Epidemiology and molecular typing of multidrug-resistant bacteria in tertiary hospitals and nursing homes in Flanders, Belgium.

This study aimed to map MDRO carriage and potential transmission within and between three Flemish tertiary care hospitals and their neighbouring nursing homes. A cross-sectional MDRO prevalence survey was organized between October 2017 and February 2019. Perianal swabs were cultured for detection of MDRO. Determination of clonal relatedness based on wgMLST allelic profiles was performed. The prevalence of MDRO in Belgian hospitals and NHs is on the rise, compared to previous studies, and transmission in and between institutions is observed. These results re-emphasize the need for a healthcare network-wide infection prevention strategy in which WGS of MDRO strains can be supportive.

Increasing usage of chlorhexidine in health care settings: blessing or curse? A narrative review of the risk of chlorhexidine resistance and the implications for infection prevention and control.

Chlorhexidine digluconate (CHG) is an antiseptic frequently used in hospitals to prevent healthcare-related infections. It is used in different formulations for skin antisepsis, oral care, patient bathing, and hand hygiene. Also, CHG impregnated vascular catheters and wound dressings contribute to increased exposure of hospital germs to this biocide. In the last decade, concerns are rising about decreasing susceptibility of microorganisms to CHG and its potential cross-resistance with antibiotics. This study reviewed the published data regarding the evidence of reduced CHG susceptibility, the cross-resistance with antibiotics, and the implications for infection control for S. aureus, coagulase-negative staphylococci, E. coli, K. pneumoniae, and P. aeruginosa. Despite incongruity in definitions of "resistance," increased CHG minimal inhibitory values of these pathogens have been described, and different mutations encoding for CHG efflux pumps have been identified. Clinical relevance of species with reduced susceptibility to CHG is debatable and cross-resistance with antibiotics remains controversial. However, some studies link the increased usage of CHG to multidrug resistance, and the potential cross-resistance with colistin for K. pneumoniae is of major concern. More research in this matter is necessary. For infection control, it is advisable to use CHG applications only for indications with a clear patient benefit. It is important to follow manufacturer's instructions, and exposure of microorganisms to sub-lethal CHG concentrations should be avoided.

Impact of multiplexed respiratory viral panels on infection control measures and antimicrobial stewardship: a review of the literature.

Multiplexed respiratory viral panels (MRVP) have recently been added to the diagnostic work-up of respiratory infections. This review provides a summary of the main literature of MRVP for patients with regard to 3 different topics. Can the results of MRVP reduce the inappropriate use of antibiotics, can they guide the use of appropriate antiviral therapy and do they have an added value with respect to infection control measures? Literature was searched for based on a defined search string using both the PubMed and Embase database. Twenty-five articles report on the impact of MRVP on antibiotic therapy. In all the articles where active antimicrobial stewardship was performed (e.g., education/advice on interpreting results of MRVP) (N = 9), a reduction in antibiotic therapy was shown (with exception of 2 studies). Three studies evaluating the effect of MRVP on antimicrobial use in a population that is not suspected of having bacterial pneumonia (e.g., absence of radiology suggestive for bacterial infection or low PCT) found a positive impact on antibiotic therapy. Eight studies with a short TAT (< 7 h) had a positive impact on use of antibiotic therapy. Eleven studies focused on the impact of MRVP on antiviral use. In contrast to antibiotic reduction, all studies systematically objectified improved antiviral use as a consequence of MRVP results. With regard to the impact of MRVP on infection control, eleven articles were withheld. All these studies led to a more accurate use of infection control measures by detecting unidentified pathogens or stopping isolation precautions in case of a negative MRVP result. MRVP don't reduce antibiotic therapy in all populations. Reduction seems more likely if the following factors are present: active antimicrobial stewardship, low likelihood of a bacterial infection, and a short turnaround time to result. With respect to antiviral therapy, all studies have an impact but the targeted use of antivirals is so far not that evidence based for all viral respiratory pathogens. Regarding infection control measures, the potential impact of MRVP is high because of the need of additional isolation precautions for many respiratory viruses, although logistical problems can occur.

The effectiveness of Check of Medication Appropriateness for antimicrobial stewardship: an interrupted time series analysis.

