Fatal Paraclostridium sordellii Infection: Post-Mortem Assessment and Review of the Literature

Abstract

Clostridium sordellii, which has recently been reclassified as Paeniclostridium sordellii and subsequently as Paraclostridium sordellii, is a rare human pathogen linked to infections of high morbidity and mortality, often presenting as fulminant toxic shock syndrome. Although most documented cases involve individuals with pre-existing health issues, such as immunosuppression and cancer, or those who have undergone specific gynecological procedures, there are few instances reported in otherwise healthy individuals. In this report, we present a case of fatality associated with P. sordellii infection in a young individual with a history of drug abuse, following post-mortem examinations. Additionally, we provide an updated review of the latest literature on this topic.

1. Introduction

Clostridium sordellii (recently renamed Paeniclostridium sordellii [1] and then Paraclostridium sordellii [2]) is an infrequent human pathogen associated with infections of high morbidity and mortality, possibly presenting as fulminant toxic shock syndrome. While most cases have been described in subjects with underlying conditions, including immunodepression [3] and oncological disease [4,5,6,7,8,9,10], or after specific gynecological procedures [11,12,13,14,15,16,17,18,19], few cases were reported among previously healthy subjects, mostly related to recent injury [20,21,22,23] or acute omphalitis in newborns [24,25,26,27,28]. A small number of cases is related to injection drug use [10,29,30,31], especially black tar heroin [32,33]. The largest review was performed by Aldape et al. in 2006 [34].

Here, we report on a case of death associated with P. sordellii infection in a young drug abuser, diagnosed by post-mortem microbiological investigations.

2. Case Presentation

Early in the morning on a cold winter’s day, a forty-year-old woman was discovered in a public park attended by drug users and other related individuals. She was warmly dressed due to the cold temperature, estimated between 9.1 and 11.7 degrees Celsius according to the weather service. She was found unconscious and unresponsive in her makeshift shelter by a groundskeeper. Medical assistance was called, and the first physician to arrive witnessed the woman’s death without attempting any resuscitative maneuvers. The physician noted that the body showed abundant hypostasis, consistent with the described position (the body was faced down). No traumatic lesions or venipunctures were detected. The woman tested positive for drug abuse on her medical history, which included intravenous heroin use dating back to her youth and, more recently, smoking crack cocaine.

Despite multiple hospitalizations and support from specific local centers in the rehabilitation community, all attempts at rehabilitation failed. Although the woman had stopped using needles, she continued to smoke crack, as recently documented. In the days preceding the discovery of her body, she showed no signs of illness and had not reported feeling unwell (the last contact with the rehab community occurred less than 24 h before her death).

The body was taken to the local Forensic Medicine Institute and stored (in supine position) in a mortuary refrigerator set to a constant temperature of 0–4 degrees Celsius until the autopsy, which was performed 72 h after the discovery.

• Autopsy findings

An autopsy was conducted on the body, including a thorough external and internal post-mortem examination. During the external examination, the pathologist noted complete hypostasis migration, rigor mortis fully set in—although easily reversible—and a small area of greenish discoloration, measuring approximately 3 × 2 cm, in the upper left abdomen.

No traumatic injuries were found, but a reddish fluid was seen leaking from the nostrils. There were no venipunctures.

Upon dissecting the head, the pathologist found a moderately edematous brain with consistent texture. The abdominal and thoracic organs appeared deteriorated, showing changes in color and texture and smelled sickeningly sweet odor. The lungs were congested and edematous, the heart had no significant abnormalities, and the liver was enlarged and structurally altered, with microvesicular steatosis and fibrosis and steatohepatitis. The intestines were distended with gas, but no mucosal changes were detected.

During the autopsy, organ samples were taken for histological examination, biological fluids were collected for toxicological analysis, and samples and swabs were obtained for microbiological testing as per the Forensic Unit’s internal protocol.

