Management of Staphylococcus aureus bacteremia and endocarditis: progresses and challenges

Physiologically based pharmacokinetic modelling to inform combination dosing regimens of ceftaroline and daptomycin in special populations

AIMS

The combination of daptomycin and ceftaroline used as salvage therapy is associated with higher survival and decreased clinical failure in complicated methicillin-resistant Staphylococcus aureus (MRSA) infections that are resistant to standard MRSA treatment. This study aimed to evaluate dosing regimens for coadministration of daptomycin and ceftaroline in special populations including paediatrics, renally impaired (RI), obese and geriatrics that generate sufficient coverage against daptomycin-resistant MRSA.

METHODS

Physiologically based pharmacokinetic models were developed from pharmacokinetic studies of healthy adults, geriatric, paediatric, obese and RI patients. The predicted profiles were used to evaluate joint probability of target attainment (PTA), as well as tissue-to-plasma ratios.

RESULTS

The adult dosing regimens of 6 mg/kg every (q)24h or q48h daptomycin and 300-600 mg q12h ceftaroline fosamil by RI categories achieved ≥90% joint PTA when the minimum inhibitory concentrations in the combination are at or below 1 and 4 μg/mL against MRSA. In paediatrics, wherein there is no recommended daptomycin dosing regimen for S. aureus bacteraemia, ≥90% joint PTA is achieved when the minimum inhibitory concentrations in the combination are up to 0.5 and 2 μg/mL for standard paediatric dosing regimens of 7 mg/kg q24h daptomycin and 12 mg/kg q8h ceftaroline fosamil. Model predicted tissue-to-plasma ratios of 0.3 and 0.7 in the skin and lung, respectively, for ceftaroline and 0.8 in the skin for daptomycin.

CONCLUSION

Our work illustrates how physiologically based pharmacokinetic modelling can inform appropriate dosing of adult and paediatric patients and thereby enable prediction of target attainment in the patients during multitherapies.

A structure activity relationship study of 3,4'-dimethoxyflavone for ArlRS inhibition in Staphylococcus aureus

Infections caused by methicillin-resistant Staphylococcus aureus (MRSA) are difficult to treat due to their resistance to many β-lactam antibiotics, and their highly coordinated excretion of virulence factors. One way in which MRSA accomplishes this is by responding to environmental stimuli using two-component systems (TCS). The ArlRS TCS has been identified as having a key role in regulating virulence in both systemic and local infections caused by S. aureus. We recently disclosed 3,4'-dimethoxyflavone as a selective ArlRS inhibitor. In this study we explore the structure-activity relationship (SAR) of the flavone scaffold for ArlRS inhibition and identify several compounds with increased activity compared to the parent. Additionally, we identify a compound that suppresses oxacillin resistance in MRSA, and begin to probe the mechanism of action behind this activity.

Staphylococcus aureus bacteremia and infective endocarditis in a patient with epidermolytic hyperkeratosis: A case report

BACKGROUND

Staphylococcus aureus bacteraemia (SAB) is among the leading causes of bacteraemia and infectious endocarditis. The frequency of infectious endocarditis (IE) among SAB patients ranges from 5% to 10%-12%. In adults, the characteristics of epidermolytic hyperkeratosis (EHK) include hyperkeratosis, erosions, and blisters. Patients with inflammatory skin diseases and some diseases involving the epidermis tend to exhibit a disturbed skin barrier and tend to have poor cell-mediated immunity.

CASE SUMMARY

We describe a case of SAB and infective endocarditis in a 43-year-old male who presented with fever of unknown origin and skin diseases. After genetic tests, the skin disease was diagnosed as EHK.

CONCLUSION

A breached skin barrier secondary to EHK, coupled with inadequate sanitation, likely provided the opportunity for bacterial seeding, leading to IE and deep-seated abscess or organ abscess. EHK may be associated with skin infection and multiple risk factors for extracutaneous infections. Patients with EHK should be treated early to minimize their consequences. If patients with EHK present with prolonged fever of unknown origin, IE and organ abscesses should be ruled out, including metastatic spreads.

Impact of neutropenia on clinical manifestations and outcome of Staphylococcus aureus bloodstream infection - A propensity score-based overlap weight analysis in two large, prospectively evaluated cohorts

OBJECTIVE

To investigate whether neutropenia influenced mortality and long-term outcome of Staphylococcus aureus bloodstream infection (SAB).

METHODS

Data from two prospective, multicentre cohort studies (INSTINCT and ISAC) conducted in 20 tertiary care hospitals in 6 countries between 2006 and 2015 were analysed. Neutropenic and severely neutropenic patients (defined by the proxy of total white blood cell count <1000/μl and <500/μl, respectively, at onset of SAB) were compared to a control group using a propensity score model and overlap weights to adjust for baseline characteristics. Overall survival and time to SAB-related late complications (SAB recurrence, infective endocarditis, osteomyelitis, or other deep-seated manifestations) were analysed by Cox regression and competing risk analyses, respectively.

RESULTS

Of 3,187 patients, 102 were neutropenic and 70 were severely neutropenic at onset of SAB. Applying overlap weights yielded two groups of 83 neutropenic and 220 non-neutropenic patients, respectively. Baseline characteristics of these groups were exactly balanced. In the Cox regression analysis, we observed no significant difference in survival between the two groups (death during follow-up: 36.1 % in neutropenic vs. 30.6 % in non-neutropenic patients, hazard ratio 1.21 (95 % CI 0.79-1.83)). This finding remained unchanged when we considered severely neutropenic patients (hazard ratio 1.08 [0.60; 1.94]). Competing risk analysis showed a cause-specific hazard ratio (CSHR) of 0.39 (95 % CI 0.11-1.39) for SAB-related late-complications in neutropenic patients.

CONCLUSIONS

Neutropenia was not associated with a higher survival during follow-up. The lower rate of SAB-related late complications in neutropenic patients should be validated in other cohorts.

Daily Administered Dual-Light Photodynamic Therapy Provides a Sustained Antibacterial Effect on Staphylococcus aureus

New means to reduce excessive antibiotic use are urgently needed. This study tested dual-light aPDT against Staphylococcus aureus biofilm with different relative ratios of light energy with indocyanine green. We applied single-light aPDT (810 nm aPDT, 405 aBL) or dual-light aPDT (simultaneous 810 nm aPDT and 405 nm aBL), in both cases, together with the ICG photosensitizer with constant energy of 100 or 200 J/cm². Single-dose light exposures were given after one-day, three-day, or six-day biofilm incubations. A repeated daily dose of identical light energy was applied during biofilm incubations for the three- and six-day biofilms. Using 100 J/cm² light energy against the one-day biofilm, the dual-light aPDT consisting of more than half of aBL was the most effective. On a three-day maturated biofilm, single-dose exposure to aPDT or dual-light aPDT was more effective than aBL alone. With total light energy of 200 J/cm², all dual-light treatments were effective. Dual-light aPDT improves the bactericidal effect on Staphylococcus aureus biofilm compared to aPDT or aBL and provides a sustained effect. An increase in the relative ratio of aBL strengthens the antibacterial effect, mainly when the treatment is repeatedly applied. Thus, the light components' energy ratio is essential with dual-light.

Impact of Immunosuppressive Agents on Clinical Manifestations and Outcome of Staphylococcus aureus Bloodstream Infection: A Propensity Score-Matched Analysis in 2 Large, Prospectively Evaluated Cohorts

BACKGROUND

Staphylococcus aureus bloodstream infection (SAB) is a common, life-threatening infection. The impact of immunosuppressive agents on the outcome of patients with SAB is incompletely understood.

METHODS

Data from 2 large prospective, international, multicenter cohort studies (Invasive Staphylococcus aureus Infections Cohort [INSTINCT] and International Staphylococcus aureus Collaboration [ISAC]) between 2006 and 2015 were analyzed. Patients receiving immunosuppressive agents were identified and a 1:1 propensity score-matched analysis was performed to adjust for baseline characteristics of patients. Overall survival and time to SAB-related late complications (SAB relapse, infective endocarditis, osteomyelitis, or other deep-seated manifestations) were analyzed by Cox regression and competing risk analyses, respectively. This approach was then repeated for specific immunosuppressive agents (corticosteroid monotherapy and immunosuppressive agents other than steroids [IMOTS]).

RESULTS

Of 3188 analyzed patients, 309 were receiving immunosuppressive treatment according to our definitions and were matched to 309 nonimmunosuppressed patients. After propensity score matching, baseline characteristics were well balanced. In the Cox regression analysis, we observed no significant difference in survival between the 2 groups (death during follow-up: 105/309 [33.9%] immunosuppressed vs 94/309 [30.4%] nonimmunosuppressed; hazard ratio [HR], 1.20 [95% confidence interval {CI}, .84-1.71]). Competing risk analysis showed a cause-specific HR of 1.81 (95% CI, .85-3.87) for SAB-related late complications in patients receiving immunosuppressive agents. The cause-specific HR was higher in patients taking IMOTS (3.69 [95% CI, 1.41-9.68]).

CONCLUSIONS

Immunosuppressive agents were not associated with an overall higher mortality. The risk for SAB-related late complications in patients receiving specific immunosuppressive agents such as IMOTS warrants further investigations.

