Infective Endocarditis in the Intensive Care Unit

Unexpected Infective Endocarditis: Towards a New Alert for Clinicians

Despite the clear indications and worldwide application of specific guidelines, the recognition of Infective Endocarditis (IE) may be challenging in day-to-day clinical practice. Significant changes in the epidemiological and clinical profile of IE have been observed, including variations in the populations at risk and an increased incidence in subjects without at-risk cardiac disease. Emergent at-risk populations for IE particularly include immunocompromised patients with a comorbidity burden (e.g., cancer, diabetes, dialysis), requiring long-term central venous catheters or recurrent healthcare interventions. In addition, healthy subjects, such as skin-contact athletes or those with piercing implants, may be exposed to the transmission of highly virulent bacteria (through the skin or mucous), determining endothelial lesions and subsequent IE, despite the absence of pre-existing at-risk cardiac disease. Emergent at-risk populations and clinical presentation changes may subvert the conventional paradigm of IE toward an unexpected clinical scenario. Owing to its unusual clinical context, IE might be overlooked, resulting in a challenging diagnosis and delayed treatment. This review, supported by a series of clinical cases, analyzed the subtle and deceptive phenotypes subtending the complex syndrome of unexpected IE. The awareness of an unexpected clinical course should alert clinicians to also consider IE diagnosis in patients with atypical features, enhancing vigilance for preventive measures in an emergent at-risk population untargeted by conventional workflows.

Perioperative Complications in Infective Endocarditis

Infective endocarditis is a challenging condition to manage, requiring collaboration among various medical professionals. Interdisciplinary teamwork within endocarditis teams is essential. About half of the patients diagnosed with the disease will ultimately have to undergo cardiac surgery. As a result, it is vital for all healthcare providers involved in the perioperative period to have a comprehensive understanding of the unique features of infective endocarditis, including clinical presentation, echocardiographic signs, coagulopathy, bleeding control, and treatment of possible organ dysfunction. This narrative review provides a summary of the current knowledge on the incidence of complications and their management in the perioperative period in patients with infective endocarditis.

Anesthesia Considerations in Infective Endocarditis

The management of infective endocarditis is complex and inherently requires multidisciplinary cooperation. About half of all patients diagnosed with infective endocarditis will meet the criteria to undergo cardiac surgery, which regularly takes place in urgent or emergency settings. The pathophysiology and clinical presentation of infective endocarditis make it a unique disorder within cardiac surgery that warrants a thorough understanding of specific characteristics in the perioperative period. This includes, among others, echocardiography, coagulation, bleeding management, or treatment of organ dysfunction. In this narrative review article, the authors summarize the current knowledge on infective endocarditis relevant for the clinical anesthesiologist in perioperative management of respective patients. Furthermore, the authors advocate for the anesthesiologist to become a structural member of the endocarditis team.

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

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

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

Pneumocardia and septic pulmonary embolism due to nongas-forming liver abscess: A case report

RATIONALE

Pneumocardia and septic pulmonary embolism are uncommon complications of Klebsiella pneumoniae primary liver abscess (KPLA); however, they may lead to a poor clinical outcome.

PATIENT CONCERNS

A 67-year-old woman was admitted to our hospital with fever, chills, cough, and dyspnea for 4 days. She had a previous history of diabetes mellitus.

DIAGNOSES

The chest computed tomography (CT) revealed multiple peripheral nodules in both lungs and wedge-shaped peripheral infiltrative lesions abutting the pleura, suggestive of septic pulmonary embolism. An abdominal CT on the following day showed a large liver abscess without gas formation and pneumocardia of the right ventricle.

INTERVENTIONS

After the antibiotic therapy of intravenous imipenem and drainage of the liver abscess, our patient made a complete recovery.

OUTCOMES

The patient was discharged on the 25th hospital day after full recovery and was doing well on follow-up at 10 months.

LESSONS

KPLA is potentially fatal due to the associated serious metastatic complications. Attention must be paid not only to the primary focus of infection but also to infection of other organs. It is important to detect to diagnose the spread of infection accurately, in a timely manner, to improve the prognosis of this condition.

The PIEPEAR Workflow: A Critical Care Ultrasound Based 7-Step Approach as a Standard Procedure to Manage Patients with Acute Cardiorespiratory Compromise, with Two Example Cases Presented

Critical care ultrasound (CCUS) has been widely used as a useful tool to assist clinical judgement. The utilization should be integrated into clinical scenario and interact with other tests. No publication has reported this. We present a CCUS based "7-step approach" workflow-the PIEPEAR Workflow-which we had summarized and integrated our experience in CCUS and clinical practice into, and then we present two cases which we have applied the workflow into as examples. Step one is "problems emerged?" classifying the signs of the deterioration into two aspects: acute circulatory compromise and acute respiratory compromise. Step two is "information clear?" quickly summarizing the patient's medical history by three aspects. Step three is "focused exam launched": (1) focused exam of the heart by five views: the assessment includes (1) fast and global assessment of the heart (heart glance) to identify cases that need immediate life-saving intervention and (2) assessing the inferior vena cava, right heart, diastolic and systolic function of left heart, and systematic vascular resistance to clarify the hemodynamics. (2) Lung ultrasound exam is performed to clarify the predominant pattern of the lung. Step four is "pathophysiologic changes reported." The results of the focused ultrasound exam were integrated to conclude the pathophysiologic changes. Step five is "etiology explored" diagnosing the etiology by integrating Step two and Step four and searching for the source of infection, according to the clues extracted from the focused ultrasound exam; additional ultrasound exams or other tests should be applied if needed. Step six is "action" supporting the circulation and respiration sticking to Step four. Treat the etiologies according step five. Step seven is "recheck to adjust." Repeat focused ultrasound and other tests to assess the response to treatment, adjust the treatment if needed, and confirm or correct the final diagnosis. With two cases as examples presented, we insist that applying CCUS with 7-step approach workflow is easy to follow and has theoretical advantages. The coming research on its value is expected.

