Infectious risk of endovaginal and transrectal ultrasonography: systematic review and meta-analysis

Recommendations for the Cleaning of Endocavity Ultrasound Transducers Between Patients

The COVID-19 pandemic highlighted the importance of infection prevention and control measures for all medical procedures, including ultrasound examinations. As the use of ultrasound increases across more medical modalities, including point-of-care ultrasound, so does the risk of possible transmission from equipment to patients and patients to patients. This is particularly relevant for endocavity transducers, such as trans-vaginal, trans-rectal and trans-oesophageal, which could be contaminated with organisms from blood, mucosal, genital or rectal secretions. This article proports to update the WFUMB 2017 guidelines which focussed on the cleaning and disinfection of trans-vaginal ultrasound transducers between patients.

The use of ultraviolet light generated from light-emitting diodes for the disinfection of transvaginal ultrasound probes

Transvaginal ultrasound probes (TVUS) are used for several gynecological procedures. These need to be disinfected between patient use. In the current study we examine whether UVC delivered using light emitting diodes for 90 seconds can provide sufficient disinfection efficacy. A new UVC device that delivers UVC radiation at 265nm-275nm for 90 seconds was used. TVUS probes were swabbed before and after use in an in vitro fertilization clinic. Microbes on the swabs were cultured and identified. In addition, the ability of the UVC device to provided repeated high-level disinfection was analysed by deliberately contaminating probes with spores of Bacillus subtilis and then performing the UVC disinfection and bacterial culture. 50% of probes were contaminated with bacteria, most commonly Bacillus sp., directly after in vivo use. Whereas 97% were sterile after UVC disinfection for 90 seconds. The UVC treatment resulted in no growth of B. subtilis spores after each of five repeated contaminations with 5-9 x 107 spores on the probes. This study has found that UVC delivered via light emitting diodes for only 90 seconds can produce high level disinfection of transvaginal probes.

Endocavity Ultrasound Transducers: Why High-Level Disinfection Is Necessary

As a medical imaging modality, ultrasound is used by a wide cross-section of practitioners including radiologists, obstetricians, gynecologists, gastroenterologists, urologists and cardiologists. The increasing popularity of ultrasound as a diagnostic tool is due not only to the ease of use and portability of systems, but also to the perceived safety aspect of the examination. This latter point needs to be examined. As with any reusable medical device, the ultrasound transducer, also known as a probe, could potentially be a vector for the transmission of pathogenic viruses and fungi between patients if not correctly disinfected after each use. This transmission risk is magnified for an endocavity transducer that has come in contact with the vagina, anal canal or oral cavity, as it could be contaminated with organisms transmitted by blood or mucosal, genital or rectal secretions. Based on the Spaulding system, transducers that come in contact with mucous membranes are classified as semi-critical devices that require high-level disinfection (HLD) after each patient procedure. This HLD process should eliminate all microorganisms except high numbers of bacterial endospores. Only a small number of countries worldwide have implemented transducer reprocessing guidelines that adhere to the Spaulding classification and recommend HLD for endocavity transducers. Overall, there is a lack of conformity among global health agencies regarding the use of HLD for endocavity transducers. This is primarily due to the perception that the infection transmission risk is negligible and that if an endocavity transducer has been covered with a single-use sheath for the procedure, then low-level disinfection provides sufficient protection against pathogen transmission. The objective of this study was to review the published risk of infection transmission from endocavity transducers. By highlighting the outbreaks and case reports that implicate pathogen transmission from transducers, we posit that HLD should be a global standard of practice for the reprocessing of endocavity transducers. It requires substantial time for national health administrations to develop and legislate new recommendations, and for practice changes to be accepted and implemented by healthcare providers. We recommend that Joint Commission International (JCI) and other equivalent organizations enforce the use of HLD of endocavity ultrasound transducers during their accreditation reviews.

