Factors associated with delayed diagnosis of infective endocarditis: A retrospective cohort study in a teaching hospital in Japan

99mTc-DTPA-Collagen Radiotracer for the Noninvasive Detection of Infective Endocarditis

Infective endocarditis (IE) represents a significant concern among hospital-acquired infections, frequently caused by the Gram-positive bacterium Staphylococcus aureus. Nuclear imaging is emerging as a noninvasive and precise diagnostic tool. However, the gold standard radiotracer [18F]-FDG cannot distinguish between infection and inflammation, resulting in false positives. Based on the presence of collagen-binding proteins in the cell wall of S. aureus, we propose the radiolabeling of collagen for its evaluation in IE animal models by single-photon emission computed tomography (SPECT) imaging. We radiolabeled rat tail collagen I using DTPA chelator and [99mTc]NaTcO4. Selectivity was evaluated in vitro using 3 Gram-positive bacteria, 1 Gram-negative bacteria and 1 yeast. In vivo SPECT/computed tomography (CT) imaging was conducted on 8 SD rat models of IE and 8 sterile sham model as controls. Ex vivo biodistribution and autoradiography were performed following imaging. Diagnosis of IE was confirmed through microbiological studies and H&E histopathology. [99mTc]-DTPA-Collagen was synthesized successfully with a yield of 42.86 ± 6.35%, a purity of 95.84 ± 1.85% and a stability higher than 90% after 50 h postincubation. In vitro uptake demonstrated the selectivity for Gram-positive bacteria (63.85 ± 15.15%). Ex vivo analysis confirmed hepato-splenic excretion. In vivo SPECT/CT imaging revealed highly localized uptake within the aortic valve with a sensitivity of 62.5% and specificity of 87.5%. We successfully synthesized and characterized a new SPECT radiotracer based on [99mTc]Tc-radiolabeled collagen. In vitro studies demonstrated the selectivity of the radiotracer for Gram-positive bacteria. In vivo SPECT/CT-based assessment in an IE model confirmed the potential of this approach to detect active IE.

Pneumococcal Endocarditis in a 49-Year-Old Male With Concomitant Myocarditis, Septic Spinal Arthritis, and Paraspinal Myositis: A Case Report

Pneumococcal infective endocarditis (PIE) is a rare but serious infection often presenting with systemic complications such as septic emboli, myocarditis, and septic arthritis. This case report highlights a 49-year-old male who presented with acute-on-chronic lower back pain and fever, later diagnosed with PIE complicated by septic spinal arthritis, paraspinal myositis, and developing myocarditis. A 49-year-old male presented to the emergency department (ED) with worsening back pain and fever after treatment failure for suspected pyelonephritis. Laboratory studies revealed leukocytosis, hypercalcemia, and acute kidney injury, while magnetic resonance imaging (MRI) identified septic facet arthritis and abscess formation. A transesophageal echocardiogram (TEE) revealed aortic valve vegetations consistent with infective endocarditis (IE). The patient required aortic valve replacement and prolonged hospital stay due to sepsis and respiratory failure. He recovered within 12 weeks with only moderate residual heart failure symptoms. This case highlights the medical complexities and difficulties of treating IE, as well as the critical importance of having it on a wide differential due to increased morbidity and mortality with delay of diagnosis, antibiotics, and surgical intervention.

A Large Tricuspid Subvalvular Apparatus Infective Endocarditis Undetected by Transthoracic Echocardiography

A 39-year-old male with a history of intravenous drug use (IVDU) and no significant cardiovascular disease was admitted to the ICU for management of septic shock and acute hypoxic respiratory failure secondary to septic pulmonary emboli. Due to a high clinical suspicion for right-sided infective endocarditis (IE), he received a transthoracic echocardiogram (TTE), which did not reveal any vegetations. However, a transesophageal echocardiogram (TEE) was subsequently performed; this showed a large 2.4 cm vegetation in the septal aspect of the tricuspid valve (TV) subvalvular apparatus. He urgently underwent surgical removal of the vegetation and repair of the TV. Postoperatively, he clinically recovered with appropriate antibiotic therapy. TEE is the ideal imaging modality in evaluation for IE, but a minimally invasive TTE is often performed first. This case highlights a highly unusual anatomic location of IE, which harbored a large vegetation undetected by TTE. In patients without cardiac devices or non-native valves, an urgent TEE remains diagnostically essential if there is a high clinical suspicion for right-sided IE, even if a TTE shows no evidence of IE.

Native valve, prosthetic valve, and cardiac device-related infective endocarditis: A review and update on current innovative diagnostic and therapeutic strategies

Infective endocarditis (IE) is a life-threatening microbial infection of native and prosthetic heart valves, endocardial surface, and/or indwelling cardiac device. Prevalence of IE is increasing and mortality has not significantly improved despite technological advances. This review provides an updated overview using recent literature on the clinical presentation, diagnosis, imaging, causative pathogens, treatment, and outcomes in native valve, prosthetic valve, and cardiac device-related IE. In addition, the experimental approaches used in IE research to improve the understanding of disease mechanisms and the current diagnostic pipelines are discussed, as well as potential innovative diagnostic and therapeutic strategies. This will ultimately help towards deriving better diagnostic tools and treatments to improve IE patient outcomes.

