Nosocomial outbreak of Klebsiella pneumoniae producing SHV-5 extended-spectrum beta-lactamase, originating from a contaminated ultrasonography coupling gel

Practice 'safe scans': why ultrasound transducer covers should be considered best practice

Single-injection, ultrasound-guided nerve block procedures involve puncturing the skin in close proximity to an ultrasound transducer, creating a potential vector for transmission of microbial organisms when skin flora and blood come into contact with the probe. Practice patterns regarding disinfection of the transducer and the use of barrier protection are inconsistent, ranging from sterile sleeve probe covers to no cover at all. Although sleeve probe covers are easy and straightforward to use and serve to protect patients, providers and medical equipment, their utilisation remains controversial. Standardisation of their use eliminates the impact of improper or haphazard probe disinfection and makes infection control practices consistent and reproducible. This position is shared by multiple societies and authorities on ultrasound and acute care medicine. In this Daring Discourse, we outline the arguments supporting the utilisation of single-use sleeve probe covers to ensure patient safety with respect to vector-borne transmission of microbes during single-injection regional anaesthesia procedures.

Characterization of Extended-Spectrum β-Lactamase-Producing Escherichia coli in Animal Farms in Hunan Province, China

Multi-drug resistance of bacteria producing extended-spectrum β-lactamase (ESBL) is a public health challenge. Thus, this study aimed to investigate the antimicrobial susceptibility of ESBL-producing Escherichia coli (ESBL-EC) in Hunan Province, China. A total of 1366 fecal samples were collected from pig, chicken, and cattle farms over a six-year period, which were assessed using strain isolation, 16S rRNA identification, polymerase chain reaction, drug sensitivity testing, whole-genome sequencing, and bioinformatics analysis. The results showed an overall prevalence of 6.66% for ESBL-EC strains, with ESBL positivity extents for pigs, chickens, and cattle isolates at 6.77%, 6.54%, and 12.5%, respectively. Most ESBL-EC isolates were resistant to cefotaxime, tetracycline, and trimethoprim-sulfamethoxazole; however, all the isolates were susceptible to meropenem, with relatively low resistance to amikacin and tigecycline. Various multi-locus sequence types with different origins and similar affinities were identified, with ST155 (n = 16) being the most common subtype. Several types of resistance genes were identified among the 91 positive strains, with beta-lactamase blaCTX-M-55 being the most common ESBL genotype. IncFIB was the predominant plasmid type. Widespread use of antibiotics in animal farming may increase antibiotic resistance, posing a serious threat to the health of farmed animals and, thus, to human food security and health.

Guideline from the Japanese society of echocardiography: guidance for the management and maintenance of echocardiography equipment: 2022 focused update

Echocardiography plays a pivotal role as an imaging modality in modern cardiology practice. Information derived from echocardiography is essential for patient care. The Japanese Society of Echocardiography has promoted echocardiography for routine clinical and research use. One of the missions of the Society is to provide information that is useful for high-quality examinations. To ensure this, we believe that maintaining equipment in good condition and providing a comfortable environment for the examination are important for both the patient and examiner. Thus, the Committee for Guideline Writing of the Japanese Society of Echocardiography originally published brief guidance for the routine use of echocardiography equipment in 2015. In 2018, the committee updated our guidance incorporating the importance of international standardization. In 2022, the committee has revised and updated our guidance in line with the increase in awareness of infection prevention due to the worldwide spread of coronavirus disease 2019 (COVID-19).

Molecular characterisation of carbapenem- and tigecycline-resistant Klebsiella pneumoniae strains isolated from blood and bile samples

INTRODUCTION

The number of carbapenem-resistant Klebsiella pneumoniae (CRKP) strains are increasing, further raising healthcare concerns worldwide. In this study, we isolated three CRKP strains from bile and blood samples of an elderly patient (90s) with acute cholangitis and characterised the features and antimicrobial resistance mechanism of CRKP isolates.

METHODS

Three CRKP isolates were characterised by Pulsed-field gel electrophoresis (PFGE), whole genome sequencing using the NovaSeq 6000, and antimicrobial susceptibility testing. Transcriptional levels of resistance-associated genes were measured by real-time RT-qPCR.

RESULTS

PFGE analysis revealed highly similar patterns for these isolates. Furthermore, they showed resistance to not only carbapenem but also tigecycline. Genomic analysis of the blood isolate identified the exogenous resistance genes bla_CTX-M14, tet(A), tet(D), opxAB, and qnrS1 but not any carbapenemase-encoding genes. In addition, nonsense mutations were found in both the outer membrane protein K36 (ompK36) and transcriptional regulator ramR, suggesting that this isolate developed multidrug resistance by acquiring both exogenous resistance genes and nonsense mutations. The extended-spectrum β-lactamase-producing carbapenem-susceptible K. pneumoniae isolate exhibited the same susceptibility pattern, except to β-lactams, as prior CRKP isolates.

CONCLUSIONS

Antimicrobial susceptibility to carbapenem and tigecycline should be continuously monitored, because it might change from susceptible to resistant during another antimicrobial treatment, even if an isolate initially shows susceptibility, and the patient has not been exposed to these agents.

[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.

Disinfection of Transvaginal Ultrasound Probes by Ultraviolet C - A clinical Evaluation of Automated and Manual Reprocessing Methods

PURPOSE

 Since pathogens can be transmitted to patients via transvaginal ultrasound probes, it is of particular importance that cleaning and disinfection are performed adequately. This study was designed to do a qualitative comparison of a low-level disinfection technique with disinfectant-impregnated wipes and an automated disinfection technique using ultraviolet C radiation in a clinical setting.

