Relationship between Gut, Blood, Aneurysm Wall and Thrombus Microbiome in Abdominal Aortic Aneurysm Patients.

Previous research confirmed gut dysbiosis and translocation of selected intestinal bacteria into the vessel wall in abdominal aortic aneurysm patients. We studied the stool, blood, thrombus and aneurysm microbiomes of 21 abdominal aortic aneurysm patients using 16S rRNA sequencing. Our goals were to determine: 1. whether the microbiome characteristic of an aneurysm differs from that of a healthy vessel, 2. whether bacteria detectable in the aneurysm are translocated from the gut through the bloodstream, 3. whether the enzymatic activity of the aneurysm microbiome can contribute to the destruction of the vessel wall. The abundance of Acinetobacter, Burkholderia, Escherichia, and Sphingobium in the aneurysm samples was significantly higher than that in the microbiome of healthy vessels, but only a part of these bacteria can come from the intestine via the blood. Environmental bacteria due to the oral cavity or skin penetration route, such as Acinetobacter, Sphingobium, Enhydrobacter, and Aquabacterium, were present in the thrombus and aneurysm with a significantly higher abundance compared to the blood. Among the enzymes of the microbiome associated with the healthy vessel wall, Iron-chelate-transporting ATPase and Polar-amino-acid-transporting ATPase have protective effects. In addition, bacterial Peptidylprolyl isomerase activity found in the aneurysm has an aggravating effect on the formation of aneurysm.

Intramyocardial abscess and endoventricular thrombosis: a complex case.

Infective endocarditis (IE) is today a public health problem, as the recent ESC Guidelines have also recalled. Abscesses can be complications of IE and their presence means that the infection is not controlled. We describe the complex case of a 57-year-old patient, presented in ED for fever and oleocranical bursitis, increase of cardiac enymes at blood samples. He was admitted to our Cardiology Unit because TTE showed a floating peduncolated formation in the left ventricle. The susequent TEE documented also the presence of a myocardial abscess, confirmed at cardiac MRI. Blood cultures were positive for MSSA and the man received specific antibiotic therapy. Anticoagulation treatment was started with UFH and then switched to Warfarin, surgical approach of the lesion would have been too dangerous according to Cardiac Surgeons. Serious and sudden neurological complications then followed, leading the patient to brain death in ICU.

Missing the blind spot in a HeartMate 3 LVAD outflow graft obstruction caused by fungal infection.

A patient was admitted in cardiogenic shock and a constant decrease of pump flow requiring combined inotropic support. To evaluate the cause, echocardiography and a ramp test were performed. The results suggested a LVAD related problem - particularly a suspected outflow graft obstruction. Wether CT scan nor angiography confirmed the assumption. However, a post-mortem LVAD examination revealed an outflow obstruction caused by a fungal thrombus formation invisible for standard imaging procedures.

White thrombus as a possible feature of atypical stroke etiology: Coxiella burnetii as the primary cause of acute ischemic stroke.

Acute ischemic stroke (AIS) is the most common neurologic complication of infective endocarditis. We describe a singular case report of a 62- year-old male with AIS related to the occlusion of the left middle cerebral artery. Thrombus-aspiration allowed retrieving a 6 millimeters white thrombus. The real-time polymerase chain reaction performed on the thrombus detected Coxiella Burnetii allowed the diagnosis of infective endocarditis (IE) and the identification of the specific pathogen. Coxiella Burnetii is an endemic, small, intracellular, gram-negative coccobacillus and it is a rare cause of IE. The management of AIS caused by IE remains controversial, although in the cases of major occlusion mechanical thrombectomy is associated with better clinical outcomes. IE patients could not present symptoms and signs related to the infection, therefore we underline the importance of the microbiological analysis of the retrieved thrombi especially when atypical etiology is suspected.

Vascular pythiosis caused by Pythium aphanidermatum: the first case report in Asia.

