Arden Syntax MLM Building Blocks for Microbiological Concepts and Their Application in Infection Surveillance.

BACKGROUND: The diagnosis - and hence definitions - of healthcare-associated infections (HAIs) rely on microbiological laboratory test results in specific constellations. OBJECTIVES: To construct a library that provides interoperable building blocks for the analysis of microbiological laboratory test results. METHODS: We used Java for preprocessing raw microbiological laboratory test results and Arden Syntax for knowledge-based querying of data based on microbiology information elements used in European surveillance criteria for HAIs. To test the library and quantify how often these information elements occur in the data, we performed a retrospective cohort study on adult patients admitted for at least 24 hours to an intensive care unit at the Vienna General Hospital in 2013. RESULTS: We identified eleven information elements for which information was electronically available. These elements were identified positively 1,239 times in 1,184 positive microbiology tests from 563 patients. DISCUSSION: The availability of a library for the analysis of microbiology laboratory test results in HAI terms facilitates electronic HAI surveillance.

Arden Syntax Clinical Foundation Framework for Event Monitoring in Intensive Care Units: Report on a Pilot Study.

The creation of clinical decision support systems has received a strong impulse over the last years, but their integration into a clinical routine has lagged behind, partly due to a lack of interoperability and trust by physicians. We report on the implementation of a clinical foundation framework in Arden Syntax, comprising knowledge units for (a) preprocessing raw clinical data, (b) the determination of single clinical concepts, and (c) more complex medical knowledge, which can be modeled through the composition and configuration of knowledge units in this framework. Thus, it can be tailored to clinical institutions or patients' caregivers. In the present version, we integrated knowledge units for several infection-related clinical concepts into the framework and developed a clinical event monitoring system over the framework that employs three different scenarios for monitoring clinical signs of bloodstream infection. The clinical event monitoring system was tested using data from intensive care units at Vienna General Hospital, Austria.

Context-Sensitive Clinical Alert Packages Written in Arden Syntax.

An increasing body of raw patient data is generated on each day of a patient's stay at a hospital. It is of paramount importance that critical patient information be extracted from these large data volumes and presented to the patient's clinical caregivers as early as possible. Contemporary clinical alert systems attempt to provide this service with moderate success. The efficacy of the systems is limited by the fact that they are too general to fit specific patient populations or healthcare institutions. In this study we present an extendable alerting framework implemented in Arden Syntax, which can be configured to the needs and preferences of healthcare institutions and individual patient caregivers. We illustrate the potential of this alerting framework via an alert package that analyzes hematological laboratory results with data from intensive care units at the Vienna General Hospital, Austria. The results show the effectiveness of this alert package and its ability to generate key alerts while avoiding over-alerting.

Detecting borderline infection in an automated monitoring system for healthcare-associated infection using fuzzy logic.

