Impact of Fixed Orthodontic Appliances on Staphylococcus aureus and Candida albicans

Objective: This study investigated the prevalence of salivary S. aureus and C. albicans in patients with fixed orthodontic appliances and assessed their resistance profiles to selected antibacterial and antifungal agents over three-time intervals. Material and Methods: A prospective cohort of 40 patients (20 males, 20 females) undergoing orthodontic treatment was followed across three time points: baseline (T0), two weeks post-application (T1), and four weeks post-application (T2). Unstimulated saliva samples were collected and cultured for microbial identification. Organisms were confirmed via Vitek biochemical testing. Antimicrobial susceptibility was determined using the disc diffusion method against six antibacterial and six antifungal agents. Data were analyzed using two way-ANOVA and chi-square tests. Results: Among the 80 total samples analyzed, 73.75% were positive for S. aureus and/or C. albicans. S. aureus was most prevalent, with Clindamycin and Vancomycin showing the strongest antibacterial activity. Resistance to Amoxicillin, Ampicillin, and Erythromycin was notably high. For C. albicans, Fluconazole and Amphotericin B demonstrated the highest efficacy, while Clotrimazole and Nystatin showed poor inhibition. Resistance patterns might suggest a biofilm-associated microbial adaptation and reduced susceptibility over time. Conclusion: Fixed orthodontic appliances significantly influence oral microbial ecology by facilitating colonization of resistant strains of S. aureus and C. albicans. The findings highlight the importance of routine microbial surveillance and personalized antimicrobial strategies in orthodontic care to mitigate infection risks and manage emerging resistance.