Preliminary investigation of bacterial surface contamination in emergency ambulances in South Korea

TL;DR

This study found that while disinfection reduces bacteria in ambulances, some surfaces still have residual contamination, suggesting the need for better cleaning methods and equipment design.

Contribution

The study evaluates disinfection effectiveness in South Korean ambulances and identifies problematic surfaces with residual contamination.

Findings

Bacterial load was highest on ventilation outlets, SpO₂ sensors, and stretcher handles before disinfection.

Disinfection reduced bacterial load but left residual contamination on the SpO₂ sensor and stretcher handle.

Cleaning effectiveness varied by surface geometry, with complex surfaces posing greater challenges.

Abstract

Emergency ambulances are vital in prehospital care but carry a high risk of healthcare-associated infections due to confined spaces, high patient turnover, and brief cleaning intervals. Routine disinfection protocols are in place; however, their effectiveness in South Korean ambulances has not been formally evaluated.

This pre–post observational study examined bacterial contamination on six high-touch surfaces across five operational ambulances in Province G, South Korea. Swabs were collected immediately before and after daily disinfection performed by paramedics. Bacterial load was quantified using colony-forming units (CFUs), and species identification was conducted via 16 S rRNA sequencing. Statistical analyses included paired t-tests, ANOVA, Cohen’s d, and MANOVA to evaluate the cleaning efficacy and contamination patterns.

All six surfaces were contaminated before cleaning, with the highest CFUs recorded on the ventilation outlet (182.6 ± 48.3), SpO₂ sensor (145.2 ± 35.7), and stretcher handle (122.4 ± 22.6). Disinfection significantly reduced bacterial load across all surfaces (p < 0.05), yet residual contamination remained on the SpO₂ sensor (Bacillus velezensis) and stretcher handle (Williamsia muralis). ANOVA revealed significant differences in baseline contamination (F(5,24) = 78.52, p < 0.001), and MANOVA confirmed that cleaning effectiveness varied by surface geometry (Wilks’ Λ = 0.202, p < 0.001).

Manual disinfection significantly lowers bacterial load in ambulances, but residual contamination on complex, high-touch surfaces remains problematic. These findings underscore the need for multimodal disinfection approaches, improved equipment design, and systematic microbial surveillance to enhance EMS infection control standards.

Figures