Postmortem diagnosis of sepsis: A preliminary immunohistochemical study with an anti-procalcitonin antibody

Sudden Death: A Practical Autopsy Approach to Unexplained Mediastinitis Due to Fatal Untreated Neck Infections-A Systematic Review

Neck infections are often prone to being underestimated and can manifest insidiously. The spread of infection can lead to translocation into thoracic areas, causing descending necrotizing mediastinitis (DNM). However, the application of the post-mortem approach in such cases is not well-described in the literature. A literature review was carried out according to the PRISMA methods. Nine papers were included in the final review, revealing different levels of involvement of neck layers that can be linked to different causes. Expertise with respect to the anatomy of the fasciae and spaces of the neck enables an understanding of the pathogenesis of DNM. However, a clear autoptic description was not provided in any of the articles. Therefore, we also employed a practical post-mortem approach to cases of death due to DNM. It is fundamental for pathologists to identify the exact head and neck structures involved. Providing dissectors with support from an otolaryngologist could be useful. This paper could help address such difficult cases.

Procalcitonin and Adrenomedullin in Infectious Diseases

Calcitonin (CT) and adrenomedullin (ADM) are members of the CT family. Procalcitonin (PCT) is a prohormone of CT. Elevations in serum PCT and ADM levels are associated with severe sepsis and coronavirus disease 2019 (COVID-19). PCT enhances sepsis mortality and it binds to the CGRP receptor, which is a heterodimer of CT receptor-like receptor and receptor activity-modifying protein 1. The N-terminal truncated form of PCT, PCT3-116, is produced by the cleavage of PCT by dipeptidyl peptidase 4 (DPP-4) and is the main form of PCT in serum during sepsis, inducing microvascular permeability. Mid-regional pro-adrenomedullin (MR-proADM) is used instead of ADM as a biological indicator because ADM is rapidly degraded, and MR-proADM is released at the same rate as ADM. ADM reduces endothelial permeability and promotes endothelial stability. Endothelial dysfunction is responsible for multiple organ failure in sepsis and COVID-19 patients. Therefore, ADM may be an important molecule for improving the severity associated with sepsis and COVID-19. This review focuses on the current knowledge of PCT and ADM in sepsis and COVID-19.

Neonatal Sepsis Caused by Streptococcus gallolyticus Complicated with Pulmonary Hypertension: A Case-Report and a Systematic Literature Review

Streptococcus gallolyticus (S. gallolyticus) has been linked to the development of infections in adults; however, in neonates S. gallolyticus sepsis is very rare and resembles Group B Streptococcal infections. In this case report, we present the case of a full-term neonate who developed early-onset sepsis due to S. gallolyticus. A systematic review of the literature was also conducted. The neonate had good APGAR scores at 1' and 5'. At 5 h postnatally, the neonate developed poor feeding and respiratory distress. She received oxygen in a head box, and a complete blood count and biochemistry, blood, CSF and body surface cultures were obtained. Empiric intravenous antibiotics (ampicillin and tobramycin) were initiated, and she was transferred to a tertiary NICU for further treatment. The neonate was mechanically ventilated and received dopamine and colloid fluids for circulatory support. A cardiology consultation revealed pulmonary hypertension on day one. S. gallolyticus was isolated in the blood culture. Central nervous system ultrasonography, brainstem auditory evoked potentials, and a second cardiology evaluation were normal on day three. Clinical and laboratory improvement was noted on day three, and the baby was discharged after a 12-day hospitalization. Follow-up visits were scheduled for reevaluation.

Circulating Inflammatory Biomarkers in Early Prediction of Stroke-Associated Infections

(1) Background: Patients with acute ischaemic stroke (AIS) are at high risk for stroke-associated infections (SAIs). We hypothesised that increased concentrations of systemic inflammation markers predict SAIs and unfavourable outcomes; (2) Methods: In 223 patients with AIS, blood samples were taken at ≤24 h, 3 d and 7d after a stroke, to determine IL-6, IL-10, CRP and LBP. The outcome was assessed using the modified Rankin Scale at 90 d. Patients were thoroughly examined regarding the development of SAIs; (3) Results: 47 patients developed SAIs, including 15 lower respiratory tract infections (LRTIs). IL-6 and LBP at 24 h differed, between patients with and without SAIs (IL-6: p < 0.001; LBP: p = 0.042). However, these associations could not be confirmed after adjustment for age, white blood cell count, reduced consciousness and NIHSS. When considering the subgroup of LRTIs, in patients who presented early (≤12 h after stroke, n = 139), IL-6 was independently associated with LRTIs (OR: 1.073, 95% CI: 1.002−1.148). The ROC-analysis for prediction of LRTIs showed an AUC of 0.918 for the combination of IL-6 and clinical factors; (4) Conclusions: Blood biomarkers were not predictive for total SAIs. At early stages, IL-6 was independently associated with outcome-relevant LRTIs. Further studies need to clarify the use of biochemical markers to identify patients prone to SAIs.