MATERIALS AND METHODS

 The transvaginal ultrasound probes used in two groups of 160 patients were compared in a prospective controlled study regarding the effectiveness of manual low-level disinfection (Mikrozid sensitive wipes) and automated disinfection using ultraviolet C radiation (Antigermix AS1). Microbiological samples were taken from the whole surface of the probe before and after the disinfection process.

RESULTS

 Before disinfection, 98.75 % (316/320) of the samples showed bacterial contamination. After automated and manual disinfection, the contamination rates were 34.2 % (54/158, automated) and 40.5 % (64/158, disinfectant wipes) (p > 0.05). Pathogens with the potential to cause healthcare-associated infections, such as Enterococcus faecalis and Klebsiella pneumoniae, were removed completely by both techniques. Manual disinfection showed a lower contamination rate after disinfection of bacteria that usually belong to the vaginal, pharyngeal and skin flora (disinfectant wipes 10.6 %, 11/104, automated 32.5 %, 38/117) (p < 0.001).

CONCLUSION

 For the clinical routine, automated disinfection with ultraviolet C is a promising technique for transvaginal ultrasound probes because of the simple handling and time efficiency. In our study, this method was completely effective against nosocomial pathogens. However, the study didn't show any significant difference in terms of effectiveness compared to low-level wipe disinfection.

Identification and Analysis of Bacterial Contamination of Ultrasound Transducers and Multiuse Ultrasound Transmission Gel Bottle Tips Before and After the Aseptic Cleansing Technique

OBJECTIVES

To provide a descriptive analysis for species identification of culture and Gram stain results from ultrasound transducers and multiuse ultrasound transmission gel bottle tips in active clinical use and to compare bacterial cultures from ultrasound transducers before and after aseptic cleansing.

METHODS

A prospective blinded descriptive analytic study of 18 distinct clinical care sites within a single primary clinical institution was conducted. Before and after a disinfectant towel cleanse, transducers were pressed against tryptic soy agar contact plates. Plates were deidentified and submitted for blind incubation, Gram staining, and species identification with microsequencing. Results were classified as clinically relevant (CR) or non-clinically relevant. In total, 188 samples were analyzed: 80 from ultrasound transducers before and cleansing, 13 from multiuse gel bottle tips before and after cleansing, and 2 precleansing samples from the data collector's pen and badge.

RESULTS

Fifty-nine precleansing samples (73.8%) grew cultures with CR bacteria, and 21 samples (26.3%) did not. Staphylococcus simulans represented 31.0% of all positive culture samples. Thirteen postcleansing samples (16.3%) grew cultures with CR bacteria, equating to a 78.0% reduction of CR bacterial growth (likelihood ratio, 57.10; P < .001).

CONCLUSIONS

Ultrasound transducers have a notable CR bacterial burden and may serve as potential infective vectors. Aseptic cleansing effectively eliminates most of the bacterial load from ultrasound transducers, but some bacteria persist, presenting a risk of nosocomial infection with ultrasound-guided interventions. These findings support American Institute of Ultrasound in Medicine 2018 guidelines intended to ensure an appropriate level of transducer preparation based on the examination type while emphasizing rational infection control measures to minimize the risk of potential patient harm.

The Washing Machine as a Reservoir for Transmission of Extended-Spectrum-Beta-Lactamase (CTX-M-15)-Producing Klebsiella oxytoca ST201 to Newborns

Washing machines should be further investigated as possible sites for horizontal gene transfer (ESBL genes) and cross-contamination with clinically important Gram-negative strains. Particularly in the health care sector, the knowledge of possible (re-)contamination of laundry (patients’ clothes and staff uniforms) with multidrug-resistant Gram-negative bacteria could help to prevent and to control nosocomial infections. This report describes an outbreak with a single strain of a multidrug-resistant bacterium (Klebsiella oxytoca sequence type 201) in a neonatal intensive care unit that was terminated only when the washing machine was removed. In addition, the study implies that changes in washing machine design and processing are required to prevent accumulation of residual water where microbial growth can occur and contaminate clothes.

During the period from April 2012 to May 2013, 13 newborns (1 to 4 weeks of age) and 1 child in a pediatric hospital ward in Germany were colonized with Klebsiella oxytoca producing an extended-spectrum beta-lactamase (ESBL) (CTX-M-15). A microbiological source-tracking analysis with human and environmental samples was carried out to identify the source and transmission pathways of the K. oxytoca clone. In addition, different hygienic intervention methods were evaluated. K. oxytoca isolates were detected in the detergent drawer and on the rubber door seal of a domestic washer-extractor machine that was used in the same ward to wash laundry for the newborns, as well as in two sinks. These strains were typed using pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing. The environmental findings were compared with those for the human strains and the isolates detected on clothing. The results from both techniques showed that the strains were identical (sequence type 201 and PFGE type 00531, a clone specific to this hospital and not previously isolated in Germany), emphasizing the washing machine as a reservoir and fomite for the transmission of these multidrug-resistant bacteria. After the washing machine was taken out of use, no further colonizations were detected during the subsequent 4-year period.

IMPORTANCE Washing machines should be further investigated as possible sites for horizontal gene transfer (ESBL genes) and cross-contamination with clinically important Gram-negative strains. Particularly in the health care sector, the knowledge of possible (re-)contamination of laundry (patients’ clothes and staff uniforms) with multidrug-resistant Gram-negative bacteria could help to prevent and to control nosocomial infections. This report describes an outbreak with a single strain of a multidrug-resistant bacterium (Klebsiella oxytoca sequence type 201) in a neonatal intensive care unit that was terminated only when the washing machine was removed. In addition, the study implies that changes in washing machine design and processing are required to prevent accumulation of residual water where microbial growth can occur and contaminate clothes.