BACKGROUND: Many electronic infection detection systems employ dichotomous classification methods, classifying patient data as pathological or normal with respect to one or several types of infection. An electronic monitoring and surveillance system for healthcare-associated infections (HAIs) known as Moni-ICU is being operated at the intensive care units (ICUs) of the Vienna General Hospital (VGH) in Austria. Instead of classifying patient data as pathological or normal, Moni-ICU introduces a third borderline class. Patient data classified as borderline with respect to an infection-related clinical concept or HAI surveillance definition signify that the data nearly or partly fulfill the definition for the respective concept or HAI, and are therefore neither fully pathological nor fully normal. OBJECTIVE: Using fuzzy sets and propositional fuzzy rules, we calculated how frequently patient data are classified as normal, borderline, or pathological with respect to infection-related clinical concepts and HAI definitions. In dichotomous classification methods, borderline classification results would be confounded by normal. Therefore, we also assessed whether the constructed fuzzy sets and rules employed by Moni-ICU classified patient data too often or too infrequently as borderline instead of normal. PARTICIPANTS AND METHODS: Electronic surveillance data were collected from adult patients (aged 18 years or older) at ten ICUs of the VGH. All adult patients admitted to these ICUs over a two-year period were reviewed. In all 5099 patient stays (4120 patients) comprising 49,394 patient days were evaluated. For classification, a part of Moni-ICU's knowledge base comprising fuzzy sets and rules for ten infection-related clinical concepts and four top-level HAI definitions was employed. Fuzzy sets were used for the classification of concepts directly related to patient data; fuzzy rules were employed for the classification of more abstract clinical concepts, and for top-level HAI surveillance definitions. Data for each clinical concept and HAI definition were classified as either normal, borderline, or pathological. For the assessment of fuzzy sets and rules, we compared how often a borderline value for a fuzzy set or rule would result in a borderline value versus a normal value for its associated HAI definition(s). The statistical significance of these comparisons was expressed in p-values calculated with Fisher's exact test. RESULTS: The results showed that, for clinical concepts represented by fuzzy sets, 1-17% of the data were classified as borderline. The number was substantially higher (20-81%) for fuzzy rules representing more abstract clinical concepts. A small body of data were found to be in the borderline range for the four top-level HAI definitions (0.02-2.35%). Seven of ten fuzzy sets and rules were associated significantly more often with borderline values than with normal values for their respective HAI definition(s) (p<0.001). CONCLUSION: The study showed that Moni-ICU was effective in classifying patient data as borderline for infection-related concepts and top-level HAI surveillance definitions.

A national point prevalence study on healthcare-associated infections and antimicrobial use in Austria.

BACKGROUND: The first point prevalence survey performed in Austria had the aim to assess the magnitude of healthcare-associated infections and antimicrobials use in the country. METHODS: A multicentre study was carried out from May until June 2012 in nine acute care hospitals with a mean bed number of 620. Data from 4321 patients' clinical charts were reviewed. RESULTS: The overall healthcare-associated infections prevalence was 6.2% (268/4321) with the highest rate in intensive care departments (20.9%; 49/234). In medical and surgical departments the healthcare-associated infections prevalence was 5.4% (95/1745) and 6.6% (105/1586), respectively. The most frequent healthcare-associated infections were: urinary tract infections (21.3%; 61/287), pneumonia (20.6%; 59/287) and surgical site infections (17.4%; 50/287). The most common isolated microorganisms were: Escherichia coli (14.8%; 26/176), Enterococcus species (13.1%; 23/176) and Pseudomonas aeruginosa (11.4%; 20/176). Thirty-three per cent (1425/4321) of the patients received antimicrobials because of community-acquired infections treatment (14.2%; 615/4321), healthcare-associated infections treatment (6.4%; 278/4321), and surgical (8.2%; 354/4321) and medical prophylaxis (3.2%; 138/4321). Surgical prophylaxis was the indication for 22.0% (394/1792) of the overall prescriptions and was prolonged for more than 1 day in 77.2% (304/394) of the cases. CONCLUSION: The national Austrian survey proved the feasibility of a nation-wide network of surveillance of both healthcare-associated infections and antimicrobial use that will be repeated in the future. Healthcare-associated infections and antimicrobial use have been confirmed to be a grave health problem. The excessive prolongation of perioperative prophylaxis in Austria needs to be limited.

Neither Single nor a Combination of Routine Laboratory Parameters can Discriminate between Gram-positive and Gram-negative Bacteremia.