Inactivation of Polyomavirus SV40 as Surrogate for Human Papillomaviruses by Chemical Disinfectants

Human papillomaviruses (HPV) are non-enveloped DNA viruses infecting cutaneous and mucosal squamous epithelia. Sexually transmitted HPV-types that are carcinogenic to humans such as HPV16 can induce cervical and other anogenital cancers. Virus transmission through fomites such as inadequately disinfected gynecological equipment is a further potential transmission route. Since HPV cannot be easily grown in cell culture, polyomavirus SV40 has been used as a surrogate virus when testing the virucidal activity of chemical disinfectants. So far, studies that have compared the virucidal activity of different disinfectants against HPV and SV40 are lacking. Here, we evaluated the susceptibility of HPV16 pseudovirus and SV40 to seven active biocidal substances using quantitative suspension tests. Ethanol, glutaraldehyde (GTA), dodecyldipropylentriamin (DPTA), and ortho-phthalaldehydes (OPA) were able to reduce the infectivity of HPV16 pseudovirus >99.99% after 5 min. In contrast, isopropanol, peracetic acid (PAA), and quaternary ammonium compounds with alkylamines (QAC) only led to a slight or no reduction in infectivity. Concerning SV40, only GTA (60 min contact time), PAA, and OPA had virus-inactivating effects. In conclusion, the virucidal activity of three out of seven disinfectants tested was different for HPV16 pseudovirus and SV40. In this study, SV40 was shown to be a reliable surrogate virus for HPV when testing isopropanol-, GTA-, QAC-, and OPA-based disinfectants.

[Disinfection of transvaginal ultrasound probes-A current overview of methods and recommendations]

Disinfection of ultrasound probes, especially of transvaginal probes, has been under discussion during recent years and there have been several new regulations and recommendations as well as trends in the field of disinfection methods. This article provides a review and summary of the current state of knowledge.

Minimizing cross transmission of SARS-CoV-2 in obstetric ultrasound during COVID-19 pandemic

Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2)-associated infection (COVID-19) is affecting populations worldwide. This statement may serve as guidance for infection prevention and safe ultrasound practices during the COVID-19 pandemic. Ultrasound examination is a fundamental part of obstetric care, yet it is a potential vector for transmission of SARS-CoV-2. Decontamination methods should always be implemented for ultrasound equipment, especially in the presence of suspected or confirmed COVID-19 cases. There must be workflow policies to protect pregnant women and healthcare providers from nosocomial cross transmission of SARS-CoV-2. Cleaning and disinfecting of equipment must be in accordance with their potential of pathogen transmission. Consider using telemedicine and genetic technologies as an adjunctive of obstetric ultrasound to reduce patient crowding. Patient triage and education of healthcare providers of infection prevention are crucial to minimize cross contamination of SARS-CoV-2 during obstetric ultrasound.

Analysis of the integrity of ultrasound probe covers used for transvaginal examinations

BACKGROUND

Ultrasound probe covers should be used for any ultrasound procedure where there is contact with body fluids or mucous membranes. The type and quality of probe covers used in clinical practice differ widely and studies in the early 1990s showed that condoms were more superior for use with transvaginal examinations than commercial probe covers. Since then, although products have changed, there have been no further studies to assess the breakage rate of different probe covers. The objectives of this study were to assess the integrity of the most commonly used probe covers for transvaginal ultrasound examinations under clinical conditions and report the breakage rate.

METHODS

The study was conducted in public and private hospitals and private practices. A total of 500 covers for each of 10 brands of commercial covers and condoms (latex and latex free) were distributed to ultrasound practitioners. The transvaginal ultrasound examination practice was unchanged except that all covers were placed in a container for assessment instead of discarding post ultrasound examination. All covers were collected and subjected to a water leak test. Covers that broke upon deployment onto the ultrasound probe prior to the ultrasound examination were recorded. All covers that were broken or had microtears or leaks were recorded as well as photographed. Statistical analysis was performed along with Chi-squared analysis of the data and significance considered at P < 0.05.

RESULTS

None of the commercial covers broke upon deployment onto the ultrasound probe prior to ultrasound examination. A total of 5000 probe covers were examined post-transvaginal ultrasound examinations. The breakage rate for condoms ranged from 0.4% to 13% and for commercial covers 0-5%. Statistical analysis of the data by comparison of p-values revealed that the best performing group were the commercial non-latex probe covers and worst performing group were the non-latex condoms.

CONCLUSION

The breakage rates for commercial covers were not as high as previously reported and do not break upon deployment onto the ultrasound probe. This is the first comprehensive study that thoroughly evaluated the integrity of commercial covers and condoms used for transvaginal ultrasound examination in a clinical setting, with regards to brand, numbers and types of covers assessed.

Reprocessing semicritical items: Outbreaks and current issues

Semicritical medical devices are defined as items that come into contact with mucous membranes or nonintact skin (eg, gastrointestinal endoscopes, endocavitary probes). Such medical devices require minimally high-level disinfection. As many of these items are temperature sensitive, low-temperature chemical methods must be used rather than steam sterilization. Strict adherence to current guidelines is required as more outbreaks have been linked to inadequately cleaned or disinfected endoscopes and other semicritical items than any other reusable medical devices.