OBJECTIVES: Inappropriate prescribing of antimicrobials in hospitals contributes to the emergence of resistance and adverse drug events. To support antimicrobial stewardship (AMS), clinical decision rules focusing on antimicrobial therapy were implemented in the 'Check of Medication Appropriateness' (CMA). The CMA is a hospital-wide pharmacist-led medication review service consisting of a clinical rule-based screening for potentially inappropriate prescriptions (PIPs). We aimed to investigate the impact of the CMA on antimicrobial prescribing. METHODS: An interrupted time series study was performed at the University Hospitals Leuven. The pre-implementation cohort was exposed to standard-of-care AMS. Afterwards, an AMS-focused CMA comprising 41 specific clinical rules, targeting six AMS objectives, was implemented in the post-implementation period. A regression model was used to assess the impact of the intervention on the number of AMS-related residual PIPs between both periods. The total number of recommendations and acceptance rate was recorded for the 2 year post-implementation period. RESULTS: Pre-implementation, a median proportion of 75% (range: 33%-100%) residual PIPs per day was observed. After the CMA intervention, the proportion was reduced to 8% (range: 0%-33%) per day. Use of clinical rules resulted in an immediate relative reduction of 86.70% (P < 0.0001) in AMS-related residual PIPs. No significant underlying time trends were observed during the study period. Post-implementation, 2790 recommendations were provided of which 81.32% were accepted. CONCLUSIONS: We proved that the CMA approach reduced the number of AMS-related residual PIPs in a highly significant and sustained manner, with the potential to further expand the service to other AMS objectives.

Risk factors for surgical site infection after colorectal resection: a prospective single centre study. An analysis on 287 consecutive elective and urgent procedures within an institutional quality improvement project.

AIM: To determine the incidence and to investigate risk factors for surgical site infections (SSIs) in a cohort of patients undergoing colorectal surgery. MATERIAL & METHODS: Data from all consecutive patients operated at our department in an elective or in an urgent setting over a 4-month period were prospectively collected and analysed. The updated Centres for Disease Control and Prevention guidelines were used to define and to score SSIs during weekly meetings. Multivariate analysis was performed considering a list of 20 potential perioperative risk factors. RESULTS: A total of 287 patients (mean age 56.9 ± 16.8 years, 51.2% male) were included. Thirty-five patients (12.2%) developed SSI. Independent risk factors for SSI were BMI <20 kg/m2 (OR 3.70; p = .022), cancer (OR 0.33; p = .046), respiratory comorbidity (OR 3.15; p = .035), presence of a preoperative stoma (OR 3.74; p = .003), and operative time ≥3 hours (OR 2.93; p = .014). CONCLUSION: Identified incidence and risk factors for the development of SSI after colorectal surgery were consistent with those already reported in the literature. The possibility to develop a validated prediction model for SSIs warrants further investigation, in order to target specific preventive measures on high-risk population.

Efficacy and safety of a Belgian tertiary care outpatient parenteral antimicrobial therapy (OPAT) program.

PURPOSE: Evidence supports the implementation of outpatient parenteral antimicrobial therapy (OPAT) as standard of care. Until 2015 the overall experience with OPAT in Belgium remained limited. The aim of this study was to evaluate the efficacy and safety of a Belgian 'OPAT at home' program, which was implemented in University Hospitals Leuven starting from January 2017. METHODS: A mono-centric, prospective, observational study was carried out. All OPAT cases discharged between 10 January 2017 and 10 January 2019 were included in the study. Relevant demographic and clinical patient data were collected. The outcomes were clinical cure rate, OPAT related readmission rate, adverse event rate and patients' satisfaction. RESULTS: Over the two-year study period, 152 OPAT episodes were started in 130 patients, resulting in 3153 avoided hospitalization days which corresponds to 5.4 freed hospital beds. Urinary tract infections accounted for 40.8% of OPAT courses and temocillin was the most frequently used antibiotic (24.3%). Cure was achieved in 97.9% of the OPAT episodes. During 22 (14.5%) OPAT episodes, patients experienced adverse events, including line related adverse events (7.9%) and adverse drug events (6.6%). An OPAT related readmission rate of 9.2% was observed, mostly related to line-associated adverse events. All patients who completed the satisfaction survey (n = 23) were very satisfied with their OPAT course. CONCLUSION: The University Hospitals Leuven OPAT program is associated with a high level of clinical cure and low all-cause readmission and adverse event rates. Improvement actions are described to further reduce the readmission rate to less than 5.0%.

Outpatient parenteral antimicrobial therapy and antibiotic stewardship: opponents or teammates?