Relative presence of Streptococcus mutans, Veillonella atypica, and Granulicatella adiacens in biofilm of complete dentures

Aims and Objective:

Oral biofilms in denture wearers are populated with a large number of bacteria, a few of which have been associated with medical conditions such as sepsis and infective endocarditis (IE). The present study was designed to investigate the relative presence of pathogenic bacteria in biofilms of denture wearers specifically those that are associated with IE.

Methods:

Biofilm samples from 88 denture wearers were collected and processed to extract total genomic DNA. Eight of these samples were subjected to 16S rRNA gene sequencing analysis to first identify the general bacterial occurrence pattern. This was followed by species-specific quantitative polymerase chain reaction (qPCR) on entire batch of 88 samples to quantify the relative copy numbers of IE-associated pathogens.

Results:

16S rRNA gene analysis of eight biofilm samples identified bacteria from Firmicutes, Actinobacteria, Proteobacteria, Bacteroidetes, and Fusobacteria species. Interestingly, Streptococcus mutans, Veillonella atypica, and Granulicatella adiacens from Firmicutes, all known to be associated with early-onset sepsis and IE was present in five of eight biofilm samples. The other three samples carried bacteria from genus Proteobacteria with Neisseria flava and Neisseria mucosa, which are known to be commensals, as dominant species. Species-specific qPCR of S. mutans V. atypica, and G. adiacens on 88 biofilm DNA samples identified the presence of S. mutans in 83%, V. atypica in 79%, and G. adiacens in 76% of samples.

Conclusion:

The findings from the present study demonstrate co-occurrence of S. mutans, V. atypica, and G. adiacens in a majority of denture wearers, which is clinically significant as elderly patients with compromised immune system are more prone to develop IE. To the best of our knowledge, the co-occurrence of S. mutans, V. atypica, and G. adiacens is being reported for the first time in biofilms of denture wearers.

Aortic and tricuspid endocarditis in hemodialysis patient with systemic and pulmonary embolism

This is a case report of a 43-year-old Caucasian male with end-stage renal disease being treated with hemodialysis and infective endocarditis in the aortic and tricuspid valves. The clinical presentation was dominated by neurologic impairment with cerebral embolism and hemorrhagic components. A thoracoabdominal computerized tomography scan revealed septic pulmonary embolus. The patient underwent empirical antibiotherapy with ceftriaxone, gentamicin and vancomycin, and the therapy was changed to flucloxacilin and gentamicin after the isolation of S. aureus in blood cultures. The multidisciplinary team determined that the patient should undergo valve replacement after the stabilization of the intracranial hemorrhage; however, on the 8^th day of hospitalization, the patient entered cardiac arrest due to a massive septic pulmonary embolism and died. Despite the risk of aggravation of the hemorrhagic cerebral lesion, early surgical intervention should be considered in high-risk patients.

Infective Endocarditis

Infective endocarditis (IE) is a noncontagious infection of the endocardium and heart valves. The epidemiology of IE has shifted recently with an increase in health care-associated IE. Infective endocarditis requiring intensive care unit stay is increasing, and nosocomial IE is frequently responsible. Diagnosis of IE requires multiple clinical data points encompassing history and physical examination, microbiology, and cardiac imaging as no one test is sufficiently sensitive or specific. The modified Duke criteria algorithm is the standard of care in the clinical diagnosis of IE. Complications from IE are common, particularly so in the critical care setting, and include congestive heart failure, embolism, septic shock, invasive infection, prosthetic valve dehiscence, heart block, and mycotic aneurysm. A multidisciplinary care team of infectious disease, cardiology, and cardiac surgery physicians is recommended to reduce complications. Intravenous antibiotics are first-line therapy with cardiac surgery being reserved for certain complications of IE and/or for clinical situations in which there is a high risk of complications. Timing of surgery for IE remains controversial and depends on a variety of clinical factors.

Infective endocarditis: a history of the development of its understanding

Inflammation of the inner layer of the heart, especially the valvular endothelium, chordae tendinae and mural endocardium was first recognized almost 350 years ago. Over the years it has had many names, but is now generally designated infective endocarditis (IE) and has an associated infectious agent. A sterile vegetative process can also affect the valves and is usually referred to as Libman-Sacks endocarditis. The developments of medical science that allowed for our understanding of this entity included refinement of the autopsy, medical microscopy, microbiology, and in recent years, molecular studies. Some observations were misleading but clarification particularly followed the reports of Morgagni, Osler and Libman. As understanding of the pathobiology of infective endocarditis grew so did the effectiveness of therapy. This paper provides a detailed history of the development of the concept of Infective endocarditis citing many key morphological observations and concludes with brief comments about current concepts of pathogenesis as well as a few remarks about therapy.