Outbreaks and deaths caused by infections from ultrasound procedures
In recent years, ultrasound use has proliferated across various clinical departments with many invasive procedures now being performed under ultrasound guidance (Figure 1). Ultrasound guided procedures such as line placements and biopsies require the use of sterile gel and appropriately reprocessed ultrasound probes.
In September 2017, 2 patients died from septic shock following an outbreak traced to contaminated ultrasound gel used in central line placements. The source was confirmed by isolation of the same bacterium Burkholderia cepacia from patient blood cultures. The outbreak involved 14 patients in total and was published in the Journal of Hospital Infection. A few months prior, the Australian Therapeutic Goods Administration (TGA) received reports of an outbreak of Burkholderia cenocepacia in 11 patients who had undergone ultrasound guided central line placements or ultrasound-guided fluid drainages. Investigations similarly identified contaminated ultrasound gel as the source and the TGA recalled the gel product. This investigation was published in the American Journal of Infection Control. Several publications now demonstrate that the inadvertent use of contaminated ultrasound gel in ultrasound guided procedures can result in serious outbreaks. There have been several alerts issued in the past by regulatory agencies including the CDC, FDA and Health Canada on infection risk with contaminated ultrasound gels used in ultrasound guided interventional procedures. These are detailed along with other outbreaks in Appendix 1.
While these cases clearly demonstrate that contaminated gel can lead to infections, they also underscore the need to ensure that the ultrasound probe is appropriately reprocessed prior to use in these procedures.
As the probe and gel may contact the sterile tissue of the puncture site the ultrasound probe is classified as a critical device and must undergo sterilization or high-level disinfection and be used with a sterile sheath (Figure 2).
As with many infection control issues, the presence of contaminated gel in these outbreaks has allowed infections to be traced and attributed to the ultrasound procedure. Causality can be established based on the same strain of organism being isolated from each patient and from the gel itself. Such situations provide a window into what is likely a broader problem. The role of ultrasound probes and gel in central line associated bloodstream infections (CLABSI) is likely underappreciated as it is difficult to link a particular infection to the ultrasound process versus other steps in the line placement procedure. While ultrasound-guided invasive procedures represent significant risk, endocavitary ultrasound procedures have also been associated with serious infections. The Medicines and Healthcare Products Regulatory Agency (UK) issued an alert in 2012 for all healthcare facilities to review their decontamination policies and procedures related to reusable transoesophageal echocardiography, transvaginal and transrectal ultrasound probes. This was in immediate response to a patient death from hepatitis B transmission from a procedure with an improperly reprocessed transoesophageal echocardiography probe.5 A further case of a patient contracting hepatitis C infection after undergoing transrectal prostate biopsy was reported in 2013. In this case the source of infection was suspected to be the use of improperly reprocessed ultrasound probes or needle guides that had biofilms deposited on them.
Given the widespread and broadening use of ultrasound, it is important to review standard procedures to ensure that they are consistent with the latest guidelines for use of ultrasound probes. Guidelines in USA, Canada, UK and Australia all require a minimum of HLD or sterilization for endocavitary procedures contacting mucous membranes and ultrasound guided surface probe procedures where there is a risk of contact with sterile tissue. These requirements apply even if the probe is used with a sterile sheath. For further information download the Clinical Bulletin.