Detection of human herpesvirus-6, Epstein-Barr virus and cytomegalovirus in formalin-fixed tissues from sudden infant death: A study with quantitative real-time PCR

Forensic Microbiology: When, Where and How

Forensic microbiology is a relatively new discipline, born in part thanks to the development of advanced methodologies for the detection, identification and characterization of microorganisms, and also in relation to the growing impact of infectious diseases of iatrogenic origin. Indeed, the increased application of medical practices, such as transplants, which require immunosuppressive treatments, and the growing demand for prosthetic installations, associated with an increasing threat of antimicrobial resistance, have led to a rise in the number of infections of iatrogenic origin, which entails important medico-legal issues. On the other hand, the possibility of detecting minimal amounts of microorganisms, even in the form of residual traces (e.g., their nucleic acids), and of obtaining gene and genomic sequences at contained costs, has made it possible to ask new questions of whether cases of death or illness might have a microbiological origin, with the possibility of also tracing the origin of the microorganisms involved and reconstructing the chain of contagion. In addition to the more obvious applications, such as those mentioned above related to the origin of iatrogenic infections, or to possible cases of infections not properly diagnosed and treated, a less obvious application of forensic microbiology concerns its use in cases of violence or violent death, where the characterization of the microorganisms can contribute to the reconstruction of the case. Finally, paleomicrobiology, e.g., the reconstruction and characterization of microorganisms in historical or even archaeological remnants, can be considered as a sister discipline of forensic microbiology. In this article, we will review these different aspects and applications of forensic microbiology.

Is There a Role for the Microbiome and Sudden Death? A Systematic Review

Background. Sudden unexpected death (SUD) is one of the most important and worthy investigation case profiles in emergency medicine and forensic pathology. Sudden unexpected deaths in adults (SUDA) are frequently caused by cardiac events, while infections usually cause those in infants younger than one year (SUDI), and to a lesser extent, in children older than one year (SUDC). However, in some instances of children under the age of one dying (SIDS), a cause is not discovered despite a thorough investigation that includes a review of clinical history, examination of the death scene, and a complete autopsy. Several studies demonstrate that the microbiome influences host immunity, alters susceptibility to viral respiratory infections, and has a vital role in various health, disease, and death outcomes. The main objective of this systematic review was to compile and offer a complete vision of the main lines of research on microbiome and sudden death that have emerged in recent years and their relationship with forensic sciences, as well as the possible contributions or limitations in the field of forensic sciences. Methods. Following PRISMA principles, a systematic evaluation of the microbiome and sudden death in forensic science was conducted. In this review, our study classified the sudden deaths as SUDA, SUDI, and SIDS. Results. The role of microbiome research in sudden death is discussed in this review. Various studies have linked the detection of different bacteria or viruses as a probable cause of sudden death. Bacteria analysed differ between studies that used autopsy specimens from deaths classified as SUDA, SUDI, and SIDS, or, except in the case of Staphylococcus aureus and Escherichia coli, which have been analysed in both SUDI and SIDS autopsies. In the case of viruses, only Cytomegalovirus has been analysed in both SIDS and SUDI cases. However, all the viruses studied are respiratory viruses found in samples of nasopharyngeal or lung fluid. Conclusions. Although the application of the microbiome in sudden death and other fields of forensic science is still in its early stages, a role of the microbiome in sudden deaths cannot be ruled out, but we cannot conclude that it is a significant factor either.