Adequate early empiric antibiotic therapy is pivotal for the outcome of patients with bloodstream infections. In clinical practice the use of surrogate laboratory parameters is frequently proposed to predict underlying bacterial pathogens; however there is no clear evidence for this assumption. In this study, we investigated the discriminatory capacity of predictive models consisting of routinely available laboratory parameters to predict the presence of Gram-positive or Gram-negative bacteremia. Major machine learning algorithms were screened for their capacity to maximize the area under the receiver operating characteristic curve (ROC-AUC) for discriminating between Gram-positive and Gram-negative cases. Data from 23,765 patients with clinically suspected bacteremia were screened and 1,180 bacteremic patients were included in the study. A relative predominance of Gram-negative bacteremia (54.0%), which was more pronounced in females (59.1%), was observed. The final model achieved 0.675 ROC-AUC resulting in 44.57% sensitivity and 79.75% specificity. Various parameters presented a significant difference between both genders. In gender-specific models, the discriminatory potency was slightly improved. The results of this study do not support the use of surrogate laboratory parameters for predicting classes of causative pathogens. In this patient cohort, gender-specific differences in various laboratory parameters were observed, indicating differences in the host response between genders.

Risk factors for development of spontaneous bacterial peritonitis and subsequent mortality in cirrhotic patients with ascites.

BACKGROUND: Patients with ascites are at risk for developing spontaneous bacterial peritonitis (SBP) - a severe complication associated with high mortality. We aimed to identify risk factors for SBP development and mortality to optimize stratification for primary prophylaxis and therapeutic strategies to improve survival. METHODS: 575 patients with cirrhosis and ascites undergoing paracentesis at a tertiary care hospital were included in this retrospective cohort study. Demographical, clinical and laboratory parameters were recorded at first paracentesis and during follow-up. Multivariate logistic regression analysis was used to identify independent predictors of SBP development and mortality. RESULTS: Child-Pugh stage C (OR: 3.323; P = 0.009), ascitic fluid polymorph-nuclear cell (PMN) count (OR: 1.544; P = 0.028) and low serum sodium (OR: 0.917; P = 0.029) emerged as independent risk factors for SBP development. SBP-naïve patients undergoing paracentesis and presenting with PMN-counts ≥100 cells/µl, or hyponatraemia <125 mM were at highest risk for developing SBP. Increases in MELD and CRP levels indicated SBP development, while no changes where observed in a matched control group with sterile ascites at multiple paracenteses. MELD score (OR: 1.565; P = 0.001) and CRP (OR: 1.067; P = 0.037) were identified as independent risk factors for 30-day mortality after SBP diagnosis. In particular SBP patients with MELD≥22, CRP ≥3.5 mg/dl and development of grade III/IV hepatic encephalopathy showed highest mortality. CONCLUSIONS: Low serum sodium levels, Child-Pugh stage C and elevated ascites PMN counts (≥100 cells/µl) indicate a significant risk for SBP development. SBP-related mortality is highest in patients with MELD≥22 and elevated CRP levels.

Proton pump inhibitor intake neither predisposes to spontaneous bacterial peritonitis or other infections nor increases mortality in patients with cirrhosis and ascites.

BACKGROUND AND AIM: The aim of this study was to assess the impact of proton pump inhibitor (PPI) intake on the development of spontaneous bacterial peritonitis (SBP) or other infections, as well as on mortality, in a thoroughly documented cohort of patients with cirrhosis and ascites. PATIENTS AND METHODS: We performed a retrospective analysis of follow-up data from 607 consecutive patients with cirrhosis undergoing their first paracentesis at a tertiary center. A binary logistic regression model investigating the association between PPI intake and SBP at the first paracentesis was calculated. Competing risk analyses and Cox models were used to investigate the effect of PPIs on the cumulative incidence of SBP or other infections and transplant-free survival, respectively. Adjustments were made for age, hepatocellular carcinoma, history of variceal bleeding, varices and model of end-stage liver disease score. RESULTS: Eighty-six percent of patients were receiving PPIs. After adjusting for potential confounding factors, PPI intake was neither associated with increased SBP prevalence at the first paracentesis (odds ratio (OR):1.11,95% confidence interval (95%CI):0.6-2.06; P = 0.731) nor cumulative incidence of SBP (subdistribution hazard ratio (SHR): 1.38; 95%CI:0.63-3.01; P = 0.42) and SBP or other infections (SHR:1.71; 95%CI:0.85-3.44; P = 0.13) during follow-up. Moreover, PPI intake had no impact on transplant-free survival in both the overall cohort (hazard ratio (HR):0.973,95%CI:0.719-1.317; P = 0.859) as well as in the subgroups of patients without SBP (HR:1.01,95%CI:0.72-1.42; P = 0.971) and without SBP or other infections at the first paracentesis (HR:0.944,95%CI:0.668-1.334; P = 0.742). CONCLUSIONS: The proportion of cirrhotic patients with PPI intake was higher than in previous reports, suggesting that PPI indications were interpreted liberally. In our cohort with a particularly high prevalence of PPI intake, we observed no association between PPIs and SBP or other infections, as well as mortality. Thus, the severity of liver disease and other factors, rather than PPI treatment per se may predispose for infectious complications.

