Routine Microbiological Monitoring Research Articles

RISK ASSESSMENT OF HOSPITAL STRAINS FORMATION AND OCCURRENCE OF HEALTH CARE-ASSOCIATED INFECTIONS AMONG PATIENTS OF A MULTIDISCIPLINARY MEDICAL ORGANIZATION

Aim. Risk assessment of the introduction of resistant strains of microorganisms and the formation of their hospital forms in the Clinics of the Irkutsk State Medical University (Clinics of the ISMU) Materials and methods. To analyze how the level of resistance of microbial strains isolated from patients effect the form of the disease the case histories of patients of the Clinic of the State Medical University for 2022 (n=123) were used. Bacteriological study of microbial contamination of air and environmental objects in the Clinics of the State Medical University in 2022 using swabs and aspiration method (n = 4523). Result. When comparing acute and chronic forms of diseases among groups of patients with highly resistant and low resistant strains of microorganisms, a statistically significant difference was found χ2 = 6.2 p<0.012. In 2022, in the structural subdivisions of the ISMU Clinics, positive results of washings from environmental objects were recorded in only 0.3% (95% CI 0.14 - 0.46) of studies. In the treatment room of the ENT department of the Clinic of the State Medical University in November 2022, during routine microbiological monitoring, S. aureus, which is resistant to benzylpenicillin, was isolated once. Microbiological study of biomaterial from patients of the ENT department who were hospitalized in the same period showed the presence of S. aureus which has identical resistance to antibiotics in one patient. The maximum level of resistance was registered in S. epidermidis, isolated from the biomaterial from the patient of the otorhinolaryngological department, and amounted to 88.9%. Conclusion. Chronic forms of diseases are associated with the presence of highly resistant strains of microorganisms in a patient. Given the constant circulation of resistant pathogens among patients, there is a risk of introduction and formation of hospital clones of microorganisms in medical organizations.

Evaluation of the Results of a Periodic Environmental Biosecurity Assessment Program on Air Quality in Controlled Environment Rooms of Hospitals.

Determine the utility of the Periodic Environmental Biosecurity Assessment Program (PEBAP) in achieving clean air as measured by the number of colony-forming units (CFU) of fungi and bacteria in the air. There is no international consensus on the sampling frequency, the recommended limits for microorganisms in the air nor on the usefulness of routine microbiological air monitoring of hospitals. During the PEBAP, data were recollected between 2010 and 2017 in eight hospitals in southeast Spain. Air samples were collected in very high risk rooms (VHRRs) and high risk rooms (HRRs), unoccupied, using active sampling methods. Temperature, relative humidity, air changes per hour (ACH), and differential pressure were measured. When limits of CFU of opportunistic fungi and bacteria established in the PEBAP were exceeded, corrective measures were adopted. We found a reduction (p < .01) of percentage of air samples with fungi growth throughout the years of PEBAP in all rooms. Aspergillus was the most frequent opportunistic fungus. We found a high compliance of the standards of CFU of bacteria in HRR, and the percentage of compliance in VHRR was lower than in HRR in all years. Differences in environmental and design parameters were statistically significant (p < .05) between rooms, except for ACH. PEBAP resulted in a useful tool to maintain and improve air quality in hospitals. The control of environmental biosecurity requires a multidisciplinary approach from preventive medicine, engineering, and cleaning services. Aspergillus is the most frequent opportunistic fungus in southeast Spain.

Quick and wide-range taxonomical repertoire establishment of the cystic fibrosis lung microbiota by tandem mass spectrometry on sputum samples.

Microorganisms proteotyping by tandem mass spectrometry has been recently shown as a powerful methodology to identify the wide-range taxonomy and biomass of microbiota. Sputum is the recommended specimen for routine microbiological monitoring of Cystic Fibrosis (CF) patients but has been rarely submitted to tandem mass spectrometry-based proteotyping. In this study, we compared the microbial components of spontaneous and induced sputum samples from three cystic fibrosis patients. Although the presence of microbial proteins is much lower than host proteins, we report that the microbiota’s components present in the samples can be identified, as well as host biomarkers and functional insights into the microbiota. No significant difference was found in microorganism abundance between paired spontaneous and induced sputum samples. Microbial proteins linked to resistance, iron uptake, and biofilm-forming ability were observed in sputa independently of the sampling method. This unbiased and enlarged view of the CF microbiome could be highly complementary to culture and relevant for the clinical management of CF patients by improving knowledge about the host-pathogen dynamics and CF pathophysiology.

