Staphylococcus Aureus Bacteremia Patients Research Articles

Determining the Prognostic Value of Complete Blood Count Subgroup Parameters in Staphylococcus aureus Bacteremia.

Serum cytokine alterations are associated with increased Staphylococcus aureus bacteremia (SAB) mortality. Unfortunately, clinical use of these cytokines is uncommon due to limited availability and high cost. Complete blood count (CBC) with differential reflects the host immune response, and CBC subgroup parameters may have prognostic value in SAB. We sought to determine the association between CBC subgroup parameters on the day of index blood culture and 30-day all-cause mortality in SAB patients. We conducted a retrospective study of adult SAB patients with infectious diseases consultation to evaluate the discriminatory capacity of CBC subgroup parameters in predicting SAB mortality. Clinical and microbiological data were collected, including severity of illness and CBC subgroup parameters, on the day of index blood culture. The primary outcome was 30-day all-cause mortality. A multivariable logistic regression model was used to determine the association between patient-level variables and mortality. A total of 119 patients were included. The overall 30-day all-cause mortality rate was 10.1%. The median neutrophil-to-lymphocyte count ratio (NLCR) among survivors was 13.6 vs 23.2 among non-survivors (p = .007). Median lymphocyte count among survivors was 0.9 x 103 cells/μL vs 0.6 x 103 cells/μL among non-survivors (p = .031). Median platelet count was higher among survivors than non-survivors (239 x 103 cells/μL vs 171 x 103 cells/μL, respectively; p = .018). All other CBC subgroup parameters were similar between the two groups. Known SAB mortality predictors, including age, were also associated with increased mortality. Lower lymphocyte count was independently associated with increased mortality (adjusted odds ratio [aOR] 0.236, 95% confidence interval [CI] 0.064-0.872), as was higher PITT bacteremia score (aOR 2.439, 95% CI 1.565-3.803). CBC subgroup parameters may have prognostic value in SAB. Additional study is warranted to further ascertain the prognostic value of these readily available laboratory values.

Low-Risk Staphylococcus aureus Bacteremia Patients Do Not Require Routine Diagnostic Imaging: A Multicenter, Retrospective, Cohort Study.

Stratification to categorize patients with Staphylococcus aureus bacteremia (SAB) as low or high risk for metastatic infection may direct diagnostic evaluation and enable personalized management. We investigated the frequency of metastatic infections in low-risk SAB patients, their clinical relevance, and whether omission of routine imaging is associated with worse outcomes. We performed a retrospective cohort study at 7 Dutch hospitals among adult patients with low-risk SAB, defined as hospital-acquired infection without treatment delay, absence of prosthetic material, short duration of bacteremia, and rapid defervescence. Primary outcome was the proportion of patients whose treatment plan changed due to detected metastatic infections, as evaluated by both actual therapy administered and by linking a adjudicated diagnosis to guideline-recommended treatment. Secondary outcomes were 90-day relapse-free survival and factors associated with the performance of diagnostic imaging. Of 377 patients included, 298 (79%) underwent diagnostic imaging. In 15 of these 298 patients (5.0%), imaging findings during patient admission had been interpreted as metastatic infections that should extend treatment. Using the final adjudicated diagnosis, 4 patients (1.3%) had clinically relevant metastatic infection. In a multilevel multivariable logistic regression analysis, 90-day relapse-free survival was similar between patients without imaging and those who underwent imaging (81.0% versus 83.6%; adjusted odds ratio, 0.749; 95% confidence interval, .373-1.504). Our study advocates risk stratification for the management of SAB patients. Prerequisites are follow-up blood cultures, bedside infectious diseases consultation, and a critical review of disease evolution. Using this approach, routine imaging could be omitted in low-risk patients.

Validation of a new risk stratification system-based management for methicillin-resistant Staphylococcus aureus bacteraemia: analysis of a multicentre prospective study.