Outbreak of Acinetobacter baumannii associated with extrinsic contamination of ultrasound gel in a tertiary centre burn unit

Background

During 2011 and 2012, an increase in occurrence of multidrug-resistant Acinetobacter baumannii infections was recorded in the Shands Hospital Burn Intensive Care Unit (BICU). An epidemic curve together with strain typing was consistent with an intermittent common source outbreak. An investigation was therefore initiated.

Aim

To identify risk factors for A. baumannii infection, characterize the source of the pathogen, implement control measures to terminate the outbreak, and institute preventive measures.

Methods

We conducted a retrospective case-control study; reviewed BICU infection control policies, practices and procedures, and patient exposure to healthcare workers (HCWs), and obtained epidemiologically-directed environmental cultures.

Findings

Eleven patients met the case definition. On multivariate analysis, case-patients were more likely to have undergone an ultrasound procedure in the BICU (adjusted odds ratio [AOR]: 19.5; confidence interval [CI]: 2.4-435) or have a FlexiSeal™ device (AOR: 11.9, CI:1.3-276). Epidemiologically-directed cultures of the environment, ultrasound equipment, and ultrasound gel from opened containers on the ultrasound trolley and in the Ultrasound Department were negative for the outbreak pathogen. Culture of an open ultrasound gel dispenser stored in the Ultrasound Department yielded an A. baumannii strain with DNA banding patterns identical to the outbreak strain.

Conclusions

Based on data from our epidemiologic, microbiologic, and observational studies, we believe that inadvertent extrinsic contamination of the gel dispenser occurred in the Ultrasound Department. Contaminated gel was then dispensed into multiuse vials of gel stored on the mobile carts. The outbreak was stemmed by instituting changes in practices in the Ultrasound Department, including introduction of single-use ultrasound vials and storage of ultrasound gel.

Outbreak of Yersiniabactin-producing Klebsiella pneumoniae in a Neonatal Intensive Care Unit

BACKGROUND

The Gram-negative bacterium Klebsiella pneumoniae is a frequent pathogen causing outbreaks in neonatal intensive care units. Some Enterobacteriaceae can acquire the ability to sequester iron from infected tissue by secretion of iron-chelating compounds such as yersiniabactin. Here we describe an outbreak and clinical management of infections because of a highly virulent yersiniabactin-producing, nonmultiresistant K. pneumoniae strain in a neonatal intensive care unit. Outbreak investigation and effectiveness assessment of multidisciplinary infection control measurements to prevent patient-to-patient transmission of highly pathogenic K. pneumoniae were undertaken.

METHODS

Outbreak cases were identified by isolation of K. pneumoniae from blood or stool of infants. Clinical data were abstracted from medical charts. K. pneumoniae isolates were genotyped using whole genome sequencing, and yersiniabactin production was evaluated by luciferase assay.

RESULTS

Fourteen cases were confirmed with 8 symptomatic and 6 colonized patients. Symptomatic patients were infants of extremely low gestational and chronologic age with fulminant clinical courses including necrotizing enterocolitis and sepsis. Whole genome sequencing for bacterial isolates confirmed the presence of an outbreak. All outbreak isolates produced yersiniabactin.

CONCLUSIONS

Yersiniabactin-producing K. pneumoniae can display a high pathogenicity in extremely premature infants with low chronologic age. This outbreak also underlines the considerable potential of today's infection control systems for recognizing and controlling nosocomial infections in highly vulnerable populations.

Low-cost antimicrobial fortification of ultrasound coupling gel: An ergonomic innovation to combat sonology-acquired nosocomial infections

Background

Recent outbreaks of highly contagious diseases have prompted hospital departments to adopt preventive hygiene protocols. Use of shared equipment, including ultrasound transducers and coupling gels, potentially exposes patients to these microbes. Inexpensive means of microbicide fortification of plain/non-sterile ultrasound gel may be useful in interrupting nosocomial infections. The purpose of this study was to evaluate the effectiveness of low-cost antimicrobial fortification of ultrasound coupling gel in preventing nosocomial infections during ultrasound examinations.

Methods

Volunteer patients, 20 in number, who presented for an ultrasound scan in a busy radiology clinic in Enugu, Nigeria, were randomly divided into 2 groups of 10 each and were scanned using plain non-sterile gel and gel-fortified with 0.5% chlorhexidine and 70% ethyl alcohol (in a volume ratio of 20:2:1) respectively. Swabs were taken from the patients' skin, gel-laden transducer, and the cleaned transducer and subjected to microbiology analysis. Subsequently, plain and fortified gel samples were allowed to stand in their respective dispensers for 72 hours. The plain and fortified gel samples were subjected to microbiology analysis. Fisher's Exact Test was utilised to compare outcomes in the 2 groups of volunteers.

Results

With fortified gel, swab cultures from patients' skin and gel-laden transducer, and from the cleaned transducer, significantly yielded no growth (P= <0.0001 and P= 0.0001 respectively) while swab cultures from the plain gel yielded a total of 19 microbial isolates from 5 micro-organisms.

Conclusion

Low-cost fortification of ultrasound coupling gel with 0.5% chlorhexidine and 70% ethyl alcohol renders it hostile to microorganisms encountered at sonology thus preventing nosocomial transmission.