BACKGROUND: Pythium, soil-borne plant pathogens, are in the class Oomycetes. They are not true fungi, but are related to diatom and algae. There are two human pathogens including P. insidiosum and P. aphanidermatum. To date, only one case of pythiosis caused by P. aphanidermatum has been reported. We present herein the first case of P. aphanidermatum vascular pythiosis in Asia. CASE PRESENTATION: A 47-year-old Thai woman, living in North Thailand, with ß thalassemia/hemoglobin E presented with acute recurrent arterial insufficiency of both legs. Emergent embolectomy with clot removal was performed. The pathology of the clot exhibited noncaseous granulomatous inflammation with many fungal hyphal elements. PCR identified P. aphanidermatum with 100% identity. Final diagnosis is vascular pythiosis. Unfortunately, the patient eventually expired after treatment with itraconazole, terbinafine, azithromycin, and doxycycline. CONCLUSIONS: To date, only one case of pythiosis caused by P. aphanidermatum has been reported. We present herein the first case of P. aphanidermatum vascular pythiosis in Asia.

The diagnostic value of [18F]FDG-PET/CT in detecting septic thrombosis in patients with central venous catheter-related Staphylococcus aureus bacteremia.

PURPOSE: Septic thrombosis often complicates Staphylococcus aureus bacteremia (SAB) in patients with a central venous catheter. Currently there is no reference standard for diagnosis. We describe the diagnostic value of [18F]FDG-PET/CT imaging in a patient cohort and the potential contribution of quantitative measurements in detecting septic thrombosis. METHODS: We selected patients with catheter-related SAB from our institutional database (2013-2020). The contribution of [18F]FDG-PET/CT on clinical diagnosis of septic thrombosis was evaluated. Standardized Uptake Values (SUV) were measured and compared with a composite reference standard (clinical signs, initial [18F]FDG-PET/CT result, Multidisciplinary Team (MDT) meeting outcome) to identify a cut-off value for detecting septic thrombosis. RESULTS: We identified 93 patients with a catheter-related SAB. Quantitative measurements were possible for 43/56 patients in whom a [18F]FDG-PET/CT scan was performed. Septic thrombosis was clinically diagnosed in 30% (13/43) of the cases. In 85% of these cases, significant [18F]FDG-PET/CT uptake at the site of the thrombus was the deciding factor for diagnosis of septic thrombosis during the MDT meeting. All mean SUV's of thrombotic lesions were higher in patients with clinically proven septic thrombosis compared to patients in whom this diagnosis was rejected (p < 0.001). A SUVpeak thrombus/SUVmean blood ratio of 1.6 (AUC-ROC value 0.982) as cut-off to differentiate between septic thrombosis and non-septic thrombosis had a sensitivity of 92% (95% CI 64-100) and specificity of 89% (95% CI 65-99). An algorithm was designed to guide diagnosis of septic thrombosis. CONCLUSION: Quantitative [18F]FDG-PET/CT-derived parameters seem helpful to differentiate between septic and non-septic thrombosis in patients with catheter-related SAB.

Induction of Sepsis Via Fibrin Clot Implantation.

Implantation of bacteria embedded in a fibrin clot allows for successful establishment of sepsis in preclinical models. This model allows the investigator to modulate the strain of bacteria as well as the bacterial load delivered. As it allows for a slow release of standardized bacteria, the use of a fibrin clot model may be considered in studying the initial and later phases of sepsis and the host response to infection. Here we describe methods for performing the fibrin clot model of sepsis.

Cardiac thrombus and stroke in a child with Mycoplasma pneumoniae pneumonia: A case report.

