Evaluation of clinical guidelines for the management of Staphylococcus aureus bacteraemia

Prediction rules for ruling out endocarditis in patients with Staphylococcus aureus bacteremia

Background

Staphylococcus aureus bacteremia (SAB) is in 10% to 20% of cases complicated by infective endocarditis. Clinical prediction scores may select patients with SAB at highest risk for endocarditis, improving the diagnostic process of endocarditis. We compared the accuracy of the Prediction Of Staphylococcus aureus Infective endocarditiseTime to positivity, Iv drug use, Vascular phenomena, preExisting heart condition (POSITIVE), Predicting Risk of Endocarditis Using a Clinical Tool (PREDICT), and VIRSTA scores for classifying the likelihood of endocarditis in patients with SAB.

Methods

Between August 2017 and September 2019, we enrolled consecutive adult patients with SAB in a prospective cohort study in 7 hospitals in the Netherlands. Using the modified Duke Criteria for definite endocarditis as reference standard, sensitivity, specificity, negative predictive (NPV), and positive predictive values were determined for the POSITIVE, PREDICT, and VIRSTA scores. An NPV of at least 98% was considered safe for excluding endocarditis.

Results

Of 477 SAB patients enrolled, 33% had community-acquired SAB, 8% had a prosthetic valve, and 11% a cardiac implantable electronic device. Echocardiography was performed in 87% of patients, and 42% received transesophageal echocardiography (TEE). Eighty-seven (18.2%) had definite endocarditis. Sensitivity was 77.6% (65.8%–86.9%), 85.1% (75.8%–91.8%), and 98.9% (95.7%–100%) for the POSITIVE (n = 362), PREDICT, and VIRSTA scores, respectively. NPVs were 92.5% (87.9%–95.8%), 94.5% (90.7%–97.0%), and 99.3% (94.9%–100%). For the POSITIVE, PREDICT, and VIRSTA scores, 44.5%, 50.7%, and 70.9% of patients with SAB, respectively, were classified as at high risk for endocarditis.

Conclusions

Only the VIRSTA score had an NPV of at least 98%, but at the expense of a high number of patients classified as high risk and thus requiring TEE.

Clinical Trials Registration

Netherlands Trial Register code 6669.

Efficacy of seven and fourteen days of antibiotic treatment in uncomplicated Staphylococcus aureus bacteremia (SAB7): study protocol for a randomized controlled trial

Background

Staphylococcus aureus bacteremia (SAB) is frequently encountered in the hospital setting, and current guidelines recommend at least 14 days of antibiotic treatment for SAB in order to minimize risks of secondary deep infections and relapse. However, evidence to support these treatment recommendations remains scarce. Patients with uncomplicated SAB are known to have a low of risk of recurrence and death. Reducing treatment length in uncomplicated SAB would reduce the total consumption of antibiotics, duration of hospital admission, and potentially the risk of adverse events. With SAB7 we seek to determine if 7 days of antibiotic treatment in patients with uncomplicated SAB is non-inferior to 14 days of treatment.

Methods/design

The study is designed as a randomized, non-blinded, non-inferiority, multicenter interventional study. Primary measure of outcome will be 90-day survival without clinical or microbiological failure to treatment or relapse. Secondary outcomes include the prevalence of severe adverse effects, in particular secondary infection with Clostridium difficile, all-cause mortality, as well as public health related costs. Patients identified with uncomplicated SAB who have received 7 days of protocol-approved antibiotics will be eligible for inclusion and randomized 1:1 in two parallel arms to either (i) discontinue antibiotic treatment at day 7 or (ii) to continue antibiotic treatment for a total of 14 days. Main exclusion criteria include signs of complicated SAB, such as the presence of secondary deep infections, persistent bacteremia, and implantable devices. Patients are followed for 6 months with clinical examinations, consecutive blood tests, and registration of adverse events. A total of 284 patients are to be included at ten centers across Denmark. The primary endpoint will be tested with a statistical non-inferiority margin of 10 percentage points.

Discussion

SAB 7 will determine if 7 days of antibiotic treatment in patients with uncomplicated SAB is sufficient and safe. Results of the study will provide important knowledge on optimized SAB management and could potentially modify the current treatment recommendations.

Trial registration

ClinicalTrails.gov, H-17027414. Registered on May 2, 2018. The Danish Medicines Agency (EudraCT), 2017–003529-13. Registered on October 30, 2017.

Electronic supplementary material

The online version of this article (10.1186/s13063-019-3357-9) contains supplementary material, which is available to authorized users.