• Histological findings

Multiple organ samples were taken from the lungs, brain, heart, kidneys, spleen, pancreas, and liver. They were included in paraffin and cut with a microtome into micrometric slides. Hematoxylin and eosin staining was performed, and specimens were observed under a microscope (Figure 1).

Histological examination revealed multi-visceral congestion, brain edema, lung edema, areas of cardiac necrosis with edema, and hepatic steatosis. In all parenchymas, congestion and the presence of lymphocytic and granulocytic infiltrates were found. Copious intravascular granulocytes and a lesser number of lymphocytes were also observed at the intravascular site. Gram-positive bacilli were widespread in the heart, lung, and kidney (Gram staining) (Figure 2). Immunohistochemical testing of tissues was conducted to disclose the inflammatory response and leukocytes cells. In particular, antibodies for CD15 (MMA) ^® and CD68 (PG-M1) ^® were obtained from Diagnostic BioSystems (DBS) (Pleasanton, CA, USA).

3. Results

• Post-mortem microbiological investigations

Microbiological cultures were carried out on specimens collected post-mortem, including blood, urine, rectal swabs, pharyngeal swabs, and samples from heart, brain, lung (right and left anterior upper lobe, right and left anterior lower lobe and right medial anterior lobe), kidneys (right and left), liver and spleen.

Blood, urine and mucosal swabs were taken during the external examination, by puncture of the femoral artery, suprapubic puncture, and direct swabbing, respectively. Tissue samples were taken during autopsy. Before sampling of blood and urine, the skin was carefully disinfected with betadine and sterile test vials and needles were used.

Blood was directly inoculated in 4 blood culture vials for aerobic and anaerobic cultures (BactAlert system, Marcy l’Etoile, France, bioMérieux). Urine was collected in a sterile tube and then transferred to a urine Sponge^TM (Copan, Murrieta, CA, USA) according to the manufacturer’s instructions. FecalSwab^TM and UTM^TM transport media (Copan, Murrieta, CA, USA) were used for rectal and pharyngeal swabs, respectively. Other samples (1–2 cm³) were collected in sterile tubes containing minimal amount (0.5 mL) of sterile normal saline to preserve from drying out. All specimens were transferred to the laboratory and processed within 1 h. Culture media, incubation conditions and incubation times are reported in Table S1.

Bacterial identification was carried out by MALDI-ToF mass spectrometry (MALDI Biotyper^® Bruker Daltonics, Bremen, Germany). Identification of P. sordellii was further confirmed by a whole-genome sequencing (WGS)-based analysis of one isolate, using the TYGS server [35].

Table 1. Each sample, which bacteria were detected and any details regarding their growth.

Biospecimen	Microbes	Note
Heart	Citrobacter freundii	Obtained after broth enrichment
Brain	Klebsiella ornithinolytica	Rare colonies
Liver	Lactobacillus rhamnosus	Obtained after broth enrichment
Spleen	Staphylococcus epidermidis	Obtained after broth enrichment
	Lactobacillus spp.
Right kidney	Enterococcus gallinarum	Rare colonies * Obtained after broth enrichment
	Escherichia coli *
	Bacterioides fragilis *
Left kidney	Lactobacillus rhamnosus	Obtained after broth enrichment
Lung: right anterior upper lobe	Veillonella parvula	Obtained after broth enrichment
Lung: right anterior medial lobe	Lactobacillus rhamnosus	Obtained after broth enrichment
Lung: right anterior lower lobe	Negative
Lung: left anterior upper lobe	Lactobacillus rhamnosus	Discrete number of colonies * Obtained after broth enrichment
	Veillonella parvula
	Enterococcus faecalis *
Lung: left anterior lower lobe	Enteroccoccus faecalis	Obtained after broth enrichment
Blood 1st sample	Staphyloccoccus epidermidis	§ obtained from anaerobic culture
	Staphylococcus lugdunensis
	Enterococcus faecalis
	Escherichia coli
	Paraclostridium sordellii §
Blood 2nd sample	Staphylococcus epidermidis	§ obtained from anaerobic culture
	Staphylococcus hominis
	Paraclostridium sordellii §
Urine	Negative
Rectal swab	Negative
Nasopharyngeal swab SARS-CoV2	Negative

