Potential bacterial biomarkers for insect colonization in forensic cases: preliminary quantitative data on Wohlfahrtiimonas chitiniclastica and Ignatzschineria indica dynamics

Abstract

For the last decades, forensic microbiology became an emerging complementary tool in criminalistics. Although the insect-microbe interactions regarding pathogen transmission were extensively studied, only scarce information is available on bacterial transfer from necrophagous insects to host tissues. Our data provides the first report on the occurrence of Wohlfahrtiimonas chitiniclastica and Ignatzschineria indica in Lucilia illustris Meigen, 1826 (Diptera: Calliphoridae), and the quantitative dynamics of the two bacterial species along the insect life-stages and transfer to beef and pork host tissues using qPCR gyrase b specific primers. The content of both bacterial species increased along the insect life stages. W. chitiniclastica was detected in all developmental stages independent of the feeding substrate. I. indica was measurable with 102 gene copies ng−1 DNA threshold starting from the third instar larvae when feeding on beef, and from the egg stage with a 102× higher representation when using the pork substrate. The transfer of bacterial species to both tissues occurred after 3 colonization days except for I. indica that was visible in beef liver only during day 5. Considering the utilization of pork tissues as human analogues, these quantitative microbial dynamics data provides first insect-specific bacterial candidates as potential colonization biomarkers in forensic investigations.

Shifting microbiomes complement life stage transitions and diet of the bird parasite Philornis downsi from the Galapagos Islands

“…This genus of bacteria is known from hematophagous flies other than P . downsi and is associated with maggots and maggot‐infested wounds (Toth et al ., 2001; Tsang et al ., 2018), adult flies feeding on wounds, and carcasses (Gupta et al ., 2011; Wei et al ., 2014b; Singh et al ., 2015; DeBruyn and Hauther, 2017; Deguenon et al ., 2019; Iancu et al ., 2020). Moreover, Ignatzschineria takes about 5 days to establish in infected tissues (Iancu et al ., 2020) and produces dimethyldisulfide ‐ one of the signature compounds of decomposition of corpses and blood by bacteria (Umber et al ., 2013; Cernosek et al ., 2020).…”

“…This genus of bacteria is known from hematophagous flies other than P. downsi and is associated with maggots and maggot-infested wounds (Toth et al, 2001;Tsang et al, 2018), adult flies feeding on wounds, and carcasses (Gupta et al, 2011;Wei et al, 2014b;Singh et al, 2015;DeBruyn and Hauther, 2017;Deguenon et al, 2019;Iancu et al, 2020). Moreover, Ignatzschineria takes about 5 days to establish in infected tissues (Iancu et al, 2020) and produces dimethyldisulfide -one of the signature compounds of decomposition of corpses and blood by bacteria (Umber et al, 2013;Cernosek et al, 2020). Accordingly, the specific detection of Ignatzschineria in laboratory-reared larvae may be associated with the deterioration of the larval diet and suggests that fresh blood is advantageous for the larvae over the defibrinated blood stored at 4 C. Our previous study identified the rare occurrence of Ignatzschineria in field-collected larvae, possibly feeding on infected nestling wounds (Ben-Yosef et al, 2017) or dead nestlings (O'Connor et al, 2010).…”

Microbiome pattern of Lucilia sericata (Meigen) (Diptera: Calliphoridae) and feeding substrate in the presence of the foodborne pathogen Salmonella enterica

“…During the last decade, forensic microbiology studies were initiated in search of microbial patterns useful for the PMI estimation 23 – 25 . These studies targeted the microbiome associated with the decomposition of human remains 26 , 27 , swine and mouse carcasses 28 – 30 , different decayed organs 31 , 32 , and different necrophagous insect species life stages 11 , 33 , 34 . Investigations of both cultured and uncultured bacterial communities showed similar dynamics patterns in animal and humans 27 , revealing the importance of using animal models in this field.…”

Myiasis absent Wohlfahrtiimonas chitiniclastica bacteremia in a lung cancer patient: a case report

“…The name of the germ refers to the strong chitinase activity described by Tòth et al [ 1 ]. The germ is used as biomarker in forensic cases [ 2 ]. In human 13 cases of human infection have been published yet including the first case of Wohlfahrtiimonas chitiniclastica bacteremia in continental United States derived from infection of open chronic wound associated with poor care and hygiene [ 3 , 4 ].…”