Distinguishing between complicated and uncomplicated Staphylococcus aureus bacteraemia (SAB) is therapeutically essential. However, this distinction has limitations in reflecting the heterogeneity of SAB and encouraging targeted diagnostics. Recently, a new risk stratification system for SAB metastatic infection, involving stepwise approaches to diagnosis and treatment, has been suggested. We assessed its applicability in methicillin-resistant SAB (MRSAB) patients. We retrospectively analysed data of a 3-year multicentre, prospective cohort of hospitalised patients with MRSAB. We classified the patients into three risk groups: low, indeterminate, and high, based on the new system and compared between-group management and outcomes. Of 380 patients with MRSAB, 6.3% were classified as low-, 7.6% as indeterminate-, and 86.1% as high-risk for metastatic infection. No metastatic infection occurred in the low-, 6.9% in the indeterminate-, and 19.6% in the high-risk groups (P < 0.001). After an in-depth diagnostic work-up, patients were finally diagnosed as 'without metastatic infection (6.3%)', 'with metastatic infection (17.4%)', and 'uncertain for metastatic infection (76.3%)'. 30-day mortality increased as the severity of diagnosis shifted from 'without metastatic infection' to 'uncertain for metastatic infection' and 'with metastatic infection' (P = 0.09). In multivariable analysis, independent factors associated with metastatic complications were suspicion of endocarditis in transthoracic echocardiography, clinical signs of metastatic infection, Pitt bacteraemia score ≥ 4, and persistent bacteraemia. The new risk stratification system shows promise in predicting metastatic complications and guiding work-up and management of MRSAB. However, reducing the number of cases labelled as 'high-risk' and 'uncertain for metastatic infection' remains an area for improvement.

209. Validation of a New Risk Stratification System-Based Management for Methicillin-Resistant Staphylococcus aureus Bacteremia: Analysis of a Multicenter Prospective Study

Abstract Background Distinguishing between complicated and uncomplicated Staphylococcus aureus bacteremia (SAB) is therapeutically essential. However, this distinction has limitations in reflecting the various manifestation of SAB. In the light of this, Koujizer et al. proposed a new risk stratification system for metastatic infection in SAB, which involves a stepwise approach to diagnosis and treatment. We tested this risk stratification system in methicillin-resistant SAB (MRSAB) patients. Methods We retrospectively analyzed data of a 3-year multicenter, prospective cohort of hospitalized patients with MRSAB. We classified the patients into three risk groups: low, indeterminate, and high, based on the new system and compared between-group management and outcomes, as well as microbiologic features. Results The demographic and baseline characteristics of patients are shown in Table 1. The most frequent source of MRSAB was central venous catheter-related infection (25.5%), followed by unknown origin (15.3%) and pneumonia (11.1%). Echocardiography was performed in 248 cases (65.3%). Of 380 patients with MRSAB, 6.3% were classified as low-, 7.6% as indeterminate-, and 86.1% as high-risk for metastatic infection (Figure 1). No metastatic infection occurred in the low-, 6.9% in the indeterminate-, and 17.7% in the high-risk groups (P=0.03) (Figure 2A). After an in-depth diagnostic work-up, patients were finally diagnosed as ‘without metastatic infection (6.3%)’, ‘with metastatic infection (15.8%)’, and ‘uncertain metastatic infection (77.9%)’. 30-day mortality increased markedly as the severity of diagnosis shifted from ‘without metastatic infection’ to ‘uncertain’ and ‘with metastatic infection’ (P=0.07) (Figure 2B). In multivariable analysis, independent factors associated with metastatic complications were suspicion of endocarditis in transthoracic echocardiography, clinical signs of metastatic infection, Pitt bacteremia score ≥4, and persistent bacteremia. Figure 1. Flowchart of risk stratification and final diagnosis Figure 2. Outcomes of metastatic infection and 30-day mortality. A, metastatic infection according to the risk stratification, B, 30-day mortality according to the final diagnosis Conclusion The new risk stratification system provides good discrimination in predicting metastatic complications, making it a reliable tool for guiding work-up and management of MRSAB. However, minimizing the number of ‘uncertain metastatic infection’ cases remains an area for improvement. Disclosures All Authors: No reported disclosures

Factors for mortality in patients with persistent Staphylococcus aureus bacteremia: The importance of treatment response rather than bacteremia duration.