Daptomycin versus Vancomycin for the Treatment of Methicillin-Resistant Staphylococcus aureus Bloodstream Infection with or without Endocarditis: A Systematic Review and Meta-Analysis

Background: Methicillin-resistant Staphylococcus aureus (MRSA) is an important cause of invasive infections, mainly bloodstream infections (BSI) with or without endocarditis. The purpose of this meta-analysis was to compare vancomycin, the mainstay treatment, with daptomycin as therapeutic options in this context. Materials: PubMed, Embase and the Cochrane Database were searched from their inception to 15 February 2020. The primary outcome was all-cause mortality. Secondary outcomes included clinical failure, infection recurrence, persistence of infection, length-of-stay, antibiotic discontinuation due to adverse events (AEs) and 30-day re-admission. This study was registered with PROSPERO, CRD42020169413. Results: Eight studies (1226 patients, 554 vs. 672 in daptomycin vs. vancomycin, respectively) were included. No significant difference in terms of overall mortality was observed [odds ratio (OR) 0.73, 95% confidence interval (CI) 0.40–1.33, I² = 67%]. Daptomycin was associated with a significantly reduced risk of clinical failure (OR 0.58, 95% CI 0.38–0.89, I² = 60%), as confirmed by pooling adjusted effect sizes (adjusted OR against the use of vancomycin 1.94, 95%CI 1.33–1.82, I² = 41%), and was linked with fewer treatment-limiting AEs (OR 0.15, 95%CI 0.06–0.36, I² = 19%). No difference emerged between the two treatments as secondary outcomes. Results were not robust to unmeasured confounding (E-value lower than 95% CI 1.00 for all-cause mortality). Conclusions: Against MRSA BSI, with or without endocarditis, daptomycin seems to be associated with a lower risk of clinical failure and treatment-limiting AEs compared with vancomycin. Further studies are needed to better characterize the differences between the two drugs.

Combination therapy with rifampicin or fosfomycin in patients with Staphylococcus aureus bloodstream infection at high risk for complications or relapse: results of a large prospective observational cohort

OBJECTIVES

To investigate whether Staphylococcus aureus bloodstream infection (SAB) patients at high risk for complications or relapse benefit from combination therapy with adjunctive rifampicin or fosfomycin.

METHODS

In this post hoc analysis, SAB patients with native valve infective endocarditis, osteoarticular infections or implanted foreign devices were included. The co-primary endpoints were all-cause 90 day mortality and death or SAB-related late complications within 180 days. To overcome treatment selection bias and account for its time dependence, inverse probability of treatment weights were calculated and included in marginal structural Cox proportional hazard models (MSCMs).

RESULTS

A total of 578 patients were included in the analysis, of which 313 (54%) received combination therapy with either rifampicin (n = 242) or fosfomycin (n = 58). In the multivariable MSCM, combination therapy was associated with a better outcome, that is, a lower rate of death or SAB-related late complications within 180 days (HR 0.65, 95% CI 0.46-0.92). This beneficial effect was primarily seen in patients with implanted foreign devices, in which combination therapy was associated with a lower rate of death or SAB-related late complications within 180 days (HR 0.53, 95% CI 0.35-0.79) and a lower 90 day mortality (HR 0.57, 95% CI 0.36-0.91). Upon agent-specific stratification, we found no significant differences in outcomes between combination therapy containing rifampicin and fosfomycin; however, the number of patients in most subgroups was not large enough to draw firm conclusions.

CONCLUSIONS

In patients with implanted foreign devices, combination therapy was associated with a better long-term outcome. Larger prospective studies are needed to validate these findings.

Role of echocardiography in uncomplicated Staphylococcus aureus catheter-related bloodstream infections

Uncomplicated bacteremia and catheter-related bloodstream infection (CRBSI) are frequently suggested as factors associated with low risk of infective endocarditis in Staphylococcus aureus bacteremia (SAB). Nevertheless, guidelines recommend that echocardiography in all patients with SAB. We evaluated the effects of echocardiography on patient outcomes. Patients with uncomplicated S. aureus CRBSI were retrospectively identified between January 2013 and June 2018 at a 1950-bed, tertiary-care university hospital. Treatment failure was defined as any case of relapse or all-cause death within 90 days. Of 890 SAB patients, 95 with uncomplicated S. aureus CRBSI were included. Thirty-two patients underwent echocardiography within 30 days of their first positive blood culture. Two patients who underwent echocardiography revealed right-sided infective endocarditis. One patient who did not undergo echocardiography experienced recurrent SAB (peripheral CRBSI) 85 days after his first positive blood culture. There were no SAB-related deaths. The Kaplan-Meier curves of treatment failure showed no significant differences between patients who did and did not undergo echocardiography (P = .77). In multivariable analysis, risk factors for treatment failure were liver cirrhosis (hazard ratio: 9.60; 95% confidence interval: 2.13-43.33; P = .003) and other prostheses (hazard ratio: 63.79; 95% confidence interval: 5.05-805.40; P = .001). This study did not verify the putative association between treatment failure and implementation of echocardiography in patients with uncomplicated S. aureus CRBSI. Given the low observed rates of adverse outcomes, routine echocardiography might not be obligatory and could be performed on an individual basis.

Combination ceftaroline and daptomycin salvage therapy for complicated methicillin-resistant Staphylococcus aureus bacteraemia compared with standard of care

Complicated methicillin-resistant Staphylococcus aureus bloodstream infections (MRSA-BSIs), particularly those with delayed culture clearance, are associated with high mortality. Combination therapy with daptomycin and ceftaroline (DAP+CPT) represents a novel therapeutic approach to MRSA-BSI owing to synergistic bactericidal activity. This study aimed to compare DAP+CPT with historical standard of care (SoC) for treatment of complicated MRSA-BSI. This single-centre retrospective cohort study included patients with complicated MRSA-BSI at University of Colorado Hospital. Patients receiving DAP+CPT for ≥48 h between November 2013 and March 2020 or SoC with vancomycin or DAP ± gentamicin and/or rifampicin from November 2011 to December 2013 were compared. The primary outcome was clinical failure defined as a composite of MRSA-related mortality and recurrent infection at 60 days. A total of 60 patients received DAP+CPT (n = 30) or SoC (n = 30). Median age was 56 years and median Pitt bacteremia score was 3. Common infectious sites were endovascular (63%) and musculoskeletal (40%). DAP+CPT was associated with a numerically lower incidence of clinical failure compared with SoC (20% vs. 43%; P = 0.052). Multivariable analysis controlling for immunocompromised status (OR, 6.90, 95% CI 1.08-44.15), Charlson comorbidity index (OR, 1.12, 95% CI 0.90-1.39) and source control (OR, 0.35, 95% CI 0.08-1.46) associated DAP+CPT with 77% lower odds of clinical failure (OR, 0.23, 95% CI 0.06-0.89). In patients with complicated MRSA-BSI with delayed clearance, DAP+CPT trended towards lower rates of clinical failure than SoC and was significantly associated with decreased clinical failure after adjustment for baseline differences.

Optimal trough concentration of teicoplanin for the treatment of methicillin-resistant Staphylococcus aureus infection: A systematic review and meta-analysis

WHAT IS KNOWN AND OBJECTIVE

It has been recommended that the trough concentration (C_min ) of teicoplanin should be maintained at ≥20 μg/ml for difficult-to-treat complicated infections caused by methicillin-resistant Staphylococcus aureus (MRSA). Conversely, C_min of teicoplanin of at least 10 μg/ml is required for non-complicated MRSA infections. Considering the low incidence of nephrotoxicity for teicoplanin, C_min  = 15-30 μg/ml has been suggested for most MRSA infections. Thus, we assessed the clinical efficacy and adverse effects of teicoplanin at this target C_min .

METHODS

We searched electronic databases (PubMed, Cochrane Central Register of Controlled Trials and Ichushi-Web) to identify eligible studies. Studies were included if they provided the incidence of treatment success, mortality in patients with MRSA infection, and/or hepatotoxicity and nephrotoxicity according to the C_min range.

RESULTS AND DISCUSSION

Four trials assessing clinical success (n = 299) and three studies assessing adverse effects (n = 546) were included. C_min  = 15-30 μg/ml significantly increased the probability of treatment success compared with C_min  < 15 μg/ml (odds ratio [OR] = 2.68, 95% confidence interval [CI] = 1.14-6.32, p = 0.02). The all-cause mortality rate did not differ between the groups (OR = 0.46, 95% CI = 0.13-1.61, p = 0.22). C_min  = 15-30 μg/ml did not increase the risks of nephrotoxicity (OR = 0.91, 95% CI = 0.49-1.69, p = 0.76) or hepatotoxicity (OR = 0.67, 95% CI = 0.18-2.44, p = 0.54).

WHAT IS NEW AND CONCLUSION

Teicoplanin therapy using a C_min target of 15-30 μg/ml is likely to be associated with better clinical responses than C_min  < 15 μg/ml without increasing the risk of adverse effects.

Clinical Characteristics and Outcomes of S. Aureus Bacteremia in Patients Receiving Total Parenteral Nutrition

Background: Patients on total parenteral nutrition (TPN) are at risk of developing central line-associated infections. Specifically, Staphylococcus aureus bacteremia (SAB) is feared for its high complication rates. This prospective cohort study compares characteristics, clinical course and outcome of SAB in patients with and without TPN support. Methods: Clinical and microbiological data from all patients with positive blood cultures for S. aureus from two facilities, including our referral center for TPN support, were retrieved (period 2013-2020). Primary outcome was overall mortality, and included survival analysis using a multivariate Cox regression model. Secondary outcomes comprised a comparison of clinical characteristics and outcomes between both patient groups and analysis of factors associated with complicated outcome (e.g., endocarditis, deep-seated foci, relapse and death) in patients on TPN specifically. Results: A total of 620 SAB cases were analyzed, of which 53 cases received TPN at the moment the blood culture was taken. Patients in the TPN group were more frequently female, younger and had less comorbidity (p < 0.001). In-hospital death and overall mortality were significantly lower in TPN patients (4% vs. 18%, p = 0.004 and 10% vs. 34%, p < 0.001, respectively). Positive follow-up blood cultures, delayed onset of therapy and previous catheter problems were associated with a higher incidence of complicated SAB outcome in patients on TPN. Conclusion: Our data show that patients on TPN have a milder course of SAB with lower mortality rates compared to non-TPN SAB patients.

