Safe shortening of antibiotic treatment duration for complicated Staphylococcus aureus bacteraemia (SAFE trial): protocol for a randomised, controlled, open-label, non-inferiority trial comparing 4 and 6 weeks of antibiotic treatment

INTRODUCTION

A major knowledge gap in the treatment of complicated Staphylococcus aureus bacteraemia (SAB) is the optimal duration of antibiotic therapy. Safe shortening of antibiotic therapy has the potential to reduce adverse drug events, length of hospital stay and costs. The objective of the SAFE trial is to evaluate whether 4 weeks of antibiotic therapy is non-inferior to 6 weeks in patients with complicated SAB.

METHODS AND ANALYSIS

The SAFE-trial is a multicentre, non-inferiority, open-label, parallel group, randomised controlled trial evaluating 4 versus 6 weeks of antibiotic therapy for complicated SAB. The study is performed in 15 university hospitals and general hospitals in the Netherlands. Eligible patients are adults with methicillin-susceptible SAB with evidence of deep-seated or metastatic infection and/or predictors of complicated SAB. Only patients with a satisfactory clinical response to initial antibiotic treatment are included. Patients with infected prosthetic material or an undrained abscess of 5 cm or more at day 14 of adequate antibiotic treatment are excluded. Primary outcome is success of therapy after 180 days, a combined endpoint of survival without evidence of microbiologically confirmed disease relapse. Assuming a primary endpoint occurrence of 90% in the 6 weeks group, a non-inferiority margin of 7.5% is used. Enrolment of 396 patients in total is required to demonstrate non-inferiority of shorter antibiotic therapy with a power of 80%. Currently, 152 patients are enrolled in the study.

ETHICS AND DISSEMINATION

This is the first randomised controlled trial evaluating duration of antibiotic therapy for complicated SAB. Non-inferiority of 4 weeks of treatment would allow shortening of treatment duration in selected patients with complicated SAB. This study is approved by the Medical Ethics Committee VUmc (Amsterdam, the Netherlands) and registered under NL8347 (the Netherlands Trial Register). Results of the study will be published in a peer-reviewed journal.

TRIAL REGISTRATION NUMBER

NL8347 (the Netherlands Trial Register).

Tales of the unexpected in antibiotic resistance

Since the 1990s few new antibiotics have become available; during the same period the appearance and spread of bacteria no longer susceptible to first- and second-line antibiotics has accelerated; indeed some bacterial infections untreatable with existing antibiotics. Control of antibiotic resistance is multifactorial, and includes restrictive antibiotic use and good infection control. The 2021 Lowbury lecture addresses three aspects of antibiotic resistance, with reference to the Netherlands, that illustrate the complexity of antibiotic resistance epidemiology. Initially selective decontamination of the digestive tract (SDD) was not adopted in the Netherlands because of concern about antibiotic resistance. However, three trials showed that SDD regimens, including 4 days of systemic cephalosporins, gave better clinical outcomes with no effect on antibiotic-resistant bacteria. Many predictions have been made about the impact of infections with antibiotic-resistant bacteria on human health. However, the situation is complex, because the risk factors for infection with multidrug-resistant bacteria are also risk factors for poor clinical outcome. A study in 8 Dutch hospitals estimated the mortality attributable to antibiotic resistance as close to zero. Concern about the emergence of resistance in Staphyloocccus aureus has limited the universal use of mupirocin to prevent surgical site infections. However, the risk may have been overstated, and universal decolonisation with mupirocin and chlorhexidine has now become standard of care in patients undergoing cardiothoracic or orthopaedic surgery in many Dutch hospitals. Prophylactic antibiotics can improve patient outcomes with acceptable risks of promoting resistance.

