Measuring the impact of antimicrobial stewardship programs

Antimicrobial Stewardship Programs (ASPs) are being implemented worldwide to optimize antimicrobial therapy, and thereby improve patient safety and quality of care. Additionally, this should counteract resistance development. It is, however, vital that correct and timely diagnostics are performed in parallel, and that an institution runs a well-organized infection prevention program. Currently, there is no clear consensus on which interventions an ASP should comprise. Indeed this depends on the institution, the region, and the patient population that is served. Different interventions will lead to different effects. Therefore, adequate evaluations, both clinically and financially, are crucial. Here, we provide a general overview of, and perspective on different intervention strategies and methods to evaluate these ASP programs, covering before mentioned topics. This should lead to a more consistent approach in evaluating these programs, making it easier to compare different interventions and studies with each other and ultimately improve infection and patient management.

Cross-border comparison of antibiotic prescriptions among children and adolescents between the north of the Netherlands and the north-west of Germany

Background

Antibiotic resistance is a worldwide problem and inappropriate prescriptions are a cause. Especially among children, prescriptions tend to be high. It is unclear how they differ in bordering regions. This study therefore examined the antibiotic prescription prevalence among children in primary care between northern Netherlands and north-west of Germany.

Methods

Two datasets were used: The Dutch (IADB) comprises representative data of pharmacists in North Netherland and the German (BARMER GEK) includes nationwide health insurance data. Both were filtered using postal codes to define two comparable bordering regions with patients under 18 years for 2010.

Results

The proportion of primary care patients receiving at least one antibiotic was lower in northern Netherlands (29.8 %; 95 % confidence interval [95 % CI]: 29.3–30.3), compared to north-west Germany (38.9 %; 95 % CI: 38.2–39.6). Within the respective countries, there were variations ranging from 27.0 to 44.1 % between different areas. Most profound was the difference in second-generation cephalosporins: for German children 25 % of the total prescriptions, while for Dutch children it was less than 0.1 %.

Conclusions

This study is the first to compare outpatient antibiotic prescriptions among children in primary care practices in bordering regions of two countries. Large differences were seen within and between the countries, with overall higher prescription prevalence in Germany. Considering increasing cross-border healthcare, these comparisons are highly valuable and help act upon antibiotic resistance in the first line of care in an international approach.

Emerging pan-resistance in Trichosporon species: a case report

Background

Trichosporon species are ubiquitously spread and known to be part of the normal human flora of the skin and gastrointestinal tract. Trichosporon spp. normally cause superficial infections. However, in the past decade Trichosporon spp. are emerging as opportunistic agents of invasive fungal infections, particularly in severely immunocompromised patients. Clinical isolates are usually sensitive to triazoles, but strains resistant to multiple triazoles have been reported.

Case presentation

We report a high-level pan-azole resistant Trichosporon dermatis isolate causing an invasive cholangitis in a patient after liver re-transplantation. This infection occurred despite of fluconazole and low dose amphotericin B prophylaxis, and treatment with combined liposomal amphotericin B and voriconazole failed.

Conclusion

This case and recent reports in literature show that not only bacteria are evolving towards pan-resistance, but also pathogenic yeasts. Prudent use of antifungals is important to withstand emerging antifungal resistance.

Genetics of Fusarium Wilt Resistance in Pigeonpea (Cajanus cajan) and Efficacy of Associated SSR Markers

Inheritance of resistance to Fusarium wilt (FW) disease caused by Fusarium udum was investigated in pigeonpea using four different long duration FW resistant genotypes viz., BDN-2004-1, BDN-2001-9, BWR-133 and IPA-234. Based on the F2 segregation pattern, FW resistance has been reported to be governed by one dominant gene in BDN-2004-1 and BDN-2001-9, two duplicate dominant genes in BWR-133 and two dominant complimentary genes in resistance source IPA-234. Further, the efficacy of six simple sequence repeat (SSR) markers namely, ASSR-1, ASSR-23, ASSR-148, ASSR-229, ASSR-363 and ASSR-366 reported to be associated with FW resistance were also tested and concluded that markers ASSR-1, ASSR-23, ASSR-148 will be used for screening of parental genotypes in pigeonpea FW resistance breeding programs. The information on genetics of FW resistance generated from this study would be used, to introgress FW resistance into susceptible but highly adopted cultivars through marker-assisted backcross breeding and in conventional breeding programs.

Cost-Analysis of Seven Nosocomial Outbreaks in an Academic Hospital

OBJECTIVES

Nosocomial outbreaks, especially with (multi-)resistant microorganisms, are a major problem for health care institutions. They can cause morbidity and mortality for patients and controlling these costs substantial amounts of funds and resources. However, how much is unclear. This study sets out to provide a comparable overview of the costs of multiple outbreaks in a single academic hospital in the Netherlands.

METHODS

Based on interviews with the involved staff, multiple databases and stored records from the Infection Prevention Division all actions undertaken, extra staff employment, use of resources, bed-occupancy rates, and other miscellaneous cost drivers during different outbreaks were scored and quantified into Euros. This led to total costs per outbreak and an estimated average cost per positive patient per outbreak day.

RESULTS

Seven outbreaks that occurred between 2012 and 2014 in the hospital were evaluated. Total costs for the hospital ranged between €10,778 and €356,754. Costs per positive patient per outbreak day, ranged between €10 and €1,369 (95% CI: €49-€1,042), with a mean of €546 and a median of €519. Majority of the costs (50%) were made because of closed beds.

