Postmortem Contamination Research Articles

The role of necroscopy and autopsy investigations in the diagno-sis and risk management of infections related to public health care: forensic and medico legal implications.

Healthcare-associated infections (HAIs) represent the most frequent adverse event in healthcare systems around the world. From a forensic point of view, HAIs show various legal implications. Therefore, it is essential in cases of death or injury from a suspected nosocomial infection that the infection itself, the source and the method of contamination are correctly diagnosed in order to evaluate any profiles of professional liability. This study combined a minireview of the scientific literature using the Pubmed search engine, the website of the Higher Institute of Health and the member states information sessions on infection prevention and control (IPC). Despite the significant impact that HAIs have on healthcare systems, their severity is often not fully understood by healthcare professionals, leading to insufficient responses. In the autopsy setting, the diagnosis of these infections is not always simple due to the risk of post-mortem contamination determined by the endogenous bacterial flora. In the forensic field, the medical examiner during the autopsy can use various diagnostic techniques and investigative tools to identify the infection. Some usefulpp approaches include: 1) Macroscopic examination of the organs; 2) Histopathological investiga-tions; 3) Microbiological analyzes with the performance of swabs; 4) Immunofluorescence tests for the detection of antigens or antibodies on biological liquids; 5) Molecular tests. The choice of methods will depend on the nature of the suspected infection and the availability of diagnostic resources.

A twenty-year survey of drowning cases in Verona territory: strengths and limits of diatom test

BACKGROUND: The medico-legal classification of cases of corpses found in water is often challenging due to the need not only to distinguish between submersion of a corpse and death in water, but also, with respect to the latter hypothesis, to understand in which cases the cause of death is actually attributable to drowning. The complexity of the diagnosis explains the constant interest of the scientific community in the subject with the development in the last hundred years of different lines of research for the identification and validation in forensic practice of diagnostic procedures, which can substantiate or exclude, on an objective basis, the hypothesis of drowning, which remains the prevailing one in these cases. This is the context in which diatom test takes place. It was first proposed at the beginning of the 1900’s, and it is based on the theoretical assumption that diatoms are present in fresh and seawater and not in the human body and then that their identification in biological fluids and tissues is an index of inhalation of water and therefore drowning. From the first reports, various studies have followed with consequent increase in knowledge on the strengths and limitations of the diatom test, even if the aspects concerning diagnostic specificity and sensitivity of this test are still debated. The purpose of this work was to critically analyze the results of diatom test in cases of bodies retrieved in water in different areas of North-Eastern Italy to evaluate the frequency of this mode of death in our area, as well as to formulate considerations on the sensitivity and specificity of the diatom test on the basis of the real forensic practice. The study period ranged from 2000, when the diatom test had been introduced in the routine practice of the Institute of Forensic Medicine of the University of Verona, to 2022.METHODS: The search of diatoms was performed on lung and sternal bone marrow through an extraction procedure based on the incubation of samples in nitric acid for 48 hours at 60 °C. The extracts were examined by light microscopy at 200X, 400X and 630X magnification. The cut-off used to consider positive the test was 10 diatoms/5 g of lung tissue and 5 diatoms/10 g of sternal bone marrow. A positive pulmonary diatom test was considered indicative of drowning in any case, even if the sternal diatom test was negative.RESULTS: Overall, 186 cases underwent diatom test. Of them, 172 were freshwater cases, five seawater cases and nine treated water cases (swimming pool, bathtubs). In 153 cases, a quantitative diatom test was performed. Of them, 106 cases (69%) yielded a positive pulmonary diatom test result, confirming the diagnosis of drowning which had been originally formulated on the basis of circumstantial data. Of the remaining 47 cases, three showed a number of diatoms below the cut-off and then were classified as doubtful cases, while 17 cases showed a cause of death different of drowning and then were classified as true negatives. In the remaining 27 cases, it was not possible to formulate a conclusive explanation of the negativity test results, as it could be attributed both to a rapid death in the water from natural causes or to complications linked to immersion and to paucity of diatoms in the aqueous medium. These cases were then classified as false negatives.CONCLUSIONS: The data of the present study confirmed the usefulness of diatom test to objectively support a diagnosis of drowning. Indeed, the diatom test shows a good diagnostic specificity, provided that it is performed taking all the suitable precautions to limit or eliminate post-mortem contamination, and that it is interpreted on a quantitative basis. In addition, compared to other tests, this diagnostic approach is significantly cheaper and can be performed at any forensic pathology facility.

Utility of postmortem bacterial culture of abdominal organs at autopsy of young calves.

