Cleaning methods for ultrasound probes

Objective: To determine the effectiveness of three different methods of ultrasound probe cleaning for the prevention of nosocomial infections. Study Design: Experimental study. Place and Duration of Study: Radiology Department, the Aga Khan University Hospital, Karachi and Microbiology Department, JPMC, Karachi, from December 2006 to April 2007. Patients and Methods: A total of 75 culture swabs from ultrasound probes used for sonographic examinations of different body parts of patients were included in the study. Probes were prospectively randomized into three equal groups with 25 probes in each group. Culture was sent before and after using three different techniques of cleaning ultrasound probe, which included sterilized paper towel, 0.9% saline and swipe over with standard bath soap applied on group A (n=25), group B (n=25) and group C (n=25) respectively. Number of Colony Forming Unit (CFU) of bacteria were calculated on standard agar plate to find out the effectiveness of cleaning methods in reducing bacterial count from the ultrasound probe after the procedures. All samples were tested in single microbiology lab by using same bacterial growth media provided by same manufacturer. Kruskall Wallis, Jonchkheere-Terpstra and Wilcoxon sign rank tests were applied to find out statistical significance. Results: There was a significant reduction in bacterial count after applying either of all three cleaning methods for ultrasound probe compared to count on the probes before cleaning (p<0.001), however, soap cleaning method was the most effective in decreasing bacterial count to the minimum level in comparison to other two methods (p<0.001). The overall reduction in pathogenic bacterial count after performing each cleaning method was 45%, 76% and 98% for paper cleaning, normal saline and soap cleaning method respectively. Conclusion: Cleaning ultrasound probe after performing each procedure is a cost-effective practice with potential of reducing nosocomial infections. Soap cleaning technique is the most effective method for reducing bacterial count acquired due to patients' body contact with the ultrasound probes.