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 bacteraemia and endocarditis - epidemiology and outcome: a review

PURPOSE

To review the epidemiology of Staphylococcus aureus bacteraemia (SAB) and endocarditis (SAE), and discuss the short- and long-term outcome.  Materials and methods: A literature review of the epidemiology of SAB and SAE.

RESULTS

The reported incidence of SAB in Western countries is 16-41/100,000 person-years. Increasing incidence has been observed in many regions, in Iceland by 27% during 1995-2008. The increase is believed to depend on changes in population risk factors and possibly better and more frequent utilization of diagnostic procedures. S. aureus is now the leading causes of infective endocarditis (IE) in many regions of the world. It accounts for 15-40% of all IE cases, and the majority of cases in people who inject drugs (PWID). Recently, the incidence of SAE in PWID in Stockholm, Sweden, was found to be 2.5/1000 person-years, with an in-hospital mortality of 2.5% in PWID as compared to 15% in non-drug users. The 30-day mortality associated with SAB amounts to 15-25% among adults in Western countries, but is lower in children (0-9%). Mortality associated with SAE is high (generally 20-30% in-hospital mortality), and symptomatic cerebral embolizations are common (12-35%). The 1-year mortality reported after SAB and SAE is 19-62% and reflects deaths from underlying diseases and complications caused by the infection. In a subset of SAE cases, valvular heart surgery is needed (15-45%), but active intravenous drug use seems to be a reason to refrain from surgery. Despite its importance, there are insufficient data on the optimal management of SAB and SAE, especially on the required duration of antibiotic therapy.  Conclusions: The epidemiology of SAB and SAE has been changing in the past decades. They still carry a substantial morbidity and mortality. Intensified studies on treatment are warranted for improving patient outcome.

Comparative Sensitivity of Transthoracic and Transesophageal Echocardiography in Diagnosis of Infective Endocarditis Among Veterans With Staphylococcus aureus Bacteremia

BACKGROUND

Echocardiography is fundamental for diagnosing infective endocarditis (IE) in patients with Staphylococcus aureus bacteremia (SAB), but whether all such patients require transesophageal echocardiography (TEE) is controversial.

METHODS

We identified SAB cases between February 2008 and April 2012. We compared sensitivity and specificity of transthoracic echocardiography (TTE) and TEE for evidence of IE, and we determined impacts of IE risk factors and TTE image quality on comparative sensitivities of TTE and TEE and their impact on clinical decision making.

RESULTS

Of 215 evaluable SAB cases, 193 (90%) had TTE and 130 (60%) had TEE. In 119 cases with both tests, IE was diagnosed in 29 (24%), for whom endocardial involvement was evident in 25 (86%) by TEE, vs only 6 (21%) by TTE (P < .001). Transesophageal echocardiography was more sensitive than TTE regardless of risk factors. Even among the 66 cases with adequate or better quality TTE images, sensitivity was only 4 of 17 (24%) for TTE, vs 16 of 17 (94%) for TEE (P < .001). Among 130 patients with TEE, the TEE results, alone or with TTE results, influenced treatment duration in 56 (43%) cases and led to valve surgery in at least 4 (6%). It is notable that, despite vigorous efforts to obtain both tests routinely, TEE was not done in 86 cases (40%) for various reasons, including pathophysiological contraindications (14%), patient refusal or other patient-related factors (16%), and provider declination or system issues (10%).

CONCLUSIONS

Patients with SAB should undergo TEE when possible to detect evidence for IE, especially if the results might affect management.

The VIRSTA score, a prediction score to estimate risk of infective endocarditis and determine priority for echocardiography in patients with Staphylococcus aureus bacteremia

OBJECTIVES

To develop and validate a prediction score, to quantify, within 48 h of Staphylococcus aureus bacteremia (SAB) diagnosis, the risk of IE, and therefore determine priority for urgent echocardiography.

METHODS

Consecutive adult patients with SAB in 8 French university hospitals between 2009 and 2011 were prospectively enrolled and followed-up 3 months. A predictive model was developed and internally validated using bootstrap procedures.

RESULTS

Among the 2008 patients enrolled, 221 (11.0%) had definite IE of whom 39 (17.6%) underwent valve surgery, 25% of them within 6 days of SAB diagnosis. Ten predictors independently associated with IE were used to build up the prediction score: intracardiac device or previous IE, native valve disease, intravenous drug use, community or non-nosocomial-acquisition, cerebral or extracerebral emboli, vertebral osteomyelitis, severe sepsis, meningitis, C-reactive protein above 190 mg/L, and H48-persistent bacteremia. Patients with a score ≤2 (n = 792, 39.4%) were at low IE-risk (1.1%; negative predictive value: 98.8% (95% CI, 98.4-99.4)) compared to those ≥3 who were at higher risk (17.4%).