Postmortem bacterial culture is controversial in human medicine, and veterinary-specific research in this area is lacking. To address this knowledge gap, we cultured liver, kidney, and spleen individually from on-farm calf mortalities to determine the number of bacterial species present, concordance between organ cultures, and agreement with gross and histologic findings. We hypothesized that the spleen, a filtering organ, would be the most useful organ with the least amount of postmortem contamination given that it does not have a direct conduit to a bacterial population. Fresh liver, kidney, and spleen were collected for culture from 30 calves 5-28-d-old with various causes of mortality. Bacterial growth of ≥2 species was observed in ~48% of cultures, with Escherichia coli and Streptococcus spp. being most frequent. One bacterial species was present in 20% of cultures, with E. coli predominating. No growth was observed in ~32% of cultures. In 43% of cases, there was agreement in the culture results for all 3 organs; however, the majority were mixed bacterial growth. The best agreement was observed when there were no gross and/or histologic septic lesions in target organs and no bacterial growth on culture. The spleen was not helpful in determining bacterial significance in comparison to kidney or liver.

The Impact of Donor Preparation for Tissue Procurement on Postmortem Vitreous Isopropanol Concentration.

Volatile chemicals can be relevant in the determination of the cause and manner of death by forensic pathologists. Isopropanol is a secondary alcohol that is occasionally seen on postmortem toxicology testing. A series of 11 forensic autopsy cases was previously reported in which the presence of isopropanol in the vitreous humor was suspected to be due to postmortem contamination from the body preparation process for tissue procurement.In collaboration with a tissue procurement agency, donor vitreous humor was collected from one eye before body preparation for procurement and from the other eye postpreparation. The specimens underwent testing for volatile substances by headspace gas chromatography.Of the 50 cases, 8 (16%) showed statistically significant changes in the prepreparation and postpreparation isopropanol concentrations. Postpreparation isopropanol concentrations ranged from 5 to 104 mg/dL (median, 18 mg/dL). Seven of the 8 cases had undetectable prepreparation isopropanol, whereas the remaining case had a detectable prepreparation isopropanol.In conclusion, surface contamination of the decedent's body with chemicals used in body preparation can lead to the passive absorption into the body, resulting in the presence of isopropanol in postmortem toxicology samples. Forensic pathologists need to be aware of this when interpreting postmortem samples after tissue procurement.

Postmortem Bacteriology in Forensic Autopsies-A Single Center Retrospective Study in Romania.

Postmortem bacteriology examinations have been a controversial topic over the years, though the value of postmortem bacteriology cultures remains promising. The aim of this study was to review the postmortem bacteriological sampling procedures and results in a single centre in Bucharest over a period of 10 years. Material and methods: The present study was a retrospective, single-center study, performed at the Mina Minovici National Institute of Legal Medicine in Bucharest, Romania, from 2011–2020. Results: Postmortem bacteriology was requested 630 forensic autopsies, 245 female (38.9%) and 385 male (61.1%), age range 0 and 94 years, median age of 52 years. Deaths occurred in hospital for 594 cases (94.3%) and out-of-hospital for 36 cases (5.7%—field case). Blood cultures were requested in the majority of cases, followed by tracheal swabs and lung tissue. In-hospital and out of hospital deaths did not differ significantly regarding the number of microorganisms identified in a positive blood culture. Postmortem bacteriology cultures of the respiratory tract showed a statistically significant association to microscopically confirmed lung infections. Conclusions Postmortem sampling for bacteriology testing in our center in Bucharest is heterogeneous with a high variation of patterns. A positive blood culture result for Staphylococcus species without the identification of a specific microorganism is more likely due to postmortem contamination.

A False-positive Diatom Test in a Non-drowned Victim of Multiple Stab Wounds

For the diagnosis of drowning in immersed bodies, the diatom test has been controversial due to false-negative and false-positive results. Causes of false positive results include antemortem penetration of diatoms, and postmortem contamination during the submersion or the diatom preparation process. Herein, we report a false-positive case in a 30-year-old woman who died from homicidal multiple stab wounds and was thrown into a shallow farm waterway approximately 10 days after her death. In addition, a discussion on the false-positive diatom test results in immersed bodies with penetrating wounds is provided.