Preparedness for admission of patients with suspected Ebola virus disease in European hospitals: a survey, August-September 2014

In response to the Ebola virus disease (EVD) outbreak in West Africa, the World Health Organization has advised all nations to prepare for the detection, investigation and management of confirmed and suspected EVD cases in order to prevent further spread through international travel. To gain insights into the state of preparedness of European hospitals, an electronic survey was circulated in August–September 2014 to 984 medical professionals representing 736 hospitals in 40 countries. The survey addressed the willingness and capacity to admit patients with suspected EVD as well as specific preparedness activities in response to the current Ebola crisis. Evaluable responses were received from representatives of 254 (32%) hospitals in 38 countries, mostly tertiary care centres, of which 46% indicated that they would admit patients with suspected EVD. Patient transfer agreements were in place for the majority of hospitals that would not admit patients. Compared with non-admitting hospitals, admitting hospitals were more frequently engaged in various preparedness activities and more often contained basic infrastructural characteristics such as admission rooms and laboratories considered important for infection control, but some gaps and concerns were also identified. The results of this survey help to provide direction towards further preparedness activities and prioritisation thereof.

Successful control of a hospital-wide outbreak of OXA-48 producing Enterobacteriaceae in the Netherlands, 2009 to 2011

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Not all patients with vancomycin-resistant enterococci need to be isolated

BACKGROUND

Vancomycin-resistant enterococci (VRE) have triggered multiple outbreaks. However, VRE of genotype vanC appear not to be associated with outbreaks. The goal of this study was to estimate the risk of bloodstream infections in patients colonized with VRE of genotype vanC who received care from a bone marrow transplant unit for patients with leukemia, where only standard precautions were implemented for VRE of genotype vanC during the last 9 years.

METHODS

Since 2000, all patients in the bone marrow transplant unit underwent routine VRE rectal screening, data were prospectively entered in a database, and isolates were molecularly characterized. Infection control policy required contact isolation for patients infected with VRE of genotype vanA or vanB but only standard precautions for patients infected with VRE of genotype vanC.

RESULTS

From January 2000 to July 2008, 290 isolates of VRE of genotype vanC obtained from 273 different patients were identified, with an incidence of 25-43 isolates/year. Of 290 isolates, 285 (98%) were identified in rectal screening swabs, 5 were from other body sites, and none required specific treatment. During the entire study period, only 1 case of bloodstream infection was detected, reflecting an incidence of 1 (0.4%) of the 273 patients, or <0.2 cases per 1000 patient-days. No outbreaks were recorded.

CONCLUSIONS

These data provide strong evidence that carriers of VRE of genotype vanC do not require contact isolation, thereby saving resources and potentially improving patient care. The genotype should be routinely determined in areas with a high prevalence of VRE of genotype vanC.

Ecological replacement of Enterococcus faecalis by multiresistant clonal complex 17 Enterococcus faecium

The proportion of enterococcal infections caused by ampicillin-resistant Enterococcus faecium (AREfm) in a European hospital increased from 2% in 1994 to 32% in 2005, with prevalence rates of AREfm endemicity of up to 35% in at least six hospital wards. Diabetes mellitus, three or more admissions in the preceding year, and use of beta-lactams and fluoroquinolones, were all associated with AREfm colonisation. Of 217 AREfm isolates that were genotyped, 97% belonged to clonal complex 17 (CC17). This ecological change mimics events preceding the emergence of vancomycin-resistant E. faecium (VREF) in the USA and may presage the emergence of CC17 VREF in European hospitals.