CLEAR: A Novel Approach to Ultrasound Equipment Homeostasis

Protocols for the sanitation and maintenance of point-of-care ultrasound (US) equipment are lacking. This study introduces the CLEAR protocol (clean, locate, energize, augment supplies, and remove patient identifiers) as a tool to improve the readiness of US equipment, termed US equipment homeostasis. The state of US equipment homeostasis in the emergency department of a single academic center was investigated before and after implementing this protocol, with an improvement in outcomes. These findings demonstrate that the CLEAR protocol can improve US homeostasis. CLEAR can function as a teaching tool to promote homeostasis as well as a checklist to assess compliance.

Medical Ultrasound Disinfection and Hygiene Practices: WFUMB Global Survey Results

As ultrasound technology rapidly evolves and is used more frequently in every area of medical diagnosis and treatment, it may be overlooked as a potential vector in the transmission of a health care-associated infection. A survey on disinfection and hygiene practice in medical ultrasound was disseminated via the World Federation for Ultrasound in Medicine and Biology (WFUMB) to its six member federations and associated ultrasound societies globally. One thousand twenty-nine responses were obtained across a broad range of ultrasound practitioners. A total of 76% of respondents used transducer covers every time to scan open wounds and 71% when blood and bodily fluids were present or for an interventional procedure. Approved high-level disinfectants are not always used, even when blood comes into contact with the transducer or after endocavity scans. Alcohol-based wipes were used by many respondents to clean both external transducers and endocavity transducers. Open-ended responses indicated that a large caseload hindered the time required for cleaning and that access to clear guidelines would be beneficial. Global survey results indicate that some users do not comply with disinfection practice, and there is a gap in knowledge on basic infection prevention and control education within the ultrasound unit. As the infectious status of a patient is not often disclosed prior to an ultrasound examination, training in suitable protocols for the cleaning and disinfection of ultrasound equipment is imperative to mitigate the risk of potential infection.

A new sampling algorithm demonstrates that ultrasound equipment cleanliness can be improved

BACKGROUND

Australia has established guidelines on cleaning for reusable ultrasound probes and accompanying equipment. This is a preliminary study investigating cleanliness standards of patient-ready ultrasound equipment in 5 separate health care facilities within a major city.

METHODS

The cleanliness was assessed using rapid adenosine triphosphate (ATP) testing used with a sampling algorithm which mitigates variability normally associated with ATP testing. Each surface was initially sampled in duplicate for relative light units (RLUs) and checked for compliance with literature recommended levels of cleanliness (<100 RLUs). Triplicate sampling was undertaken where necessary. A cleaning intervention step (CIS) followed using a disposable detergent wipe, and the surface was retested for ATP.

RESULTS

There were 253 surfaces tested from the 5 health care facilities with 26% (66/253) demonstrating either equivocal or apparent lack of cleanliness. The CIS was conducted on 148 surfaces and demonstrated that for >91% (135/148) of surfaces, the cleaning standards could be improved significantly (P > .001). For 6% (9/148) of devices and surfaces, the CIS needed to be repeated at least once to achieve the intended level of cleanliness (<25 RLUs).

CONCLUSIONS

This study indicates that ATP testing is an effective, real-time, quality assurance tool for cleanliness monitoring of ultrasound probes and associated equipment.

Risk of infection following semi-invasive ultrasound procedures in Scotland, 2010 to 2016: A retrospective cohort study using linked national datasets

INTRODUCTION

Outbreak reports indicate a risk of cross-infection following medical procedures using semi-invasive ultrasound probes. This study aimed to evaluate the risk of infection, using microbiological reports and antibiotic prescriptions as proxy measures, associated with semi-invasive ultrasound probe procedures, including transoesophageal echocardiography, transvaginal and transrectal ultrasound.

METHODS

Patient records from the Electronic Communication of Surveillance in Scotland and the Prescribing Information System were linked with the Scottish Morbidity Records for cases in Scotland between 2010 and 2016. Three retrospective cohorts were created to include inpatients/day-cases and outpatients in the following specialties: Cardiology, Gynaecology and Urology. Cox regression was used to quantify the association between semi-invasive ultrasound probe procedures and the risk of positive microbiological reports and community antibiotic prescriptions in the 30-day period following the procedure.