CONCLUSIONS

This analysis is the first to give a comparable overview of various outbreaks, caused by different microorganisms, in the same hospital and all analyzed with the same method. It shows a large variation within the average costs due to different factors (e.g. closure of wards, type of ward). All outbreaks however cost considerable amounts of efforts and money (up to €356,754), including missed revenue and control measures.

A cluster of tularaemia after contact with a dead hare in the Netherlands

Tularemia is thought to be rare in the Netherlands. Here we describe a cluster of two patients who contracted tularaemia after field dressing of a hare found dead. Additionally, infection from the same source is suggested in three animals.

An integrated stewardship model: antimicrobial, infection prevention and diagnostic (AID)

Considering the threat of antimicrobial resistance and the difficulties it entails in treating infections, it is necessary to cross borders and approach infection management in an integrated, multidisciplinary manner. We propose the antimicrobial, infection prevention and diagnostic stewardship model comprising three intertwined programs: antimicrobial, infection prevention and diagnostic stewardship, involving all stakeholders. The focus is a so-called 'theragnostics' approach. This leads to a personalized infection management plan, improving patient care and minimizing resistance development. Furthermore, it is important that healthcare regions nationally and internationally work together, ensuring that the patient (and microorganism) transfers will not cause problems in a neighboring institution. This antimicrobial, infection prevention and diagnostic stewardship model can serve as a blue print to implement innovative, integrative infection management.

Louse-borne relapsing fever (Borrelia recurrentis) in asylum seekers from Eritrea, the Netherlands, July 2015

Two patients from Eritrea, recently arrived in the Netherlands, presented with fever and were investigated for malaria. Bloodfilms showed spirochetes but no blood parasites. Louse-borne relapsing fever caused by Borrelia recurrentis was diagnosed. Treatment was complicated by severe Jarisch-Herxheimer reactions in both patients. Physicians should be aware of the possibility of B. recurrentis infection in migrant populations who travel under crowded conditions, especially after passing through endemic areas such as Ethiopia and neighbouring countries.

Allergic Rhinitis: A neglected disease - A community based assessment among adults in Delhi

BACKGROUND AND OBJECTIVES

Allergic Rhinitis is rather erroneously viewed as a trivial disease. It is important in that it can significantly affect quality of life. There is paucity of community based prevalence studies on the disease in India. This study was planned to assess the prevalence of allergic rhinitis in adults, the proportion of asthmatics among them, risk factors associated and treatment seeking behaviour among the patients.

MATERIALS AND METHODS

A community based cross sectional study was conducted in Mehrauli, South Delhi among 1200 adults, aged 30 years and over selected by systematic random sampling from two randomly selected wards. A pre-tested questionnaire was used to collect information regarding symptoms, risk factors and treatment seeking behaviour. Allergic Rhinitis was diagnosed as per ARIA guidelines. Spirometry was done to diagnose asthma among them. Multivariate logistic regression analysis was done to find the association of risk factors with disease.

RESULTS

The prevalence of Allergic Rhinitis was found to be 11% (132 subjects) and 33.3% (44 patients) among them also had asthma. Overcrowding (aOR = 6.4), absence of cross-ventilation (aOR = 2.5), occupational exposure to dust/ smoke (aOR = 2.1), tobacco smoking (aOR = 2.1), family history of allergic diseases (aOR = 2.7) and clinical allergy (aOR = 10.2) were found to be independent risk factors associated with Rhinitis. More patients of Rhinitis with asthma (75%) took treatment, relative to those without asthma (40%) who, mostly relied on home remedies (42%) or, did not seek any treatment (18%) (P = 0.031). Interpretations and Conclusion: The burden of Allergic Rhinitis is high with a considerable overlap with asthma. These allergic diseases and emphasize the importance of early and regular treatment.

Automatic day-2 intervention by a multidisciplinary antimicrobial stewardship-team leads to multiple positive effects

Background: Antimicrobial resistance rates are increasing. This is, among others, caused by incorrect or inappropriate use of antimicrobials. To target this, a multidisciplinary antimicrobial stewardship-team (A-Team) was implemented at the University Medical Center Groningen on a urology ward. Goal of this study is to evaluate the clinical effects of the case-audits done by this team, looking at length of stay (LOS) and antimicrobial use.

Methods: Automatic e-mail alerts were sent after 48 h of consecutive antimicrobial use triggering the case-audits, consisting of an A-Team member visiting the ward, discussing the patient’s therapy with the bed-side physician and together deciding on further treatment based on available diagnostics and guidelines. Clinical effects of the audits were evaluated through an Interrupted Time Series analysis and a retrospective historic cohort.

Results: A significant systemic reduction of antimicrobial consumption for all patients on the ward, both with and without case-audits was observed. Furthermore, LOS for patients with case-audits who were admitted primarily due to infections decreased to 6.20 days (95% CI: 5.59–6.81) compared to the historic cohort (7.57 days; 95% CI: 6.92–8.21; p = 0.012). Antimicrobial consumption decreased for these patients from 8.17 DDD/patient (95% CI: 7.10–9.24) to 5.93 DDD/patient (95% CI: 5.02–6.83; p = 0.008). For patients with severe underlying diseases (e.g., cancer) these outcome measures remained unchanged.