A risk prediction model for screening bacteremic patients: a cross sectional study.

BACKGROUND: Bacteraemia is a frequent and severe condition with a high mortality rate. Despite profound knowledge about the pre-test probability of bacteraemia, blood culture analysis often results in low rates of pathogen detection and therefore increasing diagnostic costs. To improve the cost-effectiveness of blood culture sampling, we computed a risk prediction model based on highly standardizable variables, with the ultimate goal to identify via an automated decision support tool patients with very low risk for bacteraemia. METHODS: In this retrospective hospital-wide cohort study evaluating 15,985 patients with suspected bacteraemia, 51 variables were assessed for their diagnostic potency. A derivation cohort (n = 14.699) was used for feature and model selection as well as for cut-off specification. Models were established using the A2DE classifier, a supervised Bayesian classifier. Two internally validated models were further evaluated by a validation cohort (n = 1,286). RESULTS: The proportion of neutrophile leukocytes in differential blood count was the best individual variable to predict bacteraemia (ROC-AUC: 0.694). Applying the A2DE classifier, two models, model 1 (20 variables) and model 2 (10 variables) were established with an area under the receiver operating characteristic curve (ROC-AUC) of 0.767 and 0.759, respectively. In the validation cohort, ROC-AUCs of 0.800 and 0.786 were achieved. Using predefined cut-off points, 16% and 12% of patients were allocated to the low risk group with a negative predictive value of more than 98.8%. CONCLUSION: Applying the proposed models, more than ten percent of patients with suspected blood stream infection were identified having minimal risk for bacteraemia. Based on these data the application of this model as an automated decision support tool for physicians is conceivable leading to a potential increase in the cost-effectiveness of blood culture sampling. External prospective validation of the model's generalizability is needed for further appreciation of the usefulness of this tool.

Healthcare-associated infection surveillance and bedside alerts.

Expectations and requirements concerning the identification and surveillance of healthcare-associated infections (HAIs) are increasing, calling for differentiated automated approaches. In an attempt to bridge the "definition swamp" of these infections and serve the needs of different users, we improved the monitoring of nosocomial infections (MONI) software to create better surveillance reports according to consented national and international definitions, as well as produce infection overviews on complex clinical matters including alerts for the clinician's ward and bedside work. MONI contains and processes surveillance definitions for intensive-care-unit-acquired infections from the European Centre for Disease Prevention and Control, Sweden, as well as the Centers for Disease Control and Prevention, USA. The latest release of MONI also includes KISS criteria of the German National Reference Center for Surveillance of Nosocomial Infections. In addition to these "classic" surveillance criteria, clinical alert criteria--which are similar but not identical to the surveillance criteria--were established together with intensivists. This is an important step to support both infection control and clinical personnel; and--last but not least--to foster co-evolution of the two groups of definitions: surveillance and alerts.

Nonselective ß blockers increase risk for hepatorenal syndrome and death in patients with cirrhosis and spontaneous bacterial peritonitis.