RESULTS

There was a greater hazard ratio of microbiological reports for patients who had undergone transoesophageal echocardiography (HR: 4.92; 95% CI: 3.17-7.63), transvaginal (HR: 1.41; 95% CI: 1.21-1.64) and transrectal ultrasound (HR: 3.40; 95% CI: 2.90-3.99), compared with unexposed cohort members after adjustment for age, co-morbidities, previous hospital admissions and past care home residence. Similarly, there was a greater hazard ratio of antibiotic prescribing for those who had received transvaginal (HR: 1.26; 95% CI: 1.20-1.32) and transrectal (HR: 1.75; 95% CI: 1.66-1.84) ultrasound, compared with unexposed patients.

CONCLUSION

Analysis of linked national datasets demonstrated a greater risk of infection within 30 days of undergoing semi-invasive ultrasound probe procedures, using microbiological reports and antibiotic prescriptions as proxy measures of infection.

APSIC guidelines for disinfection and sterilization of instruments in health care facilities

Background

The Asia Pacific Society of Infection Control launched its revised Guidelines for Disinfection and Sterilization of Instruments in Health Care Facilities in February 2017. This document describes the guidelines and recommendations for the reprocessing of instruments in healthcare setting. It aims to highlight practical recommendations in a concise format designed to assist healthcare facilities at Asia Pacific region in achieving high standards in sterilization and disinfection.

Method

The guidelines were revised by an appointed workgroup comprising experts in the Asia Pacific region, following reviews of previously published guidelines and recommendations relevant to each section.

Results

It recommends the centralization of reprocessing, training of all staff with annual competency assessment, verification of cleaning, continual monitoring of reprocessing procedures to ensure their quality and a corporate strategy for dealing with single-use and single-patient use medical equipment/devices. Detailed recommendations are also given with respect to reprocessing of endoscopes. Close working with the Infection Prevention & Control department is also recommended where decisions related to reprocessing medical equipment/devices are to be made.

Conclusions

Sterilization facilities should aim for excellence in practices as this is part of patient safety. The guidelines that come with a checklist help service providers identify gaps for improvement to reach this goal.

Electronic supplementary material

The online version of this article (10.1186/s13756-018-0308-2) contains supplementary material, which is available to authorized users.

Infection prevention and control in ultrasound - best practice recommendations from the European Society of Radiology Ultrasound Working Group

OBJECTIVES

The objective of these recommendations is to highlight the importance of infection prevention and control in ultrasound (US), including diagnostic and interventional settings.

METHODS

Review of available publications and discussion within a multidisciplinary group consistent of radiologists and microbiologists, in consultation with European patient and industry representatives.

RECOMMENDATIONS

Good basic hygiene standards are essential. All US equipment must be approved prior to first use, including hand held devices. Any equipment in direct patient contact must be cleaned and disinfected prior to first use and after every examination. Regular deep cleaning of the entire US machine and environment should be undertaken. Faulty transducers should not be used. As outlined in presented flowcharts, low level disinfection is sufficient for standard US on intact skin. For all other minor and major interventional procedures as well as all endo-cavity US, high level disinfection is mandatory. Dedicated transducer covers must be used when transducers are in contact with mucous membranes or body fluids and sterile gel should be used inside and outside covers.

CONCLUSIONS

Good standards of basic hygiene and thorough decontamination of all US equipment as well as appropriate use of US gel and transducer covers are essential to keep patients safe.

MAIN MESSAGES

• Transducers must be cleaned/disinfected before first use and after every examination. • Low level disinfection is sufficient for standard US on intact skin. • High level disinfection is mandatory for endo-cavity US and all interventions. • Dedicated transducer covers must be used for endo-cavity US and all interventions. • Sterile gel should be used for all endo-cavity US and all interventions.

Deep Needle Procedures: Improving Safety With Ultrasound Visualization

Promoting patient safety and increasing health care quality have dominated the health care landscape during the last 15 years. Health care regulators and payers are now tying patient safety outcomes and best practices to hospital reimbursement. Many health care leaders are searching for new technologies that not only make health care for patients safer but also reduce overall health care costs. New advances in ultrasonography have made this technology available to health care providers at the patient's bedside. Point-of-care ultrasound assistance now aids providers with real-time diagnosis and with visualization for procedural guidance. This is especially true for common deep needle procedures such as central venous catheter insertion, thoracentesis, and paracentesis.There is now mounting evidence that clinician-performed point-of-care ultrasound improves patient safety, enhances health care quality, and reduces health care cost for deep needle procedures. Furthermore, the miniaturization, ease of use, and the evolving affordability of ultrasound have now made this technology widely available. The adoption of point-of-care ultrasonography has reached a tipping point and should be seriously considered the safety standard for all hospital-based deep needle procedures.