Conclusion: The evaluation showed a considerable positive impact. Antibiotic use of the whole ward was reduced, transcending the intervened patients. Furthermore, LOS and mean antimicrobial consumption for a subgroup was reduced, thereby improving patient care and potentially lowering resistance rates.

Evaluation of macrolides for possible use against multidrug-resistant Mycobacterium tuberculosis

Multidrug-resistant tuberculosis (MDR-TB) is a major global health problem. The loss of susceptibility to an increasing number of drugs behoves us to consider the evaluation of non-traditional anti-tuberculosis drugs.

Clarithromycin, a macrolide antibiotic, is defined as a group 5 anti-tuberculosis drug by the World Health Organization; however, its role or efficacy in the treatment of MDR-TB is unclear. A systematic review of the literature was conducted to summarise the evidence for the activity of macrolides against MDR-TB, by evaluating in vitro, in vivo and clinical studies. PubMed and Embase were searched for English language articles up to May 2014.

Even though high minimum inhibitory concentration values are usually found, suggesting low activity against Mycobacterium tuberculosis, the potential benefits of macrolides are their accumulation in the relevant compartments and cells in the lungs, their immunomodulatory effects and their synergistic activity with other anti-TB drugs.

A future perspective may be use of more potent macrolide analogues to enhance the activity of the treatment regimen.

Cost-minimization model of a multidisciplinary antibiotic stewardship team based on a successful implementation on a urology ward of an academic hospital

BACKGROUND

In order to stimulate appropriate antimicrobial use and thereby lower the chances of resistance development, an Antibiotic Stewardship Team (A-Team) has been implemented at the University Medical Center Groningen, the Netherlands. Focus of the A-Team was a pro-active day 2 case-audit, which was financially evaluated here to calculate the return on investment from a hospital perspective.

METHODS

Effects were evaluated by comparing audited patients with a historic cohort with the same diagnosis-related groups. Based upon this evaluation a cost-minimization model was created that can be used to predict the financial effects of a day 2 case-audit. Sensitivity analyses were performed to deal with uncertainties. Finally, the model was used to financially evaluate the A-Team.

RESULTS

One whole year including 114 patients was evaluated. Implementation costs were calculated to be €17,732, which represent total costs spent to implement this A-Team. For this specific patient group admitted to a urology ward and consulted on day 2 by the A-Team, the model estimated total savings of €60,306 after one year for this single department, leading to a return on investment of 5.9.

CONCLUSIONS

The implemented multi-disciplinary A-Team performing a day 2 case-audit in the hospital had a positive return on investment caused by a reduced length of stay due to a more appropriate antibiotic therapy. Based on the extensive data analysis, a model of this intervention could be constructed. This model could be used by other institutions, using their own data to estimate the effects of a day 2 case-audit in their hospital.

Financial evaluations of antibiotic stewardship programs-a systematic review

Introduction: There is an increasing awareness to counteract problems due to incorrect antimicrobial use. Interventions that are implemented are often part of an Antimicrobial Stewardship Program (ASPs). Studies publishing results from these interventions are increasing, including reports on the economical effects of ASPs. This review will look at the economical sections of these studies and the methods that were used.

Methods: A systematic review was performed of articles found in the PubMed and EMBASE databases published from 2000 until November 2014. Included studies found were scored for various aspects and the quality of the papers was assessed following an appropriate check list (CHEC criteria list).

Results: 1233 studies were found, of which 149 were read completely. Ninety-nine were included in the final review. Of these studies, 57 only mentioned the costs associated with the antimicrobial medication. Others also included operational costs (n = 23), costs for hospital stay (n = 18), and/or other costs (n = 19). Nine studies were further assessed for their quality. These studies scored between 2 and 14 out of a potential total score of 19.

Conclusions: This review gives an extensive overview of the current financial evaluation of ASPs and the quality of these economical studies. We show that there is still major potential to improve financial evaluations of ASPs. Studies do not use similar nor consistent methods or outcome measures, making it impossible draw sound conclusions and compare different studies. Finally, we make some recommendations for the future.

Cross-border comparison of the Dutch and German guidelines on multidrug-resistant Gram-negative microorganisms

BACKGROUND

In all European countries, hospital-acquired infections caused by Gram-negative multidrug-resistant microorganisms (GN-MDRO) are a major health threat, as these pathogens cannot be adequately treated anymore, or the start of effective antibiotic treatment is delayed. The efforts to limit the selection and spread of GN-MDRO remains a problem in cross-border healthcare, as the national guidelines on hygiene standards applicable for patients colonized or infected with GN-MDRO in hospitals are not harmonized between European countries.

METHODS

In order to point out the similarities and differences in the national guidelines of Germany and The Netherlands regarding GN-MDRO, guidelines were compared and an expert workshop was organized by the INTERREG IVa project EurSafety Health-net.

RESULTS

Both guidelines divide the Gram-negative organisms into subgroups based on bacterial species and antibiotic susceptibility patterns in order to define multidrug-resistant variants of these bacteria. However, the Dutch guideline defines that GN-MDRO Enterobacteriaceae requires testing for certain mechanisms causing antibiotic resistance, whereas the German guideline makes use of a newly created classification scheme, based on phenotypic characterization. Besides diagnostic issues, the main difference between the Dutch and German guideline is the divergent evaluation of ESBL-producing Enterobacteriaceae. Special hygiene measures are required for all patients with ESBL-producing Enterobacteriaceae in The Netherlands, whereas the German guideline recommends special precautions only for those cases in which patients are colonized or infected with strains showing co-resistance to ciprofloxacin ("3MRGN").

