Evaluation of ultraviolet C for disinfection of endocavitary ultrasound transducers persistently contaminated despite probe covers

Abstract

Objective: To determine the rate of bacterial and viral contamination of endocavitary ultrasound probes after endorectal or endovaginal examination with the use of probe covers and to evaluate the antimicrobial efficacy of a disinfection procedure consisting of cleaning with a disinfectant-impregnated towel followed by disinfection with ultraviolet C (UVC) light.

Methods: Endovaginal or endorectal ultrasound examinations were performed for 440 patients in 3 institutions. All probes were covered by a condom or sheath during the examination. For bacterial analysis, 1 swab was applied lengthwise across one-half the surface of the probe just after removal of the probe cover. The second swab was similarly applied over the probe immediately after the end of a 2-step process consisting of cleaning with a towel impregnated with a disinfectant spray and a 5-minute UVC disinfection cycle. Swabs were applied onto plates and incubated for 48 hours. The number of colony-forming units was counted, and organisms were identified. A similar protocol was used for viral detection of Epstein-Barr virus, human cytomegalovirus, and human papillomavirus, except that an additional swab was applied along the entire external surface of the probe cover before its removal. Viruses were detected by means of a polymerase chain reaction-based protocol.

Results: After removal of probe covers, contamination by pathogenic bacteria was found for 15 (3.4% [95% confidence interval, 2.0%-5.6%]) of 440 probes, and viral genome was detected on 5 (1.5% [95% confidence interval, 0.5%-3.5%]) of 336 probes. After cleaning with a towel impregnated with a disinfectant spray and disinfecting with UVC light, neither bacterial pathogenic flora nor viral genome was recovered from the probe.

Conclusions: Endocavitary ultrasound probes may carry pathogens after removal of covers under routine conditions. A disinfection procedure consisting of cleaning with a disinfectant-impregnated towel followed by disinfection with UVC may provide a useful method for disinfecting endocavitary ultrasound probes.