[Infection control practices while performing prostate biopsies in France: A CIAFU survey]

In 2008, the French Public Health Committee admitted that associating ultrasound probe protection, and related precautions, and low-level disinfection would be equivalent to the intermediate level disinfection. In 2010, the French Urology Association (AFU) updated guidelines regarding trans-rectal prostate biopsies, namely preventive measures related to cross-transmission of infections. We report an evaluation of compliance to them, driven in 2016 by AFU's infection committee. Although not recommended, almost one third of the urologists still perform biopsies under general anesthesia, and two thirds of them ask for a urine culture before biopsies. Several improvements are still needed: sterilization of needle guide should always be done when not of single use, the ultrasonography gel should be sterile, probes protection should be EC labeled, and compliance to probe processing between two patients should increase. Most of urologists happened to experience blood or feces contamination of probes. Less than half of probes are entirely floodable, and when intermediate level disinfection is done, glutaraldehyde is still referred as disinfectant by one third of the urologists.

LEVEL OF EVIDENCE

4.

Guidelines for Cleaning Transvaginal Ultrasound Transducers Between Patients

The purpose of this article is to provide guidance regarding the cleaning and disinfection of transvaginal ultrasound probes. These recommendations are also applicable to transrectal probes.

Virucidal efficacy of a sonicated hydrogen peroxide system (trophon® EPR) following European and German test methods

Aim: The virucidal efficacy of an automated ultrasound probe disinfector (trophon^® EPR) was evaluated in a three step procedure according to European and German test methods. This system uses sonicated hydrogen peroxide mist (35%) at elevated temperature (50°C) in a closed chamber with control of all parameters within a 7 minute cycle. Methods: In the first step of examination, the peroxide solution was tested in a quantitative suspension assay according to the Guideline of Deutsche Vereinigung zur Bekämpfung der Viruskrankheiten (DVV) e.V. and Robert Koch-Institute (RKI) and in parallel with the European Norm EN 14476 with all test viruses creating a virucidal claim. In the second step, the virucidal efficacy of the hydrogen peroxide solution was evaluated in a hard surface carrier test according to the Guideline of DVV with adenovirus, murine norovirus and parvovirus simulating practical conditions. Finally, the efficacy was evaluated by the automated system using stainless steel carriers inoculated with test virus and positioned at different levels inside the chamber. Results: A ≥4 log₁₀ reduction of virus titre was demonstrated with all methods including carrier tests with murine norovirus, adenovirus, and parvovirus using the automated device. Conclusion: The automated device is able to inactivate test viruses of German and European norms and can therefore claim efficacy against human pathogenic enveloped and non-enveloped viruses. This includes human papillomaviruses which form part of the complete virucidal claim.

Infection prevention and ultrasound probe decontamination practices in Europe: a survey of the European Society of Radiology

OBJECTIVES

Although ultrasound (US) is considered one of the safest imaging modalities, concerns have been raised regarding potential infection transmission risks through US procedures. A survey was undertaken by the European Society of Radiology (ESR) to establish infection prevention and control measures in US and to highlight the importance of good medical practice.

METHODS

An online survey was sent to all 22,000 full ESR members.

RESULTS

The response rate of completed surveys was 4.3 % (946 practitioners, 97 % of which were radiologists, mostly working in larger hospital settings). Among respondents, 29 %, 11 % and 6 % did not disinfect the US probe after every patient when performing standard surface US, endo-cavity US and interventional procedures, respectively. Eleven percent did not always use probe covers for endo-cavity US; for interventional procedures, the proportion was 23 %. A minority used sterile gel sachets in direct patient contact for endo-cavity scans (30 %), and 77.5 % used sterile gel for interventional procedures.

CONCLUSIONS

The survey results highlight a wide range of practices throughout Europe and the need to raise awareness amongst practitioners regarding the importance of infection prevention and control measures. The development of European recommendations encompassing all US examinations, together with education is a priority.

MAIN MESSAGES

• Transmission of infection through ultrasound procedures is possible. • There is a wide range of ultrasound probe decontamination practices in Europe. • Not all practitioners use probe covers for endo-cavity or interventional ultrasound. • Not all practitioners use sterile gel for internal and invasive procedures. • Currently there are no European recommendations encompassing all US examinations.

