Bacteriology of Ultrasound Probes and the Antibacterial Efficacy of Decontaminants Used for Probes in a Tertiary Care Hospital

Abstract

BACKGROUND Nosocomial infections are one of the leading causes of death with considerable economic costs in the form of prolonged stay, loss of work hours, increased use of drugs, need for isolation, and drugs. Diagnostic equipment is used for the diagnosis, risk assessment, monitoring of disease or response to treatment for outpatient or inpatient in emergency or as a routine procedure. Ultrasound (US) is one of the most commonly used diagnostic equipment from nearly half a century. With the increasing use of ultrasound in medical diagnosis, the risk of infections via the ultrasound probe, couch, or gel from one patient to another patient is on the rise. Ultrasound equipment has been investigated to determine its role in cross infection as these devices come into direct contact with patients and sonographers during scanning procedures. We wanted to assess the microbiological flora of the ultrasound equipment used for non-invasive examinations and assess the efficacy of decontamination regimes currently used for ultrasound equipment. METHODS Swabs from 6 ultrasound machines were taken 15 times over a 3-month duration. Swabs were collected from the surface of the probe, keyboard, gel and probe holder using sterile swab soaked in thioglycolate broth. Swabs were inoculated on Blood agar and MacConkey agar at 37 o C for 24 hours. The isolated organisms were identified by standard microbiological techniques. The protocol of decontamination of the ultrasound equipment was noted. The data was then analysed as number and percentage. RESULTS A total of 80 swabs were taken from four ultrasound machines. Sixty swabs (70%) did not grow any organisms out of the total 80 swabs. Twenty swabs (30%) grew 23 organisms, out of which 3 swabs grew two organisms. Swabs collected from the gel grew the most number of organisms. Pseudomonas species was the most common organism isolated followed by Klebsiella species. CONCLUSIONS Due to increase in the patient load and ultrasound being used more commonly in day to day practice for diagnosis as well as prognosis, a routine methodology needs to be followed for the patient safety. Protocol for ultrasound equipment decontamination as well as regular swab culture has to be framed to prevent nosocomial infections.