Molecular Detection of Panton Valentine Leukocidin Toxin in Clinical Isolates of Staphylococcus aureus from Kiambu County, Kenya

Panton-Valentine leukocidin gene is produced by Staphylococcus aureus, and methicillin-resistant Staphylococcus aureus isolates as a pore-forming toxin is largely responsible for skin and soft tissue illnesses. MRSA produces PVL toxins through lukS and lukF proteins causing tissue necrosis by damaging membrane of the defense cells. Presence of PVL toxin was tested from the 54 S. aureus clinical isolates obtained from Thika and Kiambu Level 5 Hospitals, in Kiambu County, Kenya, by Geno Type® MRSA assay (Hain Life Science, Nehren, Germany). DNA was isolated from freshly harvested bacterial cultures by spin column using Geno Type DNA isolation kit. The detection of PVL toxins was performed by amplification of genomic DNA and by reverse hybridization that identifies PVL genes using Geno Type MRSA kit. Out of 138 samples that were collected from patients in Kiambu County, 54 S. aureus isolates were obtained, of which 14 (25.9%; 95% CI = 11.9-38.9) samples had PVL toxins. The isolates that were obtained from the female patients had a higher PVL toxin prevalence of 35.7%, while the isolates collected from the male patients had a lower prevalence of 15.4% (P = 0.09). The pediatrics department had the highest PVL gene prevalence compared to outpatient department and surgical units (P = 0.08). However, the age groups of patients and the hospital attended by patients showed no significant difference in terms of PVL gene prevalence (P = 0.26). Therefore, the patients' gender and hospital units were not significantly associated with PVL gene prevalence (P = 0.08). This study shows that PVL positive isolates occur in the sampled hospitals in the county and female as well as children must be taken into consideration among patients with wound infections when isolating S. aureus.

Mortality Risk Profiling of Staphylococcus aureus Bacteremia by Multi-omic Serum Analysis Reveals Early Predictive and Pathogenic Signatures

Staphylococcus aureus bacteremia (SaB) causes significant disease in humans, carrying mortality rates of ∼25%. The ability to rapidly predict SaB patient responses and guide personalized treatment regimens could reduce mortality. Here, we present a resource of SaB prognostic biomarkers. Integrating proteomic and metabolomic techniques enabled the identification of >10,000 features from >200 serum samples collected upon clinical presentation. We interrogated the complexity of serum using multiple computational strategies, which provided a comprehensive view of the early host response to infection. Our biomarkers exceed the predictive capabilities of those previously reported, particularly when used in combination. Last, we validated the biological contribution of mortality-associated pathways using a murine model of SaB. Our findings represent a starting point for the development of a prognostic test for identifying high-risk patients at a time early enough to trigger intensive monitoring and interventions.

Early Oral Switch to Linezolid for Low-risk Patients With Staphylococcus aureus Bloodstream Infections: A Propensity-matched Cohort Study

BACKGROUND

Oral switch to linezolid is a promising alternative to standard parenteral therapy (SPT) in Staphylococcus aureus bacteremia (SAB).

METHODS

We conducted a prospective cohort study of all adult cases of SAB between 2013 and 2017 in a Spanish university hospital. We compared the efficacy, safety, and length of hospital stay of patients receiving SPT and those where SPT was switched to oral linezolid between days 3 and 9 of treatment until completion. We excluded complicated SAB and osteoarticular infections. A k-nearest neighbor algorithm was used for propensity score matching with a 2:1 ratio.

RESULTS

After propensity score matching, we included 45 patients from the linezolid group and 90 patients from the SPT group. Leading SAB sources were catheter related (49.6%), unknown origin (20.0%), and skin and soft tissue (17.0%). We observed no difference in 90-day relapse between the linezolid group and the SPT group (2.2% vs 4.4% respectively; P = .87). No statistically significant difference was observed in 30-day all-cause mortality between the linezolid group and the SPT group (2.2% vs 13.3%; P = .08). The median length of hospital stay after onset was 8 days in the linezolid group and 19 days in the SPT group (P < .01). No drug-related events leading to discontinuation were noted in the linezolid group.

CONCLUSIONS

Treatment of SAB in selected low-risk patients with an oral switch to linezolid between days 3 and 9 of treatment until completion yielded similar clinical outcomes as SPT, allowing earlier discharge from the hospital.

Sequential intravenous-to-oral outpatient antibiotic therapy for MRSA bacteraemia: one step closer

Background

Published guidelines call for prolonged courses of intravenous (iv) antibiotics for the treatment of MRSA bloodstream infection (BSI) to ensure eradication of deep foci and decrease relapse risk. Sequential iv-to-oral antibiotic therapy has been successfully applied to other serious infections but has not been evaluated for MRSA BSI.

Objectives

To compare outcomes in adults completing MRSA BSI therapy with oral versus parenteral antibiotics in the outpatient setting [oral outpatient antibiotic therapy (OOAT) versus outpatient parenteral antibiotic therapy (OPAT)].

Methods

This was a single-centre, retrospective, cohort study between 2008 and 2018. The primary outcome was 90 day clinical failure (MRSA BSI recurrence, deep-seated MRSA infection or all-cause mortality). Analyses were adjusted for confounding using inverse probability of treatment weighting (IPTW).

Results

A total of 492 patients were included (70 OOAT, 422 OPAT). In general, OOAT patients had characteristics consistent with a lower risk of poor outcomes; however, after IPTW key prognostic factors were balanced. In IPTW-adjusted analysis, there was non-significant reduction in the rate of 90 day clinical failure in the OOAT group compared with the OPAT group [adjusted HR (aHR) 0.379, 95% CI 0.131-1.101]. In analyses restricted to pre-specified subgroups defined by index infection complexity and comorbidity burden, findings were consistent with the main analysis. Furthermore, OOAT patients had a significantly reduced rate of 90 day hospital readmission (aHR 0.603, 95% CI 0.388-0.937).

Conclusions

We provide preliminary evidence that selected patients with MRSA BSI may have at least equivalent clinical outcomes with OOAT versus OPAT and provide support to ongoing and future studies evaluating oral antibiotics for MRSA BSI.

Hospital-wide ELectronic medical record evaluated computerised decision support system to improve outcomes of Patients with staphylococcal bloodstream infection (HELP): study protocol for a multicentre stepped-wedge cluster randomised trial

INTRODUCTION

Staphylococci are the most commonly identified pathogens in bloodstream infections. Identification of Staphylococcus aureus in blood culture (SAB) requires a prompt and adequate clinical management. The detection of coagulase-negative staphylococci (CoNS), however, corresponds to contamination in about 75% of the cases. Nevertheless, antibiotic therapy is often initiated, which contributes to the risk of drug-related side effects. We developed a computerised clinical decision support system (HELP-CDSS) that assists physicians with an appropriate management of patients with Staphylococcus bacteraemia. The CDSS is evaluated using data of the Data Integration Centers (DIC) established at each clinic. DICs transform heterogeneous primary clinical data into an interoperable format, and the HELP-CDSS displays information according to current best evidence in bacteraemia treatment. The overall aim of the HELP-CDSS is a safe but more efficient allocation of infectious diseases specialists and an improved adherence to established guidelines in the treatment of SAB.

METHODS AND ANALYSIS

The study is conducted at five German university hospitals and is designed as a stepped-wedge cluster randomised trial. Over the duration of 18 months, 135 wards will change from a control period to the intervention period in a randomised stepwise sequence. The coprimary outcomes are hospital mortality for all patients to establish safety, the 90-day disease reoccurrence-free survival for patients with SAB and the cumulative vancomycin use for patients with CoNS bacteraemia. We will use a closed, hierarchical testing procedure and generalised linear mixed modelling to test for non-inferiority of the CDSS regarding hospital mortality and 90-day disease reoccurrence-free survival and for superiority of the HELP-CDSS regarding cumulative vancomycin use.

ETHICS AND DISSEMINATION

The study is approved by the ethics committee of Jena University Hospital and will start at each centre after local approval. Results will be published in a peer-reviewed journal and presented at scientific conferences.

TRIAL REGISTRATION NUMBER

DRKS00014320.

Diagnostic accuracy and clinical impact of loop-mediated isothermal amplification for rapid detection of Staphylococcus aureus bacteremia: a retrospective observational study

The aim of this study was to evaluate the diagnostic accuracy and the clinical impact of isothermal loop-mediated amplification (LAMP; eazyplex® MRSA kits) for rapid diagnosis of Staphylococcus aureus bacteremia (SAB) in comparison with conventional blood culture diagnostics. We performed a retrospective, single-center observational study over the period between November 2016 and December 2018 on patients (and blood cultures) with growth of Gram-positive cocci in clusters in their blood cultures. We quantified diagnostic accuracy with sensitivity and specificity for detection of S. aureus, methicillin-resistant S. aureus (MRSA), and the mecA/C resistance genes in 797 blood cultures. The clinical impact was assessed by time to result reporting, time to appropriate treatment, and length of stay in intensive care unit (ICU) in 190 SAB patients. We observed sensitivity and specificity above 90% for S. aureus detection (sensitivity (95% confidence interval (CI)), 99.57% (97.61%, 99.98%); specificity, 99.12% (97.95%, 99.71%)), for MRSA detection (sensitivity, 100% (89.11%, 100.00%); specificity, 99.72% (99.05, 99.96)), and for mecA/C detection (sensitivity, 94.71% (91.85%, 96.78%); specificity, 95.89% (93.58%, 97.54%)). LAMP testing was associated with shorter median time to result reporting (24.0 h (first and third quartiles (Q1-Q3), 20.0-27.0 h) vs 41.5 h (36.0-46.0 h); p < 0.001) and different distribution of time to appropriate treatment (2.0 days (1.0-3.0) vs 2.0 days (2.0-3.0); p = 0.004). No evidence for differences in length-of-stay in ICU was observed. Our analysis suggests for the application of LAMP (i) a high diagnostic accuracy for detection of S. aureus and the mecA/C genes in blood cultures, (ii) an earlier result reporting, and (iii) a shorter time to appropriate treatment.

