Symptomatic peripheral mycotic aneurysms due to infective endocarditis: a contemporary profile

Cardiac computed tomography in infective endocarditis: "bridging the detection gap"

Infective Endocarditis (IE) remains a significant health challenge. Despite an increasing awareness, mortality is high and has remained largely unchanged over recent decades. Early diagnosis of IE is imperative and to assist clinicians several diagnostic criteria have been proposed. The best known are the Duke criteria. Originally published in 1994, these criteria have undergone significant modifications. This manuscript provides a timeline of the successive changes that have been made over the last 30 years. Changes which to a large degree have reflected both the evolving epidemiology of IE and the proliferation and increasing availability of advanced multi-modality imaging. Importantly, many of these changes now form part of societal guidelines for the diagnosis of IE. To provide validation for the incorporation of cardiac computed tomography (CT) in current guidelines, the manuscript demonstrates a spectrum of pictorial case studies that re-enforce the utility and growing importance of early cardiac CT in the diagnosis and treatment of suspected IE.

Hepatic Artery Aneurysms in Infective Endocarditis: Report of 10 Cases and Literature Review

BACKGROUND

Hepatic artery aneurysms (HAAs), albeit rare in infective endocarditis (IE), are associated with a life-threatening morbidity.

METHODS

Retrospective review of 10 HAA-IE patients based on a total of 623 IE patients managed in 2 institutions (2008-2020) versus 35 literature cases.

RESULTS

In our patient population, HAAs (10 males, mean age 48) were incidentally found during IE workup. All were asymptomatic. IE involved mitral (n = 6), aortic (n = 3), or mitral-aortic valve (n = 1). Predisposing factors for IE were as follows: prosthetic valve (n = 6), previous IE (n = 2), IV drug user (n = 1). Streptococcus species (spp.) were predominant (n = 4), then staphylococcus spp (n = 2) and E. faecalis (n = 2). All patients presented associated lesions: infectious aneurysms (n = 5), emboli (n = 9), abscesses (n = 5), and spondylitis/spondylodiscitis (n = 2). HAA patterns on abdominal CT angiography (CTA) were solitary (70%), mean diameter 11.7 mm (range 2-30), intrahepatic location (100%) involving the right HA in 9 out of 10 (90%) patients. In 2 patients, HAAs were complicated (rectorragia and hemobilia in 1, cholestasis in the other). Six patients underwent endovascular hepatic embolization (2 with multiple HAAs). Three HAA-IEs <15 mm resolved under antibiotherapy on abdominal CTA follow-up. All patients underwent cardiac surgery. Late outcome was favorable in all followed patients (5/10). Literature review showed the preponderance of Streptococcus spp., of right lobe and intrahepatic HAA localization. Complications revealed HAAs in patients under antibiotic therapy and/or after cardiac surgery in 17 literature cases of delayed diagnosis.

CONCLUSIONS

Abdominal CTA was pivotal in the initial IE workup. Small aneurysms (≤15 mm) resolved under antibiotherapy. The usual treatment modality was HAA embolization and endovascular embolization before valve surgery was safe.

Contemporary Role of Positron Emission Tomography (PET) in Endocarditis: A Narrative Review

Endocarditis, a serious infectious disease, remains a diagnostic challenge in contemporary clinical practice. The advent of advanced imaging modalities has contributed significantly to the improved understanding and management of this complex disease. 18F-fluorodeoxyglucose (18F-FDG) positron emission tomography (PET) imaging has shown remarkable potential in improving the diagnostic accuracy of endocarditis. In the update of the Modified Duke Criteria, in 2023, The International Society for Cardiovascular Infectious Diseases (ISCVID) Working Group recognized specific 18F-FDG PET/CT findings as a major diagnostic criterion, particularly in patient with prosthetic valve endocarditis. The ability of PET to visualize metabolic activity allows for the identification of infective foci and could differentiate between infective and non-infective processes. This review examines the clinical utility of PET in differentiating infective endocarditis from other cardiovascular pathologies, highlighting its sensitivity and specificity in detecting native and prosthetic valve infections, including patients with transcatheter aortic valve implantation (TAVI), cardiac implantable devices (CIEDs), and left ventricular assistance devices (LVAD). Also, practical aspects and indications are illustrated to optimize the quality of imaging and reduce potential false positive results. In conclusion, the current use of PET in endocarditis has become a valuable diagnostic tool; as technological advances continue, PET will play an increasingly important role in the multidisciplinary approach to the management of endocarditis.

