Blood Culture-negative Infective Endocarditis Research Articles

Make modern microbiology matter more in the 2023 ESC guidelines for the management of infective endocarditis.

The ESC 2023 guidelines for the management of endocarditis stress that a multidisciplinary approach is needed to manage patients with infective endocarditis (IE). In our view the guidelines do not include the relevant perspectives from modern microbiology. The diagnostic criteria for IE were changed in the ESC 2023 guidelines and many IE-causing pathogens are either not clearly defined or not even mentioned. Moreover, the improved understanding of the relation between bacterial species and the risk for IE has not been implemented. The guidelines give detailed, and in our view not correct, instructions about diagnostic testing in blood culture negative IE without presenting proper evidence. Other important diagnostic aspects such as the value of repeated blood cultures and incubation time for blood cultures are not discussed. We believe that a multidisciplinary collaboration, including microbiologists, would have improved these guidelines and we hope for a future harmonization of diagnostic criteria for IE.

Culture-negative endocarditis with multifocal spread and flail mitral valve leaflet: a case report

Introduction: Blood culture-negative infective endocarditis is the condition in which a causative organism cannot be identified after inoculation of at least three samples using standard blood-culture systems for 7 days. It has a low reported incidence of about 2.5–31%. Causes may be infectious or non-infectious; use of prior antibiotic therapy is usually the leading factor. Case presentation: The authors present a case of true culture-negative endocarditis involving the mitral valve, with multiple foci of spread including brain, spleen, liver, and Intervertebral disc, which remained persistent despite treatment with intravenous broad-spectrum antibiotics on an inpatient and outpatient basis but eventually improved after upgrading alternative broad-spectrum antibiotic for an extended duration. The patient had complications in the form of a flail mitral valve with persistent mitral regurgitation, requiring mitra-clip placement. Discussion: Positive blood culture is one of the major diagnostic criteria to establish infective endocarditis. Patients may have persistent negative cultures due to previous antibiotic use, the presence of fastidious organisms, or the use of inappropriate techniques or media. Involvement of a multidisciplinary team, use of multimodal investigations, and appropriate antibiotic stewardship are crucial. Extended duration of treatment and upgrading antibiotics can be helpful next steps in highly suspicious cases. With multifocal spread as in our case, it further becomes challenging to control and treat the infection as it is frequently connected with higher morbidity and mortality. Conclusion: Blood culture-negative endocarditis is an entity that can present with early complications. It is diagnostically and therapeutically challenging to treat such patients. Multimodal approaches for early diagnosis and appropriate treatment are crucial owing to its high morbidity and mortality.

Clinicopathological differences between Bartonella and other bacterial endocarditis-related glomerulonephritis - our experience and a pooled analysis.

Although Staphylococcus aureus is the leading cause of acute infective endocarditis (IE) in adults, Bartonella spp. has concomitantly emerged as the leading cause of "blood culture-negative IE" (BCNE). Pre-disposing factors, clinical presentation and kidney biopsy findings in Bartonella IE-associated glomerulonephritis (GN) show subtle differences and some unique features relative to other bacterial infection-related GNs. We highlight these features along with key diagnostic clues and management approach in Bartonella IE-associated GN. We conducted a pooled analysis of 89 cases of Bartonella IE-associated GN (54 published case reports and case series; 18 published conference abstracts identified using an English literature search of several commonly used literature search modalities); and four unpublished cases from our institution. Bartonella henselae and Bartonella quintana are the most commonly implicated species causing IE in humans. Subacute presentation, affecting damaged native and/or prosthetic heart valves, high titer anti-neutrophil cytoplasmic antibodies (ANCA), mainly proteinase-3 (PR-3) specificity, fastidious nature and lack of positive blood cultures of these Gram-negative bacilli, a higher frequency of focal glomerular crescents compared to other bacterial infection-related GNs are some of the salient features of Bartonella IE-associated GN. C3-dominant, but frequent C1q and IgM immunofluorescence staining is seen on biopsy. A "full-house" immunofluorescence staining pattern is also described but can be seen in IE -associated GN due to other bacteria as well. Non-specific generalized symptoms, cytopenia, heart failure and other organ damage due to embolic phenomena are the highlights on clinical presentation needing a multi-disciplinary approach for management. Awareness of the updated modified Duke criteria for IE, a high index of suspicion for underlying infection despite negative microbiologic cultures, history of exposure to animals, particularly infected cats, and use of send-out serologic tests for Bartonella spp. early in the course of management can help in early diagnosis and initiation of appropriate treatment. Diagnosis of IE-associated GN can be challenging particularly with BCNE. The number of Bartonella IE-associated GN cases in a single institution tends to be less than IE due to gram positive cocci, however Bartonella is currently the leading cause of BCNE. We provide a much-needed discussion on this topic.