Healthcare Epidemiology: Potential Confounding in Evaluating Infection‐Control Interventions in Hospital Settings: Changing Antibiotic Prescription

The colonization dynamics of antibiotic-resistant pathogens in hospital settings are complex, with multiple and continuously interacting variables (e.g., introduction of resistance, infection-control practices, antibiotic use). Quantification of these variables is indispensable in the evaluation of intervention studies, because these variables represent potential confounders. In this article, the complexity of colonization dynamics is described. Through a systematic review, we identified studies that evaluated the modification of antibiotic prescription to reduce antibiotic resistance in intensive care units (n=19), and the extent of confounding-control was determined. Most studies evaluated antimicrobial restriction/substitution (n=12) or antibiotic rotation (n=4). Sixteen studies had a prospective cohort design (before-after), of which 12 were without a control group. Introduction of antibiotic resistance was determined in 10 studies. The relative importance of colonization routes and adherence to infection-control measures were not determined in any study. Therefore, it remains uncertain whether observed changes in the prevalence of antibiotic resistance after intervention were causally related to the intervention. Appropriate choices of study design, primary end point (colonization rates rather than infection rates) and statistical tests, determination of colonization routes, and control of potential confounders are needed to increase validity of intervention studies.

[Optimizing the antibiotics policy in The Netherlands. VIII. Revised SWAB guidelines for antimicrobial therapy in adults with community-acquired pneumonia]

The Dutch Working Party on Antibiotic Policy (SWAB) has revised the 1998 guideline for community-acquired pneumonia (CAP) in light of changing resistance patterns for common pathogens and new developments in epidemiology, diagnostic testing and treatment strategies. The current guideline is applicable to both primary and inpatient care, and has been developed by delegates of all professional organisations involved in the treatment of CAP, following recommendations for evidence-based guideline development. Assessment of a patient's 'severity of illness' at presentation is considered important when choosing an optimal empirical antibiotic regimen for CAP. Severely-ill patients should be treated with antibiotics covering the most important expected pathogens, including Legionella. Assessment of the severity of illness may be facilitated by the use of validated scoring systems like the pneumonia severity index and the 'confusion, urea, respiratory-rate, blood-pressure, 65-years-of-age' (CURB-65) score. Patients can also be stratified based on their location during treatment: in the community, a normal ward or an intensive-care unit. Legionella urine antigen testing is considered an important tool in the process of deciding on an optimal antibiotic regimen for CAP. Empirical therapy should be replaced with pathogen-directed therapy if the causative agent is identified.

Unnoticed spread of integron-carrying Enterobacteriaceae in intensive care units

BACKGROUND

Integrons are strongly associated with multidrug resistance in Enterobacteriaceae. Little is known about the natural history of integron-associated resistance in hospitals during nonoutbreak periods. The prevalence of integrons and the incidence of cross-transmission and horizontal gene transfer in Enterobacteriaceae with reduced susceptibility to cephalosporins (ERSC) were determined for 2 intensive care units (ICUs).

METHODS

Microbiological surveillance using rectal swab samples obtained 2 times per week and genotyping using amplified fragment-length polymorphism (AFLP) were used to determine colonization with and genetic relatedness of ERSC. IntI1 integrase polymerase chain reaction (PCR), conserved-segment PCR, restriction fragment-length polymorphism, and DNA sequencing were used to determine the prevalence and contents of integrons.

RESULTS

Of 457 patients, 121 patients were colonized with ERSC, and 174 isolates underwent AFLP and PCR. In 34 isolates obtained from 31 patients, 11 different integrons were identified; these integrons encoded resistance to streptomycin/spectinomycin, gentamicin/tobramycin/kanamycin, chloramphenicol, and trimethoprim. Integrons could be divided into 7 clusters of > or =2 isolates each. Compared with isolates that were negative for integrons, isolates that were positive for integrons were associated with resistance to piperacillin, cephalosporins, aminoglycosides, and quinolones. Acquisition rates of integron-carrying ERSC were 10 cases per 1000 patient-days in the first ICU and 8 cases per 1000 patient-days in the second ICU, with most cases (26 of 34) being acquired during the ICU stay. Nineteen episodes resulted from cross-transmission. In addition, 2 cases of interspecies transfer and 1 case of intraspecies transfer of integrons were recorded. Younger age was independently associated with acquisition of integron-carrying ERSC (hazard ratio, 0.953; 95% confidence interval, 0.926-0.987).