Culture Negative Infective Endocarditis Atypically Diagnosed From Mycotic Cerebral Aneurysm

Cerebral mycotic aneurysms (CMA) are a rare consequence of infective endocarditis (IE). We report a case of a 75-year-old left-handed male with comorbidities who was admitted to our facility with left-sided weakness, dysarthria, and left-sided facial droop. Initial computed tomography of the head without contrast and angiography of the head showed acute hemorrhage in the paramedian right frontal lobe with extension into the right lateral ventricle, occlusion of the left intracranial internal carotid artery, and an associated 0.3 cm aneurysm involving the distal right anterior cerebral artery. C-reactive protein and erythrocyte sedimentation rate were elevated but blood cultures showed no growth for more than five days. The patient underwent a two-vessel cerebral angiogram, primary coil embolization of the aneurysm, and selective catheterization of the left common carotid artery, right internal carotid artery, and right anterior cerebral artery. Transesophageal echocardiography showed an echogenic, highly mobile structure attached to the aortic valve suggestive of vegetation. The patient was subsequently started on a vancomycin regimen and stably discharged for further outpatient follow-up. This case highlights an uncommon presentation of CMA and the retroactive diagnosis of IE.

Epidemiology and Risk Factors of Mycotic Aneurysm in Patients With Infective Endocarditis and the Impact of its Rupture in Outcomes. Analysis of a National Prospective Cohort

Background

Several aspects of the occurrence and management of mycotic aneurysm (MA) in patients with infective endocarditis (IE) have not been studied.

Objectives

To determine the incidence and factors associated with MA presence and rupture and to assess the evolution of those initially unruptured MA.

Methods

Prospective multicenter cohort including all patients with definite IE between January 2008 and December 2020.

Results

Of 4548 IE cases, 85 (1.9%) developed MA. Forty-six (54.1%) had intracranial MA and 39 (45.9%) extracranial MA. Rupture of MA occurred in 39 patients (45.9%). Patients with ruptured MA had higher 1-year mortality (hazard ratio, 2.33; 95% confidence interval, 1.49-3.67). Of the 55 patients with initially unruptured MA, 9 (16.4%) presented rupture after a median of 3 days (interquartile range, 1-7) after diagnosis, being more frequent in intracranial MA (32% vs 3.3%, P = .004). Of patients with initially unruptured MA, there was a trend toward better outcomes among those who received early specific intervention, including lower follow-up rupture (7.1% vs 25.0%, P = .170), higher rate of aneurysm resolution in control imaging (66.7% vs 31.3%, P = .087), lower MA-related mortality (7.1% vs 16.7%, P = .232), and lower MA-related sequalae (0% vs 27.8%, P = .045).

Conclusions

MA occurred in 2% of the patients with IE. Half of the Mas occurred in an intracranial location. Their rupture is frequent and associated with poor prognosis. A significant proportion of initially unruptured aneurysms result from rupture during the first several days, being more common in intracranial aneurysms. Early specific treatment could potentially lead to better outcomes.

Endovascular Treatment of Superior Mesenteric Artery Pseudoaneurysm Due to Infective Endocarditis With Stent-Graft

PURPOSE

To report a successful case of pseudoaneurysm of the superior mesenteric artery (SMA) caused by infected endocarditis treated with a covered stent.

CASE REPORT

A patient was diagnosed with infective endocarditis and 2 months later a proximal SMA pseudoaneurysm was identified on computed tomography. Daptomycin was started on admission and continued for approximately 4 months until the inflammatory markers normalized, and then the SMA pseudoaneurysm was successfully excluded with a stent-graft and antibiotics were continued for 1 year after the procedure. There were no associated complications or recurrences at the 3-year follow-up.

CONCLUSION

Placing a covered stent with a full course of antibiotics before and after surgery may be a successful alternative to open surgery in the treatment of pseudoaneurysms of the SMA due to infective endocarditis.

CLINICAL IMPACT

This case report reports a rare case of pseudoaneurysm of the superior mesenteric artery due to infective endocarditis, which was successfully treated with an overlapping stent and confirmed by complete imaging data at a three-year follow-up. This report suggests that endovascular treatment may be an alternative to open surgery in the treatment of pseudoaneurysms of the superior mesenteric artery caused by infective endocarditis.