Blood culture-negative infective endocarditis caused by <i>Bartonella henselae</i> diagnosed through repeated echocardiography: A case report

Blood culture-negative infective endocarditis caused by <i>Bartonella henselae</i> diagnosed through repeated echocardiography: A case report

Clinical profile of infective endocarditis: a single centre experience

Background: Infective endocarditis (IE) is an illness which still has a high rate of morbidity and mortality despite the availability of improved diagnostic and treatment amenities in the developing world. With an increasing number of children with congenital heart disease (CHD) undergoing corrective treatments, improved pediatric intensive care, better antimicrobial treatments, and a relative decrease in rheumatic heart disease (RHD) over the years, the epidemiology of pediatric IE in Bangladesh may be undergoing a change. The present study aims to describe the epidemiological, clinical, laboratory profile and outcome of IE among selected patients. Methods: This prospective cross-sectional study was conducted with a total of 35 patient of IE from January 2020 to December 2021, who were admitted in pediatric cardiology department, Bangladesh Shishu hospital and institute were enrolled in this study which was diagnosed according to modified Duke criteria. Results: There were 35 children diagnosed with IE during this period. The mean age at presentation was 84 months (range: 2-216 months). CHD (n=28/35, 80%) was the most common predisposing condition. A total of 20 % (7/35) patients had no preexisting structural heart disease. Staphylococcus aureus was the most common etiological agent. Blood culture positive IE was (n=18, 51.4%), blood culture-negative IE was (n=17, 48.6 %). Six patients (17.1%) died during the hospital stay. Conclusions: Increasingly younger children are being diagnosed with IE in Bangladesh and a significant number of them are in the setting of a structurally normal heart.

Microbiological Etiology in Patients with IE Undergoing Surgery and for Patients with Medical Treatment Only: A Nationwide Study from 2010 to 2020.

Microbiological etiology has been associated with surgery for infective endocarditis (IE) during admission, especially Staphylococcus aureus. We aimed to compare patient characteristics, microbiological characteristics, and outcomes by treatment choice (surgery or not). We identified patients with first-time IE between 2010 and 2020 and examined the microbiological etiology of IE according to treatment choice. To identify factors associated with surgery during initial admission, we used the Aalen-Johansen estimator and an adjusted cause-specific Cox model. One-year mortality stratified by microbiological etiology and treatment choice was assessed using unadjusted Kaplan-Meier estimates and an adjusted Cox proportional hazard model. A total of 6255 patients were included, of which 1276 (20.4%) underwent surgery during admission. Patients who underwent surgery were younger (65 vs. 74 years) and less frequently had cerebrovascular disease, cardiovascular disease, diabetes, and chronic kidney disease. Patients with Staphylococcus aureus IE were less likely to undergo surgery during admission (13.6%) compared to all other microbiological etiologies. One-year mortality according to microbiological etiology in patients who underwent surgery was 7.0%, 5.3%, 5.5%, 9.6%, 13.2, and 11.2% compared with 24.2%, 19.1%, 27,6%, 25.2%, 21%, and 16.9% in patients who received medical therapy for Staphylococcus aureus, Streptococcus spp., Enterococcus spp., coagulase-negative Staphylococci, "other microbiological etiologies", and blood culture-negative infective endocarditis, respectively. Patients with IE who underwent surgery differed in terms of microbiology, more often having Streptococci than those who received medical therapy. Contrary to expectations, Staphylococcus aureus was more common among patients who received medical therapy only.