* = Temperature of 35 °C (±1 °C) was used for incubation; § aerobic atmosphere enriched with 5% CO₂ was used for incubation of CHOC plates; anaerobic atmosphere was obtained in dedicated sealed boxes using “Anaerogen^TM Atmosphere generation system (ThermoScientific) pad, or in dedicated incubator for blood cultures (BactAlert system, Marcy l’Etoile, France, bioMérieux)”.

shows, for each sample, which bacteria were detected and any details regarding their growth.

A BLASTn analysis performed at the NCBI server (https://blast.ncbi.nlm.nih.gov/, accessed on 4 June 2025) with the genomic sequence of the P. sordellii isolate did not detect the genes encoding the lethal toxin (tcsL) or the hemorrhagic toxin (tcsH). However, the presence of plC (phospholipase C), sdL (sordellilysin), and nanS (sialidase) genes was confirmed, suggesting their potential involvement in the observed cytotoxicity [36].

• Toxicological findings

Toxicological analyses were performed on biological samples (central and peripheral blood, urine, vitreous humor and bile) collected during the autopsy and rapidly stored at −20 °C. Cocaine, and its main metabolite (benzoylecgonine), methadone, and lorazepam were quantified as reported in

Table 2. Cocaine, benzoylecgonine, methadone, and lorazepam concentrations in biological samples.

Compound	Concentrations (ng/mL)
	Central Blood	Peripheral Blood	Urine	Vitreous Humor	Bile
Cocaine	3329	2197	2962	337	35,847
Benzoylecgonine	61	101	2120	125	-
Methadone	234	515	738	132	752
Lorazepam	12	11	-	<LOQ *	31

* LOQ: limit of quantification (1 ng/mL).

. Blood alcohol content was negative.

4. Discussion

The case is worth reporting primarily because it was a case of sudden death that autopsy and histological examination ascribed to a fulminant shock syndrome, which the associated microbiological workup suggested to be caused by a P. sordellii infection. The patient was a known cocaine addict, although they smoked the drug rather than injecting it, which is more common in these cases of chronic drugs abusers. However, in this instance, there were no signs of injections, which was recently confirmed by the patient who openly admitted to smoking crack. This case also emphasizes the importance of post-mortem microbiological samplings in cases of sudden death or death without a witness.

Clostridium sordellii, first described by Alfredo Sordelli [37] under the name “bacillus oedematis sporogenes” [38] and later categorized as Paeniclostridium [1] and then as Paraclostridium [2], is an anaerobic, Gram-positive, spore-forming rod implicated in acute and severe infections in both humans and animals [39,40,41]. Like other clostridia, P. sordellii is commonly found in soil but can also be present in a small percentage of the population in the vagina or rectum [42], although this percentage may vary between populations [43].

While non-pathogenic strains of P. sordellii exist, there are others that produce two unique toxins that are significant virulence factors [44]: the lethal toxin (TcsL) and the hemorrhagic toxin (TcsH), both of which interfere with the Rho pathway [45] and bear similarities to toxins produced by Clostridioides difficile [46,47]. P. sordellii also produces other exotoxins whose role in pathogenesis has not been extensively studied [34].

The lethal toxin was shown to induce a massive increase in vascular permeability in mice [48]. In humans, it causes a peculiar toxic shock syndrome strictly related to capillary leaking. This syndrome is characterized by diffuse edema, unresponsive to treatment hypotension with hemoconcentration, sometimes gastrointestinal or nonspecific symptoms, massive leukocytosis (frequently more than 50,000 cells/microL, a value so high it is called a “leukemoid reaction” [49]), and absence of fever, due to the specific anti-inflammatory properties of TcsL [50].