A proposal to reduce the risk of transmission of human papilloma virus via transvaginal ultrasound

Three steps must be followed to prevent the transmission of infection via a contaminated transvaginal ultrasound probe: cleaning the probe after every use, high-level disinfection, and covering the probe with a single-use barrier during the examination. There may be critical flaws in at least 2 of these steps as they are currently practiced. First, 2 widely used disinfectants, glutaraldehyde and orthophthalaldehyde, have recently been found to be ineffective at neutralizing human papilloma virus type 16 and type 18. Second, commercial ultrasound probe covers have an unacceptable rate of leakage (8-81%) compared to condoms (0.9-2%). We recommend the use of a sonicated hydrogen peroxide disinfectant system rather than aldehyde-type disinfectants. We recommend that the probe be covered with a condom rather than a commercial probe cover during transvaginal ultrasound examination. Combined with probe cleaning, these 2 steps are estimated to result in an 800 million- to 250 billion-fold reduction in human papilloma virus viral load, which should translate to greatly enhanced patient safety.

Disinfection of transvaginal ultrasound probes in a clinical setting: comparative performance of automated and manual reprocessing methods

OBJECTIVES

Transvaginal and intracavitary ultrasound probes are a possible source of cross-contamination with microorganisms and thus a risk to patients' health. Therefore appropriate methods for reprocessing are needed. This study was designed to compare the standard disinfection method for transvaginal ultrasound probes in Germany with an automated disinfection method in a clinical setting.

METHODS

This was a prospective randomized controlled clinical study of two groups. In each group, 120 microbial samples were collected from ultrasound transducers before and after disinfection with either an automated method (Trophon EPR®) or a manual method (Mikrozid Sensitive® wipes). Samples were then analyzed for microbial growth and isolates were identified to species level.

RESULTS

Automated disinfection had a statistically significantly higher success rate of 91.4% (106/116) compared with 78.8% (89/113) for manual disinfection (P = 0.009). The risk of contamination was increased by 2.9-fold when disinfection was performed manually (odds ratio, 2.9 (95% CI, 1.3-6.3)). Before disinfection, bacterial contamination was observed on 98.8% of probes. Microbial analysis revealed 36 different species of bacteria, including skin and environmental bacteria as well as pathogenic bacteria such as Staphylococcus aureus, enterobacteriaceae and Pseudomonas spp.

CONCLUSIONS

Considering the high number of contaminated probes and bacterial species found, disinfection of the ultrasound probe's body and handle should be performed after each use to decrease the risk of cross-contamination. This study favored automated disinfection owing to its significantly higher efficacy compared with a manual method. Copyright © 2015 ISUOG. Published by John Wiley & Sons Ltd.

Ultrasound scan as a potential source of nosocomial and crossinfection: a literature review

The authors review the main concepts regarding the importance of cleaning/disinfection of ultrasonography probes, aiming a better comprehension by practitioners and thus enabling strategies to establish a safe practice without compromising the quality of the examination and the operator productivity. In the context of biosafety, it is imperative to assume that contact with blood or body fluids represents a potential source of infection. Thus, in order to implement cleaning/disinfection practice, it is necessary to understand the principles of infection control, to consider the cost/benefit ratio of the measures to be implemented, and most importantly, to comprehend that such measures will not only benefit the health professional and the patient, but the society as a whole.

The importance of infection prevention and control in medical ultrasound

Infection control and prevention is critical to delivering safe and high-quality care to patients undergoing sonographic procedures. In Australia comprehensive standards for reprocessing of ultrasound probes are based on the AS/NZS, TGA and ASUM recommendations. These standards align with the US Centers for Disease Control and Prevention recommendations. However compliance to these guidelines is not ideal and there exists an unmet need for refinement of the guidelines relating to specific factors in clinical sonography. Significant microbiological evidence exists reflecting the increased risk of infection transmission specifically through inadequately reprocessed ultrasound probes. Studies have reported > 80% of transvaginal ultrasound probe handles are contaminated with disease causing pathogens since handle disinfection is omitted from standard reprocessing protocols. Significantly, it was recently discovered that widely-used high level disinfectants referred to in guidelines are unable to kill HPV while it is becoming increasingly apparent that attention must be paid to the clinical sonography environment as a potential source of nosocomial pathogens. Ultrasound probe reprocessing guidelines and standards are comprehensive however the challenge is in general awareness and effective implementation into practice. As future research in this area is performed, guidelines will need to be amenable to revision to provide patients with the best standard of care.