[Delayed renal infectious aneurysm 3 months after cardiac surgery for a Streptococcus pyogenes infective endocarditis ; case report and literature review]

Infective endocarditis (IE) due to Streptococcus pyogenes (SP) (Group A Streptococcus) is uncommon and infectious renal artery aneurysm (IRAA) is an exceptional complication of IE, with few cases reported in the literature. We describe a case of SP native mitral valve IE in a 58-year-old man, presenting with large valve vegetations, abscess and severe regurgitation. Initial CT-angiography showed bilateral kidney and splenic infarcts. He underwent successful emergent bioprosthetic valve replacement. Antibiotic regimen consisted in linezolid and rifampicin for 8 weeks. Three months later, CT-angiography for feet gangrene revealed a 16mm aneurysm of the left intraparenchymal renal artery, which was occluded by coil-embolization. This case shows that an infectious aneurysm may develop several months after antibiotic treatment and emergent valve replacement for IE.

Significant increase in mortality and risk of acute ischemic stroke in infective endocarditis patients with subarachnoid hemorrhage secondary to mycotic aneurysms

Infective Endocarditis (IE) patients are known to have a variety of complications with one of the rarest, but serious being cerebral mycotic aneurysm, which can result in subarachnoid hemorrhage (SAH). Using the National In-Patient Sample database, we sought to determine the rate of acute ischemic stroke (AIS) and outcomes in IE- patients with and without SAH. In total, we identified 82,844 IE-patients from 2010 to 2016, of which 641 had a concurrent diagnosis of SAH. IE patients with SAH had a more complicated course, higher mortality rate (OR 4.65 CI 95% 3.9-5.5, P < 0.001), and worse outcomes. This patient population also had a significantly higher rate of AIS (OR 6.3 CI 95% 5.4-7.4, P < 0.001). Overall, 41.5% of IE-patients with SAH had AIS during their hospitalization as compared to 10.1% of IE only patients. IE-patients with SAH were more likely to undergo endovascular treatment (3.6%) with 0.8% of the IE patients with AIS undergoing mechanical thrombectomy. While IE-patients are at risk for various complications, our study suggests a significant increase in the mortality and risk of AIS in those with SAH.

Mycotic Thoracic Aortic Aneurysm: Epidemiology, Pathophysiology, Diagnosis, and Management

Mycotic thoracic aortic aneurysm (MTAA) is an aneurysm of the aorta caused by infection of the vessel tissue through microbial inoculation of the diseased aortic endothelium. It is most commonly caused by bacteria. Rarely, it can be caused by fungi. However, viral aortic aneurysm has never been reported. Depending on the area and time period investigated, the infections organism discovered may vary significantly. Little is known about the natural history of MTAA due to its rarity. It is not known if they follow the same pattern as other TAAs. However, it is unclear whether MTAA follows a similar clinical course. The combination of clinical presentation, laboratory results, and radiographic results are used to make the diagnosis of MTAA. Treatment of MTAA is complex since patients frequently present at a late stage, frequently with fulminant sepsis, as well as concomitant complications such as aneurysm rupture. While medical treatment, including antibiotics, is recommended, surgery is still the mainstay of management. Surgery to treat MTAA is complicated and carries a high risk of morbidity and mortality and includes both open repairs and endovascular ones. In this review, we explore the etiology, pathogenesis, clinical presentations, diagnostic modalities as well as treatment management available for MTAA.

Surgical treatment of infectious ulnar artery aneurysm

Infectious ulnar artery aneurysm is a rare condition with no standardised treatment. Our patient was treated with a simple proximal ligature without excision of the aneurysm.

Cerebral venous thrombosis associated with infective endocarditis in a young patient

Cerebral venous thrombosis (CVT) is a rare complication of infective endocarditis. It constitutes a diagnostic and therapeutic emergency. We report a case of cerebral thrombophlebitis due to infective endocarditis in order to discuss the diagnosis and management of this situation. The patient was a 19-year-old man presenting with sudden explosive headaches with meningeal syndrome, right hemiparesis and right hypoesthesia. The cerebral CT angiography showed a left parieto-occipital and intraventricular hematoma without classic aneurysm or mycotic aneurysm or arteriovenous malformation. The injected brain magnetic resonance imaging found a CVT in front of a stopped opacification of the left lateral branch of the superior sagittal sinus. The presence of fever, poor oral status and a heart murmur justified the prescription of transthoracic echodoppler. It showed vegetations on healthy aortic valves. The patient was put on antibiotics and anticoagulants with favorable evolution. The absence of usual risk factors for CVT, the negativity of thrombophilia tests, the inflammatory and prothrombotic state associated with the infection reinforce the causal link of infective endocarditis to CVT formation. The etiology of CVT is variable, can be multiple and requires a comprehensive assessment. Infective endocarditis is one of the rare etiologies of CVT. In this case, anticoagulation and antibiotic drugs are indicated, taking into account the risk of intracerebral bleeding.