CONCLUSIONS

The usage of consistent terminology and harmonized diagnostic procedures would improve the possibilities for infection prevention, treatment and patient safety. Prevention of severe non-treatable infections and outbreaks due to MDRO, caused by an increased population seeking medical treatment abroad together with an increased number of highly susceptible individuals demands gathering of regional data, and data comparable between the two sides of the Dutch-German border. The necessity to cooperate multidisciplinary and across borders is required to prevent a post-antibiotic era - in which common infections and minor injuries may lead to death.

Different duration strategies of perioperative antibiotic prophylaxis in adult patients undergoing cardiac surgery: an observational study

Background

All international guidelines recommend perioperative antibiotic prophylaxis (PAB) should be routinely administered to patients undergoing cardiac surgery. However, the duration of PAB is heterogeneous and controversial.

Methods

Between 01.01.2011 and 31.12.2011, 1096 consecutive cardiac surgery patients were assigned to one of two groups receiving PAB with a second-generation cephalosporin for either 56 h (group I) or 32 h (group II). Patients’ characteristics, intraoperative data, and the in-hospital follow-up were analysed. Primary endpoint was the incidence of surgical site infection (deep and superficial sternal wound-, and vein harvesting site infection; DSWI/SSWI/VHSI). Secondary endpoints were the incidence of respiratory-, and urinary tract infection, as well as the mortality rate.

Results

615/1096 patients (56,1%) were enrolled (group I: n = 283 versus group II: n = 332). There were no significant differences with regard to patient characteristics, comorbidities, and procedure-related variables. No statistically significant differences were demonstrated concerning primary and secondary endpoints. The incidence of DSWI/SSWI/VHSI were 4/283 (1,4%), 5/283 (1,7%), and 1/283 (0,3%) in group I versus 6/332 (1,8%), 9/332 (2,7%), and 3/332 (0,9%) in group II (p = 0,76/0,59/0,63). In univariate analyses female gender, age, peripheral arterial obstructive disease, operating-time, ICU-duration, transfusion, and respiratory insufficiency were determinants for nosocomial infections (all ≤ 0,05). Subgroup analyses of these high-risk patients did not show any differences between the two regimes (all ≥ 0,05).

Conclusions

Reducing the duration of PAB from 56 h to 32 h in adult cardiac surgery patients was not associated with an increase of nosocomial infection rate, but contributes to reduce antibiotic resistance and health care costs.

Genome-wide analysis reveals two novel mosaic regions containing an ACME with an identical DNA sequence in the MRSA ST398-t011 and MSSA ST8-t008 isolates

OBJECTIVES

The presence of the arginine catabolic mobile element (ACME) in Staphylococcus aureus has been reported to enhance the colonization of the human host. The aim of this study was to determine the genetic organization of composite islands harbouring ACME.

METHODS

Two ACME-positive S. aureus isolates obtained during two different surveys conducted in the Netherlands and Poland were characterized in this study. The isolates were analysed by spa typing, DNA microarrays and whole-genome sequencing.

RESULTS

The two isolates harboured a truncated yet fully functional ACME type II with an identical nucleotide sequence, but differed in their adjacent mobile genetic elements. The first strain was a livestock-associated ST398-t011 MRSA, which had a staphylococcal cassette chromosome mec (SCCmec) composite island composed of SCCpls adjacent to orfX followed by ACME type II and SCCmec type IVa. The second ACME-positive isolate was an ST8-t008 MSSA. Its composite island showed an SCC-like element carrying the ccrC gene followed by ACME II.

CONCLUSIONS

This is the first report of an ACME in a livestock-associated MRSA ST398. It is also the first presentation of an ACME composite island structure in an MSSA isolate. Our findings indicate an extensive mosaicism of composite islands in S. aureus, which has implications for the transmissibility among humans and thus for public health.

Evaluation of early implementations of antibiotic stewardship program initiatives in nine Dutch hospitals

Background

Antibiotic resistance is a global threat to patient safety and care. In response, hospitals start antibiotic stewardship programs to optimise antibiotic use. Expert-based guidelines recommend strategies to implement such programs, but local implementations may differ per hospital. Earlier published assessments determine maturity of antibiotic stewardship programs based on expert-based structure indicators, but they disregard that there may be valid deviations from these expert-based programs.

Aim

To analyse the progress and barriers of local implementations of antibiotic stewardship programs with stakeholders in nine Dutch hospitals and to develop a toolkit that guides implementing local antibiotic stewardship programs.

Methods

An online questionnaire based on published guidelines and recommendations, conducted with seven clinical microbiologists, seven infectious disease physicians and five clinical pharmacists at nine Dutch hospitals.

Results

Results show local differences in antibiotic stewardship programs and the uptake of interventions in hospitals. Antibiotic guidelines and antibiotic teams are the most extensively implemented interventions. Education, decision support and audit-feedback are deemed important interventions and they are either piloted in implementations at academic hospitals or in preparation for application in non-academic hospitals. Other interventions that are recommended in guidelines - benchmarking, restriction and antibiotic formulary - appear to have a lower priority. Automatic stop-order, pre-authorization, automatic substitution, antibiotic cycling are not deemed to be worthwhile according to respondents.