PURPOSE: This narrative review aims to describe barriers of outpatient parenteral antimicrobial therapy at home (OPAT), potentially compromising general standards of antibiotic stewardship (ABS) and facilitators of OPAT for ABS. METHODS: After a literature review, five authors determined the barriers and facilitators to discuss in this review. RESULTS: Sixty-six publications were included in the narrative review and seven barriers and five facilitators are discussed in this article. The impracticability of multiple daily dosing during OPAT, the impact of real-life temperature variations, deviations of the infusion rates of elastomeric devices, access to prolonged intravenous antibiotic therapy, not administering loading doses before the initiation of extended or continuous infusions and the transmural nature of care associated with OPAT, can lead to deviations of recommended treatment regimens and sub-optimal clinical and laboratory follow-up, with a risk of inferior clinical outcomes, adverse events, drug-resistance and higher costs. On the other hand, OPAT provides access to treatments with intravenous antibiotics and simultaneously avoids prolonged hospitalization. CONCLUSION: Implementing ABS guidelines in OPAT programs, e.g., by using a multidisciplinary team approach and facility-specific protocols for OPAT with patient selection criteria and instructions for selection, storage, preparation and administration of antibiotics, can improve appropriate antibiotic use. Additionally, further research should examine the effectiveness of these interventions on outcomes of OPAT.

OXA-427, a new plasmid-borne carbapenem-hydrolysing class D ß-lactamase in Enterobacteriaceae.

Objectives: To describe a novel plasmid-borne class D carbapenemase (CHDL) named OXA-427 identified in several Enterobacteriaceae clinical isolates from nine patients in one Belgian hospital. Methods: OXA-427-producing isolates were analysed by an electrochemical imipenem hydrolysis method (BYG Carba test), Carba NP test, conventional phenotypic assays and by molecular methods (PCR, whole sequencing of the OXA-427-encoding plasmid and cloning). The antimicrobial resistance profile of OXA-427 was analysed by expression of the cloned gene in Escherichia coli DH10B and J53. Results: Eleven OXA-427-producing Enterobacteriaceae isolates of various species were identified from clinical specimens of nine patients between March 2012 and June 2014. OXA-427 shares only 22%-29% amino acid identity with OXA-48-like enzymes and other acquired CHDL (e.g. OXA-23, -24/40 and -58 of Acinetobacter spp.). Conversely, it appeared closely related to the chromosomal class D ß-lactamase of Aeromonas media, Aeromonas hydrophila and Aeromonas sobria (99%, 89% and 77% of identity, respectively). When expressed in E. coli, OXA-427 hydrolysed imipenem and conferred resistance to extended-spectrum cephalosporins (mostly ceftazidime), penicillins including temocillin, and reduced susceptibility to carbapenems. The blaOXA-427 gene was located in a 45 kb resistance island on a 177 kb IncA/C plasmid. Conclusions: OXA-427 is a novel CHDL most closely related to chromosomal class D ß-lactamase of A. media WS. It confers resistance to penicillins, ceftazidime and aztreonam and in some instances to carbapenems. OXA-427, which is not detectable by classical molecular tests, caused a protracted outbreak in one university hospital over a 2 year period.

Prevention of fracture-related infection: a multidisciplinary care package.

Fracture-related infection (FRI) remains a challenging complication. It may result in permanent functional loss or even amputation in otherwise healthy patients. For these reasons, it is important to focus attention on prevention. In treatment algorithms for FRI, antibiotic stewardship programmes have already proved their use by means of a multidisciplinary collaboration between microbiologists, surgeons, pharmacists, infectious disease physicians and nursing staff. A similar approach, however, has not been described for infection prevention. As a first step towards achieving a multidisciplinary care package for infection prevention, this review summarises the most recent guidelines published by the World Health Organization (WHO) and US National Institutes of Health Centers for Disease Control and Prevention (CDC), primarily focusing on the musculoskeletal trauma patient. The implementation of these guidelines, together with close collaboration between infection control physicians, surgeons, anaesthesiologists and nursing staff, can potentially have a beneficial effect on the rate of FRI after musculoskeletal trauma surgery. It must be stated that most evidence presented here in support of these guidelines was not obtained from musculoskeletal trauma research. Although most preventive measures described in these studies can be generalised to the musculoskeletal trauma patient, there are still important differences with nontrauma patients that require further attention. Future research should therefore focus more on this very defined patient population and more specifically on FRI prevention.

Evaluation of a chromogenic biplate medium (ChromID MRSA/ChromID S. aureus) for the simultaneous detection of methicillin-resistant and methicillin-susceptible Staphylococcus aureus in preoperative screening samples from the anterior nares.