Postmortem Evidence of Brain Inflammatory Markers and Injury in Septic Patients: A Systematic Review

OBJECTIVES

Sepsis is a life-threatening organ dysfunction caused by a host's unregulated immune response to eliminate the infection. After hospitalization, sepsis survivors often suffer from long-term impairments in memory, attention, verbal fluency, and executive functioning. To understand the effects of sepsis and the exacerbated peripheral inflammatory response in the brain, we asked the question: What are the findings and inflammatory markers in the brains of deceased sepsis patients? To answer this question, we conducted this systematic review by the recommendations of Preferred Reporting Items for Systematic Reviews and Meta-Analyses.

DATA SOURCES

Relevant studies were identified by searching the PubMed/National Library of Medicine, PsycINFO, EMBASE, Bibliographical Index in Spanish in Health Sciences, Latin American and Caribbean Health Sciences Literature, and Web of Science databases for peer-reviewed journal articles published on April 05, 2021.

STUDY SELECTION

A total of 3,745 articles were included in the primary screening; after omitting duplicate articles, animal models, and reviews, 2,896 articles were selected for the study. These studies were selected based on the title and abstract, and 2,772 articles were still omitted based on the exclusion criteria.

DATA EXTRACTION

The complete texts of the remaining 124 articles were obtained and thoroughly evaluated for the final screening, and 104 articles were included.

DATA SYNTHESIS

The postmortem brain had edema, abscess, hemorrhagic and ischemic injuries, infarction, hypoxia, atrophy, hypoplasia, neuronal loss, axonal injuries, demyelination, and necrosis.

CONCLUSIONS

The mechanisms by which sepsis induces brain dysfunction are likely to include vascular and neuronal lesions, followed by the activation of glial cells and the presence of peripheral immune cells in the brain.

Immunohistochemistry in the Postmortem Diagnosis of Sepsis: A Systematic Review

It is not uncommon for the forensic pathologist to question whether a deceased person had experienced sepsis that could have either been the cause of or contributed to the person's death. Often, the missing typical pathologic factors or lack of clinical and circumstantial information on the death render the autopsy of a sepsis-related death a difficult task for the forensic pathologist. Several authors emphasize on how an immunohistochemical analysis could help in diagnosing death related to sepsis. The research we carried out analyzes the main scientific studies in the literature, primarily the tracing of 21 immunohistochemical antigens evaluated to help diagnose death related to sepsis. The purpose of this review was to analyze and summarize the markers studied until now and to consider the limitations of immunohistochemistry that currently exist with regard to this particular field of forensic pathology. Immunohistochemistry provided interesting and promising results, but further studies are needed in order for them to be confirmed, so that they may be applied in standard forensic practice.

Black esophagus as an autopsy discovery: a challenging interpretation

Black esophagus is a rare medical condition, characterized by a circumferential blackish discoloration of the distal part of the esophageal mucosa, abruptly ending at the gastroesophageal junction. The etiology is multifactorial since patients suffer from multiple comorbidities. While the mortality rate specifically linked to black esophagus is only around 6%, the mortality rate linked to the underlying comorbidities amounts to 32%.

A series of five cases is provided in which black esophagus was an unexpected discovery at autopsy. Black esophagus is generally considered being a challenge to the forensic pathologist. There are often no other major gross anomalies found at autopsy and information about the patient’s medical history is not always available, which complicates a correct assessment.

We present a review of the literature on black esophagus, limited to reports on deceased patients. The reviewed publications are divided into autopsy and endoscopy series to correctly compare the causes of death.

The aim of this review is to identify a possible divergence in causes of death in autopsy and endoscopy series and additionally to analyze the causes of these differences to enable better assessment and interpretation of black esophagus at forensic autopsies. This paper emphasizes the importance of a minimal knowledge of the victim’s comorbidities and medical record and the use of toxicology and postmortem biochemistry analysis as a valuable tool in investigating the cause of death in the setting of black esophagus.