Conclusion

There are extensive local differences in the implementation of antibiotic stewardship interventions. These differences suggest a need to further explore the rationale behind the choice of interventions in antibiotic stewardship programs. Rather than reporting this rationale, this study reports where rationale can play a key role in the implementation of antibiotic stewardship programs. A one-size-fits-all solution is unfeasible as there may be barriers or valid reasons for local experts to deviate from expert-based guidelines. Local experts can be supported with a toolkit containing advice based on possible barriers and considerations. These parameters can be used to customise an implementation of antibiotic stewardship programs to local needs (while retaining its expert-based foundation).

Electronic supplementary material

The online version of this article (doi:10.1186/2047-2994-3-33) contains supplementary material, which is available to authorized users.

Gentamicin for prevention of intraoperative mesh contamination: demonstration of high bactericide effect (in vitro) and low systemic bioavailability (in vivo)

INTRODUCTION

Mesh infection is a severe complication after incisional hernia repair and occurs in 1-3 % of all open mesh implantations. For this reason, topical antimicrobial agent applied directly to the mesh is often used procedure. So far, however, this procedure lacks a scientific basis.

MATERIALS AND METHODS

Two different meshes (Parietex™, Covidien; Ultrapro™, Ethicon Johnson & Johnson) were incubated with increasing amounts of three different Staphylococcus aureus strains (ATCC 25923; Mu50; ST239) with or without gentamicin and growth ability were determined in vitro. To further address the question of the systemic impact of topic gentamicin, serum levels were analyzed 6 and 24 h after implantation of gentamicin-impregnated multifilament meshes in 19 patients.

RESULTS

None of the gentamicin-impregnated meshes showed any bacterial growth in vitro. This effect was independent of the mesh type for all the tested S. aureus strains. In the clinical setting, serum gentamicin levels 6 h after implantation of the gentamicin-impregnated meshes were below the through-level (range 0.4-2.9 mg/l, mean 1.2 ± 0.7 mg/l). After 24 h the gentamicin serum levels in all patients had declined 90-65 % of the 6 h values.

CONCLUSION

Local application of gentamicin to meshes can completely prevent the growth of even gentamicin-resistant S. aureus strains in vitro. The systemic relevance of gentamicin in the clinical controls showed to be very low, without reaching therapeutic concentrations.

In vitro characterization of representative clinical South African Staphylococcus aureus isolates from various clonal lineages

Data concerning the virulence and pathogenesis of South African strains of Staphylococcus aureus are limited. We investigated host–pathogen interactions of randomly selected clinical S. aureus isolates representing various clones. We characterized the ability of isolates to adhere to fibronectin, fibrinogen, collagens IV and VI, to invade host cells and to induce cell death in vitro. We analysed the possible association of these results with characteristics such as methicillin resistance, Panton–Valentine leucocidin (PVL) positivity and clonality. The S. aureus isolates displayed diversity in their abilities to adhere to various human ligands. All isolates were highly invasive except for ST121. PVL-negative isolates were significantly more invasive than the PVL-positive isolates (p 0.004). Isolates of CC5, CC30 and CC121 were non-cytotoxic, whereas isolates of CC22, CC8, CC15, CC45 and CC88 were very cytotoxic. No statistical association was identified between cell death and methicillin resistance, bacterial PVL status, clonality or patient HIV status. The vast majority of isolates were invasive and induced significant cell death. PVL-negative isolates were more invasive than PVL-positive isolates, while methicillin-resistant isolates were not found to be more invasive or cytotoxic than methicillin-susceptible isolates.

Planar Hall magnetoresistive aptasensor for thrombin detection

The use of aptamer-based assays is an emerging and attractive approach in disease research and clinical diagnostics. A sensitive aptamer-based sandwich-type sensor is presented to detect human thrombin using a planar Hall magnetoresistive (PHR) sensor in cooperation with superparamagnetic labels. A PHR sensor has the great advantages of a high signal-to-noise ratio, a small offset voltage and linear response in the low-field region, allowing it to act as a high-resolution biosensor. In the system presented here, the sensor has an active area of 50 µm × 50 µm with a 10-nm gold layer deposited onto the sensor surface prior to the binding of thiolated DNA primary aptamer. A polydimethylsiloxane well of 600-µm radius and 1-mm height was prepared around the sensor surface to maintain the same specific area and volume for each sensor. The sensor response was traced in real time upon the addition of streptavidin-functionalized magnetic labels on the sensor. A linear response to the thrombin concentration in the range of 86 pM-8.6 µM and a lower detection limit down to 86 pM was achieved by the proposed present method with a sample volume consumption of 2 µl. The proposed aptasensor has a strong potential for application in clinical diagnosis.

Poly[(μ3-3,5-di-nitro-benzoato-κ(3) O (1):O (1'):O (3))(μ2-hydroxido-κ(2) O:O)copper(II)]

The title complex, [Cu{μ₃-O₂CC₆H₃(NO₂)₂-3,5}(μ-OH)]_n, features zigzag chains in which successive pairs of Cu^II atoms are connected by OH bridges and bidentate carboxyl­ate ligands, leading to six-membered Cu(O)(OCO)Cu rings. The zigzag chains are connected into a three-dimensional architecture by Cu—O(nitro) bonds. The coordination geometry of the Cu^II atom is square-pyramidal, with the axial position occupied by the nitro O atom, which forms the longer Cu—O bond. Bifurcated hy­droxy–nitro O—H⋯O hydrogen bonds contribute to the stability of the crystal structure.