BACKGROUND & AIMS: Nonselective ß blockers (NSBBs) reduce portal pressure and the risk for variceal hemorrhage in patients with cirrhosis. However, development of spontaneous bacterial peritonitis (SBP) in these patients could preclude treatment with NSBBs because of their effects on the circulatory reserve. We investigated the effects of NSBBs in patients with cirrhosis and ascites with and without SBP. METHODS: We performed a retrospective analysis of data from 607 consecutive patients with cirrhosis who had their first paracentesis at the Medical University of Vienna from 2006 through 2011. Cox models were calculated to investigate the effect of NSBBs on transplant-free survival time and adjusted for Child-Pugh stage and presence of varices. RESULTS: NSBBs increased transplant-free survival in patients without SBP (hazard ratio = 0.75; 95% confidence interval: 0.581-0.968; P = .027) and reduced days of nonelective hospitalization (19.4 days/year for patients on NSBBs vs 23.9 days/year for patients not taking NSBBs). NSBBs had only moderate effects on systemic hemodynamics at patients' first paracentesis. However, at the first diagnosis of SBP, the proportion of hemodynamically compromised patients with systolic arterial pressure <100 mm Hg was higher among those who received NSBBs (38% vs 18% of those not taking NSBBs; P = .002), as was the proportion of patients with arterial pressure <82 mm Hg (64% of those taking NSBBs vs 44% of those not taking NSBBs; P = .006). Among patients with SBP, NSBBs reduced transplant-free survival (hazard ratio = 1.58; 95% confidence interval: 1.098-2.274; P = .014) and increased days of nonelective hospitalization (29.6 days/person-year in patients on NSBBs vs 23.7 days/person-year in those not taking NSBBs). A higher proportion of patients on NSBBs had hepatorenal syndrome (24% vs 11% in those not taking NSBBs; P = .027) and grade C acute kidney injury (20% vs 8% for those not taking NSBBs; P = .021). CONCLUSIONS: Among patients with cirrhosis and SBP, NSBBs increase the proportion who are hemodynamically compromised, time of hospitalization, and risks for hepatorenal syndrome and acute kidney injury. They also reduce transplant-free survival. Patients with cirrhosis and SBP should not receive NSBBs.

The role and utilisation of public health evaluations in Europe: a case study of national hand hygiene campaigns.

BACKGROUND: Evaluations are essential to judge the success of public health programmes. In Europe, the proportion of public health programmes that undergo evaluation remains unclear. The European Centre for Disease Prevention and Control sought to determine the frequency of evaluations amongst European national public health programmes by using national hand hygiene campaigns as an example of intervention. METHODS: A cohort of all national hand hygiene campaigns initiated between 2000 and 2012 was utilised for the analysis. The aim was to collect information about evaluations of hand hygiene campaigns and their frequency. The survey was sent to nominated contact points for healthcare-associated infection surveillance in European Union and European Economic Area Member States. RESULTS: Thirty-six hand hygiene campaigns in 20 countries were performed between 2000 and 2012. Of these, 50% had undergone an evaluation and 55% of those utilised the WHO hand hygiene intervention self-assessment tool. Evaluations utilised a variety of methodologies and indicators in assessing changes in hand hygiene behaviours pre and post intervention. Of the 50% of campaigns that were not evaluated, two thirds reported that both human and financial resource constraints posed significant barriers for the evaluation. CONCLUSION: The study identified an upward trend in the number of hand hygiene campaigns implemented in Europe. It is likely that the availability of the internationally-accepted evaluation methodology developed by the WHO contributed to the evaluation of more hand hygiene campaigns in Europe. Despite this rise, hand hygiene campaigns appear to be under-evaluated. The development of simple, programme-specific, standardised guidelines, evaluation indicators and other evidence-based public health materials could help promote evaluations across all areas of public health.

Validation of fuzzy sets in an automated detection system for intensive-care-unit-acquired central-venous-catheter-related infections.

