Patterns of Bacterial Infections and Antimicrobial Resistance in Solid-Organ Transplant Recipients: A Five-Year Retrospective Study

• Gram-negative bacilli and Gram-positive cocci showed comparable isolation rates. E. coli, K. pneumoniae, and S. epidermidis were the predominant isolates. • Quinolone and penicillin resistance had the highest resistance rate, exceeding 50% across all bacterial isolates. • Tetracyclines and vancomycin demonstrated the lowest resistance rates. • Diabetes history was significantly associated with isolated bacterial species. • No significant resistance differences observed between liver and kidney recipients. Solid-organ transplant (SOT) recipients are highly susceptible to infections due to immunosuppression and frequent hospitalizations due to multidrug-resistant (MDR) bacterial infections. Consequently, understanding the antimicrobial resistance patterns is essential for optimizing infection management strategies. This retrospective study analyzed medical records of liver and kidney transplant recipients diagnosed with post-transplantation infections between 2017 and 2022. Bacterial pathogens were identified using the VITEK 2 system. The relationship between antimicrobial resistance profiles (ARPs) and isolated bacterial species (IBS), as well as age, sex, diabetes, type of transplantation, and infection source, was assessed. Among 102 patients (mean age of 45.6 ± 16.0 years), most underwent liver transplantation (86.3%). The survival rate after the infection episode was 91.2%. Escherichia coli (19.6%), Klebsiella pneumoniae (18.6%), and Staphylococcus epidermidis (14.7%) were the most frequently isolated bacteria. Gram-negative bacilli and Gram-positive cocci were identified at comparable rates (57.8% vs. 42.2%, respectively). The highest resistance rates were against quinolones (53.9%) and penicillin (52.0%), while tetracyclines (10.8%) and vancomycin (11.6% among Gram-positive cocci) had the lowest resistance. Significant associations were found between IBS and diabetes history (P < 0.001), survival status (P < 0.001), and transplant type (P = 0.02). However, no significant associations were observed between ARP and sex, diabetes, type of transplantation, specimen source, or survival status. While the distribution of bacterial pathogens differed between liver and kidney transplant recipients, no statistically significant differences in overall antimicrobial resistance patterns were observed. Although no statistically significant differences in antimicrobial resistance patterns were observed between liver and kidney transplant recipients, this finding should be interpreted cautiously, given the limited number of kidney transplant patients.