CONCLUSION

Surveillance, genotyping, and integron analysis identified previously unnoticed outbreaks of integron-carrying ERSC. Cross-transmission appeared to be the dominant route of transmission. Therefore, barrier precautions are necessary to prevent further spread.

Transmission of nosocomial pathogens

Prevention of the spread of antibiotic-resistant micro-organisms is one of the challenges for mankind in the new millennium, according to a recent report from the World Health Organization. In our Western world resistance problems occur mainly in intensive care units (ICUs). However, the observed numbers of infections are only the tip of the iceberg of patients colonised with multiple-resistant pathogens. Remarkably, manifestation of problems with antibiotic resistant pathogens within ICUs has specific characteristics. Initially there are a few, presumably sporadic, infections, and sometimes an outbreak is feared. Such an initial outbreak may be caused by an environmental source within the ward or by the admission of a patient colonised or infected with the resistant pathogen. After some time, the incidence of infections increases and a considerable part of the patient population appears to be colonised. A situation of endemicity has developed and the eradication of the resistant micro-organisms from the ward is very difficult and may even be impossible. Classical measures of infection prevention such as hand disinfection after patient contact remain the cornerstone of infection prevention, but little is known about their quantitative effects. Compliance with this rule is not 100%, usually not even 50%, but what percentage would be sufficient, and can other measures be more effective? Modelling the dynamic processes that determine the epidemiology of colonisation may help to quantitatively predict what effects will influence this process. Moreover, these methods may help to identify new measures for infection control.

Value of phenotyping methods as an initial screening of Pseudomonas aeruginosa in epidemiologic studies

When studying the epidemiology of Pseudomonas aeruginosa, determination of the similarity of isolates is crucial. In the present study the distinctive capacity of four phenotyping methods (antibiotic susceptibility patterns, serotyping, phage-typing and outer membrane protein [OMP] profile analysis) was determined and compared to pulsed-field gel electrophoresis (PFGE) of enzyme restricted chromosomal DNA. In all, 91 isolates of P. aeruginosa were cultured from ten patients. Antibiotic susceptibility patterns were concordant for all isolates. Serotyping yielded five, phage-typing eight, OMP profile analysis nine and PFGE seven distinct types of P. aeruginosa. Compared to PFGE, the distinctive capacities were 89% (81/91) for serotyping, 87% (79/91) for phage-typing, and 90% (82/91) for OMP profile analysis. When serotyping results were different, PFGE types also were different (exclusiveness 100%). However, isolates with the same serotype may have various PFGE patterns. In contrast, isolates with similar PFGE patterns could have different phage-types or OMP types. For the study of isolates of P. aeruginosa, serotyping provides a good initial selection to reduce the number of isolates that need to be genotyped.

Clinical spectrum of ventilator-associated pneumonia caused by methicillin-sensitive Staphylococcus aureus

The incidence of tracheal colonization and its association with ventilator-associated pneumonia caused by methicillin-sensitive Staphylococcus aureus (MSSA) was studied prospectively in 530 consecutively admitted mechanically ventilated patients in a general intensive care unit. Furthermore, the clinical spectrum, outcome, and microbiological results of 27 cases of staphylococcal ventilator-associated pneumonia (SVAP) were examined. Ventilator-associated pneumonia was diagnosed by protected specimen brush and/or bronchoalveolar lavage. On admission, 7% of the patients were colonized with MSSA in the trachea. Acquired tracheal colonization was demonstrated in 10% of the patients and occurred less frequently in patients with a hospital stay of > 48 h before ICU admission compared to patients admitted directly to the ICU (6% vs. 15%, p < 0.001). Moreover, colonization was acquired more frequently among trauma and neurological/neurosurgical patients (22%) as compared to surgical and medical patients (7%) (p < 0.0001). Twenty-one patients (4%) developed SVAP, the incident being higher in patients colonized in the trachea with MSSA than in those not colonized (21% vs. 1%), p < 0.00001). Staphylococcal ventilator-associated pneumonia developed more often in trauma and neurological/neurosurgical patients as compared to surgical and medical patients (8% vs. 3%, p < 0.05). Moreover, patients with a hospital stay of < 48 h before admission to the ICU had a higher incidence of SVAP as compared to those with a longer hospital stay before ICU admission (7% vs. 2%, p < 0.01). Crude infection-related mortality was 26%. Preceding colonization with MSSA in the trachea appears to be an important risk factor for the development of SVAP, and patients with a short duration of hospitalization before intensive care unit admission have the highest incidence of ventilator-associated pneumonia caused by MSSA.