P. sordellii may also cause a less specific clinical syndrome: myonecrosis with gas gangrene that shares many features with other clostridial infections [51]. Like many other pathogenic bacteria, it can also cause a less common localized infection without any remarkable traits that may eventually evolve into sepsis.

Infections caused by P. sordellii exhibit two typical characteristics: from a clinical perspective, the rapid onset of tissue necrosis and shock leading to multi-organ failure; from a pathophysiological mechanism perspective, there is a generalized capillary leak and a massive increase in circulating leukocytes, defined as a “leukemoid reaction.”

Each clinical syndrome seems to be more closely related to a specific mode of infection: while toxic shock syndrome is predominant in infections related to obstetrics and gynecological procedures, myonecrosis seems to be prevalent in post-traumatic and drug-related infections, as well as in subjects with immunosuppression. Localized infections do not show any remarkable pattern. The largest review reported by Aldape et al. [34] highlighted that out of a total of 45 cases, the majority were related to gynecological procedures, with 11% involving medically induced abortions, 0.4% related to spontaneous abortions, and 18% concerning normal deliveries. In all three mentioned categories, the observed mortality rate was 100%. Conversely, 22% of the cases were linked to the use of injectable drugs, and in this category, a significantly lower mortality rate of 50% was observed. A similar mortality rate of 53% was noted for infections resulting from trauma or surgical procedures, which accounted for 43% of the sample. Considering the sample as a whole, the mortality rate was found to be 69% (31 subjects out of 45), with approximately 85% of deaths occurring within less than a week (2–6 days) and in the presence of a leukemoid reaction. Overall, these data show that infections caused by P. sordellii, although rare, present extremely high mortality rates, approaching 100% in certain patient categories; therefore, it is essential to maintain a high level of awareness regarding this pathogen [52,53].

Table 3. List from the case reports and case series identified in the literature.