Frequency and Duration of, and Risk Factors for, Diagnostic Delays Associated with Histoplasmosis

Histoplasmosis is often confused with other diseases leading to diagnostic delays. We estimated the incidence, length of, and risk factors for, diagnostic delays associated with histoplasmosis. Using data from IBM Marketscan, 2001–2017, we found all patients with a histoplasmosis diagnosis. We calculated the number of visits that occurred prior to the histoplasmosis diagnosis and the number of visits with symptomatically similar diagnoses (SSDs). Next, we estimated the number of visits that represented a delay using a simulation-based approach. We also computed the number of potential opportunities for diagnosis that were missed for each patient and the length of time between the first opportunity and the diagnosis. Finally, we identified risk factors for diagnostic delays using a logistic regression model. The number of SSD-related visits increased significantly in the 97 days prior to the histoplasmosis diagnosis. During this period, 97.4% of patients had a visit, and 90.1% had at least one SSD visit. We estimate that 82.9% of patients with histoplasmosis experienced at least one missed diagnostic opportunity. The average delay was 39.5 days with an average of 4.0 missed opportunities. Risk factors for diagnostic delays included prior antibiotic use, history of other pulmonary diseases, and emergency department and outpatient visits, especially during weekends. New diagnostic approaches for histoplasmosis are needed.

Catastrophic case of suppurative, embolic and fistulating infective endocarditis causing complete heart block

Complete heart block, aortic root abscess and aortic valve regurgitation are well-recognized complications of infective endocarditis of the aortic valve. Splenic abscess and aorto-cavitary fistula are rarer phenomena and are indicative of calamitous infection. The authors present the case of an otherwise healthy 61-year-old man presenting with a 2-month history of non-specific symptoms, who developed suppurative endocarditis with a fistulating aortic root abscess, combined with severe sepsis, splenic embolization and complete heart block. Staphylococcus lugdunensis was the causative bacterium identified. The combination of these sequelae in the same patient is sparsely reported, is exceedingly rare and carries a significant risk of mortality.

Severity of anaemia and association with all-cause mortality in patients with medically managed left-sided endocarditis

OBJECTIVE

To assess the prevalence and severity of anaemia in patients with left-sided infective endocarditis (IE) and association with mortality.

METHODS

In the Partial Oral versus Intravenous Antibiotic Treatment of Endocarditis trial, 400 patients with IE were randomised to conventional or partial oral antibiotic treatment after stabilisation of infection, showing non-inferiority. Haemoglobin (Hgb) levels were measured at randomisation. Primary outcomes were all-cause mortality after 6 months and 3 years. Patients who underwent valve surgery were excluded due to competing reasons for anaemia.

RESULTS

Out of 400 patients with IE, 248 (mean age 70.6 years (SD 11.1), 62 women (25.0%)) were medically managed; 37 (14.9%) patients had no anaemia, 139 (56.1%) had mild anaemia (Hgb <8.1 mmol/L in men and Hgb <7.5 mmol/L in women and Hgb ≥6.2 mmol/L) and 72 (29.0%) had moderate to severe anaemia (Hgb <6.2 mmol/L). Mortality rates in patients with no anaemia, mild anaemia and moderate to severe anaemia were 2.7%, 3.6% and 15.3% at 6-month follow-up and 13.5%, 20.1% and 34.7% at 3-year follow-up, respectively. Moderate to severe anaemia was associated with higher mortality after 6 months (HR 4.81, 95% CI 1.78 to 13.0, p=0.002) and after 3 years (HR 2.14, 95% CI 1.27 to 3.60, p=0.004) and remained significant after multivariable adjustment.

CONCLUSION

Moderate to severe anaemia was present in 29% of patients with medically treated IE after stabilisation of infection and was independently associated with higher mortality within the following 3 years. Further investigations are warranted to determine whether intensified treatment of anaemia in patients with IE might improve outcome.

Development of a Clinical Prediction Model for Infective Endocarditis Among Patients with Undiagnosed Fever: A Pilot Case-Control Study

Purpose

Infective endocarditis (IE) may be diagnosed as fever of unknown origin due to its delusively non-descriptive clinical features, especially in outpatient clinics. Our objective is to develop a prediction model to discriminate patients to be diagnosed as “definite” IE from “non-definite” by modified Duke criteria among patients with undiagnosed fever, using only history and results of physical examinations and common laboratory examinations.

Patients and Methods

The study was a single-center case–control study. Inpatients at Saga University Hospital diagnosed with IE from 2007 to 2017 and patients with undiagnosed fever from 2015 to 2017 were enrolled. Patients diagnosed with definite IE according to the modified Duke criteria, except those definitely diagnosed with other disorders responsible for fever, were allocated to the IE group. Patients without IE among those defined as non-definite according to the modified Duke criteria were allocated to the undiagnosed fever group. We developed a prediction model to pick up patients who would be “definite” by modified Duke criteria, which was subsequently assessed by area under the curve (AUC).

Results

A total of 144 adult patients were included. Of these, 59 patients comprised the IE group. We developed the prediction model using five indicators, including transfer by ambulance, cardiac murmur, pleural effusion, neutrophil count, and platelet count, with a sensitivity 84.7%, a specificity 84.7%, an AUC 0.893 (95% confidence interval 0.828–0.959), a shrinkage coefficient 0.635, and a stratum-specific likelihood ratio 0.2–50.4.

Conclusion

Our prediction model, which uses only indicators easy to gain, facilitates prediction of patients with IE. These indicators can be acquired even at common hospitals and clinics, without requiring advanced medical equipment or invasive examinations.

Trial Registration Number

UMIN000041344.