CONCLUSIONS

Physicians must be strongly encouraged to urgently perform echocardiography in SAB patients with a score ≥3 to establish IE diagnosis, to orient antimicrobial therapy and to help determine the need for valvular surgery.

Staphylococcus aureus bacteraemia: evaluation of the role of transoesophageal echocardiography in identifying clinically unsuspected endocarditis

Staphylococcus aureus bacteraemia (SAB) is an important cause of community and nosocomial sepsis, with a significant mortality rate. Infective endocarditis (IE) is a serious complication, occurring in up to 25 % of cases. Transoesophageal echocardiography (TOE) significantly improves the sensitivity of diagnosis. We compared the sensitivity and specificity of clinical evaluation alone in diagnosing IE. We evaluated all adult patients with SAB at our centre from 1998 to 2006 in order to determine what proportion of clinically unsuspected cases were diagnosed with IE on TOE. IE was defined according to modified Duke criteria. The median age of the patients was 68 years, 77 % were male and the majority of cases did not have a known pre-existing condition. Twenty-one percent were methicillin-resistant Staphylococcus aureus (MRSA). Intravascular device was the most common cause of bacteraemia. TOE was performed in 144 (100 %) of the cases. IE was suspected clinically in 15 % of cases, and the overall prevalence of possible or definite IE on TOE-inclusive Duke criteria was 29 % (n = 41). Following TOE, 22 (15 %) cases were reclassified as either possible or definite endocarditis. TOE detected a vegetation in 37 (90 %) of the 41 cases of IE. Nineteen (46 %) were not suspected clinically by Duke criteria. Sensitivity improved in the presence of pre-existing valve lesion or community acquisition. The overall in-hospital mortality was 10 %. There is a high incidence of endocarditis in SAB and a large percentage of cases are not evident on clinical grounds. TOE evaluation is indicated for all medically suitable adult patients with SAB in order to improve the detection of endocarditis.

Treatment duration for uncomplicated Staphylococcus aureus bacteremia to prevent relapse: analysis of a prospective observational cohort study

Practice guidelines recommend at least 14 days of antibiotic therapy for uncomplicated Staphylococcus aureus bacteremia (SAB). However, these recommendations have not been formally evaluated in clinical studies. To evaluate the duration of therapy for uncomplicated SAB, we analyzed data from our prospective cohort of patients with SAB. A prospective observational cohort study was performed in patients with SAB at a tertiary-care hospital in Korea between August 2008 and September 2010. All adult patients with SAB were prospectively enrolled and observed over a 12-week period. Uncomplicated SAB was defined as follows: negative results of follow-up blood cultures at 2 to 4 days, defervescence within 72 h of therapy, no evidence of metastatic infection, and catheter-related bloodstream infection or primary bacteremia without evidence of endocarditis on echocardiography. Of 483 patients with SAB, 111 met the study criteria for uncomplicated SAB. Fifty-three (47.7%) had methicillin-resistant SAB. When short-course therapy (<14 days) and intermediate-course therapy (≥14 days) were compared, the treatment failure rates (10/38 [26.3%] versus 16/73 [21.9%]) and crude mortality (7/38 [18.4%] versus 16/73 [21.9%]) did not differ significantly between the two groups. However, short-course therapy was significantly associated with relapse (3/38 [7.9%] versus 0/73; P = 0.036). In multivariate analysis, primary bacteremia was associated with a trend toward increased treatment failure (P = 0.06). Therefore, in the treatment of uncomplicated SAB, it seems reasonable to consider at least 14 days of antibiotic therapy to prevent relapse, as practice guidelines recommend. Because of its poor prognosis, primary bacteremia, even with a low risk of complication, should not be treated with short-course therapy.