Burden of bacterial bloodstream infection-a brief update on epidemiology and significance of multidrug-resistant pathogens

BACKGROUND

Bloodstream infections comprise a wide variety of pathogens and clinical syndromes with considerable overlap with similar syndromes of non-bacteraemic infections and diverse risk factors, therapeutic implications and outcomes. Yet, this heterogeneous 'entity' has the advantage to be pathogen-defined compared with the broad and even more heterogeneous entity 'sepsis', and so has become helpful for clinicians and epidemiologists for research and surveillance purposes. The increasing availability of population-based and large multicentre well-defined cohort studies should allow us to assess with much confidence and in detail its burden, the significance of antimicrobial resistance, and areas of uncertainty regarding further epidemiological evolution and optimized treatment regimens.

AIM

To review key aspects of bloodstream infection epidemiology and burden, and summarize recent news and questions concerning critical developments.

SOURCES

Peer-reviewed articles based on the search terms 'bloodstream infection' and 'bacteremia' combined with the terms 'epidemiology' and 'burden'. The emphasis was on new information from studies in adult patients and on the added burden due to pathogen resistance to first- and second-line antimicrobial agents.

CONTENT

Topics covered include recent developments in the epidemiology of bloodstream infection due to key pathogens and published information about the relevance of resistance for patient outcomes.

IMPLICATIONS

Despite the availability of population-based studies and an increasing number of large well-defined multicentre cohort studies, more surveillance and systematic data on bloodstream infection epidemiology at regional level and in resource-limited settings may be needed to better design new methods for prevention and define the need for and further develop optimized therapeutic strategies.

Reevaluation of the impact of methicillin-resistance on outcomes in patients with Staphylococcus aureus bacteremia and endocarditis

BACKGROUND/AIMS

Methicillin-resistant Staphylococcus aureus (MRSA) is highly prevalent in hospitals, and has recently emerged in the community. The impact of methicillin-resistance on mortality and medical costs for patients with S. aureus bacteremia (SAB) requires reevaluation.

METHODS

We searched studies with SAB or endocarditis using electronic databases including Ovid-Medline, Embase-Medline, and Cochrane Library, as well as five local databases for published studies during the period January 2000 to September 2011.

RESULTS

A total of 2,841 studies were identified, 62 of which involved 17,563 adult subjects and were selected as eligible. A significant increase in overall mortality associated with MRSA, compared to that with methicillin-susceptible S. aureus (MSSA), was evidenced by an odds ratio (OR) of 1.95 (95% confidence interval [CI], 1.73 to 2.21; p < 0.01). In 13 endocarditis studies, MRSA increased the risk of mortality, with an OR of 2.65 (95% CI, 1.46 to 4.80). When three studies, which compared mortality rates between CA-MRSA and CA-MSSA, were combined, the risk of methicillin-resistance increased 3.23-fold compared to MSSA (95% CI, 1.25 to 8.34). The length of hospital stay in the MRSA group was 10 days longer than that in the MSSA group (95% CI, 3.36 to 16.70). Of six studies that reported medical costs, two were included in the analysis, which estimated medical costs to be $9,954.58 (95% CI, 8,951.99 to 10,957.17).

CONCLUSION

MRSA is still associated with increased mortality, longer hospital stays and medical costs, compared with MSSA in SAB in studies published since the year 2000.

Staphylococcus aureus adhesion in endovascular infections is controlled by the ArlRS-MgrA signaling cascade

Staphylococcus aureus is a leading cause of endovascular infections. This bacterial pathogen uses a diverse array of surface adhesins to clump in blood and adhere to vessel walls, leading to endothelial damage, development of intravascular vegetations and secondary infectious foci, and overall disease progression. In this work, we describe a novel strategy used by S. aureus to control adhesion and clumping through activity of the ArlRS two-component regulatory system, and its downstream effector MgrA. Utilizing a combination of in vitro cellular assays, and single-cell atomic force microscopy, we demonstrated that inactivation of this ArlRS—MgrA cascade inhibits S. aureus adhesion to a vast array of relevant host molecules (fibrinogen, fibronectin, von Willebrand factor, collagen), its clumping with fibrinogen, and its attachment to human endothelial cells and vascular structures. This impact on S. aureus adhesion was apparent in low shear environments, and in physiological levels of shear stress, as well as in vivo in mouse models. These effects were likely mediated by the de-repression of giant surface proteins Ebh, SraP, and SasG, caused by inactivation of the ArlRS—MgrA cascade. In our in vitro assays, these giant proteins collectively shielded the function of other surface adhesins and impaired their binding to cognate ligands. Finally, we demonstrated that the ArlRS—MgrA regulatory cascade is a druggable target through the identification of a small-molecule inhibitor of ArlRS signaling. Our findings suggest a novel approach for the pharmacological treatment and prevention of S. aureus endovascular infections through targeting the ArlRS—MgrA regulatory system.

Adhesion is central to the success of Staphylococcus aureus as a bacterial pathogen. We describe a novel mechanism through which S. aureus alters adhesion to ligands by regulating expression of giant inhibitory surface proteins. These giant proteins shield normal surface adhesins, preventing binding to ligands commonly found in the bloodstream and vessel walls. Using this unique regulatory scheme, S. aureus can bypass the need for individualized regulation of numerous adhesins to control overall adhesive properties. Our study establishes the importance of these giant proteins for S. aureus pathogenesis and demonstrates that a single regulatory cascade can be targeted for treating infections.

Clinical Data on Daptomycin plus Ceftaroline versus Standard of Care Monotherapy in the Treatment of Methicillin-Resistant Staphylococcus aureus Bacteremia

Vancomycin (VAN) and daptomycin (DAP) are approved as a monotherapy for methicillin-resistant Staphylococcus aureus (MRSA) bacteremia. A regimen of daptomycin plus ceftaroline (DAP+CPT) has shown promise in published case series of MRSA salvage therapy, but no comparative data exist to compare up-front DAP+CPT head-to-head therapy versus standard monotherapy as an initial treatment. In a pilot study, we evaluated 40 adult patients who were randomized to receive 6 to 8 mg/kg of body weight per day of DAP and 600 mg intravenous (i.v.) CPT every 8 h (q8h) (n = 17) or standard monotherapy (n = 23) with vancomycin (VAN; dosed to achieve serum trough concentrations of 15 to 20 mg/liter; n = 21) or 6 to 8 mg/kg/day DAP (n = 2). Serum drawn on the first day of bacteremia was sent to a reference laboratory post hoc for measurement of interleukin-10 (IL-10) concentrations and correlation to in-hospital mortality. Sources of bacteremia, median Pitt bacteremia scores, Charlson comorbidity indices, and median IL-10 serum concentrations were similar in both groups. Although the study was initially designed to examine bacteremia duration, we observed an unanticipated in-hospital mortality difference of 0% (0/17) for combination therapy and 26% (6/23) for monotherapy (P = 0.029), causing us to halt the study. Among patients with an IL-10 concentration of >5 pg/ml, 0% (0/14) died in the DAP+CPT group versus 26% (5/19) in the monotherapy group (P = 0.057). Here, we share the full results of this preliminary (but aborted) assessment of early DAP+CPT therapy versus standard monotherapy in MRSA bacteremia, hoping to encourage a more definitive clinical trial of its potential benefits against this leading cause of infection-associated mortality. (The clinical study discussed in this paper has been registered at ClinicalTrials.gov under identifier NCT02660346.).

Increased risk of diabetes mellitus five years after an episode of Staphylococcus aureus bacteraemia

Background: Diabetes mellitus is a risk factor for infection with Staphylococcus aureus, but it is unclear whether S. aureus infection is a prediabetic condition. Methods: Nationwide population-based matched cohort study. Incidence rate and ratio with 95% confidence interval of diabetes were estimated by negative binomial regression. Results: Of 19,988 individuals with S. aureus bacteraemia and 185,579 population comparators, 667 and 4974 had a primary diagnose of diabetes within five years after discharge of S. aureus bacteraemia corresponding to a more than double risk of diabetes (adjusted incidence rate ratio 2.28 (95% confidence interval: 2.10-2.46)). Other factors associated with an increased risk of diabetes during follow-up were male sex, increasing age and level of comorbidity. Of the S. aureus bacteraemia and population cohort, 422 (2.11%) and 4048 (2.18%), respectively, developed diabetes without complications, while 245 (1.23%) and 926 (0.50%), respectively, developed diabetes with complications. Rates of diabetes without complication were increased for individuals in the S. aureus bacteraemia cohort compared to the population cohort within the first two years after which rates were comparable while rates of diabetes with complications remained higher throughout the five year follow-up period compared to the population cohort. Conclusions: The risk of diabetes was markedly increased up to five years after S. aureus bacteraemia compared to a population cohort. In addition to screening for diabetes during hospital admittance, screening cases of S. aureus bacteraemia for diabetes in the years following S. aureus bacteraemia may allow for earlier detection of diabetes.

Effect of Clinically Uninfected Orthopedic Implants and Pacemakers/AICDs in Low-Risk Staphylococcus aureus Bloodstream Infection on Crude Mortality Rate: A Post Hoc Analysis of a Large Cohort Study

Background

The standard treatment duration in low-risk Staphylococcus aureus bloodstream (SAB) is 14 days. However, it is unclear whether an extended course of antimicrobial therapy is necessary in patients with clinically uninfected prosthetic joints/osteosyntheses or pacemakers/automated implanted cardioverter-defibrillators (AICDs). Thus, we compared the duration of antimicrobial therapy and outcomes in patients with and those without clinically uninfected foreign bodies.