We evaluated the performance of the ChromID MRSA/ChromID S. aureus biplate for the simultaneous detection of Staphylococcus aureus and methicillin-resistant S. aureus (MRSA) in preoperative screening samples. The sensitivity and specificity were 94.2% and 93.6%, respectively, for the S. aureus compartment and 92.9% and 99.7% for the MRSA compartment after 48 h incubation.

Check of APpropriaTeness of Antimicrobial therapy In Nursing homes (CAPTAIN):a point prevalence study in Belgium.

Objectives: The overall prevalence of antimicrobial therapy (AMT) in nursing homes is well described. However, less is known about the appropriateness of AMT in nursing home residents. Therefore, the Check of APpropriaTeness of antimicrobial therapy in nursing homes (CAPTAIN) study aimed to assess both prevalence and appropriateness of AMT in Belgian nursing homes. Methods: In a prospective, observational, point prevalence study, researchers documented prevalence and identified potentially inappropriate prescriptions (PIPs) by evaluating accordance of AMT with national guidelines. The severity of inappropriateness was assessed by a modified Delphi expert panel. Results: Eleven nursing homes, including 1178 residents, participated in this study. On the survey day, 8.0% of residents took systemic AMT, primarily for urinary tract infections (54.2%), respiratory tract infections (36.5%), and skin and skin-structure infections (6.3%). About half of these prescriptions were used in prophylaxis (52.1%). Registration of indication and stop date was missing in 58.3% and 56.3% of AMTs, respectively. In 89.6% of the systemic AMTs, at least one discordance with national guidelines was identified, resulting in a total of 171 PIPs, with 49 unique PIPs. Of all unique PIPs, 26.5% were assessed with a high severity score (≥4). According to the expert panel, most inappropriate practice was starting AMT for cough without other symptoms. Inappropriate timing of time-dependent AMTs was common, but assessed as 'moderately severe'. One-third of systemic AMT exceeded the recommended duration. Conclusions: AMT in nursing homes is often not prescribed according to national guidelines, highlighting the need for future interventions to promote the rational use of AMT in this setting.

Impact of pasteurization on the antibacterial properties of human milk.

UNLABELLED: Growing evidence favours the use of human milk for the feeding of preterm newborns based on its many beneficial effects. Despite the many benefits, human milk has been associated as a possible vehicle of transmission for a number of infections. Although pasteurization of human milk can diminish the risk of neonatal infection, it also significantly reduces the concentrations of immunological components in human milk due to thermal damage. In order to evaluate the impact of pasteurization on the antibacterial properties of human milk, we aimed to compare the capacity of raw and pasteurized human milk to inhibit bacterial proliferation. Therefore, a single milk sample was collected from ten healthy lactating mothers. Each sample was divided into two aliquots; one aliquot was pasteurized, while the other was kept raw. Both aliquots were inoculated either with Escherichia coli or Staphylococcus aureus and incubated at 37 °C during 8 h. Viable colony counts from the inoculated samples were performed at regular time points to compare the bacterial growth in both forms of breast milk. Relative to the tryptic soy broth control sample, both raw and pasteurized milk samples exhibited an inhibitory effect on the growth of E. coli and S. aureus. Compared with the raw portion, growth inhibition was significantly lower in the pasteurized milk at every time point beyond T0 (after 2, 4 and 8 h of incubation) (p = 0.0003 for E. coli and p < 0.0001 for S. aureus). CONCLUSION: Our study shows that pasteurization adversely affects the antibacterial properties of human milk.

Performance and applicability of a first generation single-use duodenoscope: a single-center cohort study.

Background: Despite the standardization and optimization of disinfection protocols, duodenoscope-related infections (DRIs) remain an emerging threat for patients undergoing endoscopic retrograde cholangiopancreatography (ERCP). Single-use duodenoscopes could represent a potential alternative avenue to circumvent the problem of reprocessing and thus risk of exogenous patient-to-patient transmission. The aim of our study was to test the feasibility and technical success rate of a recently made available single-use duodenoscope. Methods: We carried out a thorough and standardized evaluation of the usability, performance and safety of a recently developed single-use duodenoscope in 52 consecutive patients scheduled for ERCP in a single center. Outcomes included performance ratings of the single-use duodenoscopes, adverse events (assessed at 3 days and 1 week), and crossover rate to a reusable duodenoscope. Results: The ERCP completion rate with a single-use duodenoscope was 90.4%, rising to 94.2% after crossover to reusable duodenoscope. The mean American Society for Gastrointestinal Endoscopy (ASGE) grade was 2.7, with 27 procedures (51.9%) considered as advanced level complexity (ASGE grade 3 & 4). Performance rating found that 94% of the therapeutic treatments were comparable to those using a traditional reusable duodenoscope. Overall satisfaction amounted to 80%. No major adverse events were attributable to the single-use endoscope. Conclusions: Single-use duodenoscopes can provide an alternative to avoid the intensive and often inconsistent results of cleaning and disinfection procedures. We confirmed the feasibility, adequate performance characteristics and safety of a recently developed first-generation single-use duodenoscope over a broad range of ERCP procedures, in terms of both indication and complexity.