Clinical management of Staphylococcus aureus bacteraemia

Staphylococcus aureus bacteraemia is one of the most common serious bacterial infections worldwide. In the UK alone, around 12,500 cases each year are reported, with an associated mortality of about 30%, yet the evidence guiding optimum management is poor. To date, fewer than 1500 patients with S aureus bacteraemia have been recruited to 16 controlled trials of antimicrobial therapy. Consequently, clinical practice is driven by the results of observational studies and anecdote. Here, we propose and review ten unanswered clinical questions commonly posed by those managing S aureus bacteraemia. Our findings define the major areas of uncertainty in the management of S aureus bacteraemia and highlight just two key principles. First, all infective foci must be identified and removed as soon as possible. Second, long-term antimicrobial therapy is required for those with persistent bacteraemia or a deep, irremovable focus. Beyond this, the best drugs, dose, mode of delivery, and duration of therapy are uncertain, a situation compounded by emerging S aureus strains that are resistant to old and new antibiotics. We discuss the consequences on clinical practice, and how these findings define the agenda for future clinical research.

Predisposing factors, disease progression and outcome in 430 prospectively followed patients of healthcare- and community-associated Staphylococcus aureus bacteraemia

Staphylococcus aureus bacteraemia (SAB) episodes identified in a prospective multicentre study during 1999-2002 (not including MRSA) were followed up by an infectious disease specialist. The aim of this study was to compare predisposing factors, disease progression and outcome of healthcare (HA)- and community (CA)-associated SAB. Of 430 SAB episodes, 232 (54%) were HA. The HA-SAB patients were significantly older and more chronically ill compared to CA-SAB. Deep infection foci prevalence within three days of onset of SAB for HA versus CA were deep-seated abscesses (26% vs 37%, P < 0.05), pneumonia [25% vs 31%, non-significant (NS)], osteomyelitis (24% vs 36%, P<0.01), permanent foreign body (24% vs 9%, P<0.001), endocarditis (11% vs 15%, NS), septic arthritis (9% vs 13%, NS) and no infection focus (3% vs 6%, NS). The case fatality rates for HA-SAB versus CA-SAB at 28 days were 14% vs 11% (NS). Independent risk factors according to multivariate analysis for a fatal outcome were age, chronic alcoholism, immunosuppressive treatment, ultimately or rapidly fatal underlying diseases, severe sepsis on the onset of SAB, S. aureus pneumonia and endocarditis. As a result of a prospective study design, meticulous infection foci search and infectious disease specialist follow-up of each SAB episode, the case fatality remained low and 97% of the HA-SAB episodes presented infection foci within three days of onset of bacteraemia.

Audit of treatment of Staphylococcus aureus bacteraemia

Staphylococcus aureus bacteraemia remains a significant cause of morbidity and mortality. National guidelines recommend that a minimum of 14 days of antibiotics should be used to treat uncomplicated bacteraemia. Five hospitals in the East Midlands region conducted a retrospective audit to assess compliance to these guidelines before and after the introduction of extra text to laboratory reports of S. aureus bacteraemia advising clinicians on the minimum length of treatment. Introduction of this extra text resulted in an increase in compliance with the national recommendation from 44% to 60%. This increase in compliance was noted in both methicillin-sensitive S. aureus (45% versus 58%) and methicillin-resistant S. aureus (42% versus 62%) bacteraemia. This audit demonstrated a simple and effective intervention that has improved the treatment of this potentially life-threatening condition.

Mortality of S. aureus bacteremia and infectious diseases specialist consultation--a study of 521 patients in Germany

OBJECTIVES

To evaluate the relationship between mortality of bloodstream infection due to Staphylococcus aureus and infectious diseases specialist consultation and other factors potentially associated with outcomes.

METHODS

A 6-year cohort study was conducted at a 1600-bed university hospital. Consecutive adult patients with S. aureus bacteremia were assessed using a standardised data collection and review form. A new infectious diseases service increased its consultations for S. aureus bacteremia from 33% of cases in 2002 to >80% in 2007. Infectious disease consultation and other factors potentially associated with in-hospital mortality were analysed by multivariate logistic regression.

RESULTS

A total of 521 patients were studied. All-cause in-hospital mortality was 22%, 90-day mortality was 32%. Factors significantly associated with in-hospital mortality in multivariate analysis were ICU admission (OR 5.8, CI 3.5-9.7), MRSA (OR 2.6, CI 1.4-4.9), age >/=60 years (OR 2.4, CI 1.4-4.2), a diagnosis of endocarditis (OR 2.8, CI 1.4-5.7), a non-fatal underlying disease/comorbidity according to the McCabe classification (OR 0.2, CI 0.1-0.4), and infectious disease specialist consultation (OR 0.6, CI 0.4-1.0).

CONCLUSIONS

These data suggest that outcome of S. aureus bacteremia may be improved by an expert consultation service.