A reliable and cost effective approach for radiographic monitoring in nutritional rickets

OBJECTIVE

Radiological scoring is particularly useful in rickets, where pre-treatment radiographical findings can reflect the disease severity and can be used to monitor the improvement. However, there is only a single radiographic scoring system for rickets developed by Thacher and, to the best of our knowledge, no study has evaluated radiographic changes in rickets based on this scoring system apart from the one done by Thacher himself. The main objective of this study is to compare and analyse the pre-treatment and post-treatment radiographic parameters in nutritional rickets with the help of Thacher's scoring technique.

METHODS

176 patients with nutritional rickets were given a single intramuscular injection of vitamin D (600 000 IU) along with oral calcium (50 mg kg(-1)) and vitamin D (400 IU per day) until radiological resolution and followed for 1 year. Pre- and post-treatment radiological parameters were compared and analysed statistically based on Thacher's scoring system.

RESULTS

Radiological resolution was complete by 6 months. Time for radiological resolution and initial radiological score were linearly associated on regression analysis. The distal ulna was the last to heal in most cases except when the initial score was 10, when distal femur was the last to heal.

CONCLUSION

Thacher's scoring system can effectively monitor nutritional rickets. The formula derived through linear regression has prognostic significance.

ADVANCES IN KNOWLEDGE

The distal femur is a better indicator in radiologically severe rickets and when resolution is delayed. Thacher's scoring is very useful for monitoring of rickets. The formula derived through linear regression can predict the expected time for radiological resolution.

[Bedside consultation by a multidisciplinary antibiotics team: an Antibiotic Stewardship Programme at UMCG]

In 2012, the Dutch Working Party on Antibiotic Policy (SWAB) published a vision document to counteract the rise in antibiotic use and resistance. An Antibiotic Stewardship Programme (ASP) will be implemented by a multidisciplinary antibiotics team (A-team). In 2012 University Medical Centre Groningen (UMCG) in the Netherlands started an Antibiotic Stewardship Programme (ASP) pilot project at the trauma surgery ward. The focus is on providing bedside consultation for patients based on the day 2 bundle. Implementation of the ASP on the basis of a day 2 bundle resulted in an intervention percentage of 75%. The pilot project was a success and will be extended to other wards.

Population structure analyses of Staphylococcus aureus at Tygerberg Hospital, South Africa, reveals a diverse population, a high prevalence of Panton-Valentine leukocidin genes, and unique local methicillin-resistant S. aureus clones

Studies reporting on the population structure of Staphylococcus aureus in South Africa have focused only on methicillin-resistant S. aureus (MRSA). This study describes the population structure of S. aureus, including methicillin-susceptible S. aureus (MSSA) isolated from patients at Tygerberg Academic Hospital, Western Cape province. Pulsed-field gel electrophoresis (PFGE), detection of Panton-Valentine leukocidin (PVL), spa typing, multilocus sequence typing (MLST), agr typing and SCCmec typing were used to characterize strains. Of 367 non-repetitive S. aureus isolates collected over a period of 1 year, 56 (15.3%) were MRSA. Skin and soft tissue infections were the most frequent source (54.8%), followed by bone and joint (15.3%) and respiratory tract infections (7.7%). For strain typing, PFGE was the most discriminative method, and resulted in 31 pulsotypes (n = 345, 94.0%), as compared with 16 spa clonal complexes (CCs) (n = 344, 93.4%). Four MLST CCs were identified after eBURST of sequence types (STs) of selected isolates. One hundred and sixty isolates (MSSA, n = 155, 42.2%) were PVL-positive, and agr types I-IV and SCCmec types I-V were identified. Our S. aureus population consisted of genotypically diverse strains, with PVL being a common characteristic of MSSA. MSSA and MRSA isolates clustered in different clones. However, the dominant MRSA clone (ST612) also contained an MSSA isolate, and had a unique genotype. Common global epidemic MRSA clones, such as ST239-MRSA-III and ST36-MRSA-II, were identified. A local clone, ST612-MRSA-IV, was found to be the dominant MRSA clone.

Cytoplasmic replication of Staphylococcus aureus upon phagosomal escape triggered by phenol-soluble modulin α

Staphylococcus aureus is a Gram-positive human pathogen that is readily internalized by professional phagocytes such as macrophages and neutrophils but also by non-professional phagocytes such as epithelial or endothelial cells. Intracellular bacteria have been proposed to play a role in evasion of the innate immune system and may also lead to dissemination within migrating phagocytes. Further, S. aureus efficiently lyses host cells with a battery of cytolytic toxins. Recently, phenol-soluble modulins (PSM) have been identified to comprise a genus-specific family of cytolytic peptides. Of these the PSMα peptides have been implicated in killing polymorphonuclear leucocytes after phagocytosis. We questioned if the peptides were active in destroying endosomal membranes to avoid lysosomal killing of the pathogen and monitored integrity of infected host cell endosomes by measuring the acidity of the intracellular bacterial microenvironment via flow cytometry and by a reporter recruitment technique. Isogenic mutants of the methicillin-resistant S. aureus (MRSA) strains USA300 LAC, USA400 MW2 as well as the strongly cytolytic methicillin-sensitive strain 6850 were compared with their respective wild type strains. In all three genetic backgrounds, PSMα mutants were unable to escape from phagosomes in non-professional (293, HeLa, EAhy.926) and professional phagocytes (THP-1), whereas mutants in PSMβ and δ-toxin as well as β-toxin, phosphatidyl inositol-dependent phospholipase C and Panton Valentine leucotoxin escaped with efficiencies of the parental strains. S. aureus replicated intracellularly only in presence of a functional PSMα operon thereby illustrating that bacteria grow in the host cell cytoplasm upon phagosomal escape.

