# 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.

## Key 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.