Updates in Culture-Negative Endocarditis.

Blood culture-negative infective endocarditis (BCNE) is a challenging condition associated with significant morbidity and mortality. This review discusses the epidemiology, microbiology, diagnosis, and treatment of BCNE considering advancements in molecular diagnostics and increased access to cardiac surgery. BCNE can be categorized into bacterial endocarditis with sterilized blood cultures due to previous antibiotic treatment, endocarditis caused by fastidious microorganisms, and true BCNE caused by intracellular organisms that cannot be cultured using traditional techniques. Non-infectious causes such as nonbacterial thrombotic endocarditis should also be considered. Diagnostic approaches involve thorough patient history; blood and serum testing, including appropriate handling of blood cultures; serological testing; and molecular techniques such as targeted and shotgun metagenomic sequencing. Where available, evaluation of explanted cardiac tissue through histopathology and molecular techniques is crucial. The therapy for BCNE depends on the likely causative agent and the presence of prosthetic material, with surgical intervention often required.

Patient Characteristics, Microbiology, and Mortality of Infective Endocarditis After Transcatheter Aortic Valve Implantation.

Infective endocarditis (IE) after transcatheter aortic valve implantation (TAVI) is associated with high mortality and surgery is rarely performed. Thus, to inform on preventive measures and treatment strategies, we investigated patient characteristics and microbiology of IE after TAVI. Using Danish nationwide registries, we identified patients with IE after TAVI, IE after non-TAVI prosthetic valve (nTPV), and native valve IE. Patient characteristics; overall, early (≤12 m), and late IE (>12 m) microbiology; and unadjusted and adjusted mortality were compared. We identified 273, 1022, and 5376 cases of IE after TAVI, IE after nTPV, and native valve IE. Age and frailty were highest among TAVI IE (4.8%; median age: 82 y; 61.9% frail). Enterococcus spp. were common for IE after TAVI (27.1%) and IE after nTPV (21.2%) compared with native valve IE (11.4%). Blood culture-negative IE was rare in IE after TAVI (5.5%) compared with IE after nTPV (15.2%) and native valve IE (13.5%). The unadjusted 90-day mortality was comparable, but the 5-year mortality was highest for IE after TAVI (75.2% vs 57.2% vs 53.6%). In Cox models adjusted for patient characteristics and bacterial etiology for 1-90 days and 91-365 days, there was no significant difference in mortality rates. Patients with IE after TAVI are older and frailer, enterococci and streptococci are often the etiologic agents, and are rarely blood culture negative compared with other IE patients. Future studies regarding antibiotic prophylaxis strategies covering enterococci should be considered in this setting.

16S rRNA Gene PCR/Sequencing of Heart Valves for Diagnosis of Infective Endocarditis in Routine Clinical Practice.