Reducing transmission risk through high-level disinfection of transvaginal ultrasound transducer handles

Intracavity ultrasound transducer handles are not routinely immersed in liquid high-level disinfectants. We show that residual bacteria, including pathogens, persist on more than 80% of handles that are not disinfected, whereas use of an automated device reduces contamination to background levels. Clinical staff should consider the need for handle disinfection.

Lesser-known or hidden reservoirs of infection and implications for adequate prevention strategies: Where to look and what to look for

In developing hygiene strategies, in recent years, the major focus has been on the hands as the key route of infection transmission. However, there is a multitude of lesser-known and underestimated reservoirs for microorganisms which are the triggering sources and vehicles for outbreaks or sporadic cases of infection. Among those are water reservoirs such as sink drains, fixtures, decorative water fountains and waste-water treatment plants, frequently touched textile surfaces such as private curtains in hospitals and laundry, but also transvaginal ultrasound probes, parenteral drug products, and disinfectant wipe dispensers. The review of outbreak reports also reveals Gram-negative and multiple-drug resistant microorganisms to have become an increasingly frequent and severe threat in medical settings. In some instances, the causative organisms are particularly difficult to identify because they are concealed in biofilms or in a state referred to as viable but nonculturable, which eludes conventional culture media-based detection methods. There is an enormous preventative potential in these insights, which has not been fully tapped. New and emerging pathogens, novel pathogen detection methods, and hidden reservoirs of infection should hence be given special consideration when designing the layout of buildings and medical devices, but also when defining the core competencies for medical staff, establishing programmes for patient empowerment and education of the general public, and when implementing protocols for the prevention and control of infections in medical, community and domestic settings.

Emergency department ultrasound probe infection control: challenges and solutions

Point-of-care ultrasound (US) has become a cornerstone in the diagnosis and treatment of patients in the emergency department (ED). Despite the beneficial impact on patient care, concern exists over repeat use of probes and the role as a vector for pathogen transmission. US probes are used for various applications, with the level of infection risk, based on the Spaulding Classification, ranging from noncritical with common practice to semicritical with endocavitary probes. To date, the most closely studied organisms are Staphylococcus aureus and human papilloma virus. Current evidence does confirm probe colonization but has not established a causative role in human infection. Based on current literature, US use during invasive procedures remains an infection control concern, but routine use on intact skin does not appear to cause significant risk to patients. Various barrier methods are available, each with indications based on extent of procedure and likelihood of contact with mucosal surfaces. Additionally, chemical cleansing methods have been shown to be effective in limiting probe contamination after use. New technologies utilizing ultraviolet light are available and effective but not widely used in the ED setting. As our understanding of the critical factors in US probe cleaning and disinfection improves, it is important to assess the challenges found in our current practice and to identify potential solutions to improve practices and procedures in infection control across the spectrum of US probe use in various applications in the ED. This article serves as a summary of the current literature available on infection control topics with the utilization of point-of-care US, and discusses challenges and potential solutions to improve the current practice of probe-related infection control.

Impact of vaginal-rectal ultrasound examinations with covered and low-level disinfected transducers on infectious transmissions in france

BACKGROUND

The risk of cross-infection from shared ultrasound probes in endorectal and vaginal ultrasonography due to low-level disinfection (LLD) is difficult to estimate because potential infections are also sexually transmitted diseases, and route of contamination is often difficult to establish. In France, the widely used standard for prevention of infections is through the use of probe covers and LLD of the ultrasound transducer by disinfectant wipes. We performed an in silico simulation based on a systematic review to estimate the number of patients infected after endorectal or vaginal ultrasonography examination using LLD for probes.

STUDY DESIGN

We performed a stochastic Monte Carlo computer simulation to produce hypothetical cohorts for a population of 4 million annual ultrasound examinations performed in France, and we estimated the number of infected patients for human immunodeficiency virus (HIV), herpes simplex virus, hepatitis B virus, hepatitis C virus, human papilloma virus, cytomegalovirus, and Chlamydia trachomatis. Modeling parameters were estimated by meta-analysis when possible.

RESULTS

The probability of infection from a contaminated probe ranged from 1% to 6%, depending on the pathogen. For cases of HIV infection, this would result in approximately 60 infected patients per year. For other common viral infections, the number of new cases ranged from 1,600 to 15,000 per year that could be attributable directly to ultrasound and LLD procedures.