[Monoclonal spread of multi-drug resistant CTX-M-15-producing Klebsiella pneumoniae. Impact of measures to control the outbreak]

OBJECTIVE

To describe an outbreak of multi-drug resistant extended-spectrum β-lactamases-producing Klebsiella pneumoniae (MDR-ESBL-KPN) and the impact of measures for its control.

METHODS

We reviewed the patients´ clinical records with MDR-ESBL-KPN isolation during 2013-2016 with resistance to fluoroquinolones, aminoglycosides, fosfomycin, and nitrofurantoin; susceptible to imipenem, meropenem, colistin, and tigecycline and variable to ertapenem and cotrimoxazole (Vitek-2). The genetic relationship between 35 isolates was established by PFGE and MLST. Control measures were put in place in January 2016.

RESULTS

We detected 269 patients colonized and/or infected by KPN-ESBL-MDR with a common resistance phenotype; the strains studied carried the blaCTX-M-15 gene and formed a single cluster belonging to ST11. The outbreak was detected at the end of 2015, although it began in 2013 in an elderly center. The acquisition source of the strains was: 6% community-acquired, 37% hospital-acquired (76% in internal medicine) and 57% related to long health care facilities (78% of hospitalizations in the last year). Ninety-four percent of patients had at least one underlying disease, 90% received antibiotics previously and 49% had some invasive devices. After the introduction of control measures, the incidence of cases in the quarter was reduced from 29 to 15.

CONCLUSIONS

We detected a monoclonal outbreak of MDR-CTX-M-15-KPN in 2015, with predominance of health-care associated cases. The success in the rapid spread of the outbreak was due to the delay in its detection and to the fact that most of the patients had previously received antibiotics. The control measures reduced the number of isolates by 50%.

Anesthesia in patients with infectious disease caused by multi-drug resistant bacteria

PURPOSE OF REVIEW

Up to 50% of specific bacterial strains in healthcare admission facilities are multi-drug resistant organisms (MDROs). Involvement of anesthesiologists in management of patients carrying/at risk of carrying MDROs may decrease transmission in the Operating Room (OR).

RECENT FINDINGS

Anesthesiologists, their work area and tools have all been implicated in MDRO outbreaks. Causes include contamination of external ventilation circuits and noncontribution of filters to prevention, inappropriate decontamination procedures for nondisposable equipment (e.g. laryngoscopes, bronchoscopes and stethoscopes) and the anesthesia workplace (e.g. external surfaces of cart and anesthesia machine, telephones and computer keyboards) during OR cleaning and lack of training in sterile drug management.

SUMMARY

Discussions regarding the management of potential MDRO carriers must include anesthesia providers to optimize infection control interventions as well as the anesthesia method, the location of surgery and recovery and the details of patient transport. Anesthesia staff must learn to identify patients at risk for MDRO infection. Antibiotic prophylaxis, although not evidence based, should adhere to known best practices. Adjuvant therapies (e.g. intranasal Mupirocin and bathing with antiseptics) should be considered. Addition of nonmanual OR cleaning methods such as ultraviolet irradiation or gaseous decontamination is encouraged. Anesthesiologists must undergo formal training in sterile drug preparation and administration.

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.

JOURNAL CLUB: Ultrasound-Guided Breast Interventions: Low Incidence of Infectious Complications With Use of an Uncovered Probe

OBJECTIVE

The purpose of this study was to determine the incidence of infectious complications after ultrasound-guided breast interventions performed with an intermediate-level disinfection protocol without an ultrasound probe cover.

MATERIALS AND METHODS

Two independent institutional databases were searched to identify breast infections in patients who underwent ultrasound-guided interventions between January 2005 and July 2013. The departments of radiology and infectious diseases independently maintained these databases. A comprehensive retrospective chart review based on periprocedural antibiotic use and clinical documentation of infection was also performed to reduce the likelihood of missing potential infectious complications.

RESULTS

A total of 12,708 ultrasound-guided breast procedures were performed in the time frame of this study. All potential cases of procedure-related infection were included for subspecialist review in an effort to give the most conservative (highest) estimate of infectious complications. Among these cases, 14 documented cases of possible procedure-related infection were identified, for an overall incidence of 0.11%. All infections were localized skin or soft-tissue infections and adequately treated with a short course of oral antibiotics. No cases of more serious infections or sepsis were found. None of the reported infections required IV antibiotic therapy, percutaneous intervention, surgical intervention, or hospitalization.

CONCLUSION

The incidence of infectious complications after an ultrasound-guided breast intervention without an ultrasound probe cover is extremely low. Physicians can use this information in the development of their disinfection protocols and to provide accurate information in counseling patients during preprocedural consultation.

Epidemiology and characteristics of nosocomial infections in critically ill patients in a tertiary care Intensive Care Unit of Northern India

Background and Aims:

The prevalence of nosocomial infection is higher in the Intensive Care Unit (ICU) than other areas of the hospital. The present observational study was undertaken to describe the epidemiology and characteristics of nosocomial infections acquired in a tertiary care ICU and the impact of the various risk factors in their causation.

Materials and Methods:

A retrospective study was conducted on the prospectively collected data of 153 consecutive patients admitted in a tertiary care ICU between July 2014 and December 2015. The primary objective was to assess the epidemiology of ICU-acquired bacterial infections in terms of the incidence of new infections, causative organism, and site. The secondary end point was to assess the risk factors for developing ICU-acquired infections.

Results:

Out of the 153 patients enrolled in the study, 87 had an ICU-acquired nosocomial infection (58.86%). The most common organism responsible for infection was Klebsiella pneumoniae (37%), and the most common infection was pneumonia (33%). The duration of mechanical ventilation and length of ICU stay were significantly prolonged in patients developing nosocomial infections. There was no difference in mortality between the groups. The multivariate analyses identified intubation longer than 7 days, urinary catheterization >7 days, duration of mechanical ventilation more than 7 days, and ICU length of stay longer than 7 days as independent risk factors for nosocomial infections.