Establishing a marine monitoring programme to assess antibiotic resistance: A case study from the Gulf Cooperation Council (GCC) region.

The World Health Organization considers antimicrobial resistance as one of the most pressing global issues which poses a fundamental threat to human health, development, and security. Due to demographic and environmental factors, the marine environment of the Gulf Cooperation Council (GCC) region may be particularly susceptible to the threat of antimicrobial resistance. However, there is currently little information on the presence of AMR in the GCC marine environment to inform the design of appropriate targeted surveillance activities. The objective of this study was to develop, implement and conduct a rapid regional baseline monitoring survey of the presence of AMR in the GCC marine environment, through the analysis of seawater collected from high-risk areas across four GCC states: (Bahrain, Oman, Kuwait, and the United Arab Emirates). 560 Escherichia coli strains were analysed as part of this monitoring programme between December 2018 and May 2019. Multi-drug resistance (resistance to three or more structural classes of antimicrobials) was observed in 32.5% of tested isolates. High levels of reduced susceptibility to ampicillin (29.6%), nalidixic acid (27.9%), tetracycline (27.5%), sulfamethoxazole (22.5%) and trimethoprim (22.5%) were observed. Reduced susceptibility to the high priority critically important antimicrobials: azithromycin (9.3%), ceftazidime (12.7%), cefotaxime (12.7%), ciprofloxacin (44.6%), gentamicin (2.7%) and tigecycline (0.5%), was also noted. A subset of 173 isolates was whole genome sequenced, and high carriage rates of qnrS1 (60/173) and bla CTX-M-15 (45/173) were observed, correlating with reduced susceptibility to the fluoroquinolones and third generation cephalosporins, respectively. This study is important because of the resistance patterns observed, the demonstrated utility in applying genomic-based approaches to routine microbiological monitoring, and the overall establishment of a transnational AMR surveillance framework focussed on coastal and marine environments.

Epidemiological significance of the occurrence and persistence of rotaviruses in water and sewage: a critical review and proposal for routine microbiological monitoring.

Globally, waterborne gastroenteritis attributable to rotaviruses is on the increase due to the rapid increase in population growth, poor socioeconomic conditions, and drastic changes in climatic conditions. The burden of diarrhea is quite alarming in developing nations where the majority of the populations still rely on untreated surface water that is usually polluted for their immediate water needs. Humans and animals of all ages are affected by rotaviruses. In humans, the preponderance of cases occurs in children under 5 years. Global efforts in advancing water/wastewater treatment technologies have not yet realized the objective of complete viral removal from wastewater. Most times, surface waters are impacted heavily by inadequately treated wastewater run-offs thereby exposing people or animals to preventable health risks. The relative stability of rotaviruses in aquatic matrices during wastewater treatment, poor correlation of bacteriological indicators with the presence of rotaviruses, and their infectiousness at a low dose informed the proposal for inclusion in the routine microbiological water screening panel. Environmental monitoring data have been shown to provide early warnings that can complement clinical data used to monitor the impact of current rotavirus vaccination in a community. This review was therefore undertaken to critically appraise rotavirus excretion and emission pathways, and the existence, viability and persistence in the receiving aquatic milieu. The efficiency of the current wastewater treatment modality for rotavirus removal, correlation of the current bacteriological water quality assessment strategy, public health risks and current laboratory methods for an epidemiological study were also discussed.

Microbiological contaminations of laboratory mice and rats in conventional facilities in Argentina

Routine microbiological monitoring of rodent colonies in animal facilities is essential to evaluate the health status of the animals used in research studies. In the present study, animals were examined for the presence of selected microbial infections. In order to determine the contamination rates of mice and rats in Argentina, animals from 102 conventional facilities were monitored from 2012 to 2016. The most frequent bacteria isolated were Pseudomonas aeruginosa and Proteus spp. The common parasites identified were Syphacia spp. and Tritrichomonas spp. Serological assays demonstrated the highest prevalence for Mouse hepatitis virus in mice and Sialodacryoadenitis virus in rats. The results indicate that there is a high incidence of infections, so it is suggested that an efficient management system and effective sanitary barriers should be implemented in conventional facilities in Argentina in order to improve sanitary standards.

