The interest of postmortem bacteriology in putrefied bodies

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.

Effects of Extended Postmortem Interval on Microbial Communities in Organs of the Human Cadaver

Human thanatomicrobiota studies have shown that microorganisms inhabit and proliferate externally and internally throughout the body and are the primary mediators of putrefaction after death. Yet little is known about the source and diversity of the thanatomicrobiome or the underlying factors leading to delayed decomposition exhibited by reproductive organs. The use of the V4 hypervariable region of bacterial 16S rRNA gene sequences for taxonomic classification ("barcoding") and phylogenetic analyses of human postmortem microbiota has recently emerged as a possible tool in forensic microbiology. The goal of this study was to apply a 16S rRNA barcoding approach to investigate variation among different organs, as well as the extent to which microbial associations among different body organs in human cadavers can be used to predict forensically important determinations, such as cause and time of death. We assessed microbiota of organ tissues including brain, heart, liver, spleen, prostate, and uterus collected at autopsy from criminal casework of 40 Italian cadavers with times of death ranging from 24 to 432 h. Both the uterus and prostate had a significantly higher alpha diversity compared to other anatomical sites, and exhibited a significantly different microbial community composition from non-reproductive organs, which we found to be dominated by the bacterial orders MLE1-12, Saprospirales, and Burkholderiales. In contrast, reproductive organs were dominated by Clostridiales, Lactobacillales, and showed a marked decrease in relative abundance of MLE1-12. These results provide insight into the observation that the uterus and prostate are the last internal organs to decay during human decomposition. We conclude that distinct community profiles of reproductive versus non-reproductive organs may help guide the application of forensic microbiology tools to investigations of human cadavers.

The importance of the postmortem interval for the diagnosis of Waterhouse-Friderichsen syndrome by Neisseria meningitidis in a series of forensic cases

The effective value of microbiological post-mortem examinations stands as fundamental in forensic cases involving microbiology. We ran these analyses on five victims, who suddenly died after showing persistent fever. The examinations were conducted between 48 hours and 10 days after death, and adrenal gland apoplexy was detected in all the cases.

Microbiological examinations identified Neisseria meningitidis, which was accountable for Waterhouse–Friderichsen syndrome. Diplococci were isolated from three cadavers that underwent forensic dissection between 2 and 3 days after death. The remaining two cadavers showed polymicrobial contamination, and a polymerase chain reaction technique was necessary to identify the pathogen.

We assumed that the microbial overlap could lead to diagnostic mistakes and conceal the identification of the lethal pathogen. Therefore, we suggest using molecular techniques for a postmortem interval (PMI) longer than 72 hours. Classical microbiological examination should be performed for PMI within 72 hours.

Fatal meningococcal meningitis in a 2-year-old child: A case report

BACKGROUND

In fatal cases of meningococcal septicemia, bacteriological diagnosis may not be straightforward due to postmortem replication and relocation of endogenic microflora. In medicolegal practice, aside from routine autopsy and histopathology, also other diagnostic methods, such as microbiological tests, immunohistochemistry and polymerase chain reaction (PCR), are used to examine body fluids and tissues.

CASE SUMMARY

We present the case of sudden death in a 2-year-old child. The patient died approximately 30 min after hospital admission before any routine diagnostic procedures were undertaken. Presence of whole-body rash and fulminant course of the disease raised suspicion of meningococcal septicemia. An autopsy was performed seven days after death when the body showed the signs of late postmortem decomposition. No etiological factor of septicemia could be identified based on macro- and microscopic findings. However, PCR demonstrated the presence of genetic material of group W Neisseria meningitidis in patient’s cerebrospinal fluid and blood.

CONCLUSION

Microbiological PCR should be conducted postmortem whenever a specific etiological factor could not be identified with conventional methods.

Neisseria meningitidis Isolated in Vitreous Humor in a 5-Month-Old Infant Death From Meningococcal Sepsis

Diagnosing sepsis at postmortem is challenging. With respect to meningococcal sepsis, the postmortem microbiological identification of Neisseria meningitidis is nearly always due to true infection, including in cases of decomposition. Previous case series and case reports were able to isolate N. meningitidis in vitreous humor in adult deaths from meningococcal sepsis when blood and/or cerebrospinal fluid was unavailable. It was suggested that vitreous humor polymerase chain reaction (PCR) may be useful in the diagnosis of meningococcal sepsis. We describe a fatal case of meningococcal sepsis in a 5-month-old infant where N. meningitidis was detected in vitreous humor, cerebrospinal fluid, and blood through PCR. The presented case report gives further evidence in the potential use of vitreous PCR analysis in suspected meningococcal sepsis, particularly in the pediatric population.