Conclusion:

The study demonstrated a high incidence of nosocomial infection in the ICU and identified the risk factors for acquisition of nosocomial infections in the ICU.

Sonographers and the Fight Against Nosocomial Infections

An investigation was conducted to determine how well sonographers clean transducers and other sonography-related equipment. Previous studies have shown that cross-contamination is possible between patients during a sonogram and may lead to nosocomial infections. The potential for infecting patients is now common knowledge, so research was conducted to establish how well sonographers are sterilizing the equipment. The equipment from the sonography departments of six hospitals and clinics was tested for the presence of bacteria and fungi. Growth was present at every facility. Although only normal skin flora, including yeast, were isolated, sonographers must be more diligent in the prevention of cross-contamination in patients.

Ultrasound-guided central vascular interventions, comments on the European Federation of Societies for Ultrasound in Medicine and Biology guidelines on interventional ultrasound

Central venous access has traditionally been performed on the basis of designated anatomical landmarks. However, due to patients' individual anatomy and vessel pathology and depending on individual operators' skill, this landmark approach is associated with a significant failure rate and complication risk. There is substantial evidence demonstrating significant improvement in effectiveness and safety of vascular access by realtime ultrasound (US)-guidance, as compared to the anatomical landmark-guided approach. This review comments on the evidence-based recommendations on US-guided vascular access which have been published recently within the framework of Guidelines on Interventional Ultrasound (InVUS) of the European Federation of Societies for Ultrasound in Medicine and Biology (EFSUMB) from a clinical practice point of view.

[Hygiene aspects in ultrasound-guided regional anesthesia]

BACKGROUND

Sterile and clean working conditions are one of the keystones of medical practice and this is also true for ultrasound-guided regional anesthesia. The routine clinical practice in ultrasound-guided regional anesthesia does not always comply with the principles of sterile and clean working conditions in medicine: therefore, patients are exposed to potential hazards regarding the transmission of pathogens via the ultrasound equipment.

OBJECTIVE

This article deals with the question of whether sterile working conditions in ultrasound-guided regional anesthesia are a relevant topic with medical and economic implications. Is it possible to implement the general recommendations for sterile working conditions in ultrasonography for the specific application of ultrasound-guided regional anesthesia?

MATERIAL AND METHODS

A search of the available literature and published guidelines in the field of sterile working conditions with ultrasound was carried out.

RESULTS

The association between cross-infections and ultrasound equipment is undeniable. Many methods for cleansing and disinfection of ultrasound equipment have been published. All these methods are associated with advantages and disadvantages. The direct sterilization of ultrasound probes with high-percentage alcohol can damage ultrasound probes (especially linear). The use of self-adhesive sterile ultrasound probe covers is a practical method to achieve sterile working conditions in ultrasound-guided regional anesthesia.

CONCLUSION

The use of sterile ultrasound probe covers and sterile ultrasound contact media is an important prerequisite to avoid cross-infection between patients. An appropriate scientific evaluation should serve as evidence in this field.

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 transducer disinfection in emergency medicine practice

Background

External ultrasound transducer disinfection is common practice in medicine. Unfortunately, clinically significant organisms, such as methicillin-resistant Staphylococcus aureus (MRSA), Pseudomonas aeruginosa, and Klebsiella pneumonia spread throughout healthcare facilities via direct contact despite disinfection protocols. Ultrasound transducers and coupling gel provide potential vectors for pathogen transmission, especially in immunocompromised and high-risk patient populations. Our objective was to conduct a survey to investigate the variety of cleaning solutions or sanitary wipes used and evaluate current standard practice for transducer disinfection across emergency medicine training programs in the United States.

Findings

Eighty-three academic emergency medicine programs participated in this study. Eighty-seven percent (95 % CI 80–94 %) of responding programs do not have a mandated protocol or standard contact time for transducer disinfection. Ninety percent (95 % CI 84–96 %) of institutions use disinfectant solution or disinfectant wipes, as the standard of practice, to cleanse ultrasound transducers after every use.

Conclusions

Currently, there is a great deal of variability with regard to non-endocavitary transducer disinfection protocols that seems to stem from the vast number of disinfectant products and ultrasound manufacturer disparate recommendations. In order to mitigate risk to patients and reduce health care costs linked to nosocomial infections; healthcare providers, ultrasound companies, and disinfectant manufacturers must develop a universal use disinfectant and a standard protocol for ultrasound device disinfection for noncritical device disinfection in the emergency department.

Electronic supplementary material

The online version of this article (doi:10.1186/s13756-016-0110-y) contains supplementary material, which is available to authorized users.

Bacterial contamination of inanimate surfaces and equipment in the intensive care unit

Intensive care unit (ICU)-acquired infections are a challenging health problem worldwide, especially when caused by multidrug-resistant (MDR) pathogens. In ICUs, inanimate surfaces and equipment (e.g., bedrails, stethoscopes, medical charts, ultrasound machine) may be contaminated by bacteria, including MDR isolates. Cross-transmission of microorganisms from inanimate surfaces may have a significant role for ICU-acquired colonization and infections. Contamination may result from healthcare workers’ hands or by direct patient shedding of bacteria which are able to survive up to several months on dry surfaces. A higher environmental contamination has been reported around infected patients than around patients who are only colonized and, in this last group, a correlation has been observed between frequency of environmental contamination and culture-positive body sites. Healthcare workers not only contaminate their hands after direct patient contact but also after touching inanimate surfaces and equipment in the patient zone (the patient and his/her immediate surroundings). Inadequate hand hygiene before and after entering a patient zone may result in cross-transmission of pathogens and patient colonization or infection. A number of equipment items and commonly used objects in ICU carry bacteria which, in most cases, show the same antibiotic susceptibility profiles of those isolated from patients. The aim of this review is to provide an updated evidence about contamination of inanimate surfaces and equipment in ICU in light of the concept of patient zone and the possible implications for bacterial pathogen cross-transmission to critically ill patients.