Sequential Transmission of Salmonella in the Slaughtering Process of Chicken in Korea.

Salmonella is one of the most common foodborne pathogens worldwide. Salmonella infections in humans are mainly associated with consumption of poultry products contaminated with this foodborne pathogen. Therefore, strict sanitary measures are necessary to control Salmonella contamination during the slaughtering process of poultry. The objective of this study was to determine the occurrence and transmission of Salmonella at a series of steps in the slaughtering process of chicken. A total of 601 samples were collected from a series of slaughtering steps (10 sampling sites) of 26 chicken slaughterhouses throughout Korea. Salmonella was isolated from samples and its distribution was analyzed along the slaughtering process. Isolates from each sampling site were tested for susceptibility to 15 antibiotics by the broth microdilution method. They were also genotypically characterized by pulsed-field gel electrophoresis (PFGE). Salmonela was isolated from 168 out of 601 samples. Sixteen serotypes were identified while six isolates were untypable. Salmonella enterica serovars Montevideo (n = 29) and Virchow (n = 27) were the most common serotypes out of 119 nonredundant isolates. Relatively high contamination rates of Salmonella were found in shackles (75.0%), feathers near plucking machine (68.5%), and feces from crates (44.0%). Twenty-three antibiotic resistance patterns were recognized and 40 (33.6%) isolates were resistant to five or more antibiotics. The same serotypes of Salmonella were distributed along the slaughtering process of each Salmonella-positive slaughterhouse. Most of those isolates belonging to the same serotype had identical or closely related PFGE profiles. They also shared common antibiotic resistance patterns. Overall findings of this study indicated that Salmonella were sequentially transmitted through the chicken slaughtering process. PRACTICAL APPLICATION: This study provides useful information on the distribution and transmission of Salmonella serotypes through the chicken slaughtering process. Overall findings indicated the need for routine microbiological monitoring along the slaughtering process. This study also showed that on-farm control of Salmonella is needed to obtain Salmonella-free chicken carcasses.

Chronic Bacterial Infection Prevalence, Risk Factors, and Characteristics: A Bronchiectasis Population-Based Prospective Study.

Background: Few data are available on chronic bacterial infections (CBI) in bronchiectasis patients. Given that CBI seems to trigger longer hospital stays, worse outcomes, and morbimortality, this study was undertaken to assess CBI prevalence, characteristics, and risk factors in outpatients with bronchiectasis. Methods: A total of 186 patients followed in a bronchiectasis tertiary referral centre in Portugal were included. Demographic data and information on aetiology, smoking history, mMRC score, Bronchiectasis Severity Index (BSI) score, sputum characteristics, lung function, exacerbations, and radiological involvement degree were collected. Results: Patients included (mean age 54.7 ± 16.2 years; 60.8% females) were followed up for a period of 3.8 ± 1.7 years. The most common cause of bronchiectasis was infection (31.7%) followed by immune deficiencies (11.8%), whereas in 29% of cases, no cause was identified. Haemophilus influenzae (32.3%) and Pseudomonas aeruginosa (30.1%) were the most common CBI-associated possible pathogenic microorganisms. CBI patients presented a higher follow-up time than no-CBI patients (p = 0.003), worse lung function, BSI (p < 0.001), and radiological (p < 0.001) scores, and more prominent daily sputum production (p = 0.002), estimated mean volume (p < 0.001), and purulent sputum (p < 0.001). The number of exacerbations/year (p = 0.001), including those requiring hospital admission (p = 0.009), were also higher in the CBI group. Independent CBI predictors were BSI score (OR 3.577, 95% CI 1.233–10.378), sputum characteristics (OR 3.306, 95% CI 1.107–9.874), and radiological score (OR 1.052, 95% CI 1.004–1.102). Conclusion: According to the CBI status, two different sub-groups of patients were found on the basis of several clinical outcomes, emphasizing the importance of routine sputum microbiological monitoring. Further studies are needed to better characterize CBI profiles and to define the individual clinical impact of the most prevalent pathogenic microorganisms.

Acinetobacter species in laboratory mice: species survey and antimicrobial resistance.

