Activation of the contact system at the surface of Fusobacterium necrophorum represents a possible virulence mechanism in Lemièrre's syndrome

A rare case of MRSA associated Lemierre's syndrome

Lemierre's syndrome, or postanginal sepsis, is an uncommon but potentially fatal infection of the internal jugular vein. The combination of bacteremia, internal jugular vein thrombophlebitis, and metastatic septic emboli secondary to acute pharyngeal infections is characteristic of Lemierre's syndrome. Isolated pathogens are typically oral anaerobic bacteria, most commonly Fusobacterium necrophorum. While the incidence of Lemierre's syndrome has declined over the years, the proportion of cases caused by uncommonly implicated bacteria have been increasingly cited in the literature (1). In this case report, we introduce a novel presentation of Lemierre's syndrome in a patient who presented to the emergency department with neck swelling and shortness of breath and was found to have infectious myositis and bacteremia with methicillin-resistant Staphylococcus aureus. Clinicians should be vigilant of underlying thrombus in patients with neck swelling and infectious myositis as our patient's internal jugular vein thrombus was missed on initial computed tomography read.

Proteomic Characterization of Plasma in Lemierre's Syndrome

BACKGROUND

 The underlying mechanisms of thrombosis in Lemierre's syndrome and other septic thrombophlebitis are incompletely understood. Therefore, in this case control study we aimed to generate hypotheses on its pathogenesis by studying the plasma proteome in patients with these conditions.

METHODS

 All patients with Lemierre's syndrome in the Skåne Region, Sweden, were enrolled prospectively during 2017 to 2021 as cases. Age-matched patients with other severe infections were enrolled as controls. Patient plasma samples were analyzed using label-free data-independent acquisition liquid chromatography tandem mass spectrometry. Differentially expressed proteins in Lemierre's syndrome versus other severe infections were highlighted. Functions of differentially expressed proteins were defined based on a literature search focused on previous associations with thrombosis.

RESULTS

 Eight patients with Lemierre's syndrome and 15 with other severe infections were compared. Here, 20/449 identified proteins were differentially expressed between the groups. Of these, 14/20 had functions previously associated with thrombosis. Twelve of 14 had a suggested prothrombotic effect in Lemierre's syndrome, whereas 2/14 had a suggested antithrombotic effect.

CONCLUSION

 Proteins involved in several thrombogenic pathways were differentially expressed in Lemierre's syndrome compared to other severe infections. Among identified proteins, several were associated with endothelial damage, platelet activation, and degranulation, and warrant further targeted studies.

Otogenic Cerebral Sinus Thrombosis in Children: A Narrative Review

Cerebral venous thrombosis (CVT) is a rare entity that remains a diagnostic challenge due to various clinical manifestations and a wide variety of causative agents. Local infections, such as acute (AOM) or chronic otitis media, can play a role in the pathogenesis of CVT. The proximity of the tympanic cavity and temporal bone air cells to the dural venous sinuses predisposes them to secondary thrombosis. The release of inflammatory cytokines and activation of the coagulation pathway in the middle ear space in response to infection may trigger the thrombotic mechanism in venous sinuses of the central nervous system. There is no consensus in the literature concerning the treatment of otogenic cerebral venous sinus thrombosis (CVST). Both the extent of the surgery and the use of anticoagulants are disputable. The aim of the study was to provide a thorough analysis of the literature concerning CVST in patients with AOM and acute mastoiditis (AM). The current surgical and conventional treatment strategies are presented. Special attention has been attached to the predisposing factors, the extent of the surgery, and the role of anticoagulants in the treatment of septic otogenic CVST.

Complex Lemierre syndrome with multisystemic abscesses

We present here the challenging case of severe Lemierre syndrome in a healthy woman in her late twenties, whose clinical presentation was characterised by lung abscesses and disseminated systemic abscesses in the brain, the abdomen and the soft-tissues, as a likely consequence of a patent foramen ovale. Blood cultures were positive for Fusobacterium necrophorum and a right lingual vein thrombosis was detected at a late stage when the patient developed a septic shock. Initial antimicrobial therapy with metronidazole and ceftriaxone was modified to meropenem due to progressive worsening. The patient underwent laparoscopy and neurosurgical drainage of a cerebral abscess. She spent many days in the intensive care unit and recovered fully after 6 weeks on meropenem therapy. Although considered rare, the incidence of Lemierre syndrome, a potentially life-threatening condition, is increasing. The clinician should promptly recognise and treat it while being aware of its potential atypical presentations.