CONCLUSIONS

Our simulation results showed that, despite cumulative use of probe cover and LLD, there were still some cases of de novo infection that may be attributable to ultrasound procedures. These cases are preventable by reviewing the currently used LLD and/or upgrading LLD to high-level disinfection, as recommended by the US Centers for Disease Control and Prevention.

[HPV contamination of endocavity vaginal ultrasound probes]

While the use of endovaginal ultrasound probes is increasing, the risk of contamination of women with endocavity vaginal probes was not assessed. In particular, the clinical significance of detection of human papillomavirus (HPV) infection, the most common sexually transmitted viral infection, on endovaginal ultrasound probes is uncertain. The recommendations of good practice for decontamination of these probes developed by the High Council for Public Health and the Academy of Medicine have not been evaluated. The objective of this article was to review recent publications concluding to the detection of HPV and human cellular DNA after gynecological examination and disinfection of vaginal ultrasound probes.

Persistence of microbial contamination on transvaginal ultrasound probes despite low-level disinfection procedure

AIM OF THE STUDY

In many countries, Low Level Disinfection (LLD) of covered transvaginal ultrasound probes is recommended between patients' examinations. The aim of this study was to evaluate the antimicrobial efficacy of LLD under routine conditions on a range of microorganisms.

MATERIALS AND METHODS

Samples were taken over a six month period in a private French Radiology Center. 300 specimens derived from endovaginal ultrasound probes were analyzed after disinfection of the probe with wipes impregnated with a quaternary ammonium compound and chlorhexidine. Human papillomavirus (HPV) was sought in the first set of s100 samples, Chlamydia trachomatis and mycoplasmas were searched in the second set of 100 samples, bacteria and fungi in the third 100 set samples. HPV, C. trachomatis and mycoplasmas were detected by PCR amplification. PCR positive samples were subjected to a nuclease treatment before an additional PCR assay to assess the likely viable microorganisms. Bacteria and fungi were investigated by conventional methods.

RESULTS

A substantial persistence of microorganisms was observed on the disinfected probes: HPV DNA was found on 13% of the samples and 7% in nuclease-resistant form. C. trachomatis DNA was detected on 20% of the probes by primary PCR but only 2% after nuclease treatment, while mycoplasma DNA was amplified in 8% and 4%, respectively. Commensal and/or environmental bacterial flora was present on 86% of the probes, occasionally in mixed culture, and at various levels (10->3000 CFU/probe); Staphylococcus aureus was cultured from 4% of the probes (10-560 CFU/probe). No fungi were isolated.

CONCLUSION

Our findings raise concerns about the efficacy of impregnated towels as a sole mean for disinfection of ultrasound probes. Although the ultrasound probes are used with disposable covers, our results highlight the potential risk of cross contamination between patients during ultrasound examination and emphasize the need for reviewing the disinfection procedure.

Green synthesis of silver nanoparticles by Chrysanthemum morifolium Ramat. extract and their application in clinical ultrasound gel

Eco-friendly green synthesis with plant extracts plays a very important role in nanotechnology, without any harmful chemicals. In this report, the synthesis of water-soluble silver nanoparticles was developed by treating silver ions with Chrysanthemum morifolium Ramat. extract at room temperature. The effect of the extract on the formation of silver nanoparticles was characterized by ultraviolet and visible absorption spectroscopy, X-ray diffraction, transmission electron microscopy, and Fourier transform infrared spectroscopy. The ultraviolet and visible absorption spectroscopy results show a strong resonance centered on the surface of silver nanoparticles (AgNP) at 430 nm. The Fourier transform infrared spectroscopy spectral study demonstrates Chrysanthemum morifolium Ramat. extract acted as the reducing and stabilizing agent during the synthesis. The X-ray diffraction analysis confirmed that the synthesized AgNP are single crystallines, corresponding with the result of transmission electron microscopy. Water-soluble AgNP, with an approximate size of 20 nm–50 nm were also observed in the transmission electron microscopy image. The bactericidal properties of the synthesized AgNP were investigated using the agar-dilution method and the growth-inhibition test. The results show the AgNP had potent bactericidal activity on Staphylococcus aureus and Escherichia coli, as well as a strong antibacterial activity against gram-negative bacteria, as compared to gram-positive bacteria with a dose-dependent effect, thus providing a clinical ultrasound gel with bactericidal property for prevention of cross infections.