RATIONALE: Cardiac thrombus and stroke are rare complications in Mycoplasma pneumoniae infection, which is a common cause of community-acquired pneumonia in children. Early detection and prevention of thrombus in children with M pneumoniae pneumonia is relatively difficult. PATIENT CONCERNS: A 5-year-old boy with severe M pneumoniae pneumonia was referred to our center. During the treatment with sufficient antibiotics, an echocardiography surprisingly revealed a thrombus in the left atrium, with significant changes in D-dimer level and anti-phospholipid antibodies. At day 12 after admission, the patient showed impaired consciousness, aphasia, and reduced limb muscle power. Magnetic resonance angiography (MRA) showed right middle cerebral artery infarction. DIAGNOSES: Cardiac thrombus and stroke associated with M pneumoniae pneumonia. INTERVENTIONS: He was started on aggressive antibiotic therapy and urokinase thrombolytic therapy for 24 hours, continued with low molecular heparin calcium and aspirin along with rehabilitation training. OUTCOMES: On follow up, the D-dimer decreased slowly and echocardiograms showed a steadily decreasing size of thrombus with eventual disappearance at day 22 after admission. His left limb muscle power was improved after rehabilitation for 2 months. LESSONS: Early diagnosis and treatment with multiple modalities maybe useful for improving prognosis of cardiac thrombus and stroke in M pneumoniae pneumonia. Changes in D-dimer level and anti-phospholipid antibodies should be routinely monitored in severe M pneumoniae pneumonia.

ABO Blood Types and COVID-19: Spurious, Anecdotal, or Truly Important Relationships? A Reasoned Review of Available Data.

Since the emergence of COVID-19, many publications have reported associations with ABO blood types. Despite between-study discrepancies, an overall consensus has emerged whereby blood group O appears associated with a lower risk of COVID-19, while non-O blood types appear detrimental. Two major hypotheses may explain these findings: First, natural anti-A and anti-B antibodies could be partially protective against SARS-CoV-2 virions carrying blood group antigens originating from non-O individuals. Second, O individuals are less prone to thrombosis and vascular dysfunction than non-O individuals and therefore could be at a lesser risk in case of severe lung dysfunction. Here, we review the literature on the topic in light of these hypotheses. We find that between-study variation may be explained by differences in study settings and that both mechanisms are likely at play. Moreover, as frequencies of ABO phenotypes are highly variable between populations or geographical areas, the ABO coefficient of variation, rather than the frequency of each individual phenotype is expected to determine impact of the ABO system on virus transmission. Accordingly, the ABO coefficient of variation correlates with COVID-19 prevalence. Overall, despite modest apparent risk differences between ABO subtypes, the ABO blood group system might play a major role in the COVID-19 pandemic when considered at the population level.

Microbiota thrombus colonization may influence athero-thrombosis in hyperglycemic patients with ST segment elevation myocardialinfarction (STEMI). Marianella study.

OBJECTIVES: We examined the association of the coronary thrombus microbiota and relative metabolites with major adverse cardiovascular events (MACE) in hyperglycemic patients with ST segment elevation myocardial infarction (STEMI). BACKGROUND: Hyperglycemia during STEMI may affect both development and progression of coronary thrombus via gut and thrombus microbiota modifications. METHODS: We undertook an observational cohort study of 146 first STEMI patients treated with primary percutaneous coronary intervention (PPCI) and thrombus-aspiration (TA). Patients were clustered, based on admission blood glucose levels, in hyperglycemic (≥140 mg/dl) and normoglycemic (<140 mg/dl). We analyzed gut and thrombus microbiota in all patients. Moreover, we assessed TMAO, CD40L and von Willebrand Factor (vWF) in coronary thrombi. Cox regressions were used for the association between Prevotellaspp. and TMAO terziles and MACE. MACE endpoint at 1 year included death, re-infarction, unstable angina. RESULTS: In fecal and thrombus samples, we observed a significantly different prevalence of both Prevotellaspp. and Alistipesspp. between patients with hyperglycemia (n = 56) and those with normal glucose levels (n = 90). The abundance of Prevotella increased in hyperglycemic vs normoglycemic patients whereas the contrary was observed for Alistipes. Interestingly, in coronary thrombus, the content of Prevotella was associated with admission blood glucose levels (p < 0.01), thrombus dimensions (p < 0.01), TMAO, CDL40 (p < 0.01) and vWF (p < 0.01) coronary thrombus contents. Multivariate Cox-analysis disclosed a reduced survival in patients with high levels of Prevotella and TMAO in coronary thrombus as compared to patients with low levels of Prevotella and TMAO, after 1-year follow up. CONCLUSIONS: Hyperglycemia during STEMI may increase coronary thrombus burden via gut and thrombus microbiota dysbiosis characterized by an increase of Prevotella and TMAO content in thrombi. CLINICAL TRIAL REGISTRATION: NCT03439592. September 30, 2016. Ethic Committee Vanvitelli University: 268/2016.