The criteria for antibiotic failure in persistent Staphylococcus aureus bacteremia (SAB) are unclear, but treatment response and bacteremia duration are commonly used indicators of antibiotic failure. We evaluated the effects of treatment response and bacteremia duration on mortality in persistent SAB. We retrospectively identified patients with persistent SAB in four university-affiliated hospitals between 2017 and 2021. Bacteremia duration was calculated from the first day of active antibiotic therapy, and persistent SAB was defined as bacteremia lasting for 2 or more days. Defervescence and Pitt bacteremia score (PBS) were used to evaluate treatment response at treatment day 4. The primary outcome was 30-day in-hospital mortality. Time-dependent multivariable Cox regression analysis and subgroup analysis according to methicillin resistance were performed. A total of 221 patients was included in the study, and the 30-day in-hospital mortality was 28.5%. There was no significant difference in bacteremia duration between survived and deceased patients. Independent factors for mortality included age, Charlson comorbidity index, initial PBS, pneumonia, and removal of the eradicable focus. PBS at treatment day 4≥3 was the strongest risk factor (adjusted hazard ratio [HR]=4.260), but defervescence was not. Bacteremia duration was not an independent factor except for 13 days or more of methicillin-resistant SAB (adjusted HR=1.064). In patients with persistent SAB, PBS at treatment day 4 was associated with 30-day in-hospital mortality rather than defervescence and bacteremia duration. The results of this study could help determine early intensified treatment strategies in persistent SAB patients.

Risk Factors and Outcomes of Hematogenous Vertebral Osteomyelitis in Patients With Staphylococcus aureus Bacteremia.

Hematogenous vertebral osteomyelitis (HVOM) is an incompletely understood complication of Staphylococcus aureus bacteremia (SAB). Eligible SAB patients with and without HVOM were prospectively enrolled from 1995 through 2019 at Duke University Health System. HVOM was diagnosed either radiographically or microbiologically. Multivariable logistic regression analysis was performed to identify clinical and microbial factors associated with HVOM risk. All bloodstream S. aureus isolates were genotyped using spa typing. Of 3165 cases of SAB, 127 (4.0%) developed HVOM. Patients who experienced HVOM were more likely to have community-acquired SAB (30.7% vs 16.7%, P < .001), have a longer time to diagnosis of SAB (median, 5 days; interquartile range [IQR], 2-10.5 vs median, 2 days; IQR, 0-4; P < .001), and to exhibit persistent bacteremia (48.8% vs 20.6%, P < .001). A significant number of HVOM patients developed infective endocarditis (26% vs 15.2%, P = .002). Overall, 26.2% (n = 33) of SAB patients with HVOM underwent surgical intervention. Methicillin resistance (46.6% vs 41.7%, P = .318) and bacterial genotype were not associated with the development of HVOM. At the 12-month follow-up, 22% of patients with HVOM had died. Of the surviving patients, 20.4% remained on antibiotic therapy, and 29.6% had recurrence of either HVOM or SAB. Among patients with SAB, HVOM risk was associated with clinical factors and not bacterial genotype. Despite being a rare complication of SAB, patients with HVOM had high all-cause mortality rates and healthcare resource requirements up to 1 year after their HVOM diagnosis. Close clinical monitoring is indicated in this vulnerable population.

A Retrospective Study of Staphylococcus aureus Bacteremia in a Tertiary Hospital and Factors Associated with Mortality.

Staphylococcus aureus bacteremia (SAB) is a severe infection frequently associated with significant morbidity and mortality. Recent studies have shown that SAB mortality has decreased during the last decades. However, about 25% of patients suffering from the disease will ultimately die. Hence, there is an urgent need for more timely and efficient treatment of patients with SAB. The aim of the present study was to retrospectively evaluate a cohort of SAB patients hospitalized in a tertiary hospital and to identify factors independently associated with mortality. All 256 SAB patients hospitalized from January 2005 to December 2021 in the University Hospital of Heraklion, Greece, were evaluated. Their median age was 72 years, while 101 (39.5%) were female. Most SAB patients were cared for in medical wards (80.5%). The infection was community-acquired in 49.5%. Among all strains 37.9% were methicillin-resistant S. aureus (MRSA), however, definite treatment with an antistaphylococcal penicillin was given only in 22% of patients. Only 14.4% of patients had a repeat blood culture after the initiation of antimicrobial treatment. Infective endocarditis was present in 8%. In-hospital mortality has reached 15.9%. Female gender, older age, higher McCabe score, previous antimicrobial use, presence of a central venous catheter, neutropenia, severe sepsis, septic shock, and MRSA SAB were positively associated with in-hospital mortality, while monomicrobial bacteremia was negatively associated. The multivariate logistic regression model identified only severe sepsis (p = 0.05, odds ratio = 12.294) and septic shock (p = 0.007, odds ratio 57.18) to be independently positively associated with in-hospital mortality. The evaluation revealed high rates of inappropriate empirical antimicrobial treatment and non-adherence to guidelines, as shown, by the lack of repeat blood cultures. These data underline the urgent need for interventions with antimicrobial stewardship, increased involvement of infectious diseases physicians, educational sessions, and creation and implementation of local guidelines for improvement of the necessary steps for timely and efficient SAB treatment. Optimization of diagnostic techniques is needed to overcome challenges such as heteroresistance that may affect treatment. Clinicians should be aware of the factors associated with mortality in patients with SAB to identify those who are at a higher risk and optimize medical management.

