile, elevated IgG and IgA with reduced IgM, is consistent with an advanced-phase or repeated infection pattern in this hospitalized cohort, though longitudinal data would be required to confirm chronicity. These immunological parameters may carry prognostic value in the management of UTI.