Central venous catheters play an important role in patient care in intensive care units (ICUs), but their use comes at the risk of catheter-related infections (CRIs). Electronic surveillance systems can detect CRIs more accurately than manual surveillance, but these systems often omit patients that do not exhibit all infection signs to their full degree, the so-called borderline group. By extending an electronic surveillance system with fuzzy constructs, the borderline group can be identified. In this study, we examined the size of the borderline group for systemic CRIs (CRI2) by calculating the frequency of fuzzy values for CRI2 and related infection parameters in patient data involving ten ICUs (75 beds) over one year. We also validated the expert-defined fuzzy constructs by comparing overall and CRI2-specific support. The study showed that more than 86% of the data contained fuzzy values, and that the borderline group for CRI2 consisted of 2% of the study group. It was also confirmed that most fuzzy constructs were good representatives of the borderline CRI2 patient group.

Delivering antibiotic resistance information specifically tailored to location and time.

Antibiotic resistance poses a significant threat to humanity. Hundred years since the beginning of the era of antibacterial drugs, we are facing increasing numbers of infections with multi-resistant pathogens. The current approach of distributing information on antibiotic resistance in printed form in the clinics has disadvantages with respect to the actuality of the data and the regional heterogeneity of resistance patterns. We developed an application named qRe using representational state transfer as a communication standard to deliver antibiotic resistance percentage information to the end user. The data is selected specifically for his/her geographic location. The user can display the information using either the application for Android smart phones or the web application. With the presented software we show the technical feasibility of delivering antibiotic resistance information specifically tailored to location and time. A short evaluation of the software showed an overall positive response from physicians. Based on recommendations of previous investigations, we expect a measurable clinical impact.

Can we bridge the definition diversity in healthcare-associated infection surveillance? From IT-supported surveillance to IT-supported infection prevention and control.

Expectations and requirements of the surveillance of healthcare-associated infections (HAIs) trigger a growing differentiation of HAI surveillance approaches. In an attempt to bridge this diversity of definitions and to serve the needs of different user groups, we have enhanced MONI (identification, monitoring, and reporting of nosocomial infections) not only to create better reports, but also to output overviews on complex clinical matters, as well as to generate alerts and reminders for the clinicians' bedside work.

Effectiveness of an automated surveillance system for intensive care unit-acquired infections.

This study assessed the effectiveness of a fully automated surveillance system for the detection of healthcare-associated infections (HCAIs) in intensive care units. Manual ward surveillance (MS) and electronic surveillance (ES) were performed for two intensive care units of the Vienna General Hospital. All patients admitted for a period longer than 48 h between 13 November 2006 and 7 February 2007 were evaluated according to HELICS-defined rules for HCAI. The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and personnel time spent per surveillance type were calculated. Ninety-three patient admissions were observed, whereby 30 HCAI episodes were taken as a reference standard. Results with MS versus ES were: sensitivity 40% versus 87%, specificity 94% versus 99%, PPV 71% versus 96%, NPV 80% versus 95%, and time spent per surveillance type 82.5 h versus 12.5 h. In conclusion, ES was found to be more effective than MS while consuming fewer personnel resources.

Concordance between European and US case definitions of healthcare-associated infections.

