Introduction: Healthcare-associated infections (HAIs), particularly in dialysis units, remain a significant challenge due to the frequent use of invasive devices and the immunocompromised status of patients. Among the most concerning pathogens is Staphylococcus aureus , known for its multidrug resistance and biofilm-forming capacity. This study aimed to investigate the antibiofilm effects of ethanol, chlorhexidine, and EDTA, individually and in combination, against S. aureus isolates from hospital carriers in the dialysis department of Qazvin teaching hospitals, Qazvin, Iran. Methods: A total of 400 samples were collected from nasal cavities, fingernails, patient beds, and dialysis machines. Isolates were identified by biochemical tests and PCR. Antibiotic susceptibility was evaluated via disk diffusion and E-test, with mupirocin resistance determined by mupA and mupB detection. Biofilm formation was assessed using the microtiter plate assay with crystal violet staining. The antimicrobial and antibiofilm activities of a combined solution of chlorhexidine, ethanol, and EDTA were analyzed using broth microdilution and scanning electron microscopy (SEM). Results: 70 S. aureus isolates were analyzed for antibiotic resistance and biofilm formation. High resistance rates were observed to ciprofloxacin (62.8%), doxycycline (57.1%), and tetracycline (54.2%), while mupirocin resistance was detected in 4.2% of isolates ( mupA positive). Multidrug resistance (MDR) was found in 68.6% of isolates. Strong biofilm formation was observed in 90% of isolates and was significantly associated with MDR. The combination of chlorhexidine and EDTA exhibited potent antibiofilm activity (FICI ≤ 0.5), with SEM imaging confirming disruption of biofilm structure and bacterial cell integrity. Conclusion: Our findings indicate a high prevalence of multidrug-resistant and strong biofilm-producing S. aureus in dialysis units. Among the tested disinfectant combinations, chlorhexidine in combination with EDTA demonstrated substantial antibiofilm and antimicrobial effects, whereas EDTA and ethanol alone showed no significant activity. These results highlight the potential of synergistic disinfectant combinations to disrupt biofilm structures and suggest the need for further studies to evaluate their applicability in clinical settings. Keywords: Staphylococcus aureus , biofilm formation, dialysis units, ethanol, chlorhexidine
Mohammadi et al. (Wed,) studied this question.