Methods

We conducted a post hoc analysis of data from the prospective Invasive Staphylococcus aureus Infection Cohort (INSTINCT) study. Adult low-risk patients who survived ≥4 days were assessed for duration of treatment, SAB-related events (attributable death, relapse, or new deep-seated infection), and survival.

Results

Of the 1288 patients enrolled, 292 satisfied criteria for low-risk SAB. Forty-three patients (15%) had a clinically uninfected pacemaker/AICD or orthopedic implant. Patients with foreign bodies were significantly older (mean age, 72 vs 62 years for those without; P < .001; P = .9) and had a higher Charlson score (median, 3 vs 2; P = .06). The total duration of antimicrobial therapy (median, 18 vs 17 days, respectively; P = .7), all-cause mortality rate (16% vs 14%; P = .7), and prevalence of SAB-related events within 90 days were similar (2% vs 2%) in the 2 groups. At 1-year follow-up, SAB-related events were more frequent in patients with foreign bodies (7% vs 4% in those without; P = .4) (hazard ratio, 1.41; 95% confidence interval, .35–5.69; in a multivariable Cox model), but this difference was not statistically significant.

Conclusions

Low-risk patients with clinically uninfected foreign bodies received a similar duration of antimicrobial therapy without a significant impact on mortality rate. The observed higher hazard ratio of SAB-related events within 1 year necessitates additional studies before recommendations concerning treatment duration in this patient subgroup can be adapted or modified.

Advancing Infectious Diseases Diagnostic Testing and Applications to Antimicrobial Therapy in the ICU

Treatment of suspected infections in critically ill patients requires the timely initiation of appropriate antimicrobials and rapid de-escalation of unnecessary broad-spectrum coverage. New advances in rapid diagnostic tests can now offer earlier detection of pathogen and potential resistance mechanisms within hours of initial culture growth. These technologies, combined with pharmacist antimicrobial stewardship efforts, may result in shorten time to adequate coverage or earlier de-escalation of unnecessary broad spectrum antimicrobials, which could improve patient outcomes and lower overall treatment cost. Furthermore, de-escalation of antimicrobials may lead to decreased emergence of resistant organisms and adverse events associated with antimicrobials. Clinical pharmacists should be aware of new rapid diagnostic tests, including their application, clinical evidence, and limitations, in order to implement the most appropriate clinical treatment strategy when patients have positive cultures. This review will focus on commercially available rapid diagnostic tests for infections that are routinely encountered by critically ill patients, including gram-positive and gram-negative bacterial blood stream infections, Candida, and Clostridioides difficile.

Direct detection of Staphylococcus aureus in positive blood cultures through molecular beacon-based fluorescence in situ hybridization

OBJECTIVE

Clinical diagnosis of bloodstream infection diseases depends on the blood culture results. Bacterial identification by traditional methods is time-consuming. This study aimed to utilize molecular beacon-based fluorescence in situ hybridization (MB-FISH) for rapid and direct detection of Staphylococcus aureus in positive blood cultures.

METHODS

Three molecular beacon probes (MB1, MB2 and MB3) were designed and synthesized to target the 16S rRNA gene fragment of S. aureus. The MB-FISH system was optimized, and the specificity of this method in detecting S. aureus was evaluated. This approach was used to test 41 g-positive clinical specimens with positive blood cultures. In addition, the consistency of this method with traditional methods was evaluated.

RESULTS

Signal-to-noise ratio (S/N) of the molecular beacon MB1 was significantly higher than that of MB2 and MB3 (P < .001). The S/N ratios of MB1 probe at different concentrations were all >20. Thermal denaturation curve of the probe suggested that its hairpin structure can be opened and closed. Conditions such as deionized formamide concentration, ionic strength and temperature were optimized by monitoring the fluorescence intensity of MB1 in the presence or absence of its target sequence B1. The optimized hybridization system produced fluorescence only in S. aureus. The specificity and sensitivity of MB1 probe for detecting S. aureus in 41 specimens were 100% and 93.75%, respectively. Although sample size was small, MB-FISH appeared to be consistent with traditional culture methods (Kappa value = 0.948).

CONCLUSION

MB-FISH demonstrates strong specificity and high sensitivity, and can be used for direct detection of S. aureus in positive blood cultures.

Enhanced topical delivery of non-complexed molecular iodine for Methicillin-resistant Staphylococcus aureus decolonization

Staphylococcus aureus, a leading cause of serious human infections in both healthcare and community settings, is increasingly difficult to control due to expanding resistance to multiple antibiotic classes. Methicillin-resistant S. aureus (MRSA) strains have disseminated on a global scale and are associated with adverse patient outcomes, increased hospital stays, and significant economic costs to the healthcare system. A proximal step in S. aureus infection is colonization of the nasal mucosa, and effective strategies to decolonize high risk patients to reduce the risk of invasive infection and nosocomial spread represent an important clinical priority. With rising resistance to mupirocin, the most common antibiotic utilized for nasal MRSA decontamination, we are examining the use of pure molecular iodine (I₂)-based formulations for this indication. Recently, an iodophor formulation of povidone-iodine (PVP-I) has shown significant promise for nasal MRSA decontamination by swabbing the anterior nares of patients in hospital settings, but the I₂ concentration in this treatment is less than 0.01% of total iodine species present and like all providone-iodine formulations causes skin staining. Here we determine that a novel non-staining formulation of I₂ combined with the safe organic emollient glycerin delivers high local concentrations of the active antimicrobial entity (I₂) with minimal evaporative loss, exhibits activity at ∼1 part per million against MRSA and other important Gram-positive and -negative human pathogens. This formulation for I₂ topical delivery produced similar reductions in mean bacterial burden and was associated with fewer treatment failures (<2-logfold reduction) than PVP-I in a murine model of MRSA nasal decontamination. Formulations of I₂ in glycerin emollient merit further exploration as topical disinfectants for human medical indications.

Efficacy of cloxacillin versus cefazolin for methicillin-susceptible Staphylococcus aureus bacteraemia (CloCeBa): study protocol for a randomised, controlled, non-inferiority trial

INTRODUCTION

Methicillin-susceptible Staphylococcus aureus (MSSA) bacteraemia is a common and severe disease responsible for approximately 65 000 deaths every year in Europe. Intravenous antistaphylococcal penicillins (ASP) such as cloxacillin are the current recommended antibiotics. However, increasing reports of toxicity and recurrent stock-outs of ASP prompted healthcare providers to seek for alternative antibiotic treatment. Based on retrospective studies, cefazolin, a first-generation cephalosporin, is recommended in patients at risk of severe ASP-associated toxicity.We hypothesised that cefazolin has a non-inferior efficacy in comparison to cloxacillin, with a better safety profile for the treatment of MSSA bacteraemia.

METHODS AND ANALYSIS

The CloCeBa trial is an open-label, randomised, controlled, non-inferiority trial conducted in academic centres throughout France. Eligible patients are adults with MSSA bacteraemia without intravascular device or suspicion of central nervous system infection. Patients will be randomised (1:1) to receive either cloxacillin or cefazolin by the intravenous route, for the first 14 days of therapy. The evaluation criteria is a composite criteria of negative blood cultures at day 5, survival, absence of relapse and clinical success at day 90 after randomisation. Secondary evaluation criteria include both efficacy and safety assessments. Three ancillary studies are planned to describe the epidemiology of β-lactamase encoding genes, the ecological impact and pharmacokinetic/pharmacodynamic parameters of cefazolin and cloxacillin. Including 300 patients will provide 80% power to demonstrate the non-inferiority of cefazolin over cloxacillin, assuming 85% success rate with cloxacillin and taking into account loss-to-follow-up, with a 0.12 non-inferiority margin and a one-sided type I error of 0.025.

ETHICS AND DISSEMINATION

This protocol received authorisation from the ethics committee Sud-Est I on 13 November 2017 (2017-87-PP)and French National Agency for Medicines and Health Products (170661A-43). Results will be disseminated to the scientific community through congresses and publication in peer-reviewed journals.

TRIAL REGISTRATION NUMBER

NCT03248063 and 2017-003967-36.

Survival following Staphylococcus aureus bloodstream infection: A prospective multinational cohort study assessing the impact of place of care

BACKGROUND

Staphylococcus aureus bloodstream infection (SAB) is a common, life-threatening infection with a high mortality. Survival can be improved by implementing quality of care bundles in hospitals. We previously observed marked differences in mortality between hospitals and now assessed whether mortality could serve as a valid and easy to implement quality of care outcome measure.

METHODS

We conducted a prospective observational study between January 2013 and April 2015 on consecutive, adult patients with SAB from 11 tertiary care centers in Germany, South Korea, Spain, Taiwan, and the United Kingdom. Factors associated with mortality at 90 days were analyzed by Cox proportional hazards regression and flexible parametric models.

RESULTS

1851 patients with a median age of 66 years (64% male) were analyzed. Crude 90-day mortality differed significantly between hospitals (range 23-39%). Significant variation between centers was observed for methicillin-resistant S. aureus, community-acquisition, infective foci, as well as measures of comorbidities, and severity of disease. In multivariable analysis, factors independently associated with mortality at 90 days were age, nosocomial acquisition, unknown infective focus, pneumonia, Charlson comorbidity index, SOFA score, and study center. The risk of death varied over time differently for each infective focus. Crude mortality differed markedly from adjusted mortality.

DISCUSSION

We observed significant differences in adjusted mortality between hospitals, suggesting differences in quality of care. However, mortality is strongly influenced by patient mix and thus, crude mortality is not a suitable quality indicator.