Microbiome in Death and Beyond: Current Vistas and Future Trends

Forensic medicine has, for a long time, been relying on biochemical, anthropologic, and histopathologic evidences in solving various investigations. However, depending on the method used, lengthy sample processing time, scanty sample, and less sensitivity and accuracy pervade these procedures. Accordingly, newer arenas such as the thanatomicrobiome have come forward to aid in its quandaries; furthermore, the parallel advances in genomic and proteomic techniques have complemented and are still emerging to be used in forensic experiments and investigations. Postmortem interval (PMI) is one of the most important aspects of medico-legal investigations. The current trend in PMI estimation is toward genomic analyses of autopsy samples. Similarly, determination of cause of death, although a domain of medical sciences, is being targeted as the next level of forensic casework. With the current trend in laboratory sciences moving to the discovery of newer disease-specific markers for diagnostic and prognostic purposes, the same is being explored for the determination of the cause of death by using techniques such as Real-Time PCR, DNA micro-array, to Next-Gen Sequencing. Establishing an individual’s biological profile has been done using medicolegal methods and anthropology as well as bar-bodies/Davidson bodies (gender determination); and in cases where the determination of age/gender is a challenge using morphological characteristics; the recent advances in the field of genomics and proteomics have played a significant role, e.g., use of mitochondrial DNA in age estimation and in maternity disputes. The major hurdle forensic medical research faces is the fact that most of the studies are conducted in animal models, which are often difficult to mimic in human and real-time scenarios. Additionally, the high accuracy required in criminal investigations to be used in a court of law as evidence has prevented these results to come out of the labs and be used to the optimum. The current review aims at giving a comprehensive and critical account of the various molecular biology techniques including “thanatogenomics,” currently being utilized in the veritable fields of forensic medicine.

SIDS, prone sleep position and infection: An overlooked epidemiological link in current SIDS research? Key evidence for the "Infection Hypothesis"

Mainstream researchers explain the etiology of SIDS with the cardiorespiratory paradigm. This has been the focus of intense study for many decades without providing consistent supporting data to link CNS findings to epidemiological risk factors or to the usual clinicopathological findings. Despite this, and the apparent oversight of the link between prone sleep position and respiratory infection, papers citing CNS, cardiac and sleep arousal findings continue to be published. Discovery of the prone sleep position risk factor provided tangential support for the cardiorespiratory control hypothesis which defines the mainstream approach. Despite many decades of research and huge expenditure, no aetiological answer has been forthcoming. In asking why?This paper exposes some of the shortcomings regarding this apparent oversight by mainstream SIDS researchers and examines the role of respiratory infection and puts the case for the “Infection Hypothesis.” In addition, the paper provides encouragement to neuropathologists to examine the potential link between CNS findings and cardiac function (as opposed to respiratory function) in relation to infection and to examine possible correlates between CNS findings and established risk factors such as recent infection, contaminated sleeping surfaces, maternal/obstetric/higher birth, ethnicity, non-breast-feeding, male gender, etc. or with the usual gross pathological findings of SIDS (intrathoracic petechial hemorrhages, liquid blood, congested lungs). The shortcomings exposed through this review invite questions over current research directions and hopefully encourage research into other more plausible hypotheses, such as the infection paradigm.•

Mainstream SIDS researchers appear to have overlooked the key relationship between prone sleep position and infection.

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This omission has major implications for current and future SIDS research.

Varicella zoster in sudden infant death

A 2-month-old girl with normal development and no previous physical illnesses was resuscitated having been found lifeless on her back at home. On admission to Paediatric Intensive Care, she had severe metabolic disturbance, associated with an extremely troubling neurological signs. She died 2 hours later. A full body CT scan did not reveal injury and her parents declined an autopsy. Peripheral blood and cerebrospinal fluid samples were sterile. However, a broad-range PCR coupled with electrospray-ionisation mass spectrometry onto the PLEX-ID automat of peripheral blood revealed the presence of varicella zoster virus. There was a specific viral load in whole blood of 20 542 copies/ml. It is presumed that Varicella myocarditis was the likely cause of death. Our case illustrates the potential usefulness of a broad range PCR strategy in determining infectious causes of death in sudden infant death. Varicella is a potential cause of sudden infant death.

Unrecognized viral infections and chromosome abnormalities as a cause of fetal death - examination with fluorescence in situ hybridization, immunohistochemistry and polymerase chain reaction

Fifteen to 50% of fetal deaths remain unexplained after post-mortem examination depending on inclusion criteria and classification systems. Our aim was to examine a selection of unexplained fetal deaths in order to investigate whether any common chromosome aberrations or viral infections were present. Reports from 351 fetal autopsies performed at the Department of Pathology and Medical Genetics at St. Olavs University Hospital from 2001 through 2010 were reviewed. Of these, 105 fetal deaths were classified as unexplained. Tissue samples from 30 cases were further examined with fluorescence in situ hybridization (FISH) to detect abnormalities in chromosomes 13, 18, and 21. The samples were also examined with immunohistochemistry (IHC) and polymerase chain reaction (PCR) to detect infections with cytomegalovirus, parvovirus B19, herpes simplex virus 1 and 2, enterovirus, and parechovirus. In two cases, a possible trisomy 13 mosaicism was found. No viruses were detected. In our selection of 30 unexplained cases, possible trisomy 13 mosaicism was found in two cases, and no viruses were detected. High degree of maceration and missing placental examination often complicate the investigation of fetal death, and extensive ancillary examinations do not necessarily contribute to a more specific diagnosis.

