Identification and Assessment of Microbial Contamination by <i>Staphylococcus aureus</i> on Clinical Surfaces at Zanjan Dental University During the COVID-19 Pandemic

Abstract

Background: Dental unit surfaces can serve as reservoirs for pathogens, potentially leading to cross-infections such as hepatitis, HIV, and COVID-19. Infection control in dental clinics is crucial to minimize contamination risks. Objectives: The present study aimed to assess microbial contamination and identify Staphylococcus aureus on clinical surfaces at Zanjan Dental University during the COVID-19 pandemic. Methods: This cross-sectional study was conducted over six months. Twelve enclosed active dental units in the restorative, endodontics, pediatrics, oral surgery, and prosthetics departments were examined during peak student activity hours (10:00 AM - 12:00 PM). Samples were collected midweek from four surfaces: Headrest, light arm, cabin entrance, and sidewall of the isolation cubicle. Sterile cotton swabs moistened with sterile saline were used for sampling. The collected samples were cultured on blood agar and mannitol salt agar to assess microbial load and identify S. aureus. Incubation was performed at 37°C for 24 hours. Data were analyzed using SPSS Statistics release 27.0.1, with statistical significance set at P < 0.05. Results: The mean colony-forming units (CFU) of S. aureus on mannitol salt agar before and after working hours were 0.14 CFU/cm2 (8.3%) and 1.04 CFU/cm2 (25%), respectively (P = 0.09). According to previous studies, CFU levels exceeding 0.25 - 0.5 CFU/cm2 are considered potentially hazardous in clinical settings. The total microbial load on blood agar also increased from 63.72 to 117.06 CFU/cm2 (P = 0.41). The highest S. aureus contamination was observed in the restorative department, while the prosthetics department had the highest overall microbial load. Conclusions: Our findings indicate that microbial contamination of dental units exceeded recommended thresholds. We recommend implementing UV-C disinfection of high-touch surfaces and mandating hourly surface wiping with 70% ethanol during peak hours. These interventions may help reduce contamination risks and improve infection control practices.