Impact of the COVID-19 Pandemic on the Management of Staphylococcus aureus Bloodstream Infections in a Tertiary Care Hospital.

Staphylococcus aureus bacteremia (SAB) is associated with a high mortality rate. The clinical outcome of SAB patients highly depends on early diagnosis, adequate antibiotic therapy and source control. In the context of the COVID-19 pandemic, the health care system faced additional organizational challenges and the question arose whether structured screening and triaging for COVID-19 and shifting resources influence the management of SAB. Patients (n = 115) with SAB were enrolled in a retrospective comparative study with historical controls (March 2019-February 2021). The quality of SAB therapy was assessed with a point score, which included correct choice of antibiotic, adequate dosage of antibiotic, sufficient duration of therapy, early start of therapy after receipt of findings, focus search and taking control blood cultures 3-4 days after starting adequate antibiotic therapy. The quality of treatment before and after the onset of the COVID-19 pandemic were compared. No significant differences in the total score points were found between the pre-COVID-19 and COVID-19 cohort. All quality indicators, except the correct duration of antibiotic therapy, showed no significant differences in both cohorts. Furthermore, there were no significant differences in the outcome between both cohorts. The treatment quality of SAB therapy was comparable before and during the COVID-19 pandemic.

All Staphylococcus aureus bacteraemia-inducing strains can cause infective endocarditis: Results of GWAS and experimental animal studies

We aimed at determining whether specific S. aureus strains cause infective endocarditis (IE) in the course of Staphylococcus aureus bacteraemia (SAB). A genome-wide association study (GWAS) including 924 S. aureus genomes from IE (274) and non-IE (650) SAB patients from international cohorts was conducted, and a subset of strains was tested with two experimental animal models of IE, one investigating the early step of bacterial adhesion to inflamed mice valves, the second evaluating the local and systemic developmental process of IE on mechanically-damaged rabbit valves. The genetic profile of S. aureus IE and non-IE SAB strains did not differ when considering single nucleotide polymorphisms, coding sequences, and k-mers analysed in GWAS. In the murine inflammation-induced IE model, no difference was observed between IE and non-IE SAB strains both in terms of adhesion to the cardiac valves and in the propensity to cause IE; in the mechanical IE-induced rabbit model, there was no difference between IE and non-IE SAB strains regarding the vegetation size and CFU. All strains of S. aureus isolated from SAB patients must be considered as capable of causing this common and lethal infection once they have accessed the bloodstream.

1848. Predictors of 6-Month Mortality in Staphylococcus aureus Bacteremia: A Population-Based Study in Olmsted County, Minnesota, from 2006 to 2020

