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

Hypothermic sepsis in time since death estimation - a case report

Both hyper- and hypothermia are problematic in temperature based forensic time since death estimation. Hyperthermia may occur in infection, traumatic brain injury, and intoxication. Hypothermia is encountered predominantly in exposure. Sepsis may present itself clinically as hypothermic. Sepsis is not uncommon in the forensic setting and mostly occurs in the context of malpractice accusations. There is usually little overlap between sepsis and typical forensic time since death estimation scenarios of violent or otherwise suspicious deaths. In the presented case, hypothermia and time since death estimations did collide. An inmate was found dead in his jail cell. Wardens claimed they had visually approached him alive relatively shortly prior. Rectal temperature measurements, using two separate crime scene thermometers as well as temperature loggers, revealed low rectal temperature at relatively high ambient temperature. These findings suggested a much longer postmortem interval and consequently raised doubts about the stated timeline. The wardens' claims were however confirmed by camera recordings, which also allowed a reasonable estimate of the true time of death. The cause of death was confirmed as septic organ failure at autopsy, which explained low rectal temperature. The presence of WISCHNEWSKI-spots was noted. When the PRISM-method was applied to the temperature recordings, low rectal temperature at the time of death was detected successfully. However, adaptation of the underlying equation for lower "starting temperature" did not produce satisfactory results. It is concluded that even though hypothermia at the time of death may possibly be detected from temperature data, attempts at time since death estimation for cases of hypothermia by adaptation of the equation should be avoided.

Gastric ischemia as an under-reported cause of death in older people

Acute gastric ischemia is a rare condition due to the rich vascular supply of the stomach. Here we present a case of fatal gastric ischemia associated with bowel ischemia, only diagnosed at autopsy, which was requested for the suspicion of medical liability. A complete post-mortem examination was conducted, along with a macroscopic analysis of the superior mesenteric artery and detailed histological analyses. Past clinical data was also reviewed. The macroscopic blackish discoloration of the stomach and the bowel, coupled with the presence of neutrophils in the mucosa and submucosal non-occlusive thrombi, were consistent with gastric and bowel ischemia, despite the presence of confounding putrefactive changes. The unique aspect of this case resides in the ante-mortem peculiar vascularization of the stomach, supplied by small collateral vessels. No mechanical occlusion was identified, and the cause of the ischemia was deemed as non-occlusive, likely due to systemic hypoperfusion. The analysis of clinical data and documentation of associated comorbidities are strongly recommended, especially when a rare cause of death is suspected. With the aging population, especially among women, and the prevalence of risk factors, the forensic pathologist could increasingly encounter rare cases of gastric ischemia.

Procalcitonin is associated with sudden unexpected death in infancy due to infection

Infection is an important cause of death during infancy worldwide and is a frequent etiology of sudden unexpected death in infancy (SUDI). Procalcitonin (PCT) is a useful marker to diagnose infection in patients, and several studies report the stability of PCT after death. The added value of a biological marker, such as the PCT level in the blood, remains controversial in investigating SUDI. The aim of this study was to determine if PCT can help clinicians determine whether infection caused SUDI. We conducted a retrospective, multicenter study with the French SUDI registry (Observatoire National des Morts Inattendues du Nourrisson; OMIN). We collected data from this registry on children who died between May 2015 and June 2021. The levels of PCT in the blood of 540 SUDI patients were measured. We compared PCT and other biological tests performed in terms of infection status, autopsy results, and cause of death using clinical and biological data compiled by pediatricians at the SUDI referral center. PCT levels were significantly higher in the children who died from infection than in those who did not (0.12 µg/L vs. 0.08 µg/L, p < 0.001). A PCT blood level exceeding 0.2 µg/L was more frequently observed when infection was present than in the absence of infection (44.3% vs. 15.4%, p < 0.001). The same data were obtained with a 0.5 µg/L cut-off (36.1% with infection vs. 9.2% without, p < 0.001).  Conclusions: PCT is a sensitive biomarker for detecting infections postmortem; thus, additional samples may be necessary during autopsy. What is known: • PCT is a stable marker postmortem and increases earlier than CRP, i.e., 2-4 h after the beginning of an infection vs. 6 h. • PCT can be measured up to 140 h after death. What is new: • PCT is a sensitive marker for detecting infection in SUDI patients postmortem. • This test can reveal an infection from non-standardized samples obtained during autopsy if such an infection was not determined before death.