In vitro antibacterial activity of sucralfate

The effect of sucralfate (12.5 mg/ml) on the growth of Escherichia coli (ATCC 25922), Enterococcus faecalis (ATCC 29212) and two isolates of Pseudomonas aeruginosa (ATCC 27853 and a multi-resistant clinical isolate) was studied in vitro at pH values of 3.0, 4.5, 6.0 and 7.4. A bacteriostatic effect of sucralfate was demonstrated for Pseudomonas aeruginosa at a pH of 6.0 and 7.4 and for Escherichia coli and Enterococcus faecalis at a pH of 6.0. The bacteriostatic effect was most pronounced at high pH values. Sucralfate had no bactericidal effect on the bacteria tested at the concentration used.

Antibiotic resistance of Escherichia coli in fecal samples of healthy people in two different areas in an industrialized country

Fecal samples of 310 healthy persons, from two populations from different areas in the Netherlands, were examined for the presence of Escherichia coli resistant to ampicillin, tetracycline, sulfamethoxazole, trimethoprim and nitrofurantoin. High prevalences of resistance were found in both populations, ranging from 28% for trimethoprim to 89% for ampicillin. The percentages of the fecal samples with a dominantly resistant E. coli flora (> 50% resistance) were distinctly lower, ranging from 1% for nitrofurantoin to 21% for tetracycline. No significant differences in the level of resistance were observed between these two comparable populations in two different areas. The susceptibilities to 11 antimicrobial agents of 456 at random isolated E. coli were determined. The percentages of resistance varied widely: from 80% for chloramphenicol to 9% for nitrofurantoin. Only 19% of the isolates were susceptible to all antibiotics tested and 14% were resistant to more than four of the agents tested. Great differences in resistance rates between the two populations examined were seen for chloramphenicol (80% to 41%) and trimethoprim (16% to 36%). The results of this study underscore the presence of a human reservoir of antibiotic resistant microorganisms.

High prevalence of antibiotic resistant Escherichia coli in faecal samples of students in the south-east of The Netherlands

From December 1988 to March 1989 172 faecal samples from first and second year students at the University of Limburg, Maastricht, The Netherlands, were collected and analysed for the presence of Escherichia coli strains resistant to ampicillin, sulphamethoxazole, tetracycline, trimethoprim and nitrofurantoin. In addition, the antibiotic susceptibility (MIC) to these agents and six other compounds (i.e. aminoglycosides, nitrofurantoin, nalidixic acid and cephalothin) was determined. The prevalence of resistance of the samples analysed ranged from 86% (i.e. 148 out of 172) for sulphamethoxazole to 25% for trimethoprim. The prevalence figures for ampicillin, tetracycline and nitrofurantoin resistance were 76%, 47% and 29%, respectively. The percentages of the faecal samples with a high proportion of E. coli (greater than 50% of the total number of E. coli) resistant to ampicillin, tetracycline and sulphamethoxazole were 8%, 11% and 37%, respectively. For nitrofurantoin and trimethoprim the figures were 3% and 1%, respectively. Of the isolated E. coli (n = 797), 84% was resistant to ampicillin, 82% resistant to sulphamethoxazole. The lowest percentages (9%) were observed for both nalidixic acid and nitrofurantoin.