Paediatric otogenic sinus venous thrombosis: the role of Fusobacterium necrophorum

Objectives

Sinus venous thrombosis (SVT) is a rare complication of acute otitis media (AOM) with acute mastoiditis (AM), which during recent years has been associated with Fusobacterium necrophorum (Fn) infection. Our objective was to review clinical, microbiologic, and hematologic features of paediatric otogenic SVT, with a specific focus on the role of Fn.

Methods

A retrospective database review in a tertiary paediatric hospital between 2000-2019.

Results

Fifty children aged 6-155 months were treated for AM with SVT. Forty-seven (94%) underwent cortical mastoidectomy. Forty-six children received low-molecular-weight heparin (LMWH). Follow-up imaging revealed recanalisation in 92% of cases. No long-term neurologic or haematologic complications were observed. Since 2014, when anaerobic cultures and PCR were routinely used in our institute, Fn was isolated from 15/21 children with SVT. Their time to recanalisation was longer, and the rate of lupus anticoagulant antibodies (LAC) was higher than in the 6 non-Fn patients. Children positive for LAC also had a longer time to recanalisation.

Conclusions

Fn is a common pathogen in AM with SVT; its thrombogenic role was demonstrated by a higher prevalence of LAC and a longer time to recanalisation.

Jugular Vein Thrombosis and Anticoagulation Therapy in Lemierre's Syndrome-A Post Hoc Observational and Population-Based Study of 82 Patients

Background

Lemierre’s syndrome is typically caused by Fusobacterium necrophorum where an oropharyngeal infection is followed by septic internal jugular vein thrombophlebitis with subsequent septic embolization. Yet, the pathogenesis of septic thrombophlebitis, differences dependent on the presence of jugular vein thrombosis, and the role of anticoagulant therapy are insufficiently understood.

Methods

Patients with invasive infection with F. necrophorum and Lemierre’s syndrome who had been investigated for jugular vein thrombosis were included from a previous population-based observational study in Sweden. Medical records were reviewed and compared in patients with and without jugular vein thrombosis. Then, patients with jugular vein thrombosis were compared by exposure to therapeutic, prophylactic, or no anticoagulation. Outcomes examined were thrombosis progression, early or late peripheral septic complications, chronic major sequelae, 30-day mortality, and major bleeding.

Results

Fifty-one of 82 (62%) radiologically investigated patients with Lemierre’s syndrome had jugular vein thrombosis. Patients with jugular vein thrombosis had lower platelet levels (median, 76 vs 112 ×10⁹/L; P = .04) on presentation and more days to defervesence (12 vs 7 days; P = .03) yet similar rates of major sequelae and 30-day mortality. No significant differences in outcomes were seen between patients with jugular vein thrombosis exposed to therapeutic, prophylactic, or no anticoagulation therapy, yet study outcomes were rare.

Conclusions

Patients with Lemierre’s syndrome with jugular vein thrombosis were more severely affected, yet had similar prognosis. Most patients with jugular vein thrombosis recovered well without therapeutic anticoagulation therapy, though adverse events were similarly rare in anticoagulated patients. The observational design and rarity of study outcomes require cautious interpretation.

Fusobacterium necrophorum, a major provider of sinus thrombosis in acute mastoiditis: A retrospective multicentre paediatric study

OBJECTIVE

To evaluate in children the clinical severity and evolution of otogenic lateral sinus thrombosis (OLST) due to Fusobacterium necrophorum compared with other bacterial otogenic thrombosis and propose a specific management flowchart for Fusobacterium OLST.

DESIGN

A retrospective multicentre cohort study.

SETTINGS

Four French ENT paediatric departments.

PARTICIPANTS

A total of 260 under 18 years old admitted for acute mastoiditis were included. Initial imaging was reviewed to focus on complicated mastoiditis and 52 OLST were identified. Children were then divided into two groups according to bacteriological results: 28 in the "OLST Fusobacterium group" and 24 in the "OLST other bacteria group".