Post-Mortem Investigations for the Diagnosis of Sepsis: A Review of Literature

To date, sepsis is still one of the most important causes of death due to the difficulties concerning the achievement of a correct diagnosis. As well as in a clinical context, also in a medico-legal setting the diagnosis of sepsis can reveal challenging due to the unspecificity of the signs detected during autopsies, especially when no ante-mortem clinical data, laboratory, and cultural results are available. Thus, a systematic review of literature was performed to provide an overview of the main available and updated forensic tools for the post-mortem diagnosis of sepsis. Moreover, the aim of this review was to evaluate whether a marker or a combination of markers exist, specific enough to allow a correct and definite post-mortem diagnosis. The review was conducted searching in PubMed and Scopus databases, and using variable combinations of the keywords "post mortem sepsis diagnosis", "macroscopic signs", "morphology", "histology", "immunohistochemical markers", "biochemical markers", and "forensic microbiology". The article selection was carried out following specific inclusion and exclusion criteria. A total of 44 works was identified, providing data on morphological aspects of the organs examined, histological findings, immunohistochemical and biochemical markers, and cultural assays. The review findings suggested that the post-mortem diagnosis of sepsis can be achieved by a combination of data obtained from macroscopic and microscopic analysis and microbial investigations, associated with the increased levels of at least two of three biochemical and/or immunohistochemical markers evaluated simultaneously on blood samples.

Post-Traumatic Meningitis Is a Diagnostic Challenging Time: A Systematic Review Focusing on Clinical and Pathological Features

Post-traumatic meningitis is a dreadful condition that presents additional challenges, in terms of both diagnosis and management, when compared with community-acquired cases. Post-traumatic meningitis refers to a meningeal infection causally related to a cranio-cerebral trauma, regardless of temporal proximity. The PICO (participants, intervention, control, and outcomes) question was as follows: "Is there an association between traumatic brain injury and post-traumatic meningitis?" The present systematic review was carried out according to the Preferred Reporting Items for Systematic Review (PRISMA) standards. Studies examining post-traumatic meningitis, paying particular attention to victims of traumatic brain injury, were included. Post-traumatic meningitis represents a high mortality disease. Diagnosis may be difficult both because clinical signs are nonspecific and blurred and because of the lack of pathognomonic laboratory markers. Moreover, these markers increase with a rather long latency, thus not allowing a prompt diagnosis, which could improve patients' outcome. Among all the detectable clinical signs, the appearance of cranial cerebrospinal fluid (CSF) leakage (manifesting as rhinorrhea or otorrhea) should always arouse suspicion of meningitis. On one hand, microbiological exams on cerebrospinal fluid (CSF), which represent the gold standard for the diagnosis, require days to get reliable results. On the other hand, radiological exams, especially CT of the brain, could represent an alternative for early diagnosis. An update on these issues is certainly of interest to focus on possible predictors of survival and useful tools for prompt diagnosis.

Sepsis and Nosocomial Infections: The Role of Medico-Legal Experts in Italy

Sepsis is a leading cause of morbidity and mortality worldwide. It is defined as the presence of a Systemic Inflammatory Response Syndrome, and it represents a significant burden for the healthcare system. This is particularly true when it is diagnosed in the setting of nosocomial infections, which are usually a matter of concern with regard to medical liability being correlated with increasing economic costs and people's loss of trust in healthcare. Hence, the Italian governance promotes the clinical risk management with the aim of improving the quality and safety of healthcare services. In this context, the role of medico-legal experts working in a hospital setting is fundamental for performing autopsy to diagnose sepsis and link it with possible nosocomial infections. On the other hand, medico-legal experts are party to the clinical risk management assessment, and deal with malpractice cases and therefore contribute to formulating clinical guidelines and procedures for improving patient safety and healthcare providers' work practices. Due to this scenario, the authors here discuss the role of medico-legal experts in Italy, focusing on sepsis and nosocomial infections.

Septic myocardial calcification: A case report

The histological findings in the heart in cases of fatal sepsis can show myocytolysis, interstitial fibrosis, necrotic contraction band, mononuclear infiltrates, and interstitial edema, which can be used in post mortem diagnosis of sepsis. Septic myocardial calcification is a very rare condition, and only a few cases have been reported in the literature. In general, the pathogenesis of the myocardial calcification has not been well clarified, but two pathogenic mechanisms have been universally recognized: metastatic or dystrophic. We present a rare case of sepsis-related myocardial calcification. Here we report a case involving a 72-year-old white male who was admitted to a hospital for a polytrauma caused by a motorbike accident. On the 110th day of hospitalization, the patient was diagnosed with a septic process and a subsequent transesophageal echocardiogram revealed the presence of a calcification on the right atrial wall. According to the medical history of the patient there were no systemic factors predisposing to calcium crystals deposition in tissues. Patient died due to multi-organ failure in the course of multimicrobial septic shock during the 149th day. The autopsy revealed both the presence of a greenish-brown formation and a greater consistency of the right atrial wall. The histological investigation of the right atrium wall showed a wide calcification area localized at subendocardial level, which contained fibrin deposition and was surrounded by fibrotic tissue.

