Bacterial contamination of ultrasound probes at a tertiary referral university medical center.

OBJECTIVE

The purpose of this study was to assess the adequacy of our institution's ultrasound probe-disinfecting protocols, determine compliance with the guidelines, and then implement changes if needed.

MATERIALS AND METHODS

We first assessed the prevalence of bacterial contamination (and thus the potential for bacterial transmission) by swabbing all ultrasound probes (n = 31) in the radiology department and culturing the samples. Next, in conditions simulating the typical work environment, we determined the efficacy of our probe-disinfecting protocols by seeding probes with 10(4)-10(9) CFU/mL of methicillin-resistant Staphylococcus aureus (MRSA), disinfecting the seeded probes with 0.5% accelerated hydrogen peroxide, and then swabbing the disinfected probes to assess for bacterial growth.

RESULTS

Seven of 31 (22.6%) probes were positive for bacterial growth--none of which were endocavity probes (0/4). Four of 14 visibly soiled probes (28.6%) showed bacterial growth, and four of seven probes positive for bacteria (57.1%) were visibly soiled. No MRSA grew after seeding probes with MRSA and then disinfecting with 0.5% accelerated hydrogen peroxide. Sonography guidelines and general disinfecting guidelines were reviewed.

CONCLUSION

Our protocols for disinfecting nonendocavity and endocavity probes are compliant with sonography guidelines and general disinfecting guidelines. Although limited by a small sample size, our study showed that our protocol for disinfecting endocavity probes seems adequate. With a 25.9% bacterial contamination rate for nonendocavity probes, the adequacy of our protocol for disinfecting nonendocavity probes is more debatable; however, this bacterial contamination rate is at the lower end of the values reported in the literature. With the use of an effective disinfectant, education of sonographers, and implemented changes, we hope to decrease bacterial contamination rates and thus decrease the potential for bacterial transmission.