RESULTS

There was a significant association between F necrophorum and OLST (P < .001). When compared to the OLST other bacteria group, children in the OLST Fusobacterium group were significantly younger (61 months vs 23 months, P < .01) and had a more severe clinical presentation: higher CRP (113 mg/L vs 175.7 mg/L, P = .02) and larger subperiosteal abscess (14 mm vs 21 mm, P < .01). Medical management was also more intensive in the OLST Fusobacterium group than in the OLST other bacteria group: increased number of conservative surgeries (66.7% vs 92.9%, P = .03) and longer hospital stay (13.7 days vs 19.8 days, P = .02). At the end of follow-up, the clinical course was good in both groups without any neurological sequelae.

CONCLUSIONS

Thrombotic complications are very frequent in case of Fusobacterium mastoiditis and clinicians should be aware of the initial severity of the clinical presentation. Under appropriate management, the clinical course of Fusobacterium OLST is as good as that of other bacterial otogenic thrombosis.

Cell Receptor and Cofactor Interactions of the Contact Activation System and Factor XI

The contact activation system (CAS) or contact pathway is central to the crosstalk between coagulation and inflammation and contributes to diverse disorders affecting the cardiovascular system. CAS initiation contributes to thrombosis but is not required for hemostasis and can trigger plasma coagulation via the intrinsic pathway [through factor XI (FXI)] and inflammation via bradykinin release. Activation of factor XII (FXII) is the principal starting point for the cascade of proteolytic cleavages involving FXI, prekallikrein (PK), and cofactor high molecular weight kininogen (HK) but the precise location and cell receptor interactions controlling these reactions remains unclear. FXII, PK, FXI, and HK utilize key protein domains to mediate binding interactions to cognate cell receptors and diverse ligands, which regulates protease activation. The assembly of contact factors has been demonstrated on the cell membranes of a variety of cell types and microorganisms. The cooperation between the contact factors and endothelial cells, platelets, and leukocytes contributes to pathways driving thrombosis yet the basis of these interactions and the relationship with activation of the contact factors remains undefined. This review focuses on cell receptor interactions of contact proteins and FXI to develop a cell-based model for the regulation of contact activation.

Fusobacterium necrophorum otitis and mastoiditis in infants and young toddlers

There is an increased recovery of Fusobacterium necrophorum from cases of otitis media and mastoiditis in the pediatric population. These infections may be highly severe, causing local osteomyelitis, bacteremia, and Lemierre's syndrome. The severity and difficulties in providing optimal treatment for these infections may be especially difficult in this age group due to immunological immaturity and delayed presentation. In this review of literature, we present and analyze the clinical presentation, management, and outcome of otic infections caused by F. necrophorum in infants and young toddlers less than 2 years old. Search in Pubmed was conducted for reported cases in the English literature for the time period of the last 50 years. Twelve well-described cases were retrieved with F. necrophorum otitis and mastoiditis and complications reported in all cases. Treatment included both intravenously with antimicrobial agents (beta lactams plus metronidazole) and mastoidectomy. Lemierre's syndrome and Lemierre's syndrome variants developed in 60 % of the patients. Dissemination of the infection as distal osteomyelitis and septic shock were also reported. The outcome was favorable in all the cases. Otitis and mastoiditis infections in children less then 2 years old are invasive infections, and severe complications can occur.

Infection

Community-Acquired Pneumonia (CAP) is the first leading cause of death due to infection worldwide.Many gram-positive, gram-negative bacteria, funguses and viruses can cause the infectious pulmonary disease, and the severity of pneumonia depends on the balance between the microorganism charge, the body immunity defenses and the quality of the underlying pulmonary tissue. The microorganisms may reach the lower respiratory tract from inhaled air or from infected oropharyngeal secretions. The same organism may produce several different patterns that depend on the balance between the microorganism charge and the body immunity defenses.CAP is classified into three main groups: lobar pneumonia, bronchopneumonia and interstitial pneumonia.Lobar pneumonia is characterized by the filling of alveolar spaces by edema full of white and inflammatory cells. Necrotizing pneumonia consists of a fulminant process associated with focal areas of necrosis that results in abscesses. Bronchopneumonia or lobular pneumonia, is characterized by a peribronchiolar inflammation with thickening of peripheral bronchial wall, the diffusion of inflammation to the centrilobular alveolar spaces and development of nodules.The interstitial pneumonia represents with the destruction and esfoliation of the respiratory ciliated and mucous cells. The interstitial septa, the bronchial and bronchiolar walls become thickened for the inflammation process and lymphocytes interstitial infiltrates.Chest radiography represents an important initial examination in all patients suspected of having pulmonary infection and for monitoring response to therapy.Its role is to identify the pulmonary opacities, their internal characteristics and distribution, pleural effusion and presence of other complications as abscesses and pneumothorax.High spatial CT resolution allows accurate assessment of air space inflammation.The CT findings include nodules, interlobular septal thickening, intralobular reticular opacities, ground-glass opacities, tree-in-bud pattern, lobar-segmental consolidation, lobular consolidation, abscesses, pneumatocele, pleural effusion, pericardial effusion, mediastinal and hilar lymphoadenopaties, airway dilatation and emphysema.