Implementing a hospital-wide protocol for Staphylococcus aureus bacteremia

Staphylococcus aureus bacteraemia (SAB) is associated with high-mortality and complication rates. A multidisciplinary approach is needed to predict, detect and treat complications. In this pre- and post-intervention study, we investigated the effects of a hospital-wide protocol for diagnosis, classification and treatment of SAB. It was hypothesized that complications and endocarditis would be better identified and treated. Medical records of SAB patients admitted in 2011 and 2012 (pre) were analysed. In 2013, a protocol, describing risk factors, diagnostic classification and recommended treatment, was implemented. In 2014 and 2015 (post), SAB patients were followed prospectively. Transthoracic (TTE) or transoesophageal cardiac ultrasound (TEE) was chosen following a decision tree. A resident internal medicine acted as contact person. Pre-intervention, 98 patients were eligible for analysis compared to 85 patients post-intervention. Age and number of risk factors were slightly higher post-intervention; other baseline characteristics were similar. Most SAB-patients were classified as complicated (89 and 82% pre- and post-intervention, respectively). Follow-up blood cultures drawn within 2 days after initiating treatment increased from 51 to 85%. Cardiac ultrasounds increased from 44 to 83% for TTE and 13 to 24% for TEE. Endocarditis was more frequently diagnosed (4 vs. 12%). Additionally, duration of antibiotic therapy increased. The 3-month mortality did not change significantly (33% pre-intervention vs. 35% post-intervention; p > 0.05). Introduction of a hospital-wide protocol for SAB management increased standard of care, created awareness among clinicians to properly classify SAB, search for endocarditis and adapt duration of antibiotic treatment. Mortality did not decrease.

Staphylococcus aureus colonization and non-influenza respiratory viruses: Interactions and synergism mechanisms

Viral infections of the respiratory tract can be complicated by bacterial superinfection, resulting in a significantly longer duration of illness and even a fatal outcome. In this review, we focused on interactions between S. aureus and non-influenza viruses. Clinical data evidenced that rhinovirus infection may increase the S. aureus carriage load in humans and its spread. In children, respiratory syncytial virus infection is associated with S. aureus carriage. The mechanisms by which some non-influenza respiratory viruses predispose host cells to S. aureus superinfection can be summarized in three categories: i) modifying expression levels of cellular patterns involved in S. aureus adhesion and/or internalization, ii) inducing S. aureus invasion of epithelial cells due to the disruption of tight junctions, and iii) decreasing S. aureus clearance by altering the immune response. The comprehension of pathways involved in S. aureus-respiratory virus interactions may help developing new strategies of preventive and curative therapy.

Cefazolin versus anti-staphylococcal penicillins for treatment of methicillin-susceptible Staphylococcus aureus bacteraemia: a narrative review

BACKGROUND

Anti-staphylococcal penicillins (ASPs) are recommended as first-line agents in methicillin-susceptible Staphylococcus aureus (MSSA) bacteraemia. Concerns about their safety profile have contributed to the increased use of cefazolin. The comparative clinical effectiveness and safety profile of cefazolin versus ASPs for such infections remain unclear. Furthermore, uncertainty persists concerning the use of cefazolin due to controversies over its efficacy in deep MSSA infections and its possible negative ecological impact.

AIMS

The aim of this narrative review was to gather and balance available data on the efficacy and safety of cefazolin versus ASPs in the treatment of MSSA bacteraemia and to discuss the potential negative ecological impact of cefazolin.

SOURCES

PubMed and EMBASE electronic databases were searched up to May 2017 to retrieve available studies on the topic.

CONTENTS

Although described in vitro and in experimental studies, the clinical relevance of the inoculum effect during cefazolin treatment of deep MSSA infections remains unclear. It appears that there is no significant difference in rate of relapse or mortality between ASPs and cefazolin for the treatment of MSSA bacteraemia but these results should be cautiously interpreted because of the several limitations of the available studies. Compared with cefazolin, there is more frequent discontinuation for adverse effects with ASP use, especially because of cutaneous and renal events. No study has evidenced any change in the gut microbiota after the use of cefazolin.

IMPLICATIONS

Based on currently available studies, there are no data that enable a choice to be made of one antibiotic over the other except in patients with allergy or renal impairment. This review points out the need for future prospective studies and randomized controlled trials to better address these questions.

Diabetes increases the risk of disease and death due to Staphylococcus aureus bacteremia. A matched case-control and cohort study

BACKGROUND

This study investigated the effect and influence of diabetes severity on susceptibility and 30-day mortality of Staphylococcus aureus bacteremia (SAB).

METHODS

Nationwide population-based study of individuals with SAB and matched population controls. Diabetes severity was categorized based on International Classification of Diseases codes and the odds ratio (OR) with 95% confidence intervals (CI) of SAB associated with diabetes was estimated by conditional logistic regression analysis. Hazard ratios (HR) were analyzed by Cox proportional regression. Analyses were adjusted for age, sex, comorbidity, hospital contact and diabetes duration.

RESULTS

Of 25,855 SAB cases, 2797 (10.8%) had diabetes and 2913 (11.3%) had diabetes with complications compared to 14,189 (5.5%) and 5499 (2.1%) of 258,547 controls. This corresponded to an increased risk of SAB associated with diabetes without complications (OR 1.83 (95% CI 1.74-1.92)) and of diabetes with complications (OR 3.62 (95% CI 3.43-3.81) compared to no diabetes. The risk of SAB was highest within the first year of diabetes. Diabetes without complications was associated with an increased risk of 30-day mortality (HR 1.62 (95% CI 1.01-2.60)) compared to no diabetes. Diabetes with complications was overall not associated with increased 30-d mortality (HR 1.36 (95% CI 0.84-2.20)) except for individuals with ketoacidosis/coma (HR 2.01 (95% 1.17-3.45)).

CONCLUSIONS

Diabetes, particularly, diabetes with complications significantly increased the risk of SAB. In contrast, there was an increased risk of 30-day mortality after SAB for diabetes without complications but not for diabetes with complications overall. Diabetes with ketoacidosis/coma conferred the highest relative risk of 30-day mortality.

Staphylococcus aureus bacteremia in patients with rheumatoid arthritis - Data from the prospective INSTINCT cohort

OBJECTIVES

Patients with rheumatoid arthritis (RA) are considered to be at increased risk of severe infections. We here describe the clinical characteristics, course and outcome of RA patients with Staphylococcus aureus bacteremia (SAB).

METHODS

We conducted a post hoc analysis of data from a German bi-center prospective SAB cohort study (period 2006-2014). Patients were followed-up for one year. Primary and secondary outcomes were survival time and osteoarticular infection (OAI).

RESULTS

A total of 1069 patients with SAB were analyzed, with 31 patients suffering from RA. RA patients showed significantly more often OAI (15/31 patients, 48% vs. 152/1038, 15%), disseminated infection (12/31, 39% vs. 164/1038, 16%) and severe sepsis/septic shock (12/31, 39% vs. 235/1038, 23%). Day-30 mortality in RA patients was 36% (vs. 19% in non-RA patients, p = 0.034), and day 90 mortality was 58% (vs. 32%, p = 0.003). Multivariate analyses confirmed RA to be an independent risk factor for death (HR 2.3, 95% CI 1.4-3.7) and OAI (OR 4.2, 95% CI 1.8-9.8).

CONCLUSIONS

Patients with RA exhibit a complicated SAB course and a high mortality, their management is challenging. Adequate antibiotic treatment, prompt invasive diagnostic and therapeutic procedures like joint lavage or surgery are of pivotal importance. Joint damage due to RA may confer a higher risk of acquiring OAI than immunosuppression.

Strategies to enhance rational use of antibiotics in hospital: a guideline by the German Society for Infectious Diseases

Introduction

In the time of increasing resistance and paucity of new drug development there is a growing need for strategies to enhance rational use of antibiotics in German and Austrian hospitals. An evidence-based guideline on recommendations for implementation of antibiotic stewardship (ABS) programmes was developed by the German Society for Infectious Diseases in association with the following societies, associations and institutions: German Society of Hospital Pharmacists, German Society for Hygiene and Microbiology, Paul Ehrlich Society for Chemotherapy, The Austrian Association of Hospital Pharmacists, Austrian Society for Infectious Diseases and Tropical Medicine, Austrian Society for Antimicrobial Chemotherapy, Robert Koch Institute.

Materials and methods

A structured literature research was performed in the databases EMBASE, BIOSIS, MEDLINE and The Cochrane Library from January 2006 to November 2010 with an update to April 2012 (MEDLINE and The Cochrane Library). The grading of recommendations in relation to their evidence is according to the AWMF Guidance Manual and Rules for Guideline Development.

Conclusion

The guideline provides the grounds for rational use of antibiotics in hospital to counteract antimicrobial resistance and to improve the quality of care of patients with infections by maximising clinical outcomes while minimising toxicity. Requirements for a successful implementation of ABS programmes as well as core and supplemental ABS strategies are outlined. The German version of the guideline was published by the German Association of the Scientific Medical Societies (AWMF) in December 2013.

Evidence To Support Continuation of Statin Therapy in Patients with Staphylococcus aureus Bacteremia

In addition to cholesterol-lowering capabilities, statins possess anti-inflammatory and immunomodulatory effects. We sought to quantify the real-world impact of different statin exposure patterns on clinical outcomes in Staphylococcus aureus bacteremia. We conducted a retrospective cohort study among hospitalized patients with positive S. aureus blood cultures receiving appropriate antibiotics within 48 h of culture collection (Veterans Affairs hospitals, 2002 to 2013). Three statin exposure groups were compared to nonusers: pretreated statin users initiating therapy in the 30 days prior to culture and either (i) continuing statin therapy after culture or (ii) not continuing after culture, and (iii) de novo users initiating at culture. Nonusers included patients without statins in the year prior to culture through discharge. Propensity score-matched Cox proportional hazards regression models were developed. We were able to balance significantly different baseline characteristics using propensity score matching for pretreated without continuation (n = 331), pretreated with continuation (n = 141), and de novo (n = 177) statin users compared to nonusers. We observed a significantly lower 30-day mortality rate (hazard ratio [HR], 0.46; 95% confidence interval [CI], 0.25 to 0.84; number needed to treat [NNT], 10) among pretreated and continued statin users, while protective effects were not observed in de novo (HR, 1.04; 95% CI, 0.60 to 1.82; NNT, undefined) or pretreated but not continued (HR, 0.92; 95% CI, 0.64 to 1.32; NNT, 47) users. In our national cohort study among patients with S. aureus bacteremia, continuation of statin therapy among incident statin users was associated with significant beneficial effects on mortality, including a 54% lower 30-day mortality rate.

