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

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

Ambulance contamination, Infection prevention, Emergency medical services, Bacterial persistence,
Disinfection efficacy, Bacillus velezensis, Williamsia muralis, EMS infection control

Abstract
Background 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.
Methods 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.
Results 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).
Conclusions 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.
Keywords Ambulance contamination, Infection prevention, Emergency medical services, Bacterial persistence,
Disinfection efficacy, Bacillus velezensis, Williamsia muralis, EMS infection control

Seoul-Hee Nam1

, Hyeon-Ji Lee2* and Mi-young Choi2

https://doi.org/10.1186/s12245-025-01083-z

2026

peri irawan

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