The extra-hospital epidemiology of Acinetobacter infections is a subject of debate. In recent years, the prevalence of animal multidrug-resistant Acinetobacter infections has increased considerably. The goal of the present study was to specify Acinetobacter species isolated from laboratory mice and to test them for their antimicrobial susceptibility. During routine microbiological monitoring of laboratory mice, 12 Acinetobacter spp. were isolated. By means of 16S rRNA and rpoB gene sequencing, seven of the isolates were identified as Acinetobacter radioresistens, three isolates belonged to Acinetobacter genomospecies 14BJ, one isolate was classified as Acinetobacter pitii and one as Acinetobacter sp. ANC 4051. The distribution of the minimal inhibitory concentration (MIC) values was uniform for 21 of the 23 antimicrobial agents tested, whereas a broad MIC distribution was recorded for tulathromycin and streptomycin. The MIC values recorded were low for the majority of the antibiotics tested. Nevertheless, very high MIC values, which will probably render a therapeutic approach using these substances unsuccessful, were recorded for florfenicol, tiamulin, tilmicosin and cephalothin in most of the isolates. In conclusion, we document colonization of laboratory mice with different Acinetobacter species, displaying similar antibiotic susceptibility profiles, with possible implications in the Acinetobacter epidemiology as well as in the husbandry and experimentation of the colonized animals.

Application of loop-mediated isothermal amplification with propidium monoazide treatment to detect live Salmonella in chicken carcasses

Raw chicken products are major causes of human foodborne salmonellosis worldwide. In particular, there is a significant risk of human exposure to Salmonella originating from the chicken slaughtering process. Controlling the contamination of chicken carcasses by Salmonella has been a considerable challenge in chicken-slaughtering facilities and involves routine microbiological monitoring using reliable detection methods. Simple and rapid detection methods, particularly those capable of determining cell viability, will significantly facilitate routine monitoring of Salmonella. Here, we report an invA-based loop-mediated isothermal amplification method coupled with a simple propidium monoazide treatment (PMA-LAMP) for simple and rapid detection and quantification of viable Salmonella in rinse water of chicken carcasses. In this study, PMA-LAMP consistently gave negative results for isopropanol-killed Salmonella with concentrations up to 8.0 × 106 CFU/reaction. The detection limit of PMA-LAMP was 8.0 × 101 CFU/reaction with viable Salmonella in both pure culture and rinse water of chicken carcasses, and 10-fold lower than a conventional polymerase chain reaction coupled with PMA (PMA-PCR) targeting invA. There was a high correlation (R2 = 0.99 to 0.976) between LAMP time threshold (TT) values and viable Salmonella with a quantification range of 1.0 × 103 to 1.0 × 108 CFU/mL in pure culture and rinse water of chicken carcasses. The PMA-LAMP assay took less than 2 h to detect Salmonella contaminated in test samples. Therefore, this simple and rapid method will be a very useful tool to detect live Salmonella contamination of chicken carcasses without pre-enrichment at the slaughterhouse where sanitizing treatments are commonly used.

Mortality event involving larvae of the carpet shell clam Ruditapes decussatus in a hatchery: isolation of the pathogen Vibrio tubiashii subsp. europaeus.

Diseases caused by bacteria belonging to the genus Vibrio are a common, as yet unresolved, cause of mortality in shellfish hatcheries. In this study, we report the results of routine microbiological monitoring of larval cultures of the carpet shell clam Ruditapes decussatus in a hatchery in Galicia (NW Spain). Previous episodes of mortality with signs similar to those of vibriosis affecting other species in the installation indicated the possibility of bacterial infection and led to division of the culture at the early D-veliger larval stage. One batch was cultured under routine conditions, and the other was experimentally treated with antibiotic (chloramphenicol). Differences in larval survival were assessed, and culturable bacterial population in clams and sea water was evaluated, with particular attention given to vibrios. Severe mortalities were recorded from the first stages of culture onwards. The pathogen Vibrio tubiashii subsp. europaeus was detected in both batches, mainly associated with larvae. Moreover, initial detection of the pathogen in the eggs suggested the vertical transmission from broodstock as a possible source. Experimental use of antibiotic reduced the presence and diversity of vibrios in sea water, but proved inefficient in controlling vibrios associated with larvae from early stages and it did not stop mortalities.

Draft Genome Sequences of Klebsiella oxytoca Isolates Originating from a Highly Contaminated Liquid Hand Soap Product.

