Bacterial contamination of semi-critical equipment in prehospital emergency ambulances in Ilam province, Iran: a descriptive survey with exploratory laboratory findings

Abstract Given the working environment and conditions of prehospital emergency personnel and their contact with patients, the community, hospitals, and other healthcare workers, ambulance environments and equipment are prone to contamination and subsequent transmission to patients and the community. This study primarily aimed to describe bacterial contamination of semi-critical equipment in prehospital emergency ambulances in Ilam province, Iran. As an exploratory secondary component, growth-inhibitory activity of two commonly used disinfectants (Deconex 53 Plus and Sayasept HI) against the isolated organisms was assessed using a disk diffusion assay. This semi experimental study was conducted on semi-critical equipment in ambulances belonging to 30 emergency centers. Using convenience sampling, four semi-critical items (laryngoscopes, Magill forceps, oxygen masks and connectors, and AMBU bags) were randomly selected from each ambulance. Samples were collected by sterile swabs moistened with brain heartinfusion (BHI) broth from standardized high contact surfaces. Bacteria were identified by Gram staining, selective/differential media, and standard biochemical tests. As an exploratory analysis, susceptibility to 2% solutions of Sayasept HI and Deconex 53 Plus was assessed by the disk diffusion method on Mueller-Hinton agar. Statistical analysis was performed using SPSS version 25 (two-sided independent t-tests after normality assessment). A total of 120 samples were collected, of which 74 (61.7%) yielded positive cultures. Staphylococcus epidermidis was the most frequently isolated organism (31/120, 25.8% of all samples; 41.9% of positive cultures). The highest proportion of positive cultures among the four equipment types was observed for laryngoscopes (21/30, 70.0% of laryngoscopes; 28.4% of all positive cultures). In exploratory disk diffusion testing, the mean inhibition zone diameter produced by Deconex 53 Plus was larger than that produced by Sayasept HI for the overall set of isolates and across equipment types and organism groups (all p < 0.05). These findings must be interpreted strictly as laboratory growth-inhibition observations and do not constitute evidence of comparative practical disinfectant efficacy. Semi-critical equipment in the studied ambulances showed a substantial rate of bacterial contamination, predominantly by coagulase-negative staphylococci. The exploratory laboratory disk diffusion results (larger zones with Deconex 53 Plus) are influenced by both antimicrobial activity and diffusion characteristics of the active compounds and do not measure bactericidal efficacy under practical use conditions (organic load, contact time, surface material, etc.). Therefore, these in vitro findings alone do not justify prioritization of one product over the other for routine ambulance disinfection. Standardized bactericidal tests (e.g., according to EN 13727 / EN 14885) under simulated use conditions are required before any clinical recommendations regarding disinfectant selection can be made. The primary contribution of this study is the descriptive contamination data. Therefore, these in vitro findings alone do not justify prioritization of one product over the other for routine ambulance disinfection and should be regarded solely as exploratory laboratory observations.