Factor XII: a novel target for safe prevention of thrombosis and inflammation

Plasma protein factor XII (FXII) activates the procoagulant and proinflammatory contact system that drives both the kallikrein-kinin system and the intrinsic pathway of coagulation. When zymogen FXII comes into contact with negatively charged surfaces, it auto-activates to the serine proteaseactivated FXII (FXIIa). Recently, various in vivo activators of FXII have been identified including heparin, misfolded protein aggregates, polyphosphate and nucleic acids. Murine models have established a central role of FXII in arterial and venous thrombosis. Despite its central function in thrombosis, deficiency in FXII does not impair haemostasis in animals and humans. In a preclinical cardiopulmonary bypass system in large animals, the FXIIa-blocking antibody 3F7 prevented thrombosis; however, in contrast to traditional anticoagulants, bleeding was not increased. In addition to its function in thrombosis, FXIIa initiates formation of the inflammatory mediator bradykinin. This mediator increases vascular leak, causes vasodilation, and induces chemotaxis with implications for septic, anaphylactic and allergic disease states. Therefore, targeting FXIIa appears to be a promising strategy for thromboprotection without associated bleeding risks but with anti-inflammatory properties.

The role of coagulation/fibrinolysis during Streptococcus pyogenes infection

The hemostatic system comprises platelet aggregation, coagulation and fibrinolysis and is a host defense mechanism that protects the integrity of the vascular system after tissue injury. During bacterial infections, the coagulation system cooperates with the inflammatory system to eliminate the invading pathogens. However, pathogenic bacteria have frequently evolved mechanisms to exploit the hemostatic system components for their own benefit. Streptococcus pyogenes, also known as Group A Streptococcus, provides a remarkable example of the extraordinary capacity of pathogens to exploit the host hemostatic system to support microbial survival and dissemination. The coagulation cascade comprises the contact system (also known as the intrinsic pathway) and the tissue factor pathway (also known as the extrinsic pathway), both leading to fibrin formation. During the early phase of S. pyogenes infection, the activation of the contact system eventually leads to bacterial entrapment within a fibrin clot, where S. pyogenes is immobilized and killed. However, entrapped S. pyogenes can circumvent the antimicrobial effect of the clot by sequestering host plasminogen on the bacterial cell surface that, after conversion into its active proteolytic form, plasmin, degrades the fibrin network and facilitates the liberation of S. pyogenes from the clot. Furthermore, the surface-localized fibrinolytic activity also cleaves a variety of extracellular matrix proteins, thereby enabling S. pyogenes to migrate across barriers and disseminate within the host. This review summarizes the knowledge gained during the last two decades on the role of coagulation/fibrinolysis in host defense against S. pyogenes as well as the strategies developed by this pathogen to evade and exploit these host mechanisms for its own benefit.

Associations and outcomes of septic pulmonary embolism

Background:

Septic pulmonary embolism is a serious but uncommon syndrome posing diagnostic challenges because of its broad range of clinical presentation and etiologies.

Objective:

To understand the clinical and radiographic associations of septic pulmonary embolism in patients presenting to an acute care safety net hospital.

Methods:

We conducted a retrospective analysis of imaging and electronic health records of all patients diagnosed with septic pulmonary embolism in our hospital between January 2000 and January 2013.