Convexal Subarachnoid Hemorrhage Caused by Infective Endocarditis in a Patient with Advanced Human Immunodeficiency Virus (HIV): The Culprits and Bystanders

BACKGROUND Convexal subarachnoid hemorrhage (cSAH), a rare form of non-aneurysmal subarachnoid hemorrhage, is confined to cerebral convexities without extension into basal cisterns or ventricles. Typical presentation includes thunderclap/progressive headache or transient focal neurological symptoms; rare manifestations include seizures, intractable vomiting, or altered mental status. Here, we report the first case of convexal subarachnoid hemorrhage and multifocal ischemic lesions caused by infective endocarditis (IE) in a treatment-naïve advanced HIV patient. CASE REPORT A 52-year-old HAART-naïve, HIV-positive, African American man presented with altered mental status, shortness of breath, nonproductive cough, and generalized weakness. His past medical history was significant for congestive heart failure, chronic obstructive pulmonary disease, and end-stage renal disease (noncompliant with hemodialysis). Head computed tomography (CT) showed an isolated sulcal hemorrhage in the mid-left frontal lobe. Fluid-attenuated inversion recovery/gradient recalled echo sequences confirmed a hemorrhage in the left-mid-frontal sulcus, and diffusion-weighted imaging revealed multifocal bilateral ischemic lesions. Transesophageal echocardiography exhibited mitral valve vegetations. Multifocal ischemic lesions and cSAH caused by infectious endocarditis were confirmed. Initiation of intravenous vancomycin and piperacillin-tazobactam allowed the patient to have resolution of his altered mental status. A head CT 5 days later revealed the resolution of cSAH. CONCLUSIONS Infective endocarditis should be considered as an underlying etiology of cSAH, especially when present with multifocal ischemic lesions. Risk factors contributing to the development of cSAH in the IE patient population should be explored in future studies. HIV has not been previously reported in this subgroup and its prevalence should be considered. The prognosis for cSAH in relation to IE is generally favorable.

Recurrent Infective Endocarditis with Mycotic Aneurysm - Imaging Modalities for the Detection of an Infective Focus

Staphylococcus aureus bacteremia (SAB) and infective endocarditis (IE) are infections associated with considerable morbidity, requiring prompt accurate diagnosis and treatment. We present a case of a 58-year-old male patient with four episodes of recurrent symptomatic SAB treated for IE, but without positive findings on transthoracic echocardiography, transesophageal echocardiography, and fluorodeoxyglucose-positron emission tomography (FDG-PET). On the last admission, FDG-PET showed increased uptake in the right atrial appendage, and white blood cell single-photon emission computerized tomography (WBC-SPECT) was able to identify the infective focus as IE of the aortic valve. CT of the thorax also identified an associated mycotic aneurysm of the right coronary sinus. He was subsequently treated with mechanical aortic prosthesis and right coronary sinus plasty, and his symptoms did not recur till 2 years postcardiothoracic surgery. This case report demonstrates the emergence of nuclear cardiovascular imaging modalities in the diagnostic workup of IE and the utility of FDG-PET and WBC-SPECT in the identification of the infective focus. Patients with possible IE from the modified Duke criteria should be considered for FDG-PET or WBC-SPECT to enhance sensitivity. Peripheral mycotic aneurysms are a common complication of left-sided IE, which can present late into the disease process, and aortic imaging should be considered in patients with recurrent endocarditis to identify this.

Multifocal extracranial mycotic aneurysms in a patient with endocarditis

This report describes the case of a 44-year-old man with Streptococcus gallolyticus (formerly S. bovis) endocarditis requiring surgical mitral valve replacement who developed multifocal extracranial mycotic aneurysms after the resolution of infection.