Combination antimicrobial therapy in patients with Staphylococcus aureus bacteraemia-a post hoc analysis in 964 prospectively evaluated patients

OBJECTIVES

The evidence for using combination antimicrobial therapy (CoRx) in Staphylococcus aureus bacteraemia (SAB) is limited. We aimed to investigate whether CoRx is associated with higher survival or lower SAB-related late complications.

METHODS

We performed a post hoc analysis of a prospective SAB cohort study. CoRx was defined as a cell wall-active antistaphylococcal agent plus either rifampicin, a fluoroquinolone, fosfomycin or an aminoglycoside. To adjust for survivor bias multivariable Cox models that included CoRx as a time-dependent covariable were calculated.

RESULTS

Of 964 evaluable patients, 512 (53%) received CoRx, most of them (301/512, 59%) rifampicin-containing CoRx. All-cause mortality after 30 and 90 days was similar for the two groups, although the patients in the CoRx group had more often endocarditis, deep-seated or disseminated infections and severe sepsis/septic shock. For the entire cohort, only age, comorbidity and severe sepsis/septic shock were associated with a higher mortality and infectious disease consultation, but not CoRx with a lower mortality. However, in the subgroup of patients with implanted foreign bodies or devices CoRx was independently associated with a lower mortality at 30 days (hazard ratio 0.6, 95% confidence interval 0.3-1.1) and at 90 days (hazard ratio 0.6, 95% confidence interval 0.4-0.9). SAB-related late complications in this subgroup occurred in 15 (10.6%) of 142 patients in the monotherapy group vs. nine (4.5%) of 202 patients in the CoRx group (p 0.03).

CONCLUSIONS

In a setting of optimized management of adult patients with SAB secured by infectious disease consultations, this observational study could not prove CoRx to be independently associated with improved survival or reduced late complications in the entire cohort. However, administration of CoRx may be associated with lower mortality and fewer SAB-related late complications in the subgroup of patients with implanted foreign bodies or devices. Prospective randomized trials should be performed to prove this benefit.

Long-term mortality and causes of death associated with Staphylococcus aureus bacteremia. A matched cohort study

OBJECTIVES

Data describing long-term mortality in patients with Staphylococcus aureus bacteremia (SAB) is scarce. This study investigated risk factors, causes of death and temporal trends in long-term mortality associated with SAB.

METHODS

Nationwide population-based matched cohort study. Mortality rates and ratios for 25,855 cases and 258,547 controls were analyzed by Poisson regression. Hazard ratio of death was computed by Cox proportional hazards regression analysis.

RESULTS

The majority of deaths occurred within the first year of SAB (44.6%) and a further 15% occurred within the following 2-5 years. The mortality rate was 14-fold higher in the first year after SAB and 4.5-fold higher overall for cases compared to controls. Increasing age, comorbidity and hospital contact within 90 days of SAB was associated with an increased risk of death. The overall relative risk of death decreased gradually by 38% from 1992-1995 to 2012-2014. Compared to controls, SAB patients were more likely to die from congenital malformation, musculoskeletal/skin disease, digestive system disease, genitourinary disease, infectious disease, endocrine disease, injury and cancer and less likely to die from respiratory disease, nervous system disease, unknown causes, psychiatric disorders, cardiovascular disease and senility. Over time, rates of death decreased or were stable for all disease categories except for musculoskeletal and skin disease where a trend towards an increase was seen.

CONCLUSION

Long-term mortality after SAB was high but decreased over time. SAB cases were more likely to die of eight specific causes of death and less likely to die of five other causes of death compared to controls. Causes of death decreased for most disease categories. Risk factors associated with long-term mortality were similar to those found for short-term mortality. To improve long-term survival after SAB, patients should be screened for comorbidity associated with SAB.

Use of Glucocorticoids and Risk of Community-Acquired Staphylococcus aureus Bacteremia: A Population-Based Case-Control Study

OBJECTIVE

To investigate whether the use of systemic glucocorticoids is a risk factor for community-acquired Staphylococcus aureus bacteremia (CA-SAB).

PATIENTS AND METHODS

We used population-based medical registries in Northern Denmark to conduct a case-control study including all adults with first-time CA-SAB and matched population controls from January 1, 2000, through December 31, 2011. Glucocorticoid users were categorized as current users (new or long-term use), former users, and nonusers. Using conditional logistic regression, we computed odds ratios (ORs) of CA-SAB according to glucocorticoid exposure, overall and by 90-day prednisolone-equivalent cumulative dose.

RESULTS

We identified 2638 patients with first-time CA-SAB and 26,379 matched population controls. Current glucocorticoid users experienced considerably increased risk of CA-SAB compared with nonusers (adjusted OR=2.48; 95% CI, 2.12-2.90). The adjusted OR was 2.73 (95% CI, 2.17-3.45) in new users, 2.31 (95% CI, 1.90-2.82) in long-term users, and much lower at 1.33 (95% CI, 0.98-1.81) in former users of glucocorticoids compared with nonusers. The risk of CA-SAB increased with higher 90-day cumulative doses. Compared with nonusers of glucocorticoids, the adjusted OR was 1.32 (95% CI, 1.01-1.72) for persons with a cumulative dose of 150 mg or less, 2.42 (95% CI, 1.76-3.33) for persons whose cumulative dose was greater than 500 to 1000 mg, and 6.25 (95% CI, 4.74-8.23) for persons with a cumulative dose greater than 1000 mg.

CONCLUSION

Glucocorticoid use was associated with a substantially increased risk of CA-SAB. The risk increased with higher cumulative dose, revealing a distinct dose-response relation.

Chronic heart failure and mortality in patients with community-acquired Staphylococcus aureus bacteremia: a population-based cohort study

Background

Patients with chronic heart failure (CHF) may experience higher mortality of Staphylococcus aureus bacteremia (SAB) than patients without CHF due to insufficient cardiovascular responses during systemic infection. We investigated 90-day mortality in SAB patients with and without CHF.

Methods

Using population-based medical databases, we conducted a cohort study of all adult patients with community-acquired SAB (CA-SAB) in Northern Denmark, 2000-2011. Ninety-day mortality after SAB for patients with and without CHF was estimated by the Kaplan-Meier method. Based on Cox regression analysis, we computed hazard ratios as estimates of mortality rate ratios (MRRs) overall and stratified by CHF-related conditions (e.g., cardiomyopathy and valvular heart disease), CHF severity (defined by daily dosage of loop-diuretics), and CHF duration while adjusting for potential confounders.

Results

Among 2638 SAB patients, 390 (14.8 %) had a history of CHF. Ninety-day mortality was 45 % in patients with CHF and 30 % in patients without CHF, which yielded an adjusted MRR (aMRR) of 1.24 (95 % CI, 1.04-1.48). Compared to patients without CHF, the excess risk of death was most pronounced among patients with valvular heart disease (aMRR = 1.73 (95 % CI, 1.26–2.38)), patients with daily loop-diuretic dosages of 81–159 mg/day (aMRR = 1.55 (95 % CI, 1.11–2.14)) and ≥160 mg/day (aMRR = 1.62 (95 % CI, 1.21–2.18)), and among patients with <3 years of CHF duration (aMRR = 1.43 (95 % CI, 1.14–1.78)).

Conclusion

CA-SAB patients with CHF experienced increased 90-day mortality compared to patients without CHF.

Electronic supplementary material

The online version of this article (doi:10.1186/s12879-016-1570-7) contains supplementary material, which is available to authorized users.

Diabetes and risk of community-acquired Staphylococcus aureus bacteremia: a population-based case-control study

OBJECTIVE

Patients with diabetes may experience higher risk of Staphylococcus aureus bacteremia (SAB) than patients without diabetes due to decreased immunity or coexisting morbidities. We investigated the risk of community-acquired (CA) SAB in persons with and without diabetes.

DESIGN

Using population-based medical databases, we conducted a case-control study of all adults with first-time CA-SAB and matched population controls in Northern Denmark, 2000-2011.

METHODS

Based on conditional logistic regression, we computed odds ratios (ORs) of CA-SAB according to diabetes. We further assessed whether the risk of CA-SAB differed according to various diabetes-related characteristics (e.g. duration of diabetes, glycemic control, and presence of diabetes complications).

RESULTS

We identified 2638 patients with incident CA-SAB, of whom 713 (27.0%) had diabetes, and 26,379 matched population controls (2495 or 9.5% with diabetes). Individuals with diabetes had a substantially increased risk of CA-SAB compared with population controls (adjusted OR = 2.8 (95% confidence interval (CI): 2.5-3.1)). Duration of diabetes of ≥10 years and poor glycemic control conferred higher risk estimates, with an adjusted OR = 2.3 (95% CI: 1.9-2.7) for diabetes with Hba1c < 7% (< 53 mmol/mol) and an adjusted OR = 5.7 (95% CI: 4.2-7.7) for diabetes with Hba1c ≥9% (≥75 mmol/mol). The risk of CA-SAB was particularly high in patient with diabetes complications: adjusted OR = 5.5 (95% CI: 4.2-7.2) with presence of microvascular complications and OR = 7.0 (95% CI: 5.4-9.0) with combined macro- and microvascular complications.