Sequencing is increasingly used for infective endocarditis (IE) diagnosis. Here, the performance of 16S rRNA gene PCR/sequencing of heart valves utilized in routine clinical practice was compared with conventional IE diagnostics. Subjects whose heart valves were sent to the clinical microbiology laboratory for 16S rRNA gene PCR/sequencing from August 2020 through February 2022 were studied. A PCR assay targeting V1 to V3 regions of the 16S rRNA gene was performed, followed by Sanger and/or next-generation sequencing (NGS) (using an Illumina MiSeq), or reported as negative, depending on an algorithm that included the PCR cycle threshold value. Fifty-four subjects, including 40 with IE, three with cured IE, and 11 with noninfective valvular disease, were studied. Thirty-one positive results, 11 from NGS and 20 from Sanger sequencing, were generated from analysis of 16S rRNA gene sequence(s). Positivity rates of blood cultures and 16S rRNA gene PCR/sequencing of valves were 55% and 75%, respectively (P = 0.06). In those with prior antibiotic exposure, positivity rates of blood cultures and 16S rRNA gene PCR/sequencing of valves were 11% and 76%, respectively (P < 0.001). Overall, 61% of blood culture-negative IE subjects had positive valve 16S rRNA gene PCR/sequencing results. 16S rRNA gene-based PCR/sequencing of heart valves is a useful diagnostic tool for pathogen identification in patients with blood culture-negative IE undergoing valve surgery in routine clinical practice.

A Case of Blood Culture-Negative Infective Endocarditis Presenting as Recurrent Ischemic Stroke (P8-10.007)

<h3>Objective:</h3> We present a unique case of recurrent ischemic stroke in a patient with blood culture-negative bacterial endocarditis. <h3>Background:</h3> The incidence of infective endocarditis (IE) has steadily increased in the past decade. About 2–7% of IE cases have negative blood cultures, making it difficult to diagnose with worse resulting prognoses. The risk of neurological complications in culture-negative IE, such as stroke, are high and linked to poor clinical outcomes. However, there are limited data on the incidence of stroke as an isolated presenting symptom or on the rate of stroke recurrence in this population. <h3>Design/Methods:</h3> NA <h3>Results:</h3> A 57-year-old woman with a history of diabetes mellitus, hypertension, and coronary artery disease presented with recurrent multi-territorial ischemic strokes. Her initial work-up showed unclear etiology. A transesophageal echocardiogram was obtained and demonstrated a 0.5×1 cm mobile echodensity on the mitral valve, concerning for either thrombus or vegetation. Thrombophilic laboratory results displayed an indeterminate lupus anticoagulant cascade. As the patient lacked infectious symptoms with an extensive negative infectious workup, she was started on anticoagulation due to possible thrombotic source in the setting of thrombophilia. However, the patient suffered another ischemic stroke while fully anticoagulated. With this being her third stroke in a seven-month period, the patient underwent surgical resection of the lesion. At the time of surgery, the mass was noted to appear as an infectious vegetation, and she was treated with broad-spectrum antibiotics for presumed culture-negative endocarditis. The valve culture later grew <i>Staphylococcus epidermidis</i>. Daptomycin was continued and she has had no additional strokes to date. <h3>Conclusions:</h3> It is well-established that stroke is a common complication of IE. However, little has been documented about stroke as the presenting symptom in blood culture-negative IE. Therefore, it is important to maintain a high degree of suspicion for indolent infection to pursue additional work-up and prevent any delays in treatment. <b>Disclosure:</b> Ms. Chatfield has nothing to disclose. Ms. Braddick has nothing to disclose. Dr. Sobhani has nothing to disclose.

Infectious endocarditis caused by Bartonella henselae associated with infected pets: two case reports

BackgroundBlood culture-negative infective endocarditis is a potentially severe disease that can be associated with infectious agents such as Bartonella spp., Coxiella burnetti, Tropheryma whipplei, and some fungi.Case presentationReported here are two cases of blood culture-negative infective endocarditis in patients with severe aortic and mitral regurgitation in Brazil; the first case is a 47-year-old white man and the second is a 62-year-old white woman. Bartonella henselae deoxyribonucleic acid was detectable in the blood samples and cardiac valve with vegetation paraffin-fixed tissue samples. Additionally, an investigation was carried out on patients’ pets, within the context of One Health, and serum samples collected from cats and dogs were reactive by indirect immunofluorescence assay.ConclusionsEven though the frequency of bartonellosis in Brazil is unknown, physicians should be aware of the possibility of blood culture-negative infective endocarditis caused by Bartonella, particularly in patients with weight loss, kidney changes, and epidemiological history for domestic animals.