Extra-cardiac endovascular infections in the critically ill

Vascular infections are associated with high complication rates and mortality. While there is an extensive body of literature surrounding cardiac infections including endocarditis, this is less so the case for other endovascular infections. The objective of this narrative review is to summarize the epidemiology, clinical features, and selected management of severe vascular infections exclusive of those involving the heart. Endovascular infections may involve either the arterial or venous vasculature and may arise in native vessels or secondary to implanted devices. Management is complex and requires multi-disciplinary involvement from the outset. Infective arteritis or device-related arterial infection involves removal of the infected tissue or device. In cases where complete excision is not possible, prolonged courses of antimicrobials are required. Serious infections associated with the venous system include septic thrombophlebitis of the internal jugular and other deep veins, and intracranial/venous sinuses. Source control is of paramount importance in these cases with adjunctive antimicrobial therapy. The role of anticoagulation is controversial although recommended in the absence of contraindications. An improved understanding of the management of these infections, and thus improved patient outcomes, requires multi-center, international collaboration.

Endovascular Therapy for Distal Superior Mesenteric Artery Mycotic Aneurysms due to Infective Endocarditis

Purpose: To report 3 patients with infective endocarditis who underwent transcatheter arterial embolization for mycotic aneurysm of the distal superior mesenteric artery (SMA). Case Report: Three men (60, 64, and 65 years old) were diagnosed with infective endocarditis. Antibiotics were initiated immediately after admission and continued for several weeks to months. Distal SMA mycotic aneurysm was identified on computed tomography in the vicinity of the ileocolic artery at 33, 26, and 30 days after admission. In case 1, the ileal artery was occluded distal to the aneurysm, with collateral flow to the ileum. In case 2, the mycotic aneurysm was located below the ileocolic artery, which was stenosed distal to the lesion. In case 3, the aneurysm was located on a branch of the ileal artery. Transarterial embolization using microcoils was successfully performed in all patients. No complications associated with embolotherapy or relapse of infection were observed in these 3 patients at 60, 30, and 15 months, respectively. Conclusion: Transcatheter arterial embolization for distal SMA mycotic aneurysm could provide an alternative to open surgery. Anatomical assessment of collateral flow and preprocedure long-term antibiotic therapy could play important roles in preventing bowel ischemia and minimizing the risk of infection relapse.

Surgical Repair of Axillary Artery Aneurysm in a 2-Year-Old Child: A Case Report

Peripheral aneurysm and pseudoaneurysm of an artery is a well-recognized but rare phenomenon in children. We report a case of an axillary artery aneurysm in a 2-year-old boy with methicillin-resistant Staphylococcus aureus septic shock, acute respiratory distress syndrome, and multiorgan dysfunction syndrome. Definitive surgical treatment with left axillary artery aneurysm exclusion and bypass with greater saphenous vein graft were performed. To our knowledge, this is the only axillary artery aneurysm ever reported in a child.

Hemothorax due to Ruptured Mycotic Aneurysm of Intercostal Arteries Associated with Infective Endocarditis

We present a case of hemothorax due to ruptured mycotic aneurysm in three intercostal arteries in a 40-year-old male with methicillin-resistant Staphylococcus aureus infective endocarditis (IE) due to intravenous drug use. Microcoil embolization and thoracotomy successfully achieved hemostasis. Mycotic aneurysm is a rare complication of IE and is usually found in the intracranial vessels. Ruptured mycotic aneurysm in the intercostal arteries can be associated with IE and can present as acute hemothorax.

Antineutrophil Cytoplasmic Antibodies Associated With Infective Endocarditis

To determine the prevalence of antineutrophil cytoplasmic antibodies (ANCA) in patients with infective endocarditis (IE) in internal medicine; and to compare clinical and biochemical features and outcome between patients exhibiting IE with and without ANCA.Fifty consecutive patients with IE underwent ANCA testing. The medical records of these patients were reviewed.Of the 50 patients with IE, 12 exhibited ANCA (24%). ANCA-positive patients with IE exhibited: longer duration between the onset of first symptoms and IE diagnosis (P = 0.02); and more frequently: weight loss (P = 0.017) and renal impairment (P = 0.08), lower levels of C-reactive protein (P = 0.0009) and serum albumin (P = 0.0032), involvement of both aortic and mitral valves (P = 0.009), and longer hospital stay (P = 0.016). Under multivariate analysis, significant factors for ANCA-associated IE were: longer hospital stay (P = 0.004), lower level of serum albumin (P = 0.02), and multiple valve involvement (P = 0.04). Mortality rate was 25% in ANCA patients; death was because of IE complications in all these patients.Our study identifies a high prevalence of ANCA in unselected patients with IE in internal medicine (24%). Our findings further underscore that ANCA may be associated with a subacute form of IE leading to multiple valve involvement and more frequent renal impairment. Because death was due to IE complications in all patients, our data suggest that aggressive therapy may be required to improve such patients' outcome.

