Introduction:
Healthcare-associated infections represent a persistent global threat due to the increasing emergence of multidrug-resistant pathogens. This study aimed to phenotypically characterize antimicrobial resistance profiles among nosocomial bacterial isolates from hospitalized patients and establish epidemiological baseline data.
Methodology: This cross-sectional study analyzed 209 nosocomial bacterial isolates obtained from 13,850 hospitalized patients meeting Iranian Ministry of Health HAI criteria. Bacterial identification was performed using standard culture methods, and antimicrobial susceptibility testing was conducted using the Kirby-Bauer disk diffusion method according to CLSI 2023 guidelines. Sixteen antibiotics were evaluated using Mueller-Hinton agar and quality control strains. Resistance profiles were analyzed using WHONET 2024, while statistical comparisons were performed using SPSS v22.
Results: Species-specific resistance associations were evaluated according to bacterial groups. Significant associations were observed for 11 of the 16 tested antibiotics (p < 0.001). Klebsiella spp. showed high resistance rates to ceftriaxone (93.2%), cefotaxime (94.6%), ceftazidime (93.2%), levofloxacin (87.8%), and imipenem (78.4%). Pseudomonas aeruginosa demonstrated high resistance to co-trimoxazole (87.5%) and imipenem (77.5%), while Acinetobacter spp. showed resistance to piperacillin-tazobactam (66.7%). Staphylococcus spp. remained susceptible to most tested agents except ampicillin-sulbactam (79.5%).
Conclusion: The phenotypic antimicrobial resistance patterns identified in this study provide epidemiological baseline data to support antimicrobial stewardship, optimize empirical therapy, and strengthen infection prevention and control strategies in healthcare settings.