Is Ultrasound Gel a Reservoir for Bacterial Pathogens? Results from a Tertiary Care Vascular Laboratory

Abstract

Purpose

We sought to determine whether refilling and heating of ultrasound gel bottles promotes bacterial colonization.

Methods

The study took place in a busy, university hospital–based vascular laboratory that performs approximately 300 studies per month. Six heated gel bottles, labeled A through F, along with two random bottles, were refilled with ultrasound gel, heated, and cultured weekly for 12-weeks. Control cultures were collected from clean, empty ultrasound gel bottles, a sterile pack of ultrasound gel, and a 5-liter bulk container of ultrasound gel. Of these, approximately 5% were performed on patients with bacterial isolation precautions.

Results

A total of 104 cultures was collected and analyzed for bacterial growth. Of these, 12 (12%) were positive. Propionibacterium species were present in six isolates (6%), diphtheroids in two isolates (2%), Staphylococcus species (coagulase negative) in one isolate (1%), Staphylococcus aureus in one isolate (1%), Micrococcus species in one isolate (1%), and anaerobic gram-positive cocci in one isolate (1%). All positive cultures were sporadic and did not persist throughout the sampling period. Initial control samples of the new gel bottles, sterile gel, and the 5-liter bulk container were negative for bacterial growth.

Conclusions

The isolation of pathogenic organisms from ultrasound gel is uncommon, even in a hospital environment favoring colonization of bacterial species. This suggests that ultrasound gel may resist the growth and proliferation of organisms and supports our current practice of heating and refilling bottles for 12-weeks. However, this study did not address the long-term colonization of gel bottles.