Authors	N° of Cases *	Subject Age and Sex	Type of Case	Fatal Outcome?	Autopsy Performed?	How Was C.s. Diagnosed?	Toxin Presence Verified?
Browdie et al., 1975 [20]	1	23 years M	Traumatic injury	yes	yes	Cultural from wound	no
Bogdan et al., 1976 [24]	1	13 days F	Omphalitis	yes	yes	Cultural from blood and fluid from the site of infection	no
Gormley et al., 1977 [25]	1	4 days F	Omphalitis	yes	yes	Cultural from fluid from the site of infection	no
Thys et al., 1980 [54]	1	18 years M	Other	yes **	yes	Isolated from muscle and blood sample	no
Barnes et al., 1987 [55]	1	61 years M	Other	no	--	Cultural from blood samples and pleural fluid	no
Hogan et al., 1989 [56]	1	39 years F	Gynecological/obstetrician	yes	yes	Cultural from an exudate of myometrium acquired at autopsy	no
McGregor et al., 1989 [12]	3	28 years F	Gynecological/obstetrician	yes	yes	Cultural from “clot” from vagina	no
		23 years F	Gynecological/obstetrician	yes	no	Cultural from cervical lesion	no
		23 years F	Gynecological/obstetrician	yes	yes	Cultural from intraoperative and autopsy samples	yes
Grimwood et al., 1990 [21]	1	4 years F	Traumatic injury	no	--	Cultural from necrotic tissue from the site of infection	yes
Kosloske et al., 1991 [26]	1	9 days F	Omphalitis	no	--	Cultural from exudate and tissues from site of infection	no
Buchman et al., 1991 [57]	1	95 years F	Other	no ***	no	Cultural from pleural fluid	no
Spera J, et al., 1992 [58]	1	37 years M	Drug related	no	--	Cultural from blood samples	no
Adamkiewicz et al., 1993 [27]	1	17 days F	Omphalitis	yes	yes	Cultural from peritoneal fluid and umbilical tissue	yes
Mory et al., 1995 [3]	1	48 years F	Immunosuppressed/oncological patient	yes	yes	Cultural from blood samples and liver tissue acquired at autopsy	yes
Bitti et al., 1996 [13]	1	29 years F	Gynecological/obstetrician	yes	no	Cultural from blood	yes
Cunnife et al., 1996 [4]	1	55 years M	Immunosuppressed/oncological patient	yes	yes	Cultural from blood and stool samples	yes
Sosolik et al., 1996 [14]	1	24 years F	Gynecological/obstetrician	yes	yes	Cultural from resected necrotic tissue	no
Borer et al., 1999 [59]	1	73 years M	Immunosuppressed/oncological patient	yes	yes	Cultural from blood samples	no
Gredlein et al., 2000 [22]	1	37 years M	Traumatic injury	no	--	Cultural from intraoperative samples from site of infection	no
Rorbye et al., 2000 [15]	1	40 years F	Gynecological/obstetrician	yes	no	Cultural from discharge from site of infection	no
Abdulla et al., 2000 [5]	2	81 years F	Other	yes	yes	Cultural from blood samples	no
		12 years M	Immunosuppressed/oncological patient	no	--	Cultural from blood samples	no
Cobo et al., 2001 [60]	1	17 years F	Other	no	--	Cultural from a corneal ulcer	no
CDC* 2001 [61]	1	23 years M	Other	yes	yes	Cultural from blood	no
Bangsberg et al., 2002 [32]	2	28 years F	Drug related	yes	no	Cultural from surgical wound	no
		52 years M	Drug related	no	--	Cultural from intraoperative sample of tissues from site of infection	no
Sinave et al., 2002 [16]	1	26 years F	Gynecological/obstetrician	yes	yes	Cultural from endometrial biopsy	no
Lorea et al., 2004 [62]	1	49 years M	Other	no	--	Cultural from perioperative samples	no
Zink et al., 2004 [63]	1	33 years M	Other	no	--	Cultural from vitreous sample	no
Wiebe et al., 2004 [64]	1	27 years F	Gynecological/obstetrician	yes	yes	Cultural from endometrial biopsy and perioperative samples	no
Fischer et al., 2005 [11]	4	18 years F	Gynecological/obstetrician	yes	yes	PCR assay from DNA extracted from uterine tissues fixed in formalin	yes
		21 years F	Gynecological/obstetrician	yes	yes	PCR assay from DNA extracted from uterine tissues fixed in formalin	yes
		22 years F	Gynecological/obstetrician	yes	yes	PCR assay from DNA extracted from uterine tissues fixed in formalin	yes
		34 years F	Gynecological/obstetrician	yes	yes	PCR assay from DNA extracted from uterine tissues fixed in formalin	yes
Brett et al., 2005 [29]	1	unknown M	Drug related	yes	no	not specified	no
Aldape et al., 2006 [34]	2	4 years M	Traumatic injury	yes	yes	Cultural from intraoperative samples from site of infection	no
		21 years F	Gynecological/obstetrician	yes	yes	Cultural from intraoperative samples from site of infection	no
Elsayed et al., 2006 [6]	1	61 years F	Immunosuppressed/oncological patient	yes	yes	Cultural from blood samples	yes
Cohen et al., 2007 [65]	2	25 years F	Gynecological/obstetrician	no	--	Cultural from blood and cervical samples	yes