SDS interferes with SaeS signaling of Staphylococcus aureus independently of SaePQ

The Staphylococcus aureus regulatory saePQRS system controls the expression of numerous virulence factors, including extracellular adherence protein (Eap), which amongst others facilitates invasion of host cells. The saePQRS operon codes for 4 proteins: the histidine kinase SaeS, the response regulator SaeR, the lipoprotein SaeP and the transmembrane protein SaeQ. S. aureus strain Newman has a single amino acid substitution in the transmembrane domain of SaeS (L18P) which results in constitutive kinase activity. SDS was shown to be one of the signals interfering with SaeS activity leading to inhibition of the sae target gene eap in strains with SaeS^L but causing activation in strains containing SaeS^P. Here, we analyzed the possible involvement of the SaeP protein and saePQ region in SDS-mediated sae/eap expression. We found that SaePQ is not needed for SDS-mediated SaeS signaling. Furthermore, we could show that SaeS activity is closely linked to the expression of Eap and the capacity to invade host cells in a number of clinical isolates. This suggests that SaeS activity might be directly modulated by structurally non-complex environmental signals, as SDS, which possibly altering its kinase/phosphatase activity.

Ultralarge von Willebrand factor fibers mediate luminal Staphylococcus aureus adhesion to an intact endothelial cell layer under shear stress

BACKGROUND

During pathogenesis of infective endocarditis, Staphylococcus aureus adherence often occurs without identifiable preexisting heart disease. However, molecular mechanisms mediating initial bacterial adhesion to morphologically intact endocardium are largely unknown.

METHODS AND RESULTS

Perfusion of activated human endothelial cells with fluorescent bacteria under high-shear-rate conditions revealed 95% attachment of the S aureus by ultralarge von Willebrand factor (ULVWF). Flow experiments with VWF deletion mutants and heparin indicate a contribution of the A-type domains of VWF to bacterial binding. In this context, analyses of different bacterial deletion mutants suggest the involvement of wall teichoic acid but not of staphylococcal protein A. The presence of inactivated platelets and serum increased significantly ULVWF-mediated bacterial adherence. ADAMTS13 (a disintegrin and metalloproteinase with thrombospondin motifs 13) caused a dose-dependent reduction of bacterial binding and a reduced length of ULVWF, but single cocci were still tethered by ULVWF at physiological levels of ADAMTS13. To further prove the role of VWF in vivo, we compared wild-type mice with VWF knockout mice. Binding of fluorescent bacteria was followed in tumor necrosis factor-α-stimulated tissue by intravital microscopy applying the dorsal skinfold chamber model. Compared with wild-type mice (n=6), we found less bacteria in postcapillary (60±6 versus 32±5 bacteria) and collecting venules (48±5 versus 18±4 bacteria; P<0.05) of VWF knockout mice (n=5).

CONCLUSIONS

Our data provide the first evidence that ULVWF contributes to the initial pathogenic step of S aureus-induced endocarditis in patients with an apparently intact endothelium. An intervention reducing the ULVWF formation with heparin or ADAMTS13 suggests novel therapeutic options to prevent infective endocarditis.

Glutathione preconditioning ameliorates mitochondria dysfunction during warm pulmonary ischemia-reperfusion injury

OBJECTIVES

Reduced glutathione (GSH) has been shown to improve pulmonary graft preservation. Mitochondrial dysfunction is regarded to be the motor of ischemia-reperfusion injury (IR) in solid organs. We have shown previously that IR induces pulmonary mitochondrial damage. This study elucidates the impact of GSH preconditioning on the integrity and function of pulmonary mitochondria in the setting of warm pulmonary IR.

METHODS

Wistar rats were subjected to control, sham, and to two-study-group conditions (IR30/60 and GSH-IR30/60) receiving IR with or without GSH preconditioning. Rats were anesthetized and received mechanical ventilation. Pulmonary in situ clamping followed by reperfusion generated IR. Mitochondria were isolated from pulmonary tissue. Respiratory chain complexes activities (I-IV) were analyzed by polarography. Mitochondrial viability (Ca2+-induced swelling) and membrane integrity (citrate synthase assay) were determined. Subcellular-fractional cytochrome C-content (Cyt C) was quantified by enzyme-linked immunosorbent assay (ELISA). Mitochondrial membrane potential (ΔΨm) was analyzed by fluorescence-activated cell sorting (FACS) after energizing and uncoupling. Inflammatory activation was determined by myeloperoxidase activity (MPO), matrix-metalloproteinase 9 (MMP-9) activity by gel zymography.

RESULTS

Pulmonary IR significantly reduced mitochondrial viability in combination with ΔΨm hyper-polarization. GSH preconditioning improved mitochondrial viability and normalized ΔΨm. Cyt C was reduced after IR; GSH protected from Cyt C liberation. Respiratory chain complex activities (I, II, III) declined during IR; GSH protected complex II function. GSH also protected from MMP-9 and neutrophil sequestration (P>.05).

CONCLUSIONS

GSH preconditioning is effective to prevent mitochondrial death and improves complex II function during IR, but not mitochondrial membrane stability. GSH-mediated amelioration of ΔΨm hyper-polarization appears to be the key factor of mitochondrial protection.

