Background: Co-microbial infection occupies a big portion of the urinary tract infections (UTI), especially in the elderly. Such infections are hidden, because of the dominance of one species over the other species.
Objectives: This study aimeds to detect polymicrobial urinary tract infections in middle-aged and elderly patients using both culture-based and molecular methods. It also investigates the presence of aminoglycoside resistance genes, specifically armA and rmtG, to improve diagnostic precision and support targeted therapeutic decisions.
Methods: In the current study, 100 clinical samples of urine were collected from middle-aged and elderly patients suffering from urinary tract infections. The study was conducted in two hospitals in Baghdad between October 2023 and April 2024. The age of patients was 45+ years equally divided between males and females. These samples were cultured on selective and differential culture media. The grown isolates were further purified and identified using the Vitek system. The antibiotic susceptibility test was done to evaluate the antibiotic resistance pattern. Bacterial DNA was extracted and specific primers were designated for this study, to amplify the resistance coding genes armA and rmtG by the polymerase chain reaction (PCR) technique. 
Results: Klebsiella pneumoniae and Escherichia coli were the co-existing microbes causing UTI in middle-aged and elderly patients. Significant gender differences were found in the co-infection rates and antibiotic susceptibility tests and genetic analysis identified resistance genes armA and rmtG. These co-microbes were resistant to aminoglycoside antibiotics. Both K. pneumoniae and E. coli carried the armA gene, while the rmtG gene was predominant in K. pneumoniae only. K. pneumoniae and E. coli were found in 42% of the samples. The armA gene was detected in 46% of isolates (10/15 E. coli, 4/15 K. pneumoniae), while the rmtG gene was detected in 26.6% of K. pneumoniae isolates and not found in E. coli
Conclusion: This study highlights the occurrence of polymicrobial urinary tract infections among middle-aged and elderly patients, especially females. The detection of resistance genes underscores the importance of molecular diagnostics and gender-specific treatment strategies in managing UTIs.