Results:

41 episodes of septic pulmonary embolism were identified in 40 patients aged 17 to 71 years (median 46); 29 (72%) were men. Presenting symptoms included: febrile illness (85%); pulmonary complaints (66%) including pleuritic chest pain (22%), cough (19%) and dyspnea (15%); and those related to the peripheral foci of infection (24%) and shock (19%). Sources of infection included: skin and soft tissue (44%); infective endocarditis (27%); and infected peripheral deep venous thrombosis (17%). 35/41 (85%) were bacteremic with staphylococcus aureus. All patients had peripheral nodular lesions on chest CT scan. Treatment included intravenous antibiotics in all patients. Twenty six (63%) patients required pleural drainage and/or drainage of peripheral abscesses. Seven (17%) patients received systemic anticoagulants. Eight (20%) patients died due to various complications.

Conclusion:

The epidemiology of septic pulmonary embolism has broadened over the past decade with an increase in identified extrapulmonary, non-cardiac sources. In the context of an extrapulmonary infection, clinical features of persistent fever, bacteremia and pulmonary complaints should raise suspicion for this syndrome, and typical findings on the chest CT scans confirm the diagnosis. Antibiotics, local drainage procedures and increasingly, anticoagulation are keys to successful outcomes.

Crosstalk of the plasma contact system with bacteria

Activation of the plasma contact system triggers several cascade systems such as the kallikrein-kinin system, the intrinsic pathway of coagulation, the classical complement cascade and the fibrinolytic system. Recent studies have shown a critical role of the contact system for arterial and venous thrombus formation and thromboembolic disease. In contrast, the function of the contact system for host-defense reactions and its physiological functions have remained enigmatic. Experimental animal studies and clinical data have linked the contact system to bacterial infections with implications for sepsis disease. The present review summarizes the role of the contact system and its activation for bacterial infections.

Lemierre syndrome

Lemierre's syndrome is an uncommon complication of pharyngitis in the United States and caused most commonly by the bacterium Fusobacterium necrophorum. The syndrome is characterized by a history of recent pharyngitis followed by ipsilateral internal jugular vein thrombosis and metastatic pulmonary abscesses and is a disease for which patients will seek medical care and advice. As most patients are admitted to the hospital under internal medicine, practitioners should be familiar with the usual signs and symptoms of Lemierre's syndrome along with its diagnosis and treatment. Controversy involves the choice and duration of antimicrobial therapy used for treatment and anticoagulation therapy for internal jugular vein thrombosis. As the diagnosis and management of this syndrome has generated controversy, an updated review of the literature and treatment recommendations may be helpful for providing optimal care for patients with this often unrecognized and confusing infection.

Streptococcal surface proteins activate the contact system and control its antibacterial activity

Group G streptococci (GGS) are important bacterial pathogens in humans. Here, we investigated the interactions between GGS and the contact system, a procoagulant and proinflammatory proteolytic cascade that, upon activation, also generates antibacterial peptides. Two surface proteins of GGS, protein FOG and protein G (PG), were found to bind contact system proteins. Experiments utilizing contact protein-deficient human plasma and isogenic GGS mutant strains lacking FOG or PG showed that FOG and PG both activate the procoagulant branch of the contact system. In contrast, only FOG induced cleavage of high molecular weight kininogen, generating the proinflammatory bradykinin peptide and additional high molecular weight kininogen fragments containing the antimicrobial peptide NAT-26. On the other hand, PG protected the bacteria against the antibacterial effect of NAT-26. These findings underline the significance of the contact system in innate immunity and demonstrate that GGS have evolved surface proteins to exploit and modulate its effects.

The association of septic thrombophlebitis with septic pulmonary embolism in adults

Background:

There have been an increasing number of pediatric reports of septic pulmonary embolism in the setting of septic thrombophlebitis adjacent to a primary infectious source.

Methods:

Retrospective review at an urban hospital. A total of five adults with a documented primary infectious source, adjacent septic thrombophlebitis and septic pulmonary embolism were identified between 2000 and 2011.

Results:

The predominant symptoms on presentation were fever and pleuritic chest pain, followed by chills and cough. S. aureus was the pathogen in 4 patients. Only one case had echocardiographic evidence of endocarditis. All patients received IV antibiotics and anticoagulation therapy. No new embolic events or central nervous system complications were noted.

Conclusions:

The triad of extrapulmonary infection, contiguous septic thrombophlebitis and septic pulmonary embolism is present in adult as well as pediatric populations. The use of systemic anticoagulation with appropriate antibiotics resulted in clinical and radiologic improvement but no significant complications.