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.

Clinical and Molecular Epidemiology of Extended-Spectrum Beta-Lactamase-Producing Klebsiella spp.: A Systematic Review and Meta-Analyses

Healthcare-related infections caused by extended-spectrum beta-lactamase (ESBL)-producing Klebsiella spp. are of major concern. To control transmission, deep understanding of the transmission mechanisms is needed. This systematic review aimed to identify risk factors and sources, clonal relatedness using molecular techniques, and the most effective control strategies for ESBL-producing Klebsiella spp. A systematic search of PubMed, Embase, and Outbreak Database was performed. We identified 2771 articles from November 25th, 1960 until April 7th, 2014 of which 148 were included in the systematic review and 23 in a random-effects meta-analysis study. The random-effects meta-analyses showed that underlying disease or condition (odds ratio [OR] = 6.25; 95% confidence interval [CI] = 2.85 to 13.66) generated the highest pooled estimate. ESBL-producing Klebsiella spp. were spread through person-to-person contact and via sources in the environment; we identified both monoclonal and polyclonal presence. Multi-faceted interventions are needed to prevent transmission of ESBL-producing Klebsiella spp.

Sterile working in ultrasonography: the use of dedicated ultrasound covers and sterile ultrasound gel

Ultrasound is currently an important tool for diagnostic and interventional procedures. Ultrasound imaging provides significant advantages as compared to other imaging methods. The widespread use of ultrasound also carries the risk of drawbacks such as cross-infections. A large body of literature reports this possibly life-threatening side effect and specific patient populations are particularly at risk (e.g., neonates). Various methods of ultrasound probe disinfection are described; however, none of the mechanical or chemical probe disinfection procedures is optimal and, in particular, disinfection with high concentration of alcohol might be associated with ultrasound probe damage. The preparation of ultrasound probes with dedicated probe covers is a useful alternative for sterile working conditions. One ultrasound probe cover discussed in this paper is directly glued on to the ultrasound probe without the use of ultrasound coupling gel. By the use of sterile ultrasound coupling gel at the outer surface, additional effects on aseptic working conditions can be obtained.

Burkholderia cepaciaInfections Associated With Intrinsically Contaminated Ultrasound Gel: The Role of Microbial Degradation of Parabens

Objective:

To describe an outbreak of serious nosocomialBurkholderia cepaciainfections occurring after transrectal prostate biopsy associated with ultrasound gel intrinsically contaminated with paraben-degrading microorganisms.

Methods:

A retrospective chart review prompted by a blood culture isolate ofB, cepacia.Identification of microorganisms in ultrasound gel in two Canadian centers and characterization by pulsed-field gel electrophoresis and assays for paraben degradation.

Setting:

Two Canadian university-affiliated, tertiary-care centers in Newfoundland and Alberta.

Results:

Six seriousB. cepaciainfections were identified at the two centers. Isolates ofB. cepaciarecovered from the blood of patients from both centers and the ultrasound gel used during the procedures were identical, confirming intrinsic contamination. Strains ofEnterobacter cloacaeisolated from ultrasound gel at the two centers were also identical. The ability to degrade parabens was proven for bothB. cepaciaandE. cloacaestrains recovered from the ultrasound gel.

Conclusions:

Ultrasound gel is a potential source of infection. Contamination occurs at the time of manufacture, with organisms that degrade parabens, which are commonly used as stabilizing agents. There are far-reaching implications for the infection control community.

Investigation of current infection-control practices for ultrasound coupling gel: a survey, microbiological analysis, and examination of practice patterns

BACKGROUND AND OBJECTIVES

Ultrasound coupling gel may serve as a vector for the spread of bacteria and has been the causative agent for significant health care-associated infections. The purpose of this study was to document existing infection-control procedures and level of contamination present within nonsterile ultrasound gel from several clinical departments at a single institution. A second purpose was to examine the effectiveness of clinician education and manufacturer-based ultrasound additives on ultrasound gel contamination and in vitro bacterial proliferation, respectively.

METHODS

Compliance with Health Canada recommended infection-control policies were determined by survey. Contamination of in-use ultrasound gel bottles was determined by inspecting cultures after 72 hours of incubation. After infection-control education, a 28-day interval assessment was used to examine contamination rates in newly provided ultrasound gel. The ability of ultrasound gel containing parabens to prevent bacterial growth was examined in cultures grown with and without ultrasound gel.

RESULTS

Practitioners were not compliant with Health Canada recommendations, but the baseline ultrasound gel contamination rate within these departments was only 2.5%. Education in infection control did not improve the contamination rate over 28 days. Contamination was discovered in ultrasound gel supplied directly from the manufacturer. Ultrasound gel suppressed but did not prevent bacterial growth in a species- and time-specific manner.

CONCLUSIONS

The source of contamination for in-use ultrasound gel may be of manufacturer or human origin. Because additives to the ultrasound gel are not bactericidal, sterile ultrasound gel should be used for invasive and high-risk cases, and improving infection-control policies is warranted.