Acute liver dysfunction not resulting from hepatitis virus in immunocompetent children

BACKGROUND

The aim of the present study was to clarify the roles of cytomegalovirus (CMV), Epstein-Barr virus (EBV), and human herpesvirus 6 (HHV-6) in immunocompetent children with acute liver dysfunction not resulting from hepatitis virus.

METHODS

Sixty-eight children (median age, 3 years) hospitalized as a result of acute liver dysfunction were enrolled in this study. Hepatitis A, B, and C were excluded. The prevalence of CMV, EBV, and HHV-6 and viral DNA load in whole blood was prospectively evaluated on multiplex real-time polymerase chain reaction (PCR).

RESULTS

Of the 68 children with acute liver dysfunction, multiplex real-time PCR was positive in 30 (44%). CMV, EBV, and HHV-6 DNA were detected in 13 (19%), 14 (21%), and seven (10%), respectively. Serum CMV immunoglobulin (Ig)G/IgM and EBV viral capsid antigen IgG/IgM were measured in 40 (CMV DNA positive, n = 10; negative, n = 30) and 45 (EBV DNA positive, n = 14; negative, n = 31) of the 68 children, respectively. Eighteen percent (CMV, 7/40) and 9% (EBV, 4/45) were positive for both PCR and viral-specific IgM. There was no significant difference in CMV and EBV viral load between IgM-positive and -negative children with viremia.

CONCLUSIONS

CMV, EBV, and HHV-6 DNA were frequently detected in immunocompetent children with acute liver dysfunction, but primary CMV and EBV infection were confirmed in 10-20% of the children with acute liver dysfunction. The combination of PCR assay and serology is necessary to make a diagnosis of acute liver dysfunction due to primary CMV, EBV and/or HHV-6 infection in immunocompetent children.

Animal models for assessment of infection and inflammation: contributions to elucidating the pathophysiology of sudden infant death syndrome

Sudden infant death syndrome (SIDS) is still not well understood. It is defined as the sudden and unexpected death of an infant without a definitive cause. There are numerous hypotheses about the etiology of SIDS but the exact cause or causes have never been pinpointed. Examination of theoretical pathologies might only be possible in animal models. Development of these models requires consideration of the environmental and/or developmental risk factors often associated with SIDS, as they need to explain how the risk factors could contribute to the cause of death. These models were initially developed in common laboratory animals to test various hypotheses to explain these infant deaths – guinea pig, piglet, mouse, neonatal rabbit, and neonatal rat. Currently, there are growing numbers of researchers using genetically altered animals to examine specific areas of interest. This review describes the different systems and models developed to examine the diverse hypotheses for the cause of SIDS and their potential for defining a causal mechanism or mechanisms.

