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1,2Institute of Legal Medicine1 and Institute of Clinical Microbiology, Immunology and Hygiene2, University of Erlangen-Nürnberg, Germany
Correspondence Roland Hausmann roland.hausmann{at}recht.imed.uni-erlangen.de
Received October 6, 2003
Accepted February 4, 2004
Clostridial myonecrosis or gas gangrene occurs most frequently in contaminated wounds following trauma or surgery. It is caused by a wide variety of Clostridium species, the most common being Clostridium perfringens. Spontaneous, non-traumatic clostridial myonecrosis is uncommon and is usually associated with gastrointestinal and haematological malignancy, diabetes mellitus and peripheral vascular disease. The case of a previously healthy 16-year-old boy with acute onset of gastrointestinal symptoms, who died of bacterial sepsis without apparent preceding trauma, is presented here. Clostridium fallax was identified as the most probable causative agent. As far as is known, this is the first report of fatal sepsis in humans due to C. fallax, which has been described only rarely as a cause of gas oedema in animals.
The GenBank/EMBL/DDBJ accession number for the sequence reported in this paper is AY208919.
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| Case report |
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Autopsy findings
Although the corpse had been kept at 4 °C until forensic autopsy, which was performed about 24 h post-mortem, the cadaver showed relevant signs of decomposition, with marbling and greenish discoloration of the skin. The mucous membranes of the intestine were high-grade putrefied and discoloured. The lining of the small intestine was haemorrhagic in several areas and multiple, small, erosive lesions were seen. Gastric contents, as well as the contents of the small and large intestine, were of watery consistency, a finding that is in agreement with the reported gastrointestinal disorder. The brain was swollen (1550 g) and showed signs of elevated intracranial pressure. Further relevant pathological findings, such as signs of abnormal gas formation, obvious injection marks or other superficial lesions, were not found.
Post-mortem toxicological findings
Samples of heart blood and urine, obtained at autopsy, were analysed by enzyme immunoassay and GC-mass spectrometry. Significant concentrations of toxic agents or substances with effects on the central nervous system could not be found. The concentration of ethanol in blood was 0.2 mg ml1.
Histological findings
Light microscopic examination of haematoxylin and eosin (H&E)-stained tissue samples from the stomach and bowel revealed distinct autolytic changes. Epithelial ulcerations and focal infiltrations of mononuclear inflammatory cells were found in the mucosa of the ileum (Fig. 1). Examination of Gram-stained specimens revealed accumulations of large, Gram-positive rods in these mucosal lesions, as well as in tissue sections from the left heart ventricle and the kidney (Fig. 2). Significant inflammatory reaction adjacent to these bacterial accumulations could not be detected.
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Post-mortem microbiological findings
Specimens for post-mortem bacteriology were collected as recommended by Tsokos et al. (2002). Cultures of the intestinal content plated on selective media were negative for enteric pathogens, such as Salmonella spp., Shigella spp., Campylobacter spp. and Yersinia enterocolitica. Cultures of heart blood and spleen swabs grew large, convex, slightly irregular, translucent colonies after 48 h anaerobic incubation on non-selective media. Gram-staining revealed large, Gram-positive rods with sparse formation of endospores. No growth of bacteria that are usually regarded as post-mortal flora, such as other anaerobes, enterobacteria or staphylococci, occurred on any of the anaerobic or aerobic culture plates within 7 days. The strain was further characterized by PCR amplification and sequencing of 1438 bp of the 16S rRNA gene (GenBank accession no. AY208919), as described elsewhere (Relman et al., 1992). Sequence analysis clearly identified the isolate as C. fallax [99.6 % similarity to C. fallax ATCC 19400T (GenBank accession no. M59088); primer sequences and ambiguities were omitted].
Biochemical identification by using the RAPID 32A system (bioMérieux) failed, as the resulting reaction pattern (4103 4001 10) was not in sufficient accordance with the pattern for C. fallax that was included in the database.
Conclusions
The isolation of C. fallax from two independent body sites, the absence of other bacteria in these cultures and the histological detection of clostridia-like bacteria in a variety of tissues indicated bacterial dissemination in vivo and a possible causative role of the isolate in the death of the patient.
C. fallax is generally regarded as a soil organism of little or no clinical significance and has also been described as part of the normal indigenous intestinal flora (Finegold et al., 1983). Nevertheless, it has been reported that it can cause experimental and sporadic infections in animals (Weinberg et al., 1937; Coloe et al., 1983; Vatn et al., 2000) and that it is able to produce a lethal toxin (Willis, 1977). Therefore, it can be regarded as a facultative pathogen for humans with predisposing conditions. Production of toxins may contribute to circulatory failure in these cases.
The micro-organisms could have entered the bloodstream either parenterally or via the gastrointestinal route. As no skin lesions or injection sites were detected, exogenous infection seems unlikely. It can be assumed that the intestinal mucosal lesions were the source of an endogenous infection, as described for other pathologies, such as gastrointestinal malignancy (Ray et al., 1992).
In the absence of other morphological or toxicological findings, septicotoxic circulatory failure that is attributable to C. fallax bacteriaemia, contracted through lesions of the intestinal mucosa following dysentery of unknown aetiology, is the most probable cause of death in the reported case.
This case highlights the need for vigilance in forensic pathology to consider bacterial sepsis, especially if unusually advanced signs of decomposition are present, despite a short post-mortem interval and appropriate storage of the subject. Microbiological investigation should include cultures for detection of anaerobic bacteria, such as clostridia.
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