Implementation of the Infection Risk Scan (IRIS) in nine hospitals in the Belgian-Dutch border region (i-4-1-Health project).

BACKGROUND: A tool, the Infection Risk Scan has been developed to measure the quality of infection control and antimicrobial use. This tool measures various patient-, ward- and care-related variables in a standardized way. We describe the implementation of this tool in nine hospitals in the Dutch/Belgian border area and the obtained results. METHODS: The IRIS consists of a set of objective and reproducible measurements: patient comorbidities, (appropriate) use of indwelling medical devices, (appropriate) use of antimicrobial therapy, rectal carriage of Extended-spectrum beta-lactamase producing Enterobacterales and their clonal relatedness, environmental contamination, hand hygiene performance, personal hygiene of health care workers and presence of infection prevention preconditions. The Infection Risk Scan was implemented by an expert team. In each setting, local infection control practitioners were trained to achieve a standardized implementation of the tool and an unambiguous assessment of data. RESULTS: The IRIS was implemented in 34 wards in six Dutch and three Belgian hospitals. The tool provided ward specific results and revealed differences between wards and countries. There were significant differences in the prevalence of ESBL-E carriage between countries (Belgium: 15% versus The Netherlands: 9.6%), environmental contamination (median adenosine triphosphate (ATP) level Belgium: 431 versus median ATP level The Netherlands: 793) and calculated hand hygiene actions based on alcohol based handrub consumption (Belgium: 12.5/day versus The Netherlands: 6.3/day) were found. CONCLUSION: The Infection risk Scan was successfully implemented in multiple hospitals in a large cross-border project and provided data that made the quality of infection control and antimicrobial use more transparent. The observed differences provide potential targets for improvement of the quality of care.

Variability in practice patterns regarding protective isolation measures after heart transplantation: A secondary analysis of the international BRIGHT study.

BACKGROUND: Infection control is a cornerstone of post-heart transplantation (HTx) in-hospital management when immunosuppression is highest. The use of protective isolation persists despite its questionable effectiveness. We describe and compare practice patterns internationally and assessed correlates of protective isolation. METHODS: Using the BRIGHT-study data, a cross-sectional intercontinental study, we assessed 12 protective isolation measures in 4 continents, 11 countries, and 36 HTx centers. Data were summarized descriptively, as appropriate. Comparisons between countries and continents and association testing between center characteristics and number of isolation measures used were also explored by general linear modeling. RESULTS: A total of 89% (32/36) of HTx centers used protective isolation measures with an average of 4.5 protective isolation measures per center (SD, 2.6; range 1-10). Most often applied were disinfecting high-touch surfaces (n = 27/34; 79.4%), use of private room (n = 27/36; 75.0%), and changing linen daily (n = 25/36; 69.4%). Least applied were wearing a cap (n = 6/35; 17.1%) and high-efficiency particulate air filtration (N = 5/32; 15.6 %). Larger centers and those with dedicated beds for HTx applied more isolation measures. CONCLUSIONS: Protective isolation measures are still widely applied within heart transplant centers across the world persists notwithstanding its doubtful effectiveness. Future clinical guidelines for heart transplant management should include a statement of the need for strict adherence to standard infection prevention measures.

Search and destroy policy for methicillin-resistant Staphylococcus aureus: cost-benefit analysis.