Neisseria meningitidis Isolated in Postmortem Vitreous Humor in a Death Due to Meningococcal Sepsis

Sepsis remains a difficult diagnosis at autopsy. With respect to meningococcal sepsis, a timely and definite diagnosis is critical because it requires public health department notification and the administration of prophylactic antibiotics to potential close contacts. A previous case series, in which both blood and cerebrospinal fluid were unavailable, suggested vitreous humor polymerase chain reaction might be a useful test in diagnosing meningococcal sepsis. We describe a fatal case of meningococcal sepsis where Neisseria meningitidis was detected in both vitreous humor and blood polymerase chain reaction, in addition to positive blood cultures. This gives further support to using microbiology of vitreous humor in suspected meningococcal sepsis, especially when microbiology samples are limited.

Post-mortem detection of bacteremia using pairs of blood culture samples

AIM

The objective of this study was to assess the utility of examining pairs of blood culture samples obtained from separate sites (both ventricles or the aorta and vena cava) for detecting bacteremia in the post-mortem setting.

METHODS

Autopsy cases in which bacterial species were isolated from blood cultures were identified over a 4-year period. Ante-mortem and post-mortem records and the findings of pathological examinations were reviewed.

RESULTS

Overall, 23 bacterial species were detected in 18 autopsy cases. E. coli was the most commonly detected species (5 cases, 27.8%), followed by S. aureus and K. pneumoniae, respectively. Seven of the detected bacterial species (3 cases, 16.7%) were obligate anaerobes (Clostridium spp. and Bacteroides spp.). Among the 3 cases involving obligate anaerobes, multiple bacterial species were detected in 2 cases. Clinically, 2 of the 18 patients in which bacteria were detected were treated for significant infections (urosepsis, pneumonia, and catheter-related bloodstream infection) before their deaths. Seven cases exhibited evidence of significant infection during the post-mortem pathological examination. The differences between the aerobic and anaerobic bacteria positivity rates of the single and paired blood culture samples were significant (aerobic: p=0.013 and anaerobic: p=0.018).

CONCLUSION

Analyzing pairs of blood culture samples obtained from separate sites is useful for detecting bacteremia during post-mortem examinations.

Autopsy Prevalence of Tuberculosis and Other Potentially Treatable Infections among Adults with Advanced HIV Enrolled in Out-Patient Care in South Africa

Background

Early mortality among HIV-positive adults starting antiretroviral therapy (ART) remains high in resource-limited settings, with tuberculosis (TB) the leading cause of death. However, current methods to estimate TB-related deaths are inadequate and most autopsy studies do not adequately represent those attending primary health clinics (PHCs). This study aimed to determine the autopsy prevalence of TB and other infections in adults enrolled at South African PHCs in the context of a pragmatic trial of empiric TB treatment (“TB Fast Track”).

Methods and Findings

Adults with CD4 ≤150 cells/μL, not on ART or TB treatment, were enrolled to TB Fast Track and followed up for at least six months. Minimally invasive autopsy (MIA) was conducted as soon as possible after death. Lungs, liver, and spleen were biopsied; blood, CSF, and urine aspirated; and bronchoalveolar lavage fluid obtained. Samples underwent mycobacterial, bacterial, and fungal culture; molecular testing (including Xpert® MTB/RIF); and histological examination. 34 MIAs were conducted: 18 (53%) decedents were female; median age was 39 (interquartile range 33–44) years; 25 (74%) deaths occurred in hospitals; median time from death to MIA was five (IQR 3–6) days. 16/34 (47%) had evidence of TB (14/16 [88%] with extrapulmonary disease; 6/16 [38%] not started on treatment antemortem); 23 (68%) had clinically important bacterial infections; four (12%) cryptococcal disease; three (9%) non-tuberculous mycobacterial disease; and two (6%) Pneumocystis pneumonia. Twenty decedents (59%) had evidence of two or more concurrent infections; 9/16 (56%) individuals with TB had evidence of bacterial disease and two (13%) cryptococcal disease.

Conclusions

TB, followed by bacterial infections, were the leading findings at autopsy among adults with advanced HIV enrolled from primary care clinics. To reduce mortality, strategies are needed to identify and direct those at highest risk into a structured pathway that includes expedited investigation and/or treatment of TB and other infections.