Virus Infections and Sudden Death in Infancy: The Role of Interferon-γ

Respiratory infections have been implicated in sudden infant death syndrome (SIDS). As interferon-γ (IFN-γ) is a major response to virus infection, we examined (1) the frequency of single nucleotide polymorphism (SNP), IFNG T + 874A, in SIDS infants, their parents, and ethnic groups with different incidences of SIDS; (2) model systems with a monocytic cell line (THP-1) and human peripheral blood monocytes (PBMC) for effects of levels of IFN-γ on inflammatory responses to bacterial antigens identified in SIDS; (3) interactions between genetic and environmental factors on IFN-γ responses. IFNG T + 874A genotypes were determined for SIDS infants from three countries; families who had a SIDS death; populations with high (Indigenous Australian), medium (Caucasian), and low (Bangladeshi) SIDS incidences. The effect of IFN-γ on cytokine responses to endotoxin was examined in model systems with THP-1 cells and human PBMC. The IFN-γ responses to endotoxin and toxic shock syndrome toxin (TSST-1) were assessed in relation to genotype, gender, and reported smoking. There was a marginal association with IFNG T + 874A genotype and SIDS (p = 0.06). Indigenous Australians had significantly higher proportions of the IFNG T + 874A SNP (TT) associated with high responses of IFN-γ. THP-1 cells showed a dose dependent effect of IFN-γ on cytokine responses to endotoxin. For PBMC, IFN-γ enhanced interleukin (IL)-1β, IL-6, and tumor necrosis factor-α responses but reduced IL-8 and IL-10 responses. Active smoking had a suppressive effect on baseline levels of IFN-γ. There was no effect of gender or genotype on IFN-γ responses to bacterial antigens tested; however, significant differences were observed between genotypes in relation to smoking. The results indicate virus infections contribute to dysregulation of cytokine responses to bacterial antigens and studies on physiological effects of genetic factors must include controls for recent or concurrent infection and exposure to cigarette smoke.

Exploring the risk factors for sudden infant deaths and their role in inflammatory responses to infection

The risk factors for sudden infant death syndrome (SIDS) parallel those associated with susceptibility to or severity of infectious diseases. There is no evidence that a single infectious agent is associated with SIDS; the common thread appears to be induction of inflammatory responses to infections. In this review, interactions between genetic and environmental risk factors for SIDS are assessed in relation to the hypothesis that many infant deaths result from dysregulation of inflammatory responses to "minor" infections. Risk factors are assessed in relation to three important stages of infection: (1) bacterial colonization (frequency or density); (2) induction of temperature-dependent toxins; (3) induction or control of inflammatory responses. In this article, we review the interactions among risk factors for SIDS for their effects on induction or control of inflammatory responses. The risk factors studied are genetic factors (sex, cytokine gene polymorphisms among ethnic groups at high or low risk of SIDS); developmental stage (changes in cortisol and testosterone levels associated with 2- to 4-month age range); environmental factors (virus infection, exposure to cigarette smoke). These interactions help to explain differences in the incidences of SIDS observed between ethnic groups prior to public health campaigns to reduce these infant deaths.

Congenital and postnatal CMV and EBV acquisition in HIV-infected Zimbabwean infants

Background

HIV-infected infants in sub-Saharan Africa have rapid disease progression. We hypothesized that co-infection with cytomegalovirus (CMV) or Epstein Barr virus (EBV) increases mortality in HIV-infected infants.

Methods

257 antiretroviral therapy-naïve HIV-infected Zimbabwean infants were tested for CMV and EBV at 6 weeks of age by real-time PCR; if positive, birth samples were retrieved where available to distinguish congenital and postnatal infection. The impact of co-infection on mortality through 6 months was estimated using Kaplan-Meier and Cox proportional hazards methods.

Results

At 6 weeks, 203/257 (79%) HIV-infected infants were CMV-positive; 27 (11%) had congenital CMV, 108 (42%) postnatal CMV and 68 (26%) indeterminate timing of infection. By 6 months, 37/108 (34%) infants with postnatal CMV versus 16/54 (30%) CMV-negative infants died (adjusted hazard ratio (aHR) 1.1 [95%CI 0.6, 2.2]). At 6 weeks, 33/257 (13%) HIV-infected infants had EBV co-infection; 6 (2%) had congenital EBV, 18 (7%) postnatal EBV and 9 (4%) indeterminate timing of infection. By 6 months, 5/18 (28%) infants with postnatal EBV versus 72/224 (32%) EBV-negative infants died (aHR 0.8 [95%CI 0.3, 2.3]).

Conclusions

The vast majority of HIV-infants had acquired CMV by 6 weeks, and EBV co-infection occurred earlier than expected, with one in eight HIV-infected infants positive for EBV by 6 weeks. There was a high prevalence of congenital CMV infection and we identified 6 infants with congenital EBV infection, which has not previously been reported in Africa or in the context of HIV infection. Neither CMV nor EBV co-infection was associated with increased mortality.