Quantitative determinations and imaging in different structures of buried human bones from the XVIII-XIXth centuries by energy dispersive X-ray fluorescence – Postmortem evaluation

In this work, a non-commercial triaxial geometry energy dispersive X-ray Fluorescence (EDXRF) setup and a benchtop µ-XRF system were used to identify postmortem contamination in buried bones. For two of the individuals, unusually high concentrations of Cu and Pb, but also Zn (in one individual) were observed. The pigments of the burial shroud coverings have been identified as the source of contamination.Accurate and precise quantitative results were obtained by nondestructive process using fundamental parameters method taking into account the matrix absorption effects.A total of 30 bones from 13 individuals, buried between the mid-XVIIIth to early XIXth centuries, were analyzed to study the elemental composition and elemental distribution. The bones were collected from a church in Almada (Portugal), called Ermida do Espírito Santo, located near the Tagus River and at the sea neighbourhood.The triaxial geometry setup was used to quantify Ca, Fe, Cu, Zn, Br, Sr and Pb of powder pressed bone pellets (n=9 for each bone). Cluster analysis was performed considering the elemental concentrations for the different bones. There was a clear association between some bones regarding Fe, Cu, Zn, Br and Pb content but not a categorization between cortical and trabecular bones. The elemental distribution of Cu, Zn and Pb were assessed by the benchtop μ-analysis, the M4 Tornado, based on a polycapillary system which provides multi-elemental 2D maps. The results showed that contamination was mostly on the surface of the bone confirming that it was related to the burial shroud covering the individuals.

Quantitative analysis of human remains from 18th–19th centuries using X-ray fluorescence techniques: The mysterious high content of mercury in hair

In this work, we report the unusual concentration of mercury in the hair of an individual buried in the 18th to mid-19th centuries and the comparison with the elemental composition of other remains from the same individual. Two energy dispersive X-ray fluorescence (EDXRF) setups, one with tri-axial geometry and the second one with micro-beam capabilities and a vacuum system, for light elements detection, have been used. Quantitative evaluation of the obtained spectra were made by fundamental parameters and winAXIL program by compare mode method. The levels of Hg in the hair of buried samples presented a concentration over 5% (w/w), a significantly lower presence of this element in the cranium, and no Hg in the remaining organs. Furthermore, there was no evidence of Hg in the burial soil, which has been also analyzed. From this result, we could conclude that the possibility of post-mortem contamination from the burial surroundings is very unlikely. The obtained results are indicative of the apparent use of a mercury-based compound for medical purposes, most likely lice infestation.

Markers for sepsis diagnosis in the forensic setting: state of the art.

Reliable diagnoses of sepsis remain challenging in forensic pathology routine despite improved methods of sample collection and extensive biochemical and immunohistochemical investigations. Macroscopic findings may be elusive and have an infectious or non-infectious origin. Blood culture results can be difficult to interpret due to postmortem contamination or bacterial translocation. Lastly, peripheral and cardiac blood may be unavailable during autopsy. Procalcitonin, C-reactive protein, and interleukin-6 can be measured in biological fluids collected during autopsy and may be used as in clinical practice for diagnostic purposes. However, concentrations of these parameters may be increased due to etiologies other than bacterial infections, indicating that a combination of biomarkers could more effectively discriminate non-infectious from infectious inflammations. In this article, we propose a review of the literature pertaining to the diagnostic performance of classical and novel biomarkers of inflammation and bacterial infection in the forensic setting.

Trace elements in the otoliths and dorsal spines of albacore tuna (Thunnus alalunga, Bonnaterre, 1788): An assessment of the effectiveness of cleaning procedures at removing postmortem contamination

Trace element analysis or “elemental fingerprinting” is widely used in stock structure analyses. Postmortem contamination of bony structures can confound the results of microconstituent studies or introduce an additional source of noise to the data, thus reducing the ability of the technique to detect real variation in trace element concentrations. Despite the potential for postmortem contamination during sample preparation, the effectiveness of the procedures used to remove potential contaminants from sectioned otoliths and other calcareous structures prior to laser ablation inductively coupled plasma mass spectrometry (LA ICP-MS) has not previously been addressed. Otoliths and dorsal spine sections of albacore tuna (Thunnus alalunga) collected from the North East Atlantic Ocean and the Mediterranean Sea were deliberately contaminated prior to analysis of trace element composition using LA ICP-MS. The effectiveness of three cleaning treatments (rinsing in ultrapure water, 30% hydrogen peroxide and ultrapure 5% nitric acid) at removing this postmortem contamination were compared. Magnesium and strontium were relatively robust to postmortem effects when exposed to contamination at concentrations of 50ppm and 200ppm respectively. Soaking in a solution containing Mn, Cs and Ba (50ppm) caused a marked increase in the detected concentration of each element in both structures. Translucent bands in both structures were more susceptible to contamination. Rinsing in ultrapure water or hydrogen peroxide was not effective at removing Mn, Cs and Ba contamination from either calcareous structure. Washing the otoliths and spines in nitric acid successfully removed postmortem contaminants.The removal of otoliths from tuna damages the appearance of the fish and has an adverse effect on market value. However spines are easily removed, do not affect the appearance or value of the fish and are the most commonly used structure for age determination. A weak but significant correlation was observed between Ba in opaque zones in otoliths and dorsal spines. All other spine to otolith correlations were not significant. The results do not provide support for the use of spines as an alternative to otoliths in trace elemental analyses.