		18 years F	Gynecological/obstetrician	yes	yes	Immunohistochemical and PCR assay on uterine tissue	yes
Matten et al., 2009 [7]	1	59 years M	Immunosuppressed/oncological patient	no	--	Cultural from blood samples and from pleural and liver drainage	yes
Foroulis et al., 2009 [66]	1	56 years M	Other	no	--	PCR analysis from pleural fluid	yes
Ho et al., 2009 [67]	2	32 years F	Gynecological/obstetrician	yes	yes	Immunohistochemical and PCR assay on fixed tissue	yes
		40 years F	Gynecological/obstetrician	yes	yes	Immunohistochemical and PCR assay on fixed tissue	yes
Valour et al., 2010 [68]	1	31 years F	Traumatic injury	no	--	PCR analysis on DNA from infected brain tissue	yes
Meites et al., 2010 [69]	2	29 years F	Gynecological/obstetrician	yes	no	PCR assay from infected tissue	no
		21 years F	Gynecological/obstetrician	yes	no	PCR assay from infected tissue	no
Chaudhry et al., 2011 [70]	1	8 months M	Other	no	--	Cultural and PCR assay from intraoperative samples	yes
Walk et al., 2011 [71]	1	81 years F	Other	no	--	Cultures from blood samples and PCR assay on the cultured strains	yes
Smith et al., 2013 [8]	1	37 years F	Immunosuppressed/oncological patient	no	--	Cultural from samples from site of infection	no
Marinis et al., 2013 [30]	1	25 years F	Drug related	no	--	Cultural from intraoperative samples from site of infection	no
Bouvet et al., 2015 [23]	1	78 years M	Traumatic injury	not specified	no	Cultural from blood and PCR assay on subculture	yes
Guzzetta et al., 2016 [72]	1	33 years F	Gynecological/obstetrician	yes	yes	Cultural from episiotomy site and blood samples	no
Rellinger et al., 2016 [28]	1	8 days M	Omphalitis	yes	yes	Cultural from intraoperative samples of tissues from site of infection	no
Bonnecaze et al., 2016 [9]	1	67 years F	Immunosuppressed/oncological patient	no	--	Cultural from blood samples	no
Gray et al., 2018 [73]	1	61 years M	Traumatic injury	not specified	--	Cultural from wound site	no
Mattson et al., 2018 [18]	1	45 years F	Gynecological/obstetrician	no	--	Cultural from intraoperative sample from site of infection	no
Elkubuli et al., 2018 [19]	1	31 years F	Gynecological/obstetrician	no	--	Immunohistochemical and PCR assay on intraoperative samples	no
Boyanton et al., 2019 [17]	1	29 years F	Gynecological/obstetrician	yes	no	Cultural from ascites samples	no
Silva et al., 2020 [31]	1	37 years F	Drug related	yes	no	Cultural from intraoperative samples from site of infection	no
Chaudhry et al., 2021 [74]	1	28 years F	Other	no	--	Cultural from intraoperative samples from site of infection	yes
Varley et al., 2022 [10]	1	63 years M	Immunosuppressed/oncological patient	no	--	Cultural from blood samples	yes
Milano et al., 2023 [75]	4	34 years M	Lupus/drug related	yes	no	Cultural from intraoperative samples from site of infection	yes
		41 years M	Drug related	no	--	Cultural from intraoperative samples from site of infection	yes
		42 years M	Morbid obesity/drug related	yes	yes	Cultural from abdominal wall tissue	yes
		47 years M	Drug related	yes	no	Cultural from intraoperative samples from site of infection	yes
Jacques et al., 2024 [76]	2	30 years F	42 weeks gestation	yes	yes	Uterine and placental cultures	yes
						Cultural from blood samples	no
		Adolescence F	Medication abortion	yes	yes	Endometrial culture	yes
Kurth et al., 2024 [77]	15	30	Drug related	no	--	Cultural from intraoperative samples from site of infection	yes
		69	Drug related	yes	no	Cultural from intraoperative samples from site of infection	yes
		33	Drug related	no	--	Cultural from intraoperative samples from site of infection	yes
		68	/	no	--	Cultural from intraoperative samples from site of infection	yes
		58	/	no	--	Cultural from intraoperative samples from site of infection	yes
		76	/	no	--	Cultural from intraoperative samples from site of infection	yes
		50	/	no	--	Cultural from intraoperative samples from site of infection	yes
		53	Drug related	no	--	Cultural from intraoperative samples from site of infection	yes
		64	/	no	--	Cultural from blood samples	yes
		42	Drug related	yes	no	Cultural from intraoperative samples from site of infection	yes
		54	/	no	--	Cultural from blood samples	yes
		60	Drug related	no	--	Cultural from intraoperative samples from site of infection	yes
		47	Drug related	yes	no	Cultural from intraoperative samples from site of infection	yes
		57	Drug related	yes	no	Cultural from intraoperative samples from site of infection	yes
		80	/	yes	no	Cultural from blood samples	yes