Infectious causes of sudden infant death syndrome

Investigators have long suspected the role of infection in sudden infant death syndrome (SIDS). Evidence of infectious associations with SIDS is accentuated through the presence of markers of infection and inflammation on autopsy of SIDS infants and isolates of some bacteria and viruses. Several observational studies have looked into the relation between seasonality and incidence of SIDS, which often showed a winter peak. These all may suggest an infectious aetiology of SIDS. In this review we have summarised the current literature on infectious aetiologies of SIDS by looking at viral, bacterial, genetic and environmental factors which are believed to be associated with SIDS.

Post-mortem diagnosis, of cytomegalovirus and varicella zoster virus co-infection by combined histology and tissue molecular biology, in a sudden unexplained infant death

BACKGROUND

An autopsy case of a two-month-old male infant who suddenly and unexpectedly died during his sleep, eight days after the onset of benign varicella.

OBJECTIVES

To describe post-mortem combined histological and tissue molecular biological techniques for the diagnosis of cytomegalovirus and varicella zoster virus co-infection as a cause of death.

STUDY DESIGN

Real-time quantitative PCR and RT-PCR assays for Herpesviruses, respiratory viruses, Adenovirus, Enterovirus and Parvovirus B19 were performed on multi-organ frozen samples and paraffin-embedded tissues in combination with histology.

RESULTS

Cytomegalovirus and varicella zoster virus were detected by molecular biology with highest viral loads detected in the lungs (4.6×10(7) and 1.9×10(5) genome copies per million of cells, respectively). Pulmonary extensive necrotizing inflammation and immunohistochemistry correlated to virological data. Virological molecular biology was negative on paraffin-embedded tissues.

CONCLUSIONS

This case shows that thorough quantitative virological investigations on frozen tissues must be performed in combination with histology and immunohistochemistry for the determination of the cause of a sudden unexplained infant death.

Sudden unexplained cardiac arrest in apparently healthy children: a single-center experience

This study aimed to determine the causes of sudden cardiac arrest (SCA) in apparently healthy children at a single center in the era of primary prevention (screening questionnaire [SQ]) and secondary prevention (automated external defibrillator [AED] and the automated implantable cardioverter defibrillator [AICD]). Any child 0 to 18 years of age without prior known disease, except for attention deficit disorder, who underwent out-of-the hospital cardiopulmonary resuscitation was included in the study as a SCA subject. A retrospective chart review was used to evaluate the efficacy of the SQ, electrocardiogram (ECG), chest roentgenogram (CXR), and echocardiogram. The findings showed that for 44 of 6,656 children admitted to intensive care with SCA, an AED was used for 39%, an AICD was placed in 18%,and survival to hospital discharge was 50%. The etiology for SCA was identified in 57% of the cases, mostly in those older than 1 year, and the majority of these had a cardiac etiology (50%), whereas 7% had rupture of an arteriovenous malformation. Stimulant medication use was seen in 11% of the SCA subjects. In the best-case scenario of hypothesized primary prevention, a prior SQ, CXR, ECG, or echocardiogram may have detected respectively 18, 9, 23 and 16% of the at-risk cases, and 32% of the cases may have been detected with ECG and SQ together. Based on a historical control cohort, a positive ECG was significantly higher in the children with SCA (p = 0.014). An ECG together with a screening SQ may be more effective in identifying children potentially at risk for SCA than an SQ alone.

Kikuchi-Fujimoto lymphadenitis: role of parvovirus B-19, Epstein-Barr virus, human herpesvirus 6, and human herpesvirus 8

