TRANSMISSION OF NOSOCOMIAL INFECTIONS VIA THE ULTRASOUND PROBE AND GEL- in vivo and in vitro study.

Abstract

Transmission of diseases may occur via the ultrasound probes as they are used to scan a large number of patients every day. This may especially be a problem with those patients who are immunocompromised and those with breaks in the skin. This study was to try and ascertain if the ultrasound probe and coupling agent can act as a vector in the transmission of nosocomial infection for patients with no break in the skin and to determine a cheap,efficient and cost-effective way of preventing transmission. The ultrasound probes were cleaned before every session and between patients with paper towel. At the end of the session the ultrasound probes from two ultrasound machines i.e. three probes were swabbed and then transferred to the Medical Microbiology Department where they were plated and cultured. The probes were inoculated with an ultrasound gel (Aquasonic, NJ) contaminated with Staphylococcus aureus and then cleaned with a dry paper towel, wet paper towel and chlorhexidine solution. The probes were swabbed and cultured. In addition plates of agar were inoculated with a confluent growth of Staphlococcus aureus and then half the plate was covered by the ultrasound gel to see if there was any inhibition of the growth. A total of 12 specimens out of 51 showed growth of Staphylococcus epidermidis.. Cleaning the probe with alcohol did not reveal any growth of Staphylococcus aureus as was the case with the chlorhexidine. The dry paper towel was not very good with 6 of the 7 swabs showing moderate growth and only 1 with minimal growth. The wet paper towel fared better 4 of the 8 swabs showing no growth and 3 showing minimal growth. The ultrasound gel did not inhibit the growth of the Staphylococcus aureus. Unlike other studies there seems to be high rate of transmission with the ultrasound probe and gel and chlorhexidine and alcohol were found to be effective cleaning agents.