Applications of microbiology to different forensic scenarios - A narrative review

In contrast to other forensic disciplines, forensic microbiology is still too often considered a "side activity" and is not able to make a real and concrete contribution to forensic investigations. Indeed, the various application aspects of this discipline still remain a niche activity and, as a result, microbiological investigations are often omitted or only approximated, in part due to poor report in the literature. However, in certain situations, forensic microbiology can prove to be extremely effective, if not crucial, when all other disciplines fail. Precisely because microorganisms can represent forensic evidence, in this narrative review all the major pathological forensic applications described in the literature have been presented. The goal of our review is to highlight the versatility and transversality of microbiology in forensic science and to provide a comprehensive source of literature to refer to when needed.

Utility and diagnostic value of postmortem microbiology associated with histology for forensic purposes

Nowadays, the diagnostic value of postmortem microbiological investigations is still a debated topic, but postmortem microbiology (PMM) remains a discipline with great forensic potential. To evaluate the usefulness and diagnostic-forensic value of postmortem microbiological cultures, it has been conducted a study on cadaveric material sampled during autopsy aiming to identify the correct cause of death. The study analyzed 45 cadavers subjected to judicial autopsy, divided into two groups based on the presence or absence of external or internal macroscopic autopsy signs suggesting infectious pathology. In the same cases, both the microbiological and conventional histological investigations have been simultaneously carried out. From the investigations, mono-bacterial, mono-fungal, mixed and negative cultures were observed. In mono-species microbiological growth, the histological epicrisis confirmed an infectious cause of death due to the presence of signs of acute infection with an aggressive infectious agent. In cases where growth was mixed, it was possible to distinguish between simple postmortal contamination and perimortem colonization. Finally, in some cases where the microbiology was negative, this has been essential in highlighting signs of a vital reaction to viral or parasitic infection. The joint and integrated evaluation of the laboratory results made it possible to correctly understand even those peculiar situations in which the PMM results alone would not have been significant. These methods, when combined, constitute an optimal forensic approach for the identification of the real cause of death and thus reduce the number of unsolved cases.

Autopsy Findings and Inflammatory Markers in SARS-CoV-2: A Single-Center Experience

Purpose

The systemic inflammatory response related to COVID-19 can be easily investigated in living patients. Unfortunately, not every biomarker is suitable for postmortem analysis since several factors may interfere. The aim of this study was to summarize key histopathological findings within each organ system due to COVID-19 and to assess if serological inexpensive and widely available biomarkers such as CRP, IL-6, fibrinogen and d-Dimers, associated with adverse outcomes in COVID-19, can be implemented in a post-mortem assessment.

Patients and Methods

A total of 60 subjects divided in 2 groups were included. All subjects died outside a hospital setting and therefore did not receive specific or symptomatic therapies that could have modulated the inflammatory response. The first group included 45 subjects in which mandatory autopsy was performed in order to establish the cause of death and macroscopic examination of the lungs was highly suggestive of SARS-CoV-2 infection. As controls (Group 2), 20 subjects who died from polytrauma in high velocity car accidents and suicide were selected. Bronchial fluids collected during the autopsy procedure were used for the RT-PCR diagnosis of SARS-CoV-2 and serum samples were sent for analysis of IL-6, CRP, d-Dimers and fibrinogen.

Results

Compared with the control group, the subjects of the COVID-19 group were older (59±19.5 vs.38±19.15 years, p=0.0002) and had more underlying comorbidities such as hypertension (60% vs 35%, p=0.06) or were overweight (53.3% vs 30%, p=0.08). The levels of CRP, IL-6, fibrinogen and d-Dimers in postmortem plasma samples were significantly higher in COVID-19 subjects than in control group (p< 0.0001). Moreover, the level of IL-6 was significantly higher in overweight patients (r=0.52, P<0.001). In all COVID-19 subjects, the histological examination revealed features corresponding to the exudative and/or proliferative phases of diffuse alveolar damage. Large pulmonary emboli were observed in 7 cases. Gross cardiac enlargement with left ventricular hypertrophy was observed in 19 cases. The most frequent pathological finding of the central nervous system was acute/early-subacute infarction.