Abstract Background Staphylococcus aureus has high mortality rates, which is influenced by several factors related to the host-pathogen interaction. The current study aims to provide a contemporary evaluation of predictors of 6-month mortality rate in a population-based cohort of incident Staphylococcus aureus bacteremia (SAB) cases. Methods Retrospective population-based study of 541 adult residents of Olmsted County, MN with monomicrobial SAB from January 1, 2006 through December 31, 2020. The study’s primary outcome was 6-month mortality rate, and a survival analysis was prepared by the Kaplan-Meier method. Multivariable Cox regression was used to investigate risk factors associated with 6-month mortality. Results The median (IQR) age of 541 patients with SAB was 66.8 (54.4-78.5) years and 39.6% were female. The median Charlson Comorbidity Index (CCI) was 2 (1-4). SAB cases were healthcare-associated in 49.2% and 56.2% were methicillin-susceptible. Twenty percent of SAB cases had an unknown infection source and 38.3% had complicated bacteremia. There were 7 relapses within the first 12 weeks of follow-up, corresponding to a cumulative incidence rate of 1.3%. There were no re-infections through the remainder of the 6-month follow-up, although there were 2 recurrences after 7 months. Eighty-nine (16.5%) patients died within 1 month of SAB diagnosis and 144 (26.7%) patients died during the 6-month follow-up period. In a multivariable analysis, older age, elevated CCI, unknown source of SAB, and intensive care unit (ICU) admission were significant predictors of an increased 6-month mortality rate. In contrast, presence of diabetes mellitus was significantly associated with a decreased 6-month mortality rate; also, undergoing infectious diseases consultation was associated with reduced mortality in the first 2 weeks, but not for the remainder of the 6-month follow-up period. Conclusion To our knowledge, the current investigation represents the only contemporary population-based study determining significant predictors of mortality in SAB patients, namely, older age, higher CCI, unknown source of SAB, and ICU admission. This study also described one of the lowest 30-day mortality rates reported over the past 2 decades. Figure 1.Survival and reinfection rates of patients with SAB over 6 months. Abbreviations: SAB, Staphylococcus aureus bacteremia. Foot notes: The overall survival curve was derived by the Kaplan-Meier estimator, while the curve for reinfection was estimated by the cumulative incidence function taking into account the competing risk of death. Disclosures Larry M. Baddour, M.D., Boston Scientific: Advisor/Consultant|Botanix Pharmaceuticals: Advisor/Consultant|Roivant Sciences: Advisor/Consultant|UpToDate, Inc.: Royalty payments - authorship duties.

Abstract 15255: Clinical Risk Factors for Infective Endocarditis in Patients With Staphylococcus Aureus Bacteremia and the Diagnostic Utility of Transesophageal Echocardiogram

Background: Approximately 25% of patients with staphylococcus aureus bacteremia (SAB) develop infective endocarditis (IE), which has a consequent mortality of 46%. Current guidelines recommend routine transthoracic echocardiography (TTE) for patients with SAB; transesophageal echocardiogram (TEE) is reserved for those patients in whom initial TTE is negative and clinical suspicion for IE remains high. We sought to elucidate high risk features of SAB associated with the development of IE that warrant a TEE after a negative TTE. Methods: This retrospective study included 213 patients who were diagnosed with SAB at the University of New Mexico Hospital between 2010-2020. A pre-determined list of clinical risk factors along with TTE and TEE status was extracted from the electronic medical record (Table 1). Our primary outcome was the development of IE in patients with SAB. Multivariate logistic regression analysis was used to identify clinical risk factors for IE. Sensitivity and specificity of TTE and TEE was also calculated (Table 1). Results: Out of 213 patients with SAB, 68 patients met diagnostic criteria for infectious endocarditis. Most patients (n=209) underwent TTE and 117 patients underwent subsequent TEE. Initial TTE was diagnostic in 42 patients with a sensitivity of 63% and specificity of 94%; 45 patients had a diagnostic TEE with a sensitivity of 83% and specificity of 98%. Multivariate analysis showed significantly increased risk of IE in patients who had a permanent pacemaker (aOR 32.3, CI 5.23 - 281, p&lt;0.001) or a persistent fever (aOR 6.97, CI 2.42 - 21.0, P&lt;0.001). Conclusions: The routine use of TEE in patients with SAB for the diagnosis of IE may not be necessary and introduces unnecessary procedural risk. Based on our analysis, we recommend that SAB patients with a permanent pacemaker (or other intracardiac prosthetic) or a persistent fever despite appropriate antibiotic therapy be screened with TEE when initial TTE is negative.

A Fully Integrated Infectious Diseases and Antimicrobial Stewardship Telehealth Service Improves Staphylococcus aureus Bacteremia Bundle Adherence and Outcomes in 16 Small Community Hospitals.

