Streptococcal toxic shock syndrome presenting as suspected child abuse

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.

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.

Child abuse followed by fatal systemic Pseudomonas aeruginosa infection

Child abuse has become an increasingly serious diagnostic challenge for physicians. The clinical manifestations include malnutrition and sometimes infection. In fact, stress in children has been reported to increase corticosteroid levels. As a consequence, the thymus begins an involution process, producing a severe impairment in cellular and humoral immunity. Here, we report the case of a 7-year-old child who suffered a prolonged history of abuse and died from a systemic Pseudomonas aeruginosa infection. An initial local chronic infection propagated to the pelvic lymph nodes in an immunologically weak body and evolved into abscesses/phlegmons of the pelvic tissue, sepsis, acute respiratory distress syndrome, multiple organ failure and finally, death. Abused children have to be considered as potentially immunologically impaired patients; therefore, it is very important to screen them for opportunistic infections. Moreover, a history of unusual or recurring infections may indicate abuse, especially neglect or malnutrition. In these cases, further investigations should be conducted to determine if a protective service case should be opened. Thus, there is a need for multidisciplinary cooperation to ensure the early identification and prevention of child abuse.

Clinicopathological findings in fulminant-type pneumococcal infection: Report of three autopsy cases

Reported herein are three autopsy cases of fulminant-type pneumococcal sepsis with disseminated intravascular coagulation (DIC) resulting in death within a few days of onset of symptoms. Two of the three patients had previously had a splenectomy because of a hematological disorder. None of the patients had received pneumococcal vaccination. On post-mortem every organ had congestion as well as bleeding. Interestingly, severe inflammation of the alveoli was absent despite the sepsis. The cause of death was rapidly progressive pneumococcal sepsis leading to DIC and circulatory failure, which appeared to cause pulmonary congestion and hemorrhage without pneumonia. It is important to understand the pathogenesis of fulminant-type pneumococcal infection because it is life-threatening for compromised hosts.

Acute Deaths in Nonpregnant Adults Due to Invasive Streptococcal Infections

Streptococcal organisms, part of the normal human bacterial flora, occasionally become infectious pathogens responsible for a wide array of clinical syndromes, ranging from mild pharyngitis to death. Notably, infections due to group A and group B beta-hemolytic strains are well known for causing invasive disease leading to death. These deaths, while often suspected clinically, occasionally are not diagnosed until autopsy. We present 3 rapid deaths, with very different presentations, due to streptococcal infection. Two decedents experienced sudden deaths due to pneumonia and severe meningoencephalitis caused by group B beta-hemolytic streptococcal infection, a common cause of neonatal meningitis but only rarely reported in nonpregnant adults. The final case involves a 69-year-old male who presented to the emergency room with a complaint of shoulder pain but over the next several hours developed signs of necrotizing fasciitis, became septic, and died. While antemortem cultures were negative, owing to antibiotic administration, postmortem cultures of bone and deep soft tissue were positive for group A beta-hemolytic Streptococcus sp. Acute and sudden deaths due to infectious etiology represent an uncommon yet well-documented occurrence. The importance of appropriate postmortem cultures in these situations and a review of the literature will be discussed.

Sudden Unexpected Death in a Child With Varicella Caused by Necrotizing Fasciitis and Streptococcal Toxic Shock Syndrome

A 4-year-old child with chickenpox infection for 5 days prior to death complained of swelling and pain in his right leg that required medical assistance in the emergency department. Radiologic study was normal, and analgesic and bandage of the leg were prescribed. Some hours later, he presented cyanosis, dizziness, and vomiting and collapsed. A complete forensic autopsy was performed 12 hours after death. External examination of the body showed numerous crusty varicella skin lesions, especially over the trunk, and swelling and reddening of his right leg. The brain was swollen, with cerebellar herniation, and both adrenal glands were hemorrhagic.Microscopically, neutrophilic infiltration and muscle fiber necrosis were observed in soft tissues of his right leg, and fibrin microthrombus were numerous in capillaries of the plexus choroideus, larynx, lungs, and adrenals. Bacterial emboli were present in most of the tissues. Microbiologic cultures of blood and cerebrospinal fluid showed group A beta-hemolytic streptococcus (Streptococcus pyogenes). Death was attributed to fulminant streptococcal toxic shock syndrome, with necrotizing fasciitis as a complication of varicella.

Postmortem bacteriology in forensic pathology: diagnostic value and interpretation

The proof of a pathogenetic germ can be of evidential value for the medico-legal expertise concerning etiopathogenetic conclusions towards a causal relationship between infection and fatal outcome. In specific cases the forensic pathologist may be confronted with the decision whether cultures for postmortem bacteriological investigations should be obtained at autopsy. The present review surveys the value and practicability of postmortem bacteriological cultures in the light of the literature. The most promising media for postmortem bacteriological cultures are spleen and heart blood. In contrast, postmortem lung culture results are often unreliable due to frequently false positive results. The collection of specimens from at least two different sampling sites should be the standard procedure in cases where an underlying (potentially fatal) infection is presumed. Multiple postmortem cultures from different sampling sites raise the probability to identify the etiologic agent of antemortem infection. A careful correlation of culture results from different anatomical sampling sites with autopsy and histological findings is essential for the differentiation between vitally acquired infection and postmortem contamination. Various factors (e.g. the time interval between death and sampling of specimens, agonal spread of microorganisms or preceding antibiotic therapy prior to death) may limit the diagnostic utility of postmortem culture results. Contamination of specimens may, e.g. originate from inadequate sampling techniques, use of unsuitable transport media or postmortem growth of bacteria. The number of contaminated postmortem cultures increases when bowel manipulation or evisceration occurs prior to sampling and is depending on the anatomy of the sampling site. Polymicrobial growth can be considered contamination in the majority of cases. For the medico-legal expertise a thorough histological examination of inner organs and tissues is needed; the histological section has to represent the sampling site for culture. The presence of an underlying infection can be proven when postmortem bacteriological cultures yield a primary infectious pathogen and a cellular response in the affected tissue can be detected on the histopathological level. Postmortem bacteriology can be regarded as a reliable diagnostic tool for postmortem quality control of preceding diagnostic and therapeutic procedures and can serve as an additional indicator of nosocomial infections within a specific hospital environment. From the medico-legal point of view, a more widespread application of this valuable investigative procedure, that adds to diminish the number of otherwise unresolved deaths in forensic autopsy practice, is desirable.