Studies on drug metabolism by fungi colonizing decomposing human cadavers. Part I: DNA sequence-based identification of fungi isolated from postmortem material

Abstract

Cadavers can be colonized by a wide variety of bacteria and fungi. Some of these microbes could change the concentration or the metabolic pattern of drugs present in postmortem samples. The purpose of this study was to identify fungi from human postmortem material and to further assess their potential role in the metabolism of drugs. Aliquots of 252 postmortem samples (heart blood, liver, kidney, and lung) taken from 105 moderately to severely decomposed bodies were streaked on Sabouraud agar for isolation of fungal species. One part of the samples was worked up immediately after autopsy (group I). The second part had previously been stored at -20 °C for at least 1 year (group II). Identification of the isolates was achieved morphologically by microscopy and molecularly by polymerase chain reaction amplification and sequencing of markers allowing species identification of the respective genera. Depending on the genus, different gene fragments were used: calmodulin for Aspergillus, β-tubulin for Penicillium, translation elongation factor 1α for Fusarium, and the internal transcribed spacer region of the ribosomal DNA for all remaining genera. A total of 156 fungal strains were isolated from 62% of the postmortem materials. By using these primers, 98% of the isolates could be identified to the species level. The most common genera were Candida (60.0%-six species), Penicillium (10.3%-two species), Rhodotorula (7.1%-one species), Mucor (6.4%-four species), Aspergillus (3.2%-four species), Trichosporon (3.2%-one species), and Geotrichum (3.2%-one species). Group I samples contained 53% more fungal species than stored samples suggesting some fungi did not survive the freezing process. The isolated fungi might be characteristic for decomposed bodies. The proposed methodology proved to be appropriate for the identification of fungi in this type of material.

Studies on drug metabolism by fungi colonizing decomposing human cadavers. Part II: biotransformation of five model drugs by fungi isolated from post‐mortem material

“…In fact, some of them have been used for the simulation of the mammalian metabolism because of their capability to catalyze metabolic reactions by various enzymes including intracellular cytochrome P450 and extracellullar lignin peroxidase, manganese peroxidase and laccase . As demonstrated in Part I of this communication and by other authors, the most common fungi colonizing cadavers belong to the genera Candida , Aspergillus , Penicillium , Mucor , Geotrichum, Fusarium, and Trichosporon. In vitro studies with some of these fungi were dedicated to bioremediation of soils, synthesis of natural products, and synthesis of drug metabolites of different substrates and showed that fungi may catalyze typical mammalian phase I as well as some phase II metabolic reactions .…”

“…, Fusarium solani, Geotrichum candidum, Mucor circinelloides, Mucor hiemalis, Mucor plumbeus, Mucor racemosus, Penicillium rubens, Penicillium crustosum, Rhodotorula mucilaginosa, Trichoderma harzianum, Trichoderma sp. (section: longibrachiatum), and Trichosporon asahii have previously been isolated from post‐mortem material in decomposition stage and identified as described in part I of this communication . All the fungal strains were grown on Sabouraud agar plates (glucose 1%) at 25 °C and transferred to fresh plates every month.…”

“…In Part I of this communication, the isolation and identification of 156 fungal strains from authentic post‐mortem material in the stage of decomposition was described . The aim of this second part was to evaluate the capability of these strains to metabolize drugs in vitro .…”

“…In Part I of this communication, the isolation and identification of 156 fungal strains from authentic post-mortem material in the stage of decomposition was described. [17] The aim of this second part was to evaluate the capability of these strains to metabolize drugs in vitro. The experiments were performed employing our previously described approach for studying in vitro fungal metabolism using incubation experiments with five model drugs followed by gas chromatography-mass spectrometry (GC-MS) or liquid chromatography-tandem mass spectrometry (LC-MS/MS)-based analysis and interpretation of mass spectral data.…”

The evolutionary logic of sepsis

“…At the same time, Candida species constitute the most frequent agents of fungal-related human mortality (Pfaller and Diekema, 2007), being the 4th leading cause of nosocomial bloodstream infection in the United States (accounting for 8-10% of all such infections acquired in hospitals) (Wisplinghoff et al, 2004). Remarkably, such Candida species are also the most frequently isolated fungal saprobes in human cadavers (Martínez-Ramírez et al, 2013).…”