S-Nitrosoglutathione-Based Nitric Oxide-Releasing Nanofibers Exhibit Dual Antimicrobial and Antithrombotic Activity for Biomedical Applications.

The novel use of nanofibers as a physical barrier between blood and medical devices has allowed for modifiable, innovative surface coatings on devices ordinarily plagued by thrombosis, delayed healing, and chronic infection. In this study, the nitric oxide (NO) donor S-nitrosoglutathione (GSNO) is blended with the biodegradable polymers polyhydroxybutyrate (PHB) and polylactic acid (PLA) for the fabrication of hemocompatible, antibacterial nanofibers tailored for blood-contacting applications. Stress/strain behavior of different concentrations of PHB and PLA is recorded to optimize the mechanical properties of the nanofibers. Nanofibers incorporated with different concentrations of GSNO (10, 15, 20 wt%) are evaluated based on their NO-releasing kinetics. PLA/PHB + 20 wt% GSNO nanofibers display the greatest NO release over 72 h (0.4-1.5 × 10-10  mol mg-1 min-1 ). NO-releasing fibers successfully reduce viable adhered bacterial counts by ≈80% after 24 h of exposure to Staphylococcus aureus. NO-releasing nanofibers exposed to porcine plasma reduce platelet adhesion by 64.6% compared to control nanofibers. The nanofibers are found noncytotoxic (>95% viability) toward NIH/3T3 mouse fibroblasts, and 4',6-diamidino-2-phenylindole and phalloidin staining shows that fibroblasts cultured on NO-releasing fibers have improved cellular adhesion and functionality. Therefore, these novel NO-releasing nanofibers provide a safe antimicrobial and hemocompatible coating for blood-contacting medical devices.

HSF1 Alleviates Microthrombosis and Multiple Organ Dysfunction in Mice with Sepsis by Upregulating the Transcription of Tissue-Type Plasminogen Activator.

Sepsis is a life-threatening complication of infection closely associated with coagulation abnormalities. Heat shock factor 1 (HSF1) is an important transcription factor involved in many biological processes, but its regulatory role in blood coagulation remained unclear. We generated a sepsis model in HSF1-knockout mice to evaluate the role of HSF1 in microthrombosis and multiple organ dysfunction. Compared with septic wild-type mice, septic HSF1-knockout mice exhibited a greater degree of lung, liver, and kidney tissue damage, increased fibrin/: fibrinogen deposition in the lungs and kidneys, and increased coagulation activity. RNA-seq analysis revealed that tissue-type plasminogen activator (t-PA) was upregulated in the lung tissues of septic mice, and the level of t-PA was significantly lower in HSF1-knockout mice than in wild-type mice in sepsis. The effects of HSF1 on t-PA expression were further validated in HSF1-knockout mice with sepsis and in vitro in mouse brain microvascular endothelial cells using HSF1 RNA interference or overexpression under lipopolysaccharide stimulation. Bioinformatics analysis, combined with electromobility shift and luciferase reporter assays, indicated that HSF1 directly upregulated t-PA at the transcriptional level. Our results reveal, for the first time, that HSF1 suppresses coagulation activity and microthrombosis by directly upregulating t-PA, thereby exerting protective effects against multiple organ dysfunction in sepsis.

The Commensal Microbiota Enhances ADP-Triggered Integrin αIIbß3 Activation and von Willebrand Factor-Mediated Platelet Deposition to Type I Collagen.