Infectious diseases (ID) and antimicrobial stewardship (AS) improve Staphylococcus aureus bacteremia (SAB) outcomes. However, many small community hospitals (SCHs) lack on-site access to these services, and it is not known if ID telehealth (IDt) offers the same benefit for SAB. We evaluated the impact of an integrated IDt service on SAB outcomes in 16 SCHs. An IDt service offering IDt physician consultation plus IDt pharmacist surveillance was implemented in October 2016. Patients treated for SAB in 16 SCHs between January 2009 and August 2019 were identified for review. We compared SAB bundle adherence and outcomes between patients with and without an IDt consult (IDt group and control group, respectively). A total of 423 patients met inclusion criteria: 157 in the IDt group and 266 in the control group. Baseline characteristics were similar between groups. Among patients completing their admission at an SCH, IDt consultation increased SAB bundle adherence (79% vs 23%; odds ratio [OR], 16.9; 95% CI, 9.2-31.0). Thirty-day mortality and 90-day SAB recurrence favored the IDt group, but the differences were not statistically significant (5% vs 9%; P = .2; and 2% vs 6%; P = .09; respectively). IDt consultation significantly decreased 30-day SAB-related readmissions (9% vs 17%; P = .045) and increased length of stay (median [IQR], 5 [5-8] days vs 5 [3-7] days; P = .04). In a subgroup of SAB patients with a controllable source, IDt appeared to have a mortality benefit (2% vs 9%; OR, 0.12; 95% CI, 0.01-0.98). An integrated ID/AS telehealth service improved SAB management and outcomes at 16 SCHs. These findings provide important insights for other IDt programs.

Diagnostic MALDI-TOF MS can differentiate between high and low toxic Staphylococcus aureus bacteraemia isolates as a predictor of patient outcome.

Staphylococcus aureus bacteraemia (SAB) is a major cause of blood-stream infection (BSI) in both healthcare and community settings. While the underlying comorbidities of a patient significantly contributes to their susceptibility to and outcome following SAB, recent studies show the importance of the level of cytolytic toxin production by the infecting bacterium. In this study we demonstrate that this cytotoxicity can be determined directly from the diagnostic MALDI-TOF mass spectrum generated in a routine diagnostic laboratory. With further development this information could be used to guide the management and improve the outcomes for SAB patients.

Clinically unsuspected orthopedic implants during S. aureus bacteremia do not require additional diagnostic work-up

PurposeTo assess the likelihood of occult infection in patients with clinically unsuspected orthopedic implants during Staphylococcus aureus bacteremia (SAB).MethodsIn a retrospective study in two Dutch hospitals, we included all patients with SAB between 2013 and 2020 with one or more orthopedic implants in whom [18F]FDG-PET/CT was performed. The primary outcome was the percentage of patients who had an orthopedic implant-related infection by S. aureus. We also compared clinical parameters in patients with clinically suspected and unsuspected implants.ResultsFifty-five of 191 (29%) orthopedic implants in 118 SAB patients included had clinical signs of infection. Of all 136 unsuspected implants, 5 (3%, all arthroplasties), showed increased [18F]FDG uptake around the prosthesis on [18F]FDG-PET/CT. The clinical course of these patients without clinically overt infection or relapse of bacteremia during follow-up of a median of 48 months (range 0–48), however, argued against prosthetic joint infection.ConclusionAlthough orthopedic implants are evidently a risk factor for metastatic infection during SAB, the absence of clinical symptoms obviate the need of additional investigations or prolonged antibiotic treatment.

Discrimination of Methicillin-resistant Staphylococcus aureus by MALDI-TOF Mass Spectrometry with Machine Learning Techniques in Patients with Staphylococcus aureus Bacteremia.

Early administration of proper antibiotics is considered to improve the clinical outcomes of Staphylococcus aureus bacteremia (SAB), but routine clinical antimicrobial susceptibility testing takes an additional 24 h after species identification. Recent studies elucidated matrix-assisted laser desorption/ionization time-of-flight mass spectra to discriminate methicillin-resistant strains (MRSA) or even incorporated with machine learning (ML) techniques. However, no universally applicable mass peaks were revealed, which means that the discrimination model might need to be established or calibrated by local strains’ data. Here, a clinically feasible workflow was provided. We collected mass spectra from SAB patients over an 8-month duration and preprocessed by binning with reference peaks. Machine learning models were trained and tested by samples independently of the first six months and the following two months, respectively. The ML models were optimized by genetic algorithm (GA). The accuracy, sensitivity, specificity, and AUC of the independent testing of the best model, i.e., SVM, under the optimal parameters were 87%, 75%, 95%, and 87%, respectively. In summary, almost all resistant results were truly resistant, implying that physicians might escalate antibiotics for MRSA 24 h earlier. This report presents an attainable method for clinical laboratories to build an MRSA model and boost the performance using their local data.

