Study reveals high levels of bacterial contamination on ultrasound probes in emergency departments

A multi-centre study published in the Journal of Hospital Infection has reported high levels of bacterial contamination on ultrasound probes in emergency departments (EDs) disinfected using water-based and low-level disinfectant wipes. The findings included antibiotic-resistant strains such as methicillin-resistant Staphylococcus epidermidis (MRSE) and methicillin-resistant Staphylococcus aureus (MRSA). A high rate of bacterial contamination was observed across all types of ultrasound probes, regardless of facility type or reprocessing method.

The prospective observational study involved random swabbing of probes used in the ED, followed by analysis of bacterial growth and resistance profiles. Findings revealed that bacterial contamination, after patient examination but before reprocessing, was prevalent across the three different hospitals, regardless of the facility type or reprocessing method:

• Overall contamination rates were 74.3%, 88.2%, and 92.2% across the three different hospitals.
• Up to 76.5% of ultrasound probes were contaminated with pathogenic bacteria.
• Resistant strains were identified on nearly one in five probes.
• Blood contamination was also detected on the probes.

Ultrasound probes remained contaminated after reprocessing with water-moistened, ethanol, or quaternary ammonium wipes. Probes cleaned using quaternary ammonium wipes exhibited the highest contamination rate (100%) after reprocessing. Introducing a secondary wiping step with ethanol or sodium hypochlorite reduced contamination rates; however, bacterial contamination remained substantial, affecting approximately 50% of probes.

The study findings highlight potential limitations of water-based and low-level disinfectant wipes for reprocessing ultrasound probes. The authors noted several potential factors contributing to the high bacterial contamination rates in the EDs, including

• the absence of standardised disinfection protocols,
• time constraints,
• inadequate decontamination practices, and
• probe design features (e.g. grooves or depressions), that may have presented challenges in achieving thorough disinfection.

To help mitigate these risks, the authors advocate for improved cleaning protocols and standardized disinfection procedures.

Read the full study here:

Yamanaka, T., Yamamoto, R., Yajima, K., et al. Bacterial contamination of ultrasound probes in emergency departments: a multi-centre observational study. Journal of Hospital Infection. 2025;163:23–29. https://doi.org/10.1016/j.jhin.2025.03.017