Thromboembolic phenomenon to bilateral lower limbs is a catastrophic complication of blood culture-negative infective endocarditis

Background: Blood culture-negative infective endocarditis (BCNIE) refers to infective endocarditis (IE) with negative microorganism growth using usual blood culture method. It poses dilemma in terms of diagnosis, associated complication, and treatment. The study aims to highlight the occurrence of acute bilateral lower limb ischemia in BCNIE and its management approach. Case presentation: We present a BCNIE patient who developed acute bilateral lower limb ischemia, Rutherford stage 2b despite on course of antibiotic treatment. Patient underwent emergency bilateral open femoral embolectomy and right profundaplasty. A full six-weeks course of antibiotics and short-term anticoagulant successfully reverse the acute ischemic event. Conclusion: This case highlighted that despite the rarity of BCNIE causing limb ischemia, it can still occur due to significant risk factors. The early recognition of acute limb ischemia and prompt treatment are deemed important in saving the threatened limb from being amputated.

Complex pathogens in infective endocarditis

Infective endocarditis (IE) is a complex disease whose prognosis depends on the causative microorganism, among other factors. The latter can be difficult to identify and/or treat. In this narrative review, we identify knowledge gaps in the diagnosis and antimicrobial treatment of IE, and attempt to shed light on current questions. Specifically, we: (1) analyze the factors that may hinder the microbiological diagnosis of blood culture-negative IE, as well as the role of new imaging techniques, such as 18F-fluorodeoxyglucose ([18F]FDG PET/CT), in the diagnostic capacity of this disease, understanding their advantages and assuming their limitations; (2) discuss the therapeutic approach to various difficult-to-treat microorganisms. In particular, we focus on the treatment of staphylococcal IE since, at present, staphylococci are the most frequent cause of IE in developed countries and staphylococcal IE is one of those with the highest short- and long-term mortality. We critically evaluate the current evidence on combination therapy and address the occurrence of serious side effects, an aspect that is often overlooked owing to the severity of the infection; and (3) emphasize the need for home antimicrobial treatment of patients with IE, as these are fragile people who benefit from an early return to their environment. This poses undoubted logistical challenges and requires robust evidence to ensure the best short- and long-term outcomes.

Blood Culture Negative Endocarditis: A Review of Laboratory Diagnostic Approaches

Infective endocarditis is a potentially fatal condition, and identifying the pathogen is crucial to optimizing antibiotic treatment. While a blood culture takes time and may yield negative results, it remains the gold standard for diagnosis, blood culture-negative endocarditis, which accounts for up to 20% of infective endocarditis cases, poses a clinical challenge with increasing mortality. To better understand the etiology of blood culture-negative infective endocarditis, we reviewed non-culture-based strategies and compared the results. Serology tests work best in limited pathogens, such as Coxiella burnetii and Bartonella infections. Most of the pathogens identified by broad-range PCR tests are Streptococcus spp, Staphylococcus spp and Propionibacterium spp. adding specific real-time PCR assays to the systematic PCR testing of patients with blood culture-negative endocarditis will increase the efficiency of diagnosis. Recently, metagenomic next-generation sequencing has also shown promising results.

