Can diagnostic ultrasound scanners be a potential vector of opportunistic bacterial infection?

Ultrasound examinations are recognised as being safe. The greatest epidemiological threat during the performance of examination is the transfer of pathogenic and opportunistic microorganisms between patients and from personnel to patients. Colonization of the skin with opportunistic bacteria of immunocompromised and high risk patients may lead to infection following an ultrasound scan.

To identify and evaluate the strains of bacteria occurring on ultrasound equipment subjected to unexpected control performed by a local infectious diseases control team. We assumed that transducers, gel holders and gel bottles can be contaminated with normal human skin microflora. The remaining tested parts of the ultrasound equipment could possibly be contaminated with normal human skin microflora and other pathogens.

The swabs were taken from ultrasound scanners located in various hospital settings, from out-patient based radiology scanning rooms to operating theatre, and cultured.

Among all isolated 23% strains were classified as environmental microflora; 8% as strains related to patient's skin contamination; and 13 % strains constituted pathogenic Gram-negative rods.. The remaining strains were classified as opportunistic flora 38%. High prevalence of opportunistic bacteria cultured in our study lead to the modification of the ultrasound cleaning procedures in both institutions and recommendation of the use of antibacterial wipes to clean all parts of ultrasound equipment in contact with patients' skin and examiners.

Contamination not only affects parts of diagnostic equipment placed in direct contact with the patient, but also, those surfaces that only medical personnel have had contact with.