Conclusion

Due to the complexity of the inflammatory response, we postulate that a combination of biomarkers, rather than a single laboratory parameter, might be more effective in obtaining a reliable postmortem COVID-19 diagnosis.

Fatal Pediatric Streptococcal Infection: A Clinico-Pathological Study

PURPOSE AND CONTEXT

Streptococcal Infection (SI) is an important cause of pediatric death in children, yet limited reports exist on autopsy findings in fatal SI cases.

METHOD

Case records (1997-2019) of SI with no pre-existing risk factors were reviewed and selected. Their clinical and pathological findings in the autopsy reports were analyzed.

RESULTS

In our cohort of 38 cases based on bacterial culture results, SI was most commonly caused by Streptococcus pneumoniae (SPn; 45%) and Streptococcus pyogenes (SPy; 37%). 92% of decedents had some prodromal symptoms prior to terminal presentation. The clinical course was often rapid, with 89% found unresponsive, suddenly collapsing, or dying within 24 hours of hospital admission. 64% of deaths were attributed to sepsis, more frequently diagnosed in the SPy group than in the SPn group (71% vs 48%). Pneumonia was found in both SPn and SPy groups, whereas meningitis was exclusively associated with SPn.

CONCLUSION

Our study shows fatal SI is most commonly caused by either SPn or SPy, both of which are frequently associated with prodromal symptoms, rapid terminal clinical course, and evidence of sepsis. Postmortem diagnosis of sepsis is challenging and should be correlated with clinical features, bacterial culture results, and autopsy findings.

Post-Mortem Microbiology: Retrospective Analysis of Infections Caused by Enterococcus Strains

Post-mortem microbiological tests are one of the basic methods for diagnosing the etiology of infections in forensic pathology. One of the major groups of microorganisms abundant in various parts of the human body during life and after death is Enterococcus spp. Depending on the area of the body involved and the patient’s condition, enterococci can be considered to be a microbiome, transient flora or a pathogen responsible for infection. The data used for the analysis were 12 medico-legal autopsy and microbiological reports. Enterococcus spp. was isolated in 10 out of 12 cultures of blood samples collected post-mortem. The abdominal origin of enterococci in the blood was detected in 8 cases. The non-abdominal origin of enterococci in the blood was associated with a skin and soft tissue infection, purulent pneumonia and infective endocarditis. These results suggest that enterococci may be considered a cause of severe infections and with high likelihood. Microbiological cultures are a valuable source of information for helping to confirm the cause of infection. Interpretation of the results of post-mortem examinations must be carried out on the basis of data collected before and after death with the participation of specialists from various fields.

An Insight into the Role of Postmortem Immunohistochemistry in the Comprehension of the Inflammatory Pathophysiology of COVID-19 Disease and Vaccine-Related Thrombotic Adverse Events: A Narrative Review

On 11 March 2020, the World Health Organization (WHO) declared a pandemic due to the spread of COVID-19 from Wuhan, China, causing high mortality rates all over the world. The related disease, which mainly affects the lungs, is responsible for the onset of Diffuse Alveolar Damage (DAD) and a hypercoagulability state, frequently leading to Severe Acute Respiratory Syndrome (SARS) and multiorgan failure, particularly in old and severe-critically ill patients. In order to find effective therapeutic strategies, many efforts have been made aiming to shed light on the pathophysiology of COVID-19 disease. Moreover, following the late advent of vaccination campaigns, the need for the comprehension of the pathophysiology of the fatal, although rare, thrombotic adverse events has become mandatory as well. The achievement of such purposes needs a multidisciplinary approach, depending on a correct interpretation of clinical, biochemical, biomolecular, and forensic findings. In this scenario, autopsies have helped in defining, on both gross and histologic examinations, the main changes to which the affected organs undergo and the role in assessing whether a patient is dead “from” or “with” COVID-19, not to mention whether the existence of a causal link exists between vaccination and thrombotic adverse events. In the present work, we explored the role of postmortem immunohistochemistry, and the increasingly used ancillary technique, in helping to understand the mechanism underlying the pathophysiology of both COVID-19 disease and COVID-19 vaccine-related adverse and rare effects.