The commensal microbiota is a recognized enhancer of arterial thrombus growth. While several studies have demonstrated the prothrombotic role of the gut microbiota, the molecular mechanisms promoting arterial thrombus growth are still under debate. Here, we demonstrate that germ-free (GF) mice, which from birth lack colonization with a gut microbiota, show diminished static deposition of washed platelets to type I collagen compared with their conventionally raised (CONV-R) counterparts. Flow cytometry experiments revealed that platelets from GF mice show diminished activation of the integrin αIIbß3 (glycoprotein IIbIIIa) when activated by the platelet agonist adenosine diphosphate (ADP). Furthermore, washed platelets from Toll-like receptor-2 (Tlr2)-deficient mice likewise showed impaired static deposition to the subendothelial matrix component type I collagen compared with wild-type (WT) controls, a process that was unaffected by GPIbα-blockade but influenced by von Willebrand factor (VWF) plasma levels. Collectively, our results indicate that microbiota-triggered steady-state activation of innate immune pathways via TLR2 enhances platelet deposition to subendothelial matrix molecules. Our results link host colonization status with the ADP-triggered activation of integrin αIIbß3, a pathway promoting platelet deposition to the growing thrombus.

Presence of bacterial DNA in thrombotic material of patients with myocardial infarction.

Infectious agents have been suggested to be involved in etiopathogenesis of Acute Coronary Syndrome (ACS). However, the relationship between bacterial infection and acute myocardial infarction (AMI) has not yet been completely clarified. The objective of this study is to detect bacterial DNA in thrombotic material of patients with ACS with ST-segment elevation (STEMI) treated with Primary Percutaneous Coronary Intervention (PPCI). We studied 109 consecutive patients with STEMI, who underwent thrombus aspiration and arterial peripheral blood sampling. Testing for bacterial DNA was performed by probe-based real-time Polymerase Chain Reaction (PCR). 12 probes and primers were used for the detection of Aggregatibacter actinomycetemcomitans, Chlamydia pneumoniae, viridans group streptococci, Porphyromonas gingivalis, Fusobacterium nucleatum, Tannarella forsythia, Treponema denticola, Helycobacter pylori, Mycoplasma pneumoniae, Staphylococus aureus,  Prevotella intermedia and Streptococcus mutans. Thus, DNA of four species of bacteria was detected in 10 of the 109 patients studied. The most frequent species was viridans group streptococci (6 patients, 5.5%), followed by Staphylococus aureus (2 patients, 1.8%). Moreover, a patient had DNA of Porphyromonas gingivalis (0.9%); and another patient had DNA of Prevotella intermedia (0.9%). Bacterial DNA was not detected in peripheral blood of any of our patients. In conclusion, DNA of four species of endodontic and periodontal bacteria was detected in thrombotic material of 10 STEMI patients. Bacterial DNA was not detected in the peripheral blood of patients with bacterial DNA in their thrombotic material. Bacteria could be latently present in plaques and might play a role in plaque instability and thrombus formation leading to ACS.

Left Ventricular Infected Thrombus Detected by 18F-FDG PET/CT and MRI in Disseminated Staphylococcus Infection.

We present the case of a 61-year-old woman with fever and acute meningitis. Clinical evaluation revealed maculopapular rash, right gluteus cellulitis, and centered retinal hemorrhages. In the intensive care unit, persistent Staphylococcus bacteremia was detected. However, transesophageal echocardiography did not reveal pathologic features. F-FDG PET/CT and cardiac MRI diagnosed a left ventricular infected thrombus, an extremely rare condition especially in patients without structural cardiopathy.

[A fungus in a thrombus by mechanical thrombectomy in acute cerebral infarction: a case report].

A 88-year-old man suddenly presented with aphasia and right hemiparesis. The diffusion-weighted image of MRI showed ischemic lesions on the left middle cerebral artery area, and MRA showed the left intracranial artery (ICA) occlusion. Therefore, we diagnosed him as having acute ischemic stroke and treated with mechanical thrombectomy (MT). The DWI of MRI showed ischemic lesions on the left middle cerebral artery area, and MRA showed the left ICA occlusion. Therefore, we performed MT and continued best medical treatment, but ICA was reoccluded. Six day later, aspergillus was found in the thrombus from ICA. Then, we considered that ICA occlusion was caused by aspergillus. We experienced a patient specified the cause by thrombus pathology. The pathological diagnosis of the thrombus getting by MT is usefulness for stroke etiology.