Kikuchi-Fujimoto lymphadenitis is a self-limited disorder that typically presents in young females as painless cervical lymphadenopathy with fever, anemia, and leukopenia. The clinical manifestations and pathologic findings suggest a viral etiology, yet specific etiologic agents remain unknown. Although there are studies reporting positive associations between Kikuchi-Fujimoto lymphadenitis and parvovirus B19 and herpesviruses, other studies have failed to find an association with these viruses. To our knowledge, this current study is the largest study of Kikuchi-Fujimoto lymphadenitis in Western patients that used polymerase chain reaction testing for 4 different common viral pathogens often implicated as etiologic agents in Kikuchi-Fujimoto lymphadenitis. Archival material from 3 institutions was included, following confirmation of the diagnosis of Kikuchi-Fujimoto lymphadenitis by 2 independent pathologists. Polymerase chain reaction from the paraffin-embedded tissue sections for parvovirus B19, Epstein-Barr virus, human herpesvirus 6, and human herpesvirus 8 was performed. Eighteen cases of Kikuchi-Fujimoto lymphadenitis were analyzed, 12 of which (60%) were cervical lymph nodes. All the cases showed typical geographic necrosis with abundant apoptotic debris, although the degree of necrosis was variable. Polymerase chain reaction revealed a high prevalence of parvovirus B19 in the controls (44%); there were fewer positive cases seen in the Kikuchi-Fujimoto lymphadenitis cases (11%), but this did not reach statistical significance (P = .25).There were no significant differences between cases and controls in the prevalence of Epstein-Barr virus, human herpesvirus 6, and human herpesvirus 8 (P = .50 for all 3). Polymerase chain reaction failed to reveal a positive association between Kikuchi-Fujimoto lymphadenitis and 4 common suspected viral agents. These findings do not support a role for Epstein-Barr virus, human herpesvirus 6, human herpesvirus 8, or parvovirus B19 in the pathogenesis of Kikuchi-Fujimoto lymphadenitis.

[Cytomegalovirus. Pathological-anatomical manifestations and detection methods]

Human cytomegalovirus, a double-stranded DNA virus, is a member of the Herpesviridae family with high rates of transmission. Primary infection is often asymptomatic and leads to life-long latency. Reactivation may induce different organ manifestations, particularly in the setting of immunosuppression. Histopathologically, the virus can be detected by light microscopy. Different cell populations in different organs are transformed into"owl's eye" cells, which are pathognomonic. Immunohistochemistry and electron microscopy can be applied as complementary methods. Various PCR approaches in molecular pathology including nested PCR, capture probe ELISA-PCR and real time PCR confer HCMV tests high sensitivity and specificity. The present article discusses the methods of pathological diagnostic approaches and describes organ manifestations of HCMV.

Ljungan virus: a commentary on its association with fetal and infant morbidity and mortality in animals and humans

Epidemiologic and experimental data support the notion that Ljungan virus (LV), endemic in some rodent populations in Sweden, Denmark, and the United States, can cause morbidity and mortality in animals and humans. LV infection can cause type I diabetes mellitus, myocarditis, and encephalitis in bank voles and experimental mice, and lemmings. Mouse dams infected with LV experience high rates of stillbirth that may persist across generations, and their fetuses may develop cranial, brain, and limb malformations. In humans, epidemiologic and serologic data suggest that LV infection correlates with intrauterine fetal death, malformations, placental inflammation, myocarditis, encephalitis, and Guillain-Barré syndrome. The proposed role of LV infection in SIDS is unconvincing. Further research is necessary to clarify the role of LV infection in animal and human disease.

Coinfection with EBV/CMV and other respiratory agents in children with suspected infectious mononucleosis

BACKGROUND

Numerous studies have shown that Epstein-Barr virus (EBV) and cytomegalovirus (CMV) can infect immunocompetent patients simultaneously with other agents. Nonetheless, multiple infections with other agents in EBV/CMV-infected children have received little attention. We conducted a retrospective study of children with suspected infectious mononucleosis. Peripheral blood samples were analyzed by indirect immunofluorescence to detect EBV, CMV and other respiratory agents including respiratory syncytial virus; adenovirus; influenza virus types A and B; parainfluenza virus types 1, 2 and 3; Chlamydia pneumoniae and Mycoplasma pneumoniae. A medical history was collected for each child.

RESULTS

The occurrence of multipathogen infections was 68.9%, 81.3% and 63.6% in the children with primary EBV, CMV or EBV/CMV, respectively, which was significantly higher than that in the past-infected group or the uninfected group (p < 0.001). Of the multipathogen-infected patients, the incidence of C. pneumoniae in children with primary infection was as high as 50%, significantly higher than in the other groups (p < 0.001). In the patients with multipathogen infection and EBV/CMV primary infection, fever, rash, lymphadenopathy, hepatomegaly, splenomegaly, atypical lymphocytes and abnormal liver function were more frequent and the length of hospital stay and duration of fever were longer than in other patients.

CONCLUSION

Our study suggests that there is a high incidence of multipathogen infections in children admitted with EBV/CMV primary infection and that the distribution of these pathogens is not random.