AIM: This paper is a report of a cost-benefit analysis of a 'search and destroy' policy as compared with the absence of such a policy for methicillin-resistant Staphylococcus aureus from a hospital perspective, including the impact of nurses on the costs and benefits of this policy. BACKGROUND: The 'search and destroy' policy involved screening, isolation, decontamination and antimicrobial treatment of methicillin-resistant Staphylococcus aureus. METHODS: A prospective analysis was carried out in one intensive care unit and one gerontology unit of a university hospital in 2007. A benefit-cost ratio was calculated by dividing the benefits of the 'search and destroy' policy by its costs related to screening and quarantine. Benefits consisted of hospital savings through avoidance of isolation, decontamination, antimicrobial therapy and extended hospital stay of affected patients. Resource utilization data were gathered from a time-and-motion study of nurses, patient medical records, hospital databases and the literature. Unit costs pertained to 2005. RESULTS: The benefit-cost ratio of the 'search and destroy' policy as compared with the absence of such a policy was 1.17 in the intensive care unit and 1.16 in the gerontology unit. Nurses accounted for 23% of costs and 16% of benefits of the policy as compared with the absence of such a policy in the intensive care unit, and 19% of costs and 28% of benefits in the gerontology unit. CONCLUSION: Hospital managers should consider implementing a 'search and destroy' policy for methicillin-resistant Staphylococcus aureus and to support the contribution of nurses and other healthcare workers to such a policy.

Compliance with evidence-based guidelines for the prevention of central line-associated bloodstream infections in a Belgian home care setting: An observational study.

This study assessed the compliance of Belgian home care nurses with good practice recommendations to prevent central line-associated bloodstream infections. The compliance to 3 care bundles was 0% (0 out of 7), 13.3% (2 out of 15), and 22.2% (2 out of 9), respectively. This finding is important given the increasing number of home care patients with an intravascular catheter and underscores the need for quality improvement strategies to prevent central line-associated bloodstream infections in home care.

Methicillin-resistant Staphylococcus aureus colonization is associated with higher mortality in nursing home residents with impaired cognitive status.

OBJECTIVES: To assess the effect of methicillin-resistant Staphylococcus aureus (MRSA) colonization on morbidity and mortality of nursing home residents. DESIGN: Three-year cohort study from 2000 to 2003. SETTING: Twenty-three nursing homes of all types and regions in the northern part of Belgium (Flanders). PARTICIPANTS: Two thousand eight hundred fourteen nursing home residents. MEASUREMENTS: The consequences of MRSA colonization on mortality and hospitalization were studied, adjusting for potential confounders. Dates and cause of death and hospitalization were collected every 6 months during 3 years of follow-up. RESULTS: After adjustment for age, sex, and Charlson comorbidity index, the risk for 36-month mortality remained significantly higher in MRSA carriers (hazard ratio (HR) = 1.4, 95% confidence interval (CI) = 1.1-1.8) than in noncarriers. The effect of MRSA on mortality was dependent on the degree of cognitive impairment, with the highest effect in patients with severe cognitive impairment (adjusted HR = 1.8, 95% CI = 1.1-2.8) and absence of effect in residents with good mental status (adjusted HR = 0.8, 95% CI = 0.43-1.62). Deaths were more frequently reported to be infection-related in MRSA carriers. No association was found between MRSA colonization and hospitalization for any reason, but during follow-up, MRSA carriers were twice as frequently hospitalized for respiratory tract infections. CONCLUSION: Colonization of MRSA in Belgian nursing home residents was associated with higher mortality. This excess mortality was restricted to residents with impaired cognitive function, probably reflecting differences in therapeutic approaches, in delay of diagnosis of pneumonia and other acute disorders in these patients, or in both.

Comparison of free and bound iodine and iodide species as a function of the dilution of three commercial povidone-iodine formulations and their microbicidal activity.

Equilibrium dialysis on povidone-iodine-solutions (Braunol, standardized Betadine and non-standardized iso-Betadine reveal that the amount of available iodine, free iodine, iodide and triiodide varies significantly both in the undiluted and diluted forms. These differences are reflected in the different bactericidal activity against Staphyloccus aureus as determined by the standard quantitative in vitro suspension test. The amount of available iodine is not an appropriate measure for an assessment of the microbicidal activity. For this, the free iodine has to be determined by means of equilibrium dialysis. The free iodine concentration in the Braunol concentrate was found to be 22 mg/L, in the standardized Betadine 9.7 mg/L and in the non-standardized Betadine concentrate only 2.1mg/L. Because of the atypical behaviour of iodophores and the increase of free iodine at dilution and because of a bactericidal level of free iodine of 5mg/L, Braunol and standardized Betadine can be employed as disinfectant as such, iso-Betadine has to be diluted before use. Summarizing all results, it can be stated that Braunol is superior to standardized Betadine and unstandardized iso-Betadine both as to the release of free iodine in the undiluted and in the diluted forms as in the killing rate of S. aureus.