A retrospective analysis of blood culture-negative endocarditis at a tertiary care centre in Switzerland

Numerous studies from different countries have contributed to an improved understanding of blood culture-negative infective endocarditis. However, little is known about its epidemiology and microbiology in Switzerland. We aimed to assess the epidemiology and microbiology of blood culture-negative endocarditis at the University Hospital Zurich, Switzerland. We screened all patients hospitalised between 1997 and 2020 with possible or definite endocarditis at our institution. Thereof, we identified all cases with blood culture-negative endocarditis and retrospectively retrieved patient characteristics, microbiological, histopathological, radiographicand surgical data from medical records. Among 861 patients screened, 66 (7.7%) cases of blood culture-negative endocarditis were identified. Thereof, 31 cases could be microbiologically documented or not documented (n = 30), and in five cases a non-infectious aetiology was confirmed. Endocarditis predominantly affected men (77%) and the left heart (79%);predisposing factors were prosthetic valves (42%), congenital heart disease (35%) and prior endocarditis (14%). The most common reasons for negative blood cultures were antibiotic treatment prior to blood culture sampling (35%), fastidious and slow growing microorganisms (30%) and definite non-infective endocarditis (8%). Coxiella burnetii and Bartonella spp. were the most common fastidious bacteria identified. In addition to serology, identification of causative microorganisms was possible by microbiological and/or histopathological analysis of tissue samples, of which polymerasechain reaction testing (PCR) of the 16S ribosomal RNA proved to be most successful. The present study provides a detailed analysis of blood culture-negative endocarditis over a time span of more than 20 years in Zurich, Switzerland. Antibiotic treatment prior to blood collection, and fastidious and slow growing organisms were identified as main reasons for sterile blood cultures. Typical culture-negative bacteria were mainly found by PCR and/or culture of tissue samples.

Blood culture-negative infective endocarditis with thalassemia and neurological complication: A dangerous combination

Blood culture-negative infective endocarditis with thalassemia and neurological complication: A dangerous combination

Molecular and Serological Diagnostic Approach to Define the Microbiological Origin of Blood Culture-Negative Infective Endocarditis.

Blood culture-negative infective endocarditis (BCNIE) poses a significant challenge in determining the best antibiotic regimen for this life-threatening infection, which should be treated with as specific and effective a regimen as feasible. The goal of this study was to determine the prevalence of BCNIE among definite infective endocarditis (IE) cases and to study the impact of a molecular and serological diagnostic approach in defining the microbiological origin of BCNIE. This study included 94 definite IE cases. Serum and blood samples from BCNIE patients were tested using serological, broad-range PCR, and sequencing assays. Valve tissue sections obtained from 42 operated patients were subjected to culture and molecular studies. BCNIE accounted for 63 (67%) of the cases. Of these cases, blood PCR followed by sequencing could diagnose 11 cases. Zoonotic infective endocarditis was detected in 7 (11%) patients by serology and PCR (four Brucella, two Bartonella, and one Coxiella). Sequencing of valve PCR bands revealed 30 positive cases. Therefore, the percentage of BCNIE with unidentified etiology was reduced from 67% to 27.7% through a combination of all diagnostic procedures utilized in our study. Blood and valve PCR and sequencing assays are valuable techniques for the etiological diagnosis of BCNIE, especially in cases with previous antibiotic therapy. However, these tests should be used as part of a larger diagnostic strategy that includes serology, microscopy, and valve culture. The use of an automated blood culture system, and proper blood culture collection before ordering antibiotics, will guide IE etiological diagnosis.

Temporal Changes, Patient Characteristics, and Mortality, According to Microbiological Cause of Infective Endocarditis: ANationwide Study.