Forensic Autopsy of Human Decomposed Bodies as a Valuable Tool for Prevention: A French Regional Study

Post mortem changes due to putrefaction sometimes make people wrongly consider the autopsy of a decomposed body as unrewarding. A 5-year retrospective study was conducted and included all types of decomposed body subject to medicolegal autopsy, excluding bone remains and charred bodies. Sociodemographic, medical, and forensic data were collected. In the 350 cases included, most were socially isolated mature males discovered at home. The cause of death was determined in 80% of cases, and the manner of death in 86.6%. Identification was considered effective in 99.7% of cases by the chief prosecutor. The authors show that such an autopsy usually answers most questions raised by the investigation but can also be a valuable tool in the prevention, making it possible to define a profile of persons at risk of dying alone. In addition, they underline that forensic scientists should be cautious in their identification of conclusion as diverging views regarding the concept of "presumed identity" may lead to ethical tensions between judiciary and prosecutors as well as the medical community.

Microbial Signatures of Cadaver Gravesoil During Decomposition

Genomic studies have estimated there are approximately 10(3)-10(6) bacterial species per gram of soil. The microbial species found in soil associated with decomposing human remains (gravesoil) have been investigated and recognized as potential molecular determinants for estimates of time since death. The nascent era of high-throughput amplicon sequencing of the conserved 16S ribosomal RNA (rRNA) gene region of gravesoil microbes is allowing research to expand beyond more subjective empirical methods used in forensic microbiology. The goal of the present study was to evaluate microbial communities and identify taxonomic signatures associated with the gravesoil human cadavers. Using 16S rRNA gene amplicon-based sequencing, soil microbial communities were surveyed from 18 cadavers placed on the surface or buried that were allowed to decompose over a range of decomposition time periods (3-303 days). Surface soil microbial communities showed a decreasing trend in taxon richness, diversity, and evenness over decomposition, while buried cadaver-soil microbial communities demonstrated increasing taxon richness, consistent diversity, and decreasing evenness. The results show that ubiquitous Proteobacteria was confirmed as the most abundant phylum in all gravesoil samples. Surface cadaver-soil communities demonstrated a decrease in Acidobacteria and an increase in Firmicutes relative abundance over decomposition, while buried soil communities were consistent in their community composition throughout decomposition. Better understanding of microbial community structure and its shifts over time may be important for advancing general knowledge of decomposition soil ecology and its potential use during forensic investigations.

The importance of microbiological testing for establishing cause of death in 42 forensic autopsies

Microorganisms have always been one of the great challenges of humankind, being responsible for both high morbidity and mortality throughout history. In a forensic setting microbiological information will always be difficult to interpret due to lack of antemortem information and changes in flora postmortem. With this study we aim to review the use of microbiological procedures at our forensic institute. In a retrospective study including 42 autopsies performed at our Institute, where microbiological test had been applied, analyses were made with regard to: type of microbiological tests performed, microorganisms found, histological findings, antemortem information, C-reactive protein measurement and cause of death. Fiftyone different microorganisms were found distributed among 37 cases, bacteria being the most abundant. Nineteen of the cases were classified as having a microbiological related cause of death. C-reactive protein levels were raised in 14 cases of the 19 cases, histological findings either supported or were a decisive factor for the classification of microbiologically related cause of death in 14 cases. As a multitude of abundant microorganisms are able to cause infection under the right circumstances, all findings should be compared to anamnestic antemortem information, before conclusions are drawn. A definite list of true pathogens is nearly impossible to compile.

Postmortem diagnosis of invasive meningococcal disease

We diagnosed invasive meningococcal disease by using immunohistochemical staining of embalmed tissue and PCR of vitreous humor from 2 men in New York City. Because vitreous humor is less subject than other body fluids to putrefaction, it is a good material for postmortem analysis.

Cerebrospinal fluid PCR analysis and biochemistry in bodies with severe decomposition

The aim of this study was to assess whether Neisseria meningitidis, Listeria monocytogenes, Streptococcus pneumoniae and Haemophilus influenzae can be identified using the polymerase chain reaction technique in the cerebrospinal fluid of severely decomposed bodies with known, noninfectious causes of death or whether postmortem changes can lead to false positive results and thus erroneous diagnostic information. Biochemical investigations, postmortem bacteriology and real-time polymerase chain reaction analysis in cerebrospinal fluid were performed in a series of medico-legal autopsies that included noninfectious causes of death with decomposition, bacterial meningitis without decomposition, bacterial meningitis with decomposition, low respiratory tract infections with decomposition and abdominal infections with decomposition. In noninfectious causes of death with decomposition, postmortem investigations failed to reveal results consistent with generalized inflammation or bacterial infections at the time of death. Real-time polymerase chain reaction analysis in cerebrospinal fluid did not identify the studied bacteria in any of these cases. The results of this study highlight the usefulness of molecular approaches in bacteriology as well as the use of alternative biological samples in postmortem biochemistry in order to obtain suitable information even in corpses with severe decompositional changes.