In 2013, contaminated liquid soap was detected by routine microbiological monitoring of consumer products through state health authorities. Because of its high load of Klebsiella oxytoca, the liquid soap was notified via the European Union Rapid Alert System for Dangerous Non-Food Products (EU-RAPEX) and recalled. Here, we present two draft genome sequences and a summary of their general features.

Diagnostic problems of nosocomial infections in patients with severe sepsis and ongoing antimicrobial treatment - efficiency and value of serum inflammatory markers and routine microbiological monitoring

Diagnostic problems of nosocomial infections in patients with severe sepsis and ongoing antimicrobial treatment - efficiency and value of serum inflammatory markers and routine microbiological monitoring

Infectiological diagnostic problems in tertiary peritonitis

The tertiary peritonitis causes the highest mortality in intraabdominal infections. Surgical interventions and antibiotic therapy may only provide an incomplete impact on nosocomial infections acquired at an intensive care unit (ICU) [Nathens et al., World J Surg 22:158-163, 28]. To open up new resources in the management, in particular, in the previous infectious diagnostic, the aim was to investigate the infectious course as well as the diagnostic value of laboratory parameters and microbiological monitoring. In this retrospective patient cohort study from the Surgical ICU of a University Hospital (capacity, n=12), overall, 60 patients with a tertiary peritonitis were enrolled. Approximately 20% of the patients with an intraabdominal infection developed a tertiary peritonitis. A tertiary peritonitis can more frequently develop in nosocomial intraabdominal infections, in particular, in case of necrotizing pancreatitis. The device-associated infection rate in the spectrum of nosocomial infections is sevenfold higher than in all ICU patients. Compared with the secondary peritonitis, its mortality is double as high: 35%. In the diagnostic characterizing the course of the nosocomial, prognosis-relevant infections, usual inflammatory parameters show a considerable loss of their sensitivity with a range from 35-57%. By the mean of a routine microbiological monitoring, 47.3% of the analysed subsequent infections could be identified at an early stage. In patients with a severe infection, an early diagnostic and treatment of infectious "second hits" can improve the complication rate and prognosis. During the prolonged and complicated septic course of tertiary peritonitis, an additional routine microbiological monitoring contributed effectively to early detection and diagnostic of nosocomial infections. Further studies to investigate the value and efficacy of such monitoring, which have been abandoned, should be undertaken in infectious high-risk patients.

Diagnostic problems of nosocomial infections in patients with severe sepsis and ongoing antimicrobial treatment — efficiency and value of serum inflammatory markers and routine microbiological monitoring

Abstract Purpose. The use of routine microbiological monitoring in the intensive care unit (ICU) setting has been controversially discussed in the past. Therefore, the primary goal of this study was to evaluate the efficiency and value of both laboratory and microbiological monitoring as useful diagnostic tools for nosocomial infections, particularly in patients with severe sepsis. Materials and methods. Between 2000 and 2002, 60 consecutive patients with severe sepsis and tertiary peritonitis on a surgical ICU were retrospectively analysed for this study. All nosocomial infections that occurred during ongoing treatment as well as parameters that finally initiated screening for infections were registered. The time course of serum inflammatory parameters (C-reactive protein, leucocyte count, procalcitonin, interleukin-6) and core temperature (fever > =38.0°C) for 72 h before definite diagnosis of an infection as well as their predictive value were analysed. The results of a routine microbiological monitori...

Microbiological control in stem cell banks: approaches to standardisation

The transplant of cells of human origin is an increasingly complex sector of medicine which entails great opportunities for the treatment of a range of diseases. Stem cell banks should assure the quality, traceability and safety of cultures for transplantation and must implement an effective programme to prevent contamination of the final product. In donors, the presence of infectious micro-organisms, like human immunodeficiency virus, hepatitis B virus, hepatitis C virus and human T cell lymphotrophic virus, should be evaluated in addition to the possibility of other new infectious agents (e.g. transmissible spongiform encephalopathies and severe acute respiratory syndrome). The introduction of the nucleic acid amplification can avoid the window period of these viral infections. Contamination from the laboratory environment can be achieved by routine screening for bacteria, fungi, yeast and mycoplasma by European pharmacopoeia tests. Fastidious micro-organisms, and an adventitious or endogenous virus, is a well-known fact that will also have to be considered for processes involving in vitro culture of stem cells. It is also a standard part of current good practice in stem cell banks to carry out routine environmental microbiological monitoring of the cleanrooms where the cell cultures and their products are prepared. The risk of viral contamination from products of animal origin, like bovine serum and mouse fibroblasts as a “feeder layer” for the development of embryonic cell lines, should also be considered. Stem cell lines should be tested for prion particles and a virus of animal origin that assure an acceptable quality.