A Characterization of Sources of Isopropanol Detected on Postmortem Toxicologic Analysis

Isopropanol is an important chemical to forensic pathologists in that intoxication can result in death yet presence does not necessarily indicate intoxication. Several reports have been published, which indicate that isopropanol can be created endogenously in certain situations including diabetes mellitus, starvation, dehydration, and chronic ethanol use; however, a large-scale analysis addressing all of the possible causes of postmortem isopropanol detection has not been performed. A retrospective review of all cases examined at the Bexar County Medical Examiner's Office between 1993 and 2008 in which isopropanol was detected in routine alcohol screening was undertaken. The cases were categorized by the source of the isopropanol, and the concentrations of isopropanol and acetone were analyzed. Analysis revealed isopropanol concentrations to be low (<100 mg/dL) in cases of antemortem and postmortem creation and in postmortem contamination and high (>100 mg/dL) in cases of antemortem exposure. These results are consistent with other published reports.

The Relationship of Methanol and Formate Concentrations in Fatalities Where Methanol Is Detected

An automated headspace gas chromatography method was developed for the determination of formate (formic acid) in postmortem specimens, based on the in situ sulfuric acid-methanol methylation of formic acid to methyl formate. Diisopropyl ether was used as an internal standard. The method was applied to over 150 postmortem cases where methanol was detected. Of the 153 cases presented, 107 deaths were attributed to acute methanol toxicity. In the vast majority of the remaining 46 deaths, the methanol was determined to be present as a postmortem or perimortem artifact, or was otherwise incidental to the cause of death. Of the 76 victims who were found dead and blood was collected by the medical examiner, all but one had a postmortem blood formate concentration greater than 0.50 g/L (mean 0.85 g/L; n = 74). The sole exception involved suicidal ingestion of methanol where the blood methanol concentration was 7.9 g/L (790 mg/100 mL) and blood formate 0.12 g/L. In 97% (72/74) of the cases where blood was available, the blood formate was between 0.60 and 1.40 g/L. In 31 of the 153 cases, the victim was hospitalized and blood obtained on admission or soon after was analyzed for methanol and formate during the subsequent death investigation; the vast majority (27/30) had antemortem blood formate concentrations greater than 0.50 g/L. Cases with samples taken prior to death with blood formate concentrations less than 0.5 g/L can readily be explained by active treatment such as dialysis. The blood formate method has also been useful in confirming probable perimortem or postmortem contamination of one of more fluids or tissues with methanol (e.g., windshield washer fluid or embalming fluid), where methanol ingestion was unlikely.

Ancient skeletons as silent witnesses of lead exposures in the past.

Lead is stored in calcified tissues, and the lead levels in human remains will therefore reflect in vivo exposures in the past, provided that postmortem contamination can be ruled out or successfully removed. Reliable chemical testimonies from archeological finds indicate that prepollution exposures to lead were of the order of 1% of current-day exposures in industrialized countries. Examination of these silent witnesses of past times has also shown that lead exposures during recent historical periods were much higher than today. Studies in this area provide a framework for evaluation of lead exposures. The results would suggest that an ideal control group should not be exposed to lead levels any higher than the low, prepollution levels.

Bacteriologic studies of bovine genital tracts: The use of dye as an indicator of postmortem contamination of the uterus by vaginal fluids

Non-specific bacteria were more frequently isolated from uteri of culled dairy cattle than beef cows (P <.01). In some studies, food dye was placed in the vagina just prior to slaughter as an indicator of postmortem contamination of the uterus by vaginal fluids and bacteria. The dye was more often found in the uteri of dairy cows than beef cows (P <0.05). Bacteria could always be isolated from uteri totally contaminated by the dye. Bacteria were more frequently isolated from uncontaminated areas of uteri that were partially contaminated by the dye, as compared to uteri in which no dye was found (P <.01). It is hypothesized that an enlarged cervical canal may allow dye and also bacteria to transverse the cervical canal into the uterus during the slaughtering process. It is further hypothesized that an enlarged cervical canal may more readily permit nonspecific bacteria of the vagina to ascend into the uterus in the live animal and cause reproductive failure.