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.

Superiority of chlorhexidine 2%/alcohol 70% wipes in decontaminating ultrasound equipment

Ultrasound equipment is known to act as a reservoir for potentially pathogenic organisms. The aims of these studies were to establish current cleaning practices, to review the extent of bacterial contamination of ultrasound equipment in our hospital, to establish an effective cleaning regimen and to ensure that cleaning does not cause damage. A questionnaire was sent to all acute NHS hospitals in England to establish current cleaning practices. A review of our current practice was performed to establish the extent of bacterial contamination of ultrasound equipment currently in use. Laboratory studies compared cleaning the probes with soap and water with decontaminating with a chlorhexidine 2% and alcohol 70% wipe, including quantifying the residual effect. Accelerated aging was performed on the probe and staff surveyed to establish potential problems with using the wipes on the probe. The survey revealed that a variety of cleaning methods were used to decontaminate ultrasound probes; 57% of our ultrasound machines were contaminated with bacteria. The laboratory studies showed superiority of the chlorhexidine and alcohol wipes over soap and water due to a residual effect, both immediately after cleaning and after 24 hours. The staff survey demonstrated no apparent change in function of the probe after cleaning with the chlorhexidine wipes. Cleaning ultrasound probes with chlorhexidine and alcohol wipes is effective and provides additional protection against bacterial contamination due to its residual effect, and appears in the short term to have no detrimental effect on the probe.

Extended-spectrum β-lactamase-producing Klebsiella pneumoniae in the neonatal intensive care unit: does vancomycin play a role?

BACKGROUND

Extended-spectrum β-lactamase (ESBL)-producing Klebsiella species cause worldwide problems in neonatal intensive care units (NICUs). This study aimed to determine possible risk factors for infection or colonization with ESBL-producing Klebsiella pneumoniae (ESBLKp) during an outbreak in the NICU.

METHODS

A retrospective cohort study was conducted among neonates admitted to the NICU of a teaching hospital in Riyadh, Saudi Arabia, during an outbreak of ESBLKp from April to July 2008. The incidence density ratio was calculated to determine possible predictors of ESBLKp colonization or infection.

RESULTS

During 2,265 person-days of follow-up of 118 neonates, 4 became infected, and 8 were colonized with ESBLKp. Univariate analyzes revealed that, among 14 neonates who were treated with vancomycin, 9 (64.3%) developed infection or colonization with ESBLKp, whereas, among 104 neonates who were not treated with vancomycin, 3 (2.9%) were affected, with an incidence density ratio of 4.22 (95% confidence interval: 1.47-5.15). Parenteral feeding and mechanical ventilation were found to be marginally significant risk factors.

CONCLUSION

Treatment with vancomycin appears to be a risk factor for infection or colonization with ESBLKp in the NICU setting.

Comparison of probe disinfection procedures in routine ultrasonography: hot water versus antiseptic wiping

OBJECTIVE

It is commonly known that ultrasonography (US) transducers function as both a reservoir and means of transfer for hospital infections. The current study aimed to compare the antimicrobial effectiveness of using >80 °C water versus antiseptic wipes to disinfect US transducers.

METHODS

Subsequent to abdominal inspections in three groups of 20 patients, a swab culture was taken from the transducer in each case. Neither a mechanical nor chemical disinfection was applied to the transducer in the first group. As for the second group, the transducer was placed in >80 °C hot water for five minutes. In the third group, the transducer was wiped clean using antiseptic wipes.

RESULTS

Of the 60 swab samples collected, 40 did not produce any growth. The number of samples exhibiting growth in the first group involved 18 cases of coagulase-negative staphylococcus (CNS), as well as 15 cases of Listeria spp., one case of Corynebacterium spp. and one case of Bacillus spp., while only one case of CNS was observed in the second and third groups, respectively. The culture growth and colony forming units rate were significantly higher in the samples obtained from the first group than in those obtained from the other groups (p<0.01). As for the second and third groups, no significant differences were found in terms of the amount of colonization and growth (p=1.00).

CONCLUSION

Being a practical and a simple method for particular use in developing and underdeveloped countries, where it is hard to access relatively costly transducer disinfection materials, such as antiseptic wipes, hot water disinfection may play an active role in fighting hospital infections.

Decontamination of ultrasound equipment used for peripheral ultrasound-guided regional anaesthesia

Portable ultrasound machines are frequently used in operating theatres for peripheral single-shot nerve block procedures. This equipment must be decontaminated by reducing the microbial load to a sufficient level to reduce the risk of nosocomial infection. In our institution we use a simple three-step decontamination protocol utilising 70% isopropyl alcohol as chemical disinfectant. We performed a prospective, quality assurance study to assess the efficacy of this protocol, as it is unclear if this is suitable for disinfecting semi-critical equipment. The primary endpoint was presence of microbial contamination prior to re-use of equipment. Over a four-week period, 120 swabs were taken from multiple sites on our ultrasound machines and linear array transducers for microbial culture. Swabs were taken after decontamination and immediately prior to patient contact. Any pathogenic and environmental bacterial organisms were isolated and identified. No pathogenic organisms were grown from any of the collected swabs. In 85% (n=102) of cultures, no growth was detected. Of the remaining 15% (n=18), commensal organisms commonly found on skin, oral and environmental surfaces were isolated. Our results suggest that our decontamination protocol may be an effective, rapid and cost-effective method of cleaning ultrasound equipment used for peripheral invasive single-shot nerve blocks. Further guidance from national bodies is required to define appropriate cleaning protocols for these machines.