Disseminated Peripheral Mycotic Aneurysms and Septic Embolizations Related to an Infected Stent Deployed for Restenosis of Surgically Repaired Supravalvular Aortic Stenosis

Percutaneous treatment of supravalvular aortic stenosis (SVAS) by means of balloon dilation and stent deployment has been rarely reported in the literature. In this report, we present the case of a patient with mycotic aneurysms, disseminated peripheral and cerebral septic embolizations, and infected vegetations associated with a stent that had previously been deployed to treat restenosis of surgically corrected SVAS in the infancy.

Renal colic caused by mycotic iliac artery aneurysm

A 33-year-old female presented with acute colicky left loin-to-groin pain and microscopic haematuria, with a background of 6 months of muscle and joint pains and diplopia. A CT kidneys/ureters/bladder demonstrated fat stranding surrounding the left ureter, as it passed over the left common iliac vessels. Arterial and delayed phase imaging revealed an obstructed ureter secondary to a left common iliac artery aneurysm, later found to be mycotic. No previous descriptions of a mycotic aneurysm presenting as renal colic have been found in the literature. The diagnosis and management of infective endocarditis and mycotic aneurysm are discussed, with a review of the literature. This serves as a good example of a common presenting complaint occurring secondary to a rare and serious pathology.

Infections and cardiovascular disease: is Bartonella henselae contributing to this matter?

Cardiovascular disease is still the major cause of death worldwide despite the remarkable progress in its prevention and treatment. Endothelial progenitor cells (EPCs) have recently emerged as key players of vascular repair and regenerative medicine applied to cardiovascular disease. A large amount of effort has been put into discovering the factors that could aid or impair the number and function of EPCs, and also into characterizing these cells at the molecular level in order to facilitate their therapeutic applications in vascular disease. Interestingly, the major cardiovascular risk factors have been associated with reduced number and function of EPCs. The bacterial contribution to cardiovascular disease represents a long-standing controversy. The discovery that Bartonella henselae can infect and damage EPCs revitalizes the enduring debate about the microbiological contribution to atherosclerosis, thus allowing the hypothesis that this infection could impair the cardiovascular regenerative potential and increase the risk for cardiovascular disease. In this review, we summarize the rationale suggesting that Bartonella henselae could favour atherogenesis by infecting and damaging EPCs, thus reducing their vascular repair potential. These mechanisms suggest a novel link between communicable and non-communicable human diseases, and put forward the possibility that Bartonella henselae could enhance the susceptibility and worsen the prognosis in cardiovascular disease.

Clinical utility of cerebral angiography in the preoperative assessment of endocarditis

Cerebral angiography is an invasive procedure utilized without supporting guidelines in preoperative evaluations of infective endocarditis (IE). It is used to identify mycotic intracranial aneurysm, which is suspected to increase the risk of intracranial bleeding during cardiac surgery. Our objectives were to: (1) assess the utility of cerebral angiography by determining which subset of IE patients benefit from its performance; and (2) identify clinical and noninvasive screening tests that can preclude the need for invasive cerebral angiography. Retrospective analysis was performed of all patients treated surgically for IE from 7/2007 to 1/2012 and discharged with medical treatment for IE from 7/2007 to 7/2009 presenting to a large academic center. Of the 151 patients who underwent cerebral angiography, mycotic aneurysm was identified in seven (prevalence=4.6%; 95% CI 2.3–9.3%). Five had viridans group streptococci as the causative IE microorganism ( p=0.0017). Noninvasive imaging and particularly absence of intracranial bleed on magnetic resonance imaging conveys a negative predictive value (NPV) of 0.977 (95% CI 0.879–0.996). Absence of a focal neurologic deficit or altered mental status convey a NPV of 0.990 (95% CI 0.945–0.998) and 0.944 (95% CI 0.883–0.974), respectively. Clinical suspicion for mycotic aneurysm and thus utilization of cerebral angiography is likely necessary only in the setting of acute neurologic deficits and when noninvasive imaging demonstrates acute intracranial bleed. A novel association between viridans group streptococci and intracranial mycotic aneurysm is demonstrated.