18F]FDG-PET/CT in Staphylococcus aureus bacteremia: a systematic review

Objectives[18F]FDG-PET/CT is used for diagnosing metastatic infections in Staphylococcus aureus bacteremia (SAB) and guidance of antibiotic treatment. The impact of [18F]FDG-PET/CT on outcomes remains to be determined. The aim of this systematic review was to summarize the effects of [18F]FDG-PET/CT on all-cause mortality and new diagnostic findingsin SAB.MethodsWe systematically searched PubMed, EMBASE.com, Web of Science, and Wiley’s Cochrane library from inception to 29 January 2021. Eligible studies were randomized controlled trials, clinically controlled trials, prospective and retrospective cohort studies, and case–control studies investigating the effects of [18F]FDG-PET/CT in hospitalized adult patients with SAB. We excluded studies lacking a control group without [18F]FDG-PET/CT. Risk of bias was assessed using the ROBINS-I tool and certainty of evidence using the GRADE approach by two independent reviewers.ResultsWe identified 1956 studies, of which five were included in our qualitative synthesis, including a total of 880 SAB patients. All studies were non-randomized and at moderate or serious risk of bias. Four studies, including a total of 804 patients, reported lower mortality in SAB patients that underwent [18F]FDG-PET/CT. One study including 102 patients reported more detected metastatic foci in the participants in whom [18F]FDG-PET/CT was performed.DiscussionWe found low certainty of evidence that [18F]FDG-PET/CT reduces mortality in patients with SAB. This effect is possibly explained by a higher frequency of findings guiding optimal antibiotic treatment and source control interventions.

Unreliability of Clinical Prediction Rules to Exclude without Echocardiography Infective Endocarditis in Staphylococcus aureus Bacteremia

Background: It is unclear whether the use of clinical prediction rules is sufficient to rule out infective endocarditis (IE) in patients with Staphylococcus aureus bacteremia (SAB) without an echocardiogram evaluation, either transthoracic (TTE) and/or transesophageal (TEE). Our primary purpose was to test the usefulness of PREDICT, POSITIVE, and VIRSTA scores to rule out IE without echocardiography. Our secondary purpose was to evaluate whether not performing an echocardiogram evaluation is associated with higher mortality. Methods: We conducted a unicentric retrospective cohort including all patients with a first SAB episode from January 2015 to December 2020. IE was defined according to modified Duke criteria. We predefined threshold cutoff points to consider that IE was ruled out by means of the mentioned scores. To assess 30-day mortality, we used a multivariable regression model considering performing an echocardiogram as covariate. Results: Out of 404 patients, IE was diagnosed in 50 (12.4%). Prevalence of IE within patients with negative PREDICT, POSITIVE, and VIRSTA scores was: 3.6% (95% CI 0.1–6.9%), 4.9% (95% CI 2.2–7.7%), and 2.2% (95% CI 0.2–4.3%), respectively. Patients with negative VIRSTA and negative TTE had an IE prevalence of 0.9% (95% CI 0–2.8%). Performing an echocardiogram was independently associated with lower 30-day mortality (OR 0.24 95% CI 0.10–0.54, p = 0.001). Conclusion: PREDICT and POSITIVE scores were not sufficient to rule out IE without TEE. In patients with negative VIRSTA score, it was doubtful if IE could be discarded with a negative TTE. Not performing an echocardiogram was associated with worse outcomes, which might be related to presence of occult IE. Further studies are needed to assess the usefulness of clinical prediction rules in avoiding echocardiographic evaluation in SAB patients.

181. Demographic and Geographic Epidemiology of Staphylococcus aureus Bacteremia using Geographic Information Systems Mapping and Spatial Statistics