Enumeration of faecal indicator bacteria in large water volumes using on site membrane filtration to assess water treatment efficiency

With sample volumes as tested in routine microbiological monitoring for the presence and absence of faecal indicator bacteria in treated water the actual concentration in the final stages of water treatment cannot be assessed. Consequently, no accurate information can be obtained about the removal efficiency of a water treatment for microorganisms. Therefore a method for on site isolation of faecal indicator bacteria from large volumes (100 l or more) of treated water using membrane filtration (MF-sampling) was developed and tested. The procedures for culturing the isolated microorganisms were similar to those applied in the routine methods for small volumes using membrane filtration (mf-method). The recovery efficiency of MF-sampling for E. coli, S. faecalis and spores of sulphite-reducing clostridia ranged from 74.6 to 100% and only for E. coli a slight decrease with increasing sample volume was found. Field studies revealed that MF-sampling can easily be implemented in (routine) laboratory practice for an accurate determination of the concentration of faecal indicator bacteria in treated water after various treatment stages. From these data the treatment efficiency of the involved processes and the overall treatment for those microorganisms and the fluctuation in microorganism removal were determined. Such data can be used to improve water treatment regarding the removal of microorganisms. Validation of the use of faecal indicator bacteria as a surrogate parameter for the assessment of the effects of treatment processes on pathogenic microorganisms needs further investigation.

Prevalence and Risk Factors for Colonisation with Gram-Negative Bacteria in an Intensive Care Unit

Objective: To investigate prevalence and determine risk factors for colonisation with Gram-negative bacteria in ICU patients.Design: Prospective, surveillance study.Setting: 26-bed surgical and paediatric ICU.Patients: 159 patients - whereof 22 infants - admitted to the surgical/paediatric ICU over a two-month period.Intervention: In all patients routine microbiological monitoring was performed by thrice weekly oral swabs, urine sampling and, additionally, tracheal aspirates in patients on mechanical ventilation (MV) and by anal swabs once weekly.Results: Population characteristics: Mean age of the adult population was 51.1 ± 17.6 year. Mean age of the paediatric population was 6.3 ± 5.3 year. The mean APACHE II-score was 18 ± 9.1. The mean PRISM-score was 9.7 ± 5.4. The mean ICU stay was 7.5 ± 11.4 days. 43.4 percent of patients received mechanical ventilation (MV). The mean number of mechanical ventilation days was 11.1 ± 14.7 days.32.1% of patients experienced colonisation with Gram-negative bacteria. Prevalence of colonisation increased with length of ICU stay. The probability of colonisation was 24% after an ICU stay of 3 days (=median ICU stay). Time to colonisation was not different between the controlled sites (p>0.05). 47% of colonisations were due to multiresistant strains. Higher APACHE II-scores and MV were associated with a higher prevalence of colonisation (p<0.01). The ICU mortality was 8%among adult and 4% among paediatric patients.Conclusion: Patients with high APACHE II-scores, on mechanical ventilation and with an ICU stay of more than 3 days are most at risk for colonisation with Gram-negative bacteria. These patients should be cared with the optimal precautions in the prevention of colonisation and infection.

Risk of bacillus cereus and pseudomonas aeruginosa nosocomial infections in a burns centre: the microbiological monitoring of water supplies for a preventive strategy

Opportunist bacteria are a potentially very serious problem in hospital burns units, particularly where the quantity and quality of water supplies may not be reliable, and patients are especially vulnerable. A programme of routine microbiological monitoring is described which minimises the risk to patients.

Risk of Bacillus cereus And Pseudomonas aeruginosa nosocomial infections in a burns centre: The microbiological monitoring of water supplies for a preventive strategy

Opportunist bacteria are a potentially very serious problem in hospital bums units, particularly where the quantity and quality of water supplies may not be reliable, and patients are especially vulnerable. A programme of routine microbiological monitoring is described which minimises the risk to patients.