Intracellular Staphylococcus aureus: live-in and let die

Staphylococcus aureus uses a plethora of virulence factors to accommodate a diversity of niches in its human host. Aside from the classical manifestations of S. aureus-induced diseases, the pathogen also invades and survives within mammalian host cells.The survival strategies of the pathogen are as diverse as strains or host cell types used. S. aureus is able to replicate in the phagosome or freely in the cytoplasm of its host cells. It escapes the phagosome of professional and non-professional phagocytes, subverts autophagy, induces cell death mechanisms such as apoptosis and pyronecrosis, and even can induce anti-apoptotic programs in phagocytes. The focus of this review is to present a guide to recent research outlining the variety of intracellular fates of S. aureus.

Glycine preconditioning to ameliorate pulmonary ischemia reperfusion injury in rats

This study examines the impact of glycine (Gly) preconditioning on ischemia reperfusion (IR)-induced pulmonary mitochondrial injury to research the previously, in pig lungs, demonstrated Gly-dependent amelioration of pulmonary IR injury. IR injury was induced in rat lungs by 30 min pulmonary hilum clamping followed by 60 min reperfusion time. Rats were subjected to controls, shams and two study groups (IR30/60, Gly-IR30/60) receiving 37.5 mg Gly i.v. or not before IR induction. The wet/dry-weight ratio, mitochondria viability (MV), membrane integrity (MI), respiratory chain complex (RCC) activities, mitochondrial membrane potential (ΔΨm) and cytochrome C (Cyt C) content were analysed. In IR30/60, RCC and MV were impaired; Cyt C loss and MI combined with matrix metalloproteinase-9 (MMP-9) activation and ΔΨm alteration were observed when compared with controls. In Gly-IR30/60, complex II function and mitochondrial viability were protected during IR, and MMP-9 activation combined with tissue-water content accumulation and ΔΨm alteration were ameliorated. Cyt C loss, mitochondrial membranes damage, tissue GSH oxidation or neutrophil sequestration was not extenuated in Gly-IR30/60. Gly ameliorates IR-associated mitochondrial dysfunction and decay of viability and normalizes ΔΨm but does not protect from Cyt C liberation and mitochondrial membrane damage. Our data suggest that the previously described effect of Gly preconditioning results at least partially from mitochondrial protection. A dose-finding study is necessary to improve results of Gly preconditioning.

Ischemia-reperfusion injury-induced pulmonary mitochondrial damage

BACKGROUND

Mitochondrial dysfunction is a key factor in solid organ ischemia-reperfusion (IR) injury. Impaired mitochondrial integrity predisposes to cellular energy depletion, free radical generation, and cell death. This study analyzed mitochondrial damage induced by warm pulmonary IR.

METHODS

Anesthetized Wistar rats received mechanical ventilation. Pulmonary clamping was followed by reperfusion to generate IR injury. Rats were subjected to control, sham, and to 2 study group conditions: 30 minutes of ischemia without reperfusion (IR30/0), or ischemia followed by 60 minutes of reperfusion (IR30/60). Pulmonary edema was quantified by wet/dry-weight ratio. Polarography determined activities of respiratory chain complexes. Mitochondrial viability was detected by using Ca(2+)-induced swelling, and integrity by citrate synthase assay. Enzyme-linked immunosorbent assay determined cytochrome C content. Mitochondrial membrane potential (ΔΨm) stability was analyzed by flow cytometry using JC1, inflammation by myeloperoxidase (MPO) activity, and matrix-metalloproteinase-9 (MMP-9) activity by gel zymography, respectively.

RESULTS

In IR30/60 rats, tissue water content was elevated from 80.6 % (sham) to 86.9%. After ischemia, ΔΨm showed hyperpolarization and rapid decline after uncoupling compared with controls. IR, but not ischemia alone, impaired respiratory chain function complexes I, II and III (p < 0.05). Mitochondrial viability (p < 0.001) and integrity (p < 0.01) was impaired after ischemia and IR, followed by mitochondrial cytochrome C loss (p < 0.05). Increased activation of MPO (p < 0.01) and MMP-9 (p < 0.001) was induced by reperfusion after ischemia.

CONCLUSIONS

Ischemia-related ΔΨm hyper-polarization induces reperfusion-associated mitochondrial respiratory chain dysfunction in parallel with tissue inflammation and degradation. Controlling ΔΨm during ischemia might reduce IR injury.

Expression of δ-toxin by Staphylococcus aureus mediates escape from phago-endosomes of human epithelial and endothelial cells in the presence of β-toxin

Staphylococcus aureus is able to invade non-professional phagocytes by interaction of staphylococcal adhesins with extracellular proteins of mammalian cells and eventually resides in acidified phago-endosomes. Some staphylococcal strains have been shown to subsequently escape from this compartment. A functional agr quorum-sensing system is needed for phagosomal escape. However, the nature of this agr dependency as well as the toxins involved in disruption of the phagosomal membrane are unknown. Using a novel technique to detect vesicular escape of S. aureus, we identified staphylococcal virulence factors involved in phagosomal escape. Here we show that a synergistic activity of the cytolytic peptide, staphylococcal δ-toxin and the sphingomyelinase β-toxin enable the phagosomal escape of staphylococci in human epithelial as well as in endothelial cells. The agr dependency of this process can be directly explained by the location of the structural gene for δ-toxin within the agr effector RNAIII.