BackgroundRisk factors for community-associated Staphylococcus aureus bacteremia (SAB) are incompletely understood. We used Geographic Information Systems (GIS) and spatial statistics to analyze demographic and geographic epidemiology of SAB in the community.MethodsWe used the S. aureus Bacteremia Group Prospective Cohort Study (SABG-PCS) at Duke University Medical Center to obtain demographic and clinical data. We used the American Community Survey and U.S. Census to supply neighborhood variables. Secular trends in demographic and clinical characteristics of SAB patients prospectively enrolled between 1995 and 2015 (n = 2478) were determined using linear regressions. To characterize spatial patterns in Methicillin-resistant S. aureus (MRSA) bacteremia compared to Methicillin-susceptible S. aureus (MSSA) bacteremia, we used GIS mapping and selected a subgroup of patients (n = 667) living in and around Durham County, North Carolina. We then created generalized additive models (GAMs) using this subgroup to detect geographic heterogeneities in probabilities of MRSA infections compared to MSSA infections.ResultsWe found evidence of changing demographic and clinical characteristics of SAB patients over the 21-year period. The proportion of infections acquired in the community increased significantly (p < 0.0001). However, we did not detect spatial heterogeneities of MRSA infections in Durham County. Patient location of residence was not significantly associated with antimicrobial-resistant infections. Patient age and year of hospital admission were the only statistically significant covariates in our spatial models.ConclusionWe utilized a novel method to analyze SAB in the community using GIS and spatial statistics. Future research should prioritize community transmission of S. aureus to identify robust risk factors for infection.Disclosures Vance G. Fowler, Jr., MD, MHS, Achaogen (Consultant)Advanced Liquid Logics (Grant/Research Support)Affinergy (Consultant, Grant/Research Support)Affinium (Consultant)Akagera (Consultant)Allergan (Grant/Research Support)Amphliphi Biosciences (Consultant)Aridis (Consultant)Armata (Consultant)Basilea (Consultant, Grant/Research Support)Bayer (Consultant)C3J (Consultant)Cerexa (Consultant, Other Financial or Material Support, Educational fees)Contrafect (Consultant, Grant/Research Support)Debiopharm (Consultant, Other Financial or Material Support, Educational fees)Destiny (Consultant)Durata (Consultant, Other Financial or Material Support, educational fees)Genentech (Consultant, Grant/Research Support)Green Cross (Other Financial or Material Support, Educational fees)Integrated Biotherapeutics (Consultant)Janssen (Consultant, Grant/Research Support)Karius (Grant/Research Support)Locus (Grant/Research Support)Medical Biosurfaces (Grant/Research Support)Medicines Co. (Consultant)MedImmune (Consultant, Grant/Research Support)Merck (Grant/Research Support)NIH (Grant/Research Support)Novadigm (Consultant)Novartis (Consultant, Grant/Research Support)Pfizer (Grant/Research Support)Regeneron (Consultant, Grant/Research Support)sepsis diagnostics (Other Financial or Material Support, Pending patent for host gene expression signature diagnostic for sepsis.)Tetraphase (Consultant)Theravance (Consultant, Grant/Research Support, Other Financial or Material Support, Educational fees)Trius (Consultant)UpToDate (Other Financial or Material Support, Royalties)Valanbio (Consultant, Other Financial or Material Support, Stock options)xBiotech (Consultant)

The Impact of a Pharmacist-Driven Staphylococcus aureus Bacteremia Initiative in a Community Hospital: A Retrospective Cohort Analysis.

Purpose: Staphylococcus aureus is a leading cause of bacteremia with a 30-day mortality of 20%. This study evaluated outcomes after implementation of a pharmacist-driven Staphylococcus aureus bacteremia (SAB) initiative in a community hospital. Methods: This retrospective cohort analysis compared patients admitted with SAB between May 2015 and April 2018 (intervention group) to those admitted between May 2012 and April 2015 (historical control group). Pharmacists were notified of and responded to blood cultures positive for Staphylococcus aureus by contacting provider(s) with a bundle of recommendations. Components of the SAB bundle included prompt source control, selection of appropriate intravenous antibiotics, appropriate duration of therapy, repeat blood cultures, echocardiography, and infectious diseases consult. Demographics (age, gender, and race) were collected at baseline. Primary outcome was in-hospital mortality. Compliance with bundle components was also assessed. Results: Eighty-three patients in the control group and 110 patients in the intervention group were included in this study. Demographics were similar at baseline. In-hospital mortality was lower in the intervention group (3.6% vs. 15.7%; p = 0.0033). Bundle compliance was greater in the intervention group (69.1% vs. 39.8%; p < 0.0001). Conclusions: We observed a significant reduction in in-hospital mortality and increased treatment bundle compliance in the intervention cohort with implementation of a pharmacist-driven SAB initiative. Pharmacists’ participation in the care of SAB patients in the form of recommending adherence to treatment bundle components drastically improved clinical outcomes. Widespread adoption and implementation of similar practice models at other institutions may reduce in-hospital mortality for this relatively common and life-threatening infection.

Prediction Rules for Ruling Out Endocarditis in Patients With Staphylococcus aureus Bacteremia.

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. 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. 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. 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. Netherlands Trial Register code 6669.