An outbreak of Pseudomonas aeruginosa respiratory tract infections associated with intrinsically contaminated ultrasound transmission gel

We describe an outbreak of Pseudomonas aeruginosa respiratory tract infections related to intrinsically contaminated ultrasound gel used for intraoperative transesophageal echocardiograms in cardiovascular surgery patients. This investigation led to a product safety alert by the Food and Drug Administration and the development of guidelines for appropriate use of ultrasound gel.

Early identification and control of carbapenemase-producing Klebsiella pneumoniae, originating from contaminated endoscopic equipment

Klebsiella producing carbapenemase is an emerging pathogen. We report transmission of this organism by contaminated endoscopic instruments. Quick identification of source, staff education, contact precautions, and emphasis on hand and environmental hygiene led to case control and prevention of outbreak.

The emergence of multidrug-resistant Klebsiella pneumoniae of international clones ST13, ST16, ST35, ST48 and ST101 in a teaching hospital in the Paris region

Despite infection control measures, an important increase in the extended-spectrum β-lactamase (ESBL)-producing Klebsiella pneumoniae incidence density occurred in our hospital from 2006 onwards. This study, focusing on the 2005-2007 period, was performed in an attempt to explain this increase. ESBLs were characterized, isolates were typed by ERIC2-PCR, and sequence type (ST) of clustered isolates was determined. Temporal-spatial relationships of patients were analysed to assess possible cross-contamination. Of the 74 ESBL-producing isolates, 30 (40%) were detected at admission, 53 (71∙5%) produced CTX-M enzymes, 40 displayed unique ERIC2-PCR profiles and 34 were assigned into six clusters: ST16 (n=21), ST101, ST48, ST35, ST13, and ST436. Relationships were identified in 22 of the 34 patients harbouring clustered isolates. This study highlights the complex epidemiology of ESBL-producing K. pneumoniae in the mid-2000s with potential cross-contamination for only 30% of the 74 patients in our hospital, and the emergence of clones that are currently spreading worldwide.

Noncontact ultrasound imaging applied to cortical bone phantoms

PURPOSE

The purpose of this paper was to take the first steps toward applying noncontact ultrasound (NCU) to the tasks of monitoring osteoporosis and quantitative ultrasound imaging (QUS) of cortical bone. The authors also focused on the advantages of NCU, such as its lack of reliance on a technologist to apply transducers and a layer of acoustical coupling gel, the ability of the transducers to operate autonomously as specified by preprogrammed software, and the likely reduction in statistical and systematic errors associated with the variability in the pressure applied by the clinician to the transmitting transducer that NCU might provide. The authors also undertook this study in order to find additional applications of NCU beyond its past limited usage in assessing the severity of third degree burns.

METHODS

A noncontact ultrasound imaging system using a pair of specially designed broadband, 1.5 MHz noncontact piezoelectric transducers and cortical bone phantoms, were used to determine bone mineral density (BMD), speed of sound (SOS), integrated response (IR), and ultrasonic transmittance. Air gaps of greater than 3 cm, two transmission and two reflection paths, and a digital signal processor were also used in the collection of data from phantoms of nominal mass densities that varied from 1.17 to 2.25 g/cm(3) and in bone mineral density from 0 to 1.7 g/cm(3).

RESULTS

Good correlations between known BMD and measured SOS, IR, and transmittance were obtained for all 17 phantoms, and methods for quantifying and minimizing sources of systematic errors were outlined. The BMD of the phantom sets extended through most of the in vivo range found in cortical bone. A total of 16-20 repeated measurements of the SOS, thickness, and IR for the phantom set that were conducted over a period of several months showed a small variation in the range of measurements of ±1%-2%. These NCU data were shown to be in agreement with similar results using contact ultrasound to be within 1%-2%. Transmittance images of cortical bone phantoms showed differences in the nominal overall BMD values of the phantoms that were large enough to be distinguished by a visual examination. A list of possible sources of errors in quantitative NCU was also included in this study.

CONCLUSIONS

The results of this paper suggest that NCU might find additional applications in medical imaging, beyond its original and only previous usage in assessing third degree burns. The fact that the authors' phantom measurements using conventional, gel coupled ultrasound are in agreement with those obtained with NCU demonstrates that in spite of large additional levels of attenuation of up to 150 dB and new error sources, NCU could have comparable levels of accuracy to those of conventional quantitative ultrasound, while providing the medical and patient comfort-related advantages of not involving direct contact.

Decontamination of transvaginal ultrasound probes: review of national practice and need for national guidelines

AIM

To determine the national practice of transvaginal ultrasound (TVUS) probe decontamination in English hospitals and to develop recommendations for guidance.

MATERIALS AND METHODS

A literature review was undertaken to clarify best practice and evaluate methods of decontamination of TVUS probes. A questionnaire was developed to ascertain TVUS probe decontamination programmes in current use within English hospitals. This was sent to ultrasound leads of 100 English hospitals; 68 hospitals responded.

RESULTS

There is a wide variation in TVUS probe decontamination across English hospitals. Although the majority of respondents (87%, 59/68) reported having clear and practical written guidelines for TVUS decontamination, the frequency, methods, and types of decontamination solutions utilized were widely variable and none meet the standards required to achieve high-level disinfection.

CONCLUSION

While the decontamination of other endoluminal medical devices (e.g., flexible endoscopes) is well defined and regulated, the decontamination of TVUS probes has no such guidance. There appears to be incomplete understanding of the level of risk posed by TVUS probes, and in some cases, this has resulted in highly questionable practices regarding TVUS hygiene. There is an urgent need to develop evidence-based national guidance for TVUS probe decontamination.