* In some cases, death reports due to other Clostridia were presented but had not been counted in the table. ** Brain death of the subject had been already declared; the infection led to cardiac arrest. *** Patient survived the infection but died of unknown causes after a prolonged hospitalization; / Not drug related.

provides a list from the case reports and case series identified in the literature and some summary notes regarding the content of each.

The authors present here a case of death in a female drug addict who was found dead in a park. The autopsy and subsequent histopathological examinations revealed findings consistent with acute heart failure due to sepsis syndrome, including morphonuclear lymphocyte infiltration intravascular in the heart and lungs with granulocytes, as well as the presence of Gram-positive bacilli in the same organs. Microbiological workup performed on autopsy specimens revealed the presence of P. sordellii in two separate blood samples, which was considered highly suggestive, in combination with the patient’s history and the anatomical and histopathological findings, with a case of fulminant shock syndrome associated with P. sordellii infection.

However, it should be noted that the blood cultures were also positive for various species of coagulase negative staphylococci (which are common skin colonizers), which might reflect the occurrence of contamination upon sampling, and that one vial was also positive for Enterococcus faecalis and Escherichia coli, which are normally members of the intestinal microbiota. The latter finding could reflect the fact that autopsy was performed 72 h after time of death, i.e., when post-mortem changes might have led to the permeabilization of the intestinal wall and subsequent migration of gastrointestinal bacteria to inner organs and blood. Therefore, we cannot exclude that the occurrence of P. sordellii in the blood could have been the result of a post-mortem scenario.

Moreover, in our case, numerous Gram-positive bacilli were observed in the heart by microscopy, but upon cultivation, a Gram-negative rod (namely a Citrobacter freundii) was detected. The latter finding could reflect the fact that culture conditions used for tissue specimens were different from those uses for blood specimens, and might have been no permissive for growth of P. sordellii.

Toxicological analysis revealed consumption of lorazepam, methadone, and cocaine at “therapeutic/normal” levels. Bile concentrations suggested recent consumption of cocaine and methadone, confirming a history of cocaine abuse and therapeutic use of opioids. None of the substances played a significant role in the cause of death.

The forensic diagnosis and conclusion are consistent with the information available from what is reported in the literature regarding findings from rare cases. P. sordellii infections are characterized by the absence or only mild local inflammatory response. Experimental infection with P. sordellii induces edema, muscle fiber disruption, tissue necrosis, and significant increase in white blood cells, specifically neutrophils, in vessels of all tissue specimens.

The infection can occur in subjects who use drugs, especially injectable ones, as in this case. Regardless of the cause of infection, P. sordellii cases are often apyrexial and develop a profound leukemoid reaction, as witnessed here. The case involves a sudden death suspected to be caused by an overdose, occurring without any prodromal symptoms or signs of infection in the 24 h leading up to death, linked to P. sordellii, a pathology that is often lethal but infrequently encountered.

This case highlights the importance of microbiological testing in cases of sudden and/or unwitnessed deaths. Despite the difficulties related to interpreting microbiological results, which represent a limitation of our findings, they underscore the importance of integrating these results with macroscopic investigations during the autopsy and histopathological results can help in discriminating between microbiological positivity from post-mortem bacterial translocation or contamination and positivity from local or systemic infection contracted in the pre-mortem period.

5. Conclusions

The case presented highlights the significance of conducting comprehensive microbiological investigations in cases of sudden death, even in the absence of clear signs of an active infection. It is important to carefully evaluate the results of these tests, as several factors can affect them. Therefore, it is crucial to combine microbiological findings with a thorough examination that takes into account both the macroscopic and microscopic evidence seen during the autopsy.