Frequency and risk factors for deep focus of infection in children with Staphylococcus aureus bacteremia

BACKGROUND

Staphylococcus aureus bacteremia (SAB) in children may be associated with development of deep-seated foci of infection, often prompting extensive diagnostic testing. The objective of this study was to establish the frequency and risk factors for deep foci of infection from SAB in pediatric patients.

METHODS

Medical charts of all children admitted with SAB to a tertiary-care center from January 1992 to June 2006 were reviewed. Study outcome was the presence of a deep focus of infection as documented by positive echocardiogram, bone imaging or abdominal imaging.

RESULTS

We studied 298 children, of whom 190 (64%) had echocardiograms, 116 (39%) had abdominal imaging, and 103 (35%) had bone imaging. Forty-seven subjects (16%) had symptoms of a deep focus of infection on discovery of SAB, which then was confirmed by 1 of the 3 tests. Eleven (3.7%) additional subjects had a clinically unsuspected deep focus identified before discharge. All children with an unsuspected deep focus of infection had either an underlying medical condition that potentially obscured the diagnosis or a central venous catheter. More than 1 day of positive blood cultures was associated with an unsuspected deep-seated infection (P < 0.01). Endocarditis was uncommon (2.7%), and occurred only in children with known congenital heart disease or with a central catheter.

CONCLUSIONS

Deep-seated infections from SAB in children are most often clinically apparent at discovery of bacteremia. Unsuspected deep-seated infection is uncommon and confined to specific hosts. Routine diagnostic imaging is not indicated in all children with SAB.

Clinical and molecular epidemiology of nursing home-associated Staphylococcus aureus bacteremia

BACKGROUND AND OBJECTIVES

Although nursing home residents who have Staphylococcus aureus bacteremia (SAB) have been included in large studies of this infection, there are no published descriptions of SAB solely in nursing home residents. The objectives were to describe the clinical and molecular epidemiology of SAB in nursing home residents admitted to one hospital.

METHODS

This was a retrospective review of hospital medical records of nursing home residents from 22 separate facilities who had SAB and were admitted to a specialty unit at one hospital from 1997 to 2003.

RESULTS

For the seven-year study period, 39 episodes of SAB were identified; 15 were due to methicillin-susceptible S. aureus (MSSA) and 24 were due to methicillin-resistant S. aureus (MRSA). The incidence of SAB among all residents admitted to the specialty unit increased by more than eightfold primarily because of an increased incidence of bacteremia due to MRSA. The most common identified source was the urinary tract (18% of all episodes) but for 17 (44%) episodes, no focus was identified. Hospital mortality was 28% with all deaths occurring within 15 days of admission. Analysis of the MRSA strains by pulsed-field gel electrophoresis revealed that two pulsed-field types predominated when compared with the CDC national database: USA100- (N = 13) and USA 800-like strains (N = 7).

CONCLUSIONS

In the study population there was a substantial increase in incidence of SAB over a 7-year period due almost exclusively to an increased occurrence of MRSA. Hospital strains of MRSA predominated, as one would expect. Mortality was high but complications were low among survivors. These findings have important implications for choosing empiric antibiotic therapy in nursing home residents who have suspected S. aureus infection.

The value of process measures in evaluating an evidence-based guideline

BACKGROUND

Linking the process of evidence-based guidelines to outcomes is difficult. We hypothesized that the process of implementing an evidence-based clinical guideline for blunt splenic trauma would reduce resource consumption and improve outcome.

METHODS

Time periods were divided into period 1 (7/1/96-6/30/99) and period 2 (7/1/99-6/30/01). On 7/1/99 our American College of Surgeons-verified level I trauma center instituted an evidence-based approach for managing splenic trauma incorporating hemodynamic normality as the process measure triggering clinical decisions. Outcomes included the number of hemodynamically normal patients treated without operation, patient death, length of stay, and cost.

RESULTS

Two hundred thirty-one patients had blunt splenic injury; 115 patients were seen during period 1 and 116 during period 2. Hemodynamically normal patients undergoing splenectomy decreased during period 2 (P<.05). Median length of stay was 8 days in period 1 and 6 days in period 2 (P<.03). Cost per patient was $34,972 US dollars in period 1 and $24,037 US dollars in period 2 (P<.03). The mortality rate was unchanged.

CONCLUSIONS

Compliance with evidence-based data in the management of blunt splenic injury improved rates of nonoperative management, decreased hospital days, and did not change mortality rates. An evidence-based clinical guideline evaluated with process measures can reduce resource use and improve outcome in a trauma program.