An immunohistochemical study of the diagnostic value of TREM-1 as marker for fatal sepsis cases

Triggering receptor expressed on myeloid cells-1 (TREM-1) is produced and up-regulated by exposure of myeloid cells to lipopolysaccharides or other components of either bacterial or fungal origin, which causes it to be strongly expressed on phagocytes that accumulate in inflamed areas. Because TREM-1 participates in septic shock and in amplifying the inflammatory response to bacterial and fungal infections, we believe it could be an immunohistochemical marker for postmortem diagnosis of sepsis. We tested the anti-TREM-1 antibody in 28 cases of death by septic shock and divided them into two groups. The diagnosis was made according to the criteria of the Surviving Sepsis Campaign. In all cases, blood cultures were positive. The first group was comprised subjects that presented high ante-mortem serum procalcitonin and the soluble form of TREM-1 (s-TREM-1) values. The second group comprised subjects in which s-TREM-1 was not measured ante-mortem. We used samples of brain, heart, lung, liver and kidney for each case to test the anti-TREM-1 antibody. A semiquantitative evaluation of the immunohistochemical findings was made. In lung samples, we found immunostaining in the cells of the monocyte line in 24 of 28 cases, which suggests that TREM-1 is produced principally by cells of the monocyte line. In liver tissue, we found low TREM-staining in the hepatocyte cytoplasm, duct epithelium, the portal-biliary space and blood vessel. In kidney tissue samples, we found the TREM-1 antibody immunostaining in glomeruli and renal tubules. We also found TREM-1 staining in the lumen of blood vessels. Immunohistochemical staining using the anti-TREM-1 antibody can be useful for postmortem diagnosis of sepsis.

Searching for highly sensitive and specific biomarkers for sepsis: State-of-the-art in post-mortem diagnosis of sepsis through immunohistochemical analysis

The autoptical observations commonly ascribed to sepsis deal with unspecific general and local signs of inflammation or ischemia, such as myocardial inflammation, pulmonary edema and infiltration, cerebral swallowing, and tubular necrosis in the kidney. In the two last decades, some studies have been carried out to implement immunohistochemical markers for post-mortem diagnosis. All of these target molecules are specifically up-regulated or down-regulated during systemic inflammatory responses, especially for infective causes. Among these, we found some antigens expressed on leukocyte surfaces (very late antigen-4 (VLA-4), cluster differentiation-15 (CD15)), enzyme contained in neutrophils granules (lysozyme (LZ), lactoferrin (LF)), endothelial markers and junctions (E-selectin, vascular endothelial cadherin (VE-cadherin)), and soluble factors (vascular endothelial growth factor (VEGF), tumor necrosis factor alpha (TNFα), procalcitonin (PCT), soluble triggering receptor expressed on myeloid cells-1 (s-TREM-1)). All of these showed potential reliability in differentiating sepsis cases from controls. Further studies are needed to provide a concrete validation for a combination of markers on specific organ samples in order to reach a post-mortem diagnosis of sepsis also in the absence of clinical records.

Identifying the Epitope Regions of Therapeutic Antibodies Based on Structure Descriptors

Therapeutic antibodies are widely used for disease detection and specific treatments. However, as an exogenous protein, these antibodies can be detected by the human immune system and elicit a response that can lead to serious illnesses. Therapeutic antibodies can be engineered through antibody humanization, which aims to maintain the specificity and biological function of the original antibodies, and reduce immunogenicity. However, the antibody drug effect is synchronously reduced as more exogenous parts are replaced by human antibodies. Hence, a major challenge in this area is to precisely detect the epitope regions in immunogenic antibodies and guide point mutations of exogenous antibodies to balance both humanization level and drug effect. In this article, the latest dataset of immunoglobulin complexes was collected from protein data bank (PDB) to discover the spatial features of immunogenic antibody. Furthermore, a series of structure descriptors were generated to characterize and distinguish epitope residues from non-immunogenic regions. Finally, a computational model was established based on structure descriptors, and results indicated that this model has the potential to precisely predict the epitope regions of therapeutic antibodies. With rapid accumulation of immunoglobulin complexes, this methodology could be used to improve and guide future antibody humanization and potential clinical applications.