BACKGROUND: Surveillance of healthcare-associated infections (HAI) is a valuable measure to decrease infection rates. Across Europe, inter-country comparisons of HAI rates seem limited because some countries use US definitions from the US Centers for Disease Control and Prevention (CDC/NHSN) while other countries use European definitions from the Hospitals in Europe Link for Infection Control through Surveillance (HELICS/IPSE) project. In this study, we analyzed the concordance between US and European definitions of HAI. METHODS: An international working group of experts from seven European countries was set up to identify differences between US and European definitions and then conduct surveillance using both sets of definitions during a three-month period (March 1st -May 31st, 2010). Concordance between case definitions was estimated with Cohen's kappa statistic (κ). RESULTS: Differences in HAI definitions were found for bloodstream infection (BSI), pneumonia (PN), urinary tract infection (UTI) and the two key terms "intensive care unit (ICU)-acquired infection" and "mechanical ventilation". Concordance was analyzed for these definitions and key terms with the exception of UTI. Surveillance was performed in 47 ICUs and 6,506 patients were assessed. One hundred and eighty PN and 123 BSI cases were identified. When all PN cases were considered, concordance for PN was κ = 0.99 [CI 95%: 0.98-1.00]. When PN cases were divided into subgroups, concordance was κ = 0.90 (CI 95%: 0.86-0.94) for clinically defined PN and κ = 0.72 (CI 95%: 0.63-0.82) for microbiologically defined PN. Concordance for BSI was κ = 0.73 [CI 95%: 0.66-0.80]. However, BSI cases secondary to another infection site (42% of all BSI cases) are excluded when using US definitions and concordance for BSI was κ = 1.00 when only primary BSI cases, i.e. Europe-defined BSI with "catheter" or "unknown" origin and US-defined laboratory-confirmed BSI (LCBI), were considered. CONCLUSIONS: Our study showed an excellent concordance between US and European definitions of PN and primary BSI. PN and primary BSI rates of countries using either US or European definitions can be compared if the points highlighted in this study are taken into account.

Assessing the clinical uses of fuzzy detection results in the automated detection of CVC-related infections: a preliminary report.

Central venous catheters (CVCs) play an essential role in the care of the critically ill, but their use comes at the risk of infection. By using fuzzy set theory and logic to model clinical linguistic CVC-related infection criteria, clinical detection systems can detect borderline infections where not all infection parameters have been (fully) met, also called fuzzy results. In this paper we analyzed the clinical use of these results. We used a fuzzy-logic-based computerized infection control system for the monitoring of healthcare-associated infections to uncover fuzzy results and periods, after which we classified them, and used these classifications together with knowledge of prior CVC-related infection episodes in temporal association rule mining. As a result, we uncovered several rules which can help with the early detection of re-occurring CVC-related infections.

Concise healthcare-associated infection reporting and benchmarking with minimal staff resources.

We report on intelligent information technology tools that produce fully-automated surveillance reports of high precision for 12 intensive care units (ICUs) without relevant time expenditure of infection control or ICU staff. This is accomplished by MONI-ICU, a computerized system for automated identification and continuous monitoring of ICU-associated infections, which makes surveillance data readily accessible and presents them in easily perceptible reporting format.

Lumen claims of the STERRAD 100NX sterilizer: testing performance limits when processing equipment containing long, narrow lumens.

BACKGROUND: According to manufacturers information, the STERRAD 100NX sterilizer-a low temperature H(2)O(2) gas plasma sterilizer-can adequately process single channel stainless steel lumens with an inside diameter of 0.7 mm or larger and a maximum length of 500 mm using standard cycle sterilizing conditions. The aim of this study was to qualify the performance of this H(2)O(2) gas plasma sterilizer under different experimental settings representing worst case conditions. METHODS: Inoculated carriers were placed at the midpoint position of specified lumens and then submitted to flex scope sterilizing conditions. To simulate insufficient cleaning or crystalline residues, we added organic and inorganic challenges to our inoculated carriers. RESULTS: For experiments done with unchallenged carriers, quantitative analysis reached a log(10) reduction rate of ≥5.71, whereas qualitative results showed no growth in 24 out of 30 biologic indicators tested using flex scope half cycle conditions. Any additional kind of challenge significantly impaired the sterilization outcome. CONCLUSION: The findings of our current study emphasize the importance of a thorough validated cleaning of medical devices as well as timing for cleaning and decontamination before being exposed to the H(2)O(2) sterilization process and, furthermore, the need for strict adherence to manufacturer's recommendations.