CONCLUSIONS

Diabetes is associated with a substantially increased risk of CA-SAB, particularly in patients with diabetes of long duration, poor glycemic control, and diabetes complications.

Outcome of Community-Acquired Staphylococcus aureus Bacteraemia in Patients with Diabetes: A Historical Population-Based Cohort Study

Background

Patients with diabetes (DM) experience increased risk of Staphylococcus aureus bacteraemia (SAB), but the prognostic impact of diabetes in patients with SAB remain unclear. Therefore, we investigated 30-day all-cause mortality in patients with and without DM.

Methods

Population-based medical databases were used to conduct a cohort study of all adult patients with community-acquired SAB in Northern Denmark, 2000–2011. Using Cox proportional hazards regression, we computed hazard ratios as estimates of 30-day mortality rate ratios (MRRs) among patients with and without DM. We further investigated whether the prognostic impact of DM differed among patients with and without recent preadmission healthcare contacts (within 30 days of the current hospitalization) and by age, sex, marital status, level of comorbidity, and DM-related characteristics (e.g., duration of DM and presence of DM complications).

Results

Among 2638 SAB patients, 713 (27.0%) had DM. Thirty-day cumulative mortality was 25.8% in patients with DM and 24.3% in patients without DM, for an adjusted MRR (aMRR) of 1.01 (95% confidence interval (CI), 0.84–1.20). In analyses with and without recent healthcare contacts, the corresponding aMRRs were 0.84 (95% CI, 0.62–1.14) and 1.13 (95% CI, 0.91–1.41), respectively. Compared to patients without DM, the aMRR was 0.94 (95% CI, 0.74–1.20) for male patients with DM and 1.13 (95% CI, 0.87–1.47) for female patients with DM. The prognostic influence of DM on mortality did not differ notably with age, level of comorbidity, or characteristics of patients with DM.

Conclusion

Patients with DM and community-acquired SAB did not experience higher 30-day mortality than patients without DM.

The Impact of Infectious Disease Specialist Consultation for Staphylococcus aureus Bloodstream Infections: A Systematic Review

Staphylococcus aureus is a common cause of severe bloodstream infection. We performed a systematic review to assess whether consultation with infectious disease specialists decreased all-cause mortality or rate of complications of S aureus bloodstream infections. The review also assessed parameters associated with the quality of management of the infection. We searched for eligible studies in PubMed, Embase, Scopus, and clinical trials.gov as well as the references of included studies. We identified 22 observational studies and 1 study protocol for a randomized trial. A meta-analysis was not performed because of the high risk of bias in the included studies. The outcomes are reported in a narrative review. Most included studies reported survival benefit, in the adjusted analysis. Recommended management strategies were carried out significantly more often among patients seen by an infectious disease specialist. Trials, such as cluster-randomized controlled trials, can more validly assess the studies at low risk of bias.

Infectious diseases consultations can make the difference: a brief review and a plea for more infectious diseases specialists in Germany

Trained infectious diseases (ID) specialists are an integral part of inpatient and outpatient care in many countries, however, these specialized services are established only in selected tertiary care hospitals in Germany. This review summarises studies that addressed the impact of ID consultation services on patient care and outcome. Extensive data for a clinical benefit is available in the context of Staphylococcus aureus bacteremia (SAB), in which in-hospital or 30-day mortality was significantly reduced by 40-50 % in patients evaluated and treated in cooperation with ID consultants. This effect was associated with improved adherence to quality-of-care standards. Moreover, newer studies show a reduced length of hospital stay due to ID consultations, especially if patients are evaluated early in the course of their hospital stay. Of note, informal consultations do not seem to be equivalent to a formal ID consultation with bedside patient evaluation. Studies in other patient groups (solid organ transplant recipients or intensive care unit patients) or in the context of other infections (infective endocarditis, pneumonia, other bloodstream infections) also revealed positive effects of ID consultations. Higher rates of appropriate empirical and targeted antimicrobial treatments and de-escalation strategies due to successful pathogen identification were documented. These modifications resulted in lower treatment costs and decreased antimicrobial resistance development. Although there are methodological limitations in single studies, we consider the consistent and reproducible positive effects of ID consultations shown in studies in different countries and health care systems as convincing evidence for improved quality-of-care and treatment outcomes in patients with infectious diseases. Thus, we strongly recommend efforts to establish significantly more ID consultation services in hospitals in Germany.

Mortality predictors of Staphylococcus aureus bacteremia: a prospective multicenter study

Background

Staphylococcus aureus is one of the causes of both community and healthcare-associated bacteremia. The attributable mortality of S. aureus bacteremia (SAB) is still higher and predictors for mortality and clinical outcomes of this condition are need to be clarified. In this prospective observational study, we aimed to examine the predictive factors for mortality in patients with SAB in eight Turkish tertiary care hospitals.

Methods

Adult patients with signs and symptoms of bacteremia with positive blood cultures for S. aureus were included. All data for episodes of SAB including demographics, clinical and laboratory findings, antibiotics, and outcome were recorded for a 3-year (2010–2012) period. Cox proportional hazard model with forward selection was used to assess the independent effect of risk factors on mortality. A 28-day mortality was the dependent variable in the Cox regression analysis.

Results

A total of 255 episodes of SAB were enrolled. The median age of the patients was 59 years. Fifty-five percent of the episodes were considered as primary SAB and vascular catheter was the source of 42.1 %. Healthcare associated SAB was defined in 55.7 %. Blood cultures yielded methicillin-resistant S. aureus (MRSA) as a cause of SAB in 39.2 %. Initial empirical therapy was inappropriate in 28.2 %. Although overall mortality was observed in 52 (20.4 %), 28-day mortality rate was 15.3 %. Both the numbers of initial inappropriate empirical antibiotic treatment and the median hours to start an appropriate antibiotic between the cases of fatal outcome and survivors after fever onset were found to be similar (12/39 vs 60/216 and 6 vs 12 h, respectively; p > 0.05). High Charlson comorbidity index (CCI) score (p = 0.002), MRSA (p = 0.017), intensive care unit (ICU) admission (p < 0.001) and prior exposure to antibiotics (p = 0.002) all were significantly associated with mortality. The Cox analysis defined age [Hazard Ratio (HR) 1.03; p = 0.023], ICU admission (HR 6.9; p = 0.002), and high CCI score (HR 1.32; p = 0.002) as the independent predictive factors mortality.

Conclusions

The results of this prospective study showed that age, ICU stay and high CCI score of a patient were the independent predictors of mortality and MRSA was also significantly associated with mortality in SAB.

Quality Improvement of Staphylococcus aureus Bacteremia Management and Predictors of Relapse-free Survival

PURPOSE

The purpose of this study is to improve the quality of care and patient outcomes for Staphylococcus aureus bacteremia.

METHODS

A quasi-experimental pre- and postintervention study design was used to compare process and clinical endpoints before and after a quality-improvement initiative. All inpatients >18 years of age with a positive blood culture for S. aureus during the specified pre- and postintervention period with clinical information available in the electronic medical record were included. An institutional protocol for the care of patients with S. aureus bacteremia was developed, formalized, and distributed to providers using a pocket card, an electronic order set, and targeted lectures over a 9-month period.

RESULTS

There were 167 episodes of S. aureus bacteremia (160 patients) identified in the preintervention period, and 127 episodes (123 patients) in the postintervention period. Guideline adherence improved in the postintervention period for usage of transesophageal echocardiogram (43.9% vs 20.2%, P <.01) and adequate duration of intravenous therapy (71% vs 60%, P = .05). In a multivariate Cox proportional hazard model, the variables associated with increased relapse-free survival were postintervention period (hazard ratio [HR] 0.48; confidence interval [CI], 0.24-0.95; P .035) and appropriate source control (HR 0.53; CI, 0.24-0.92; P .027). Regardless of intervention, presence of cancer was associated with an increased risk of relapse or mortality at 90 days (HR 2.88; P <.0001; CI, 1.35-5.01).

CONCLUSION

A bundled educational intervention to promote adherence to published guidelines for the treatment of S. aureus bacteremia resulted in a significant improvement in provider adherence to guidelines as well as increased 90-day relapse-free survival.

Simplified risk stratification criteria for identification of patients with MRSA bacteremia at low risk of infective endocarditis: implications for avoiding routine transesophageal echocardiography in MRSA bacteremia

The aim of this study was to identify patients with methicillin-resistant Staphylococcus aureus (MRSA) bacteremia with low risk of infective endocarditis (IE) who might not require routine trans-esophageal echocardiography (TEE). We retrospectively evaluated 398 patients presenting with MRSA bacteremia for the presence of the following clinical criteria: intravenous drug abuse (IVDA), long-term catheter, prolonged bacteremia, intra-cardiac device, prosthetic valve, hemodialysis dependency, vertebral/nonvertebral osteomyelitis, cardio-structural abnormality. IE was diagnosed using the modified Duke criteria. Of 398 patients with MRSA bacteremia, 26.4 % of cases were community-acquired, 56.3 % were health-care-associated, and 17.3 % were hospital-acquired. Of the group, 44 patients had definite IE, 119 had possible IE, and 235 had a rejected diagnosis. Out of 398 patients, 231 were evaluated with transthoracic echocardiography (TTE) or TEE. All 44 patients with definite IE fulfilled at least one criterion (sensitivity 100 %). Finally, a receiver operator characteristic (ROC) curve was obtained to evaluate the total risk score of our proposed criteria as a predictor of the presence of IE, and this was compared to the ROC curve of a previously proposed criteria. The area under the ROC curve for our criteria was 0.710, while the area under the ROC curve for the criteria previously proposed was 0.537 (p < 0.001). The p-value for comparing those 2 areas was less than 0.001, indicating statistical significance. Patients with MRSA bacteremia without any of our proposed clinical criteria have very low risk of developing IE and may not require routine TEE.