BackgroundMonitoring of microbiological cause of infective endocarditis (IE) remains key in the understanding of IE; however, data from large, unselected cohorts are sparse. We aimed to examine temporal changes, patient characteristics, and in‐hospital and long‐term mortality, according to microbiological cause in patients with IE from 2010 to 2017.Methods and ResultsLinking Danish nationwide registries, we identified all patients with first‐time IE. In‐hospital and long‐term mortality rates were assessed according to microbiological cause and compared using multivariable adjusted logistic regression analysis and Cox proportional hazard analysis, respectively. A total of 4123 patients were included. Staphylococcus aureus was the most frequent cause (28.1%), followed by Streptococcus species (26.0%), Enterococcus species (15.5%), coagulase‐negative staphylococci (6.2%), and “other microbiological causes” (5.3%). Blood culture–negative IE was registered in 18.9%. The proportion of blood culture–negative IE declined during the study period, whereas no significant changes were seen for any microbiological cause. Patients with Enterococcus species were older and more often had a prosthetic heart valve compared with other causes. For Streptococcus species IE, in‐hospital and long‐term mortality (median follow‐up, 2.3 years) were 11.1% and 58.5%, respectively. Compared with Streptococcus species IE, the following causes were associated with a higher in‐hospital mortality: S aureus IE (odds ratio [OR], 3.48 [95% CI, 2.74–4.42]), Enterococcus species IE (OR, 1.48 [95% CI, 1.11–1.97]), coagulase‐negative staphylococci IE (OR, 1.79 [95% CI, 1.21–2.65]), “other microbiological cause” (OR, 1.47 [95% CI, 0.95–2.27]), and blood culture–negative IE (OR, 1.99 [95% CI, 1.52–2.61]); and the following causes were associated with higher mortality following discharge (median follow‐up, 2.9 years): S aureus IE (hazard ratio [HR], 1.39 [95% CI, 1.19–1.62]), Enterococcus species IE (HR, 1.31 [95% CI, 1.11–1.54]), coagulase‐negative staphylococci IE (HR, 1.07 [95% CI, 0.85–1.36]), “other microbiological cause” (HR, 1.45 [95% CI, 1.13–1.85]), and blood culture–negative IE (HR, 1.05 [95% CI, 0.89–1.25]).ConclusionsThis nationwide study showed that S aureus was the most frequent microbiological cause of IE, followed by Streptococcus species and Enterococcus species. Patients with S aureus IE had the highest in‐hospital mortality.

Blood Culture-Negative Infective Endocarditis by Mycoplasma hominis: Case Report and Literature Review.

Mycoplasma hominis is a habitual colonizing microorganism of the lower genital tract but can exceptionally be the causal agent of blood culture-negative infective endocarditis (IE). Only 11 cases of this entity have been published to date. The study objectives were to describe the first case diagnosed in our center of IE by M. hominis on pacemaker lead and to carry out a narrative review. Among published cases of IE by this microorganism, 72.7% were male, with a mean age of 45 years and a history of valve surgery; the diagnosis was by culture (54.5%) or molecular technique (45.5%), and the prognosis was favorable in 72.7% of cases. The most frequently prescribed antibiotics were doxycycline, quinolones, and clindamycin.

Comparing Treatment Outcomes of Ampicillin-Sulbactam, Other β-Lactams, and Vancomycin in Blood Culture-Negative Infective Endocarditis.

Selection of proper antibiotics for blood culture-negative infective endocarditis (BCNIE) is difficult due to limited data on antibiotic regimens for BCNIE in existing literature. The aim of this study was to compare ampicillin-sulbactam, other β-lactams antibiotics, and vancomycin among patients with BCNIE to determine the proper antibiotic regimens. This retrospective study included adult patients with BCNIE admitted to Severance Hospital from November 2005 to August 2017. Patients were classified into three groups as, treated with ampicillin-sulbactam, other β-lactams, and vancomycin. The primary outcome was 1-year all-cause mortality. A total of 74 cases with BCNIE were enrolled in this study. There were no statistically significant differences in clinical characteristics between the three groups. One-year mortality did not significantly differ between the study groups either. Further, in-hospital mortality, 28-day mortality and overall mortality showed no difference. However, Cox-regression analysis showed nosocomial infective endocarditis as an independent risk factor and a protective effect of surgery on 1-year mortality. This study showed no clear difference in the outcomes of BCNIE as per the antibiotic therapy but suggested the beneficial effect of surgical treatment. With increasing global concern of antimicrobial resistance, it might be reasonable to select ampicillin-sulbactam-based antibiotic therapy while actively considering surgical treatment in BCNIE.