Caspase 9 and Caspase 3 Immunohistochemical Pattern in Skeletal and Cardiac Muscles at Different Times after Death: An Experimental Study on PMI Estimation

(1) Background: The estimation of the post mortem interval (PMI) is a challenge for forensic pathologists because data emerging from methods commonly applied are not always conclusive, since several conditions exist that may affect the reliability of these parameters. Thus, new approaches have been proposed to overcome such a limit. In recent years, several studies have been performed on proteins analyzing their expression/degradation patterns in relation to the progressing of the post mortem interval. (2) Methods: The immunoreactivity patterns of two apoptosis mediators—Caspase 9 and Caspase 3—have been tested in order to evaluate their potential role as markers of the post mortem interval. The immunohistochemical analysis was performed on samples of skeletal and cardiac muscles obtained from rats at 0, 4, 8, 12, 24 and 72 h after death. (3) Results: The observed immunoreactivity patterns of both Caspase 9 and Caspase 3 showed a significant correlation with increasing post mortem interval either in skeletal or cardiac muscles, while the comparison of the immunoreactivity patterns of the two apoptotic mediators within each tissue appeared consistent with a preliminary activation of the “initiator” Caspase 9, which, in turn, subsequently activates the “executioner” Caspase 3. (4) Conclusion: The different expressions and decrease immunohistochemically observed on both caspases with progressing PMI support the usefulness of the combined analysis for post mortem interval estimation.

Pathological Findings in COVID-19 as a Tool to Define SARS-CoV-2 Pathogenesis. A Systematic Review

Introduction: The World Health Organization declared the COVID-19 pandemic in March 2020. COVID-19 still represents a worldwide health emergency, which causesa severe disease that has led to the death of many patients. The pathophysiological mechanism of SARS-CoV-2 determining the tissue damage is not clear and autopsycan be auseful tool to improve the knowledge of this infection and, thus, it can help achieve a timely diagnosis and develop an appropriate therapy. This is an overview of the main post-mortem findings reporting data on the infection effects on several organs. Methods: A systematic literature search was conducted in the PubMed database searching for articles from 1 January to August 31, 2020. Thearticles were selected identifying words/concepts in the titles and/or abstracts that indicated the analysis of the morphological/pathological tissue injuries related to SARS-CoV-2 disease by several investigations. Results: A total of 63 articles were selected. The main investigated tissue was the lung showing a diffuse alveolar damage (DAD) frequently associated with pulmonary thrombotic microangiopathy. Inflammatory findings and vascular damage were observed in other organs such as heart, liver, kidney, brain, spleen, skin and adrenal gland. The immunohistochemical analysis showed tissue inflammatory cells infiltrates. The virus presence was detected by several investigations such as RT-PCR, immunohistochemistry and electron microscope, showing the effect ofSARS-CoV-2not exclusively in the lung. Discussion: The evidence emerging from this review highlighted the importance of autopsy to provide a fundamental base in the process of understanding the consequences ofSARS-CoV-2 infection. COVID-19 is strictly related to a hyper inflammatory state that seems to start with DAD and immuno-thrombotic microangiopathy. Massive activation of the immune system and microvascular damage might also be responsible for indirect damage to other organs, even if the direct effect of the virus on these tissues cannot be excluded.

Membrane Attack Complex in Myocardial Ischemia/Reperfusion Injury: A Systematic Review for Post Mortem Applications

The complement system has a significant role in myocardial ischemia/reperfusion injury, being responsible for cell lysis and amplification of inflammatory response. In this context, several studies highlight that terminal complement complex C5b-9, also known as the membrane attack complex (MAC), is a significant contributor. The MAC functions were studied by many researchers analyzing the characteristics of its activation in myocardial infarction. Here, a systematic literature review was reported to evaluate the principal features, advantages, and limits (regarding the application) of complement components and MAC in post mortem settings to perform the diagnosis of myocardial ischemia/infarction. The review was performed according to specific inclusion and exclusion criteria, and a total of 26 studies were identified. Several methods studied MAC, and each study contributes to defining better how and when it affects the myocardial damage in ischemic/reperfusion injury. The articles were discussed, focusing on the specificity, sensibility, and post mortem stability of MAC as a marker of myocardial ischemia/infarction, supporting the usefulness in routine post mortem investigations.