Gram-negative septic thrombosis in critically ill patients: A retrospective case-control study.

BACKGROUND: Data on septic thrombosis caused by Gram-negative bacilli (GN-ST) in intensive care unit (ICU) patients are currently limited. METHODS: The aim of this retrospective case-control study (matched 1:3) performed over a 15-month period on ICU patients with bacteraemia, associated (cases) or not (controls) with GN-ST, was to assess 30-day mortality and clinical/microbiological features of GN-ST. RESULTS: During the study period, 16 patients with GN-ST and 48 controls were analyzed. Polytrauma was the cause of ICU admission in 12 (75%) cases and 22 (46%) controls (p = 0.019). In no case of septic thrombosis was surgical debridement performed. The site of venous thrombosis was more frequently in the lower limbs, associated with bone fracture in nine out of 12 (75%) cases. The median duration of bacteraemia (22 days vs 1 day; p < 0.001) and time to clinical improvement (15 days vs 4 days; p < 0.001) were significantly longer in cases than in controls. On analysis of the receiver operating characteristics (ROC) curve, bacteraemia >72 h was significantly associated with GN-ST (area under the curve (AUC) 0.95, sensitivity 0.996 and specificity 0.810; p < 0.001). Finally, 30-day mortality was 20% in cases and 67% in controls (p < 0.001). CONCLUSIONS: Critically ill patients with GN-ST showed specific clinical features. Despite delayed bacteraemia clearance, targeted antibiotic therapy plus anticoagulation usually provided clinical improvement and a low 30-day mortality rate.

A Cardiovascular Disease-Linked Gut Microbial Metabolite Acts via Adrenergic Receptors.

Using untargeted metabolomics (n = 1,162 subjects), the plasma metabolite (m/z = 265.1188) phenylacetylglutamine (PAGln) was discovered and then shown in an independent cohort (n = 4,000 subjects) to be associated with cardiovascular disease (CVD) and incident major adverse cardiovascular events (myocardial infarction, stroke, or death). A gut microbiota-derived metabolite, PAGln, was shown to enhance platelet activation-related phenotypes and thrombosis potential in whole blood, isolated platelets, and animal models of arterial injury. Functional and genetic engineering studies with human commensals, coupled with microbial colonization of germ-free mice, showed the microbial porA gene facilitates dietary phenylalanine conversion into phenylacetic acid, with subsequent host generation of PAGln and phenylacetylglycine (PAGly) fostering platelet responsiveness and thrombosis potential. Both gain- and loss-of-function studies employing genetic and pharmacological tools reveal PAGln mediates cellular events through G-protein coupled receptors, including α2A, α2B, and ß2-adrenergic receptors. PAGln thus represents a new CVD-promoting gut microbiota-dependent metabolite that signals via adrenergic receptors.

Prothrombotic and Proinflammatory Activities of the ß-Hemolytic Group B Streptococcal Pigment.

A prominent feature of severe streptococcal infections is the profound inflammatory response that contributes to systemic toxicity. In sepsis the dysregulated host response involves both immunological and nonimmunological pathways. Here, we report a fatal case of an immunocompetent healthy female presenting with toxic shock and purpura fulminans caused by group B streptococcus (GBS; serotype III, CC19). The strain (LUMC16) was pigmented and hyperhemolytic. Stimulation of human primary cells with hyperhemolytic LUMC16 and STSS/NF-HH strains and pigment toxin resulted in a release of proinflammatory mediators, including tumor necrosis factor, interleukin (IL)-1ß, and IL-6. In addition, LUMC16 induced blood clotting and showed factor XII activity on its surface, which was linked to the presence of the pigment. The expression of pigment was not linked to a mutation within the CovR/S region. In conclusion, our study shows that the hemolytic lipid toxin contributes to the ability of GBS to cause systemic hyperinflammation and interferes with the coagulation system.