Hospital infestation by the cluster fly, Pollenia rudis sensu stricto Fabricius 1794 (Diptera: Calliphoridae), and its possible role in transmission of bacterial pathogens in Germany

A survey of Wolbachia infection in brachyceran flies from Iran

Wolbachia is a maternally inherited intracellular bacterium that is considered to be the most plentiful endosymbiont found in arthropods. It reproductively manipulates its host to increase the chances of being transmitted to the insect progeny; and it is currently used as a means of suppressing disease vector populations or controlling vector-borne diseases. Studies of the dissemination and prevalence of Wolbachia among its arthropod hosts are important for its possible use as a biological control agent. The molecular identification of Wolbachia relies on different primers sets due to Wolbachia strain variation. Here, we screened for the presence of Wolbachia in a broad range of Brachycera fly species (Diptera), collected from different regions of Iran, using nine genetic markers (wsp, ftsZ, fbpA, gatB, CoxA, gltA, GroEL dnaA, and 16s rRNA), for detecting, assessing the sensitivity of primers for detection, and phylogeny of this bacterium. The overall incidence of Wolbachia among 22 species from six families was 27.3%. The most commonly positive fly species were Pollenia sp. and Hydrotaea armipes. However, the bacterium was not found in the most medically important flies or in potential human disease vectors, including Musca domestica, Sarcophaga spp., Calliphora vicinia, Lucilia sericata, and Chrysomya albiceps. The primer sets of 16s rRNA with 53.0% and gatB with 52.0% were the most sensitive primers for detecting Wolbachia. Blast search, phylogenetic, and MLST analysis of the different locus sequences of Wolbachia show that all the six distantly related fly species likely belonging to supergroup A. Our study showed some primer sets generated false negatives in many of the samples, emphasizing the importance of using different loci in detecting Wolbachia. The study provides the groundwork for future studies of a Wolbachia-based program for control of flies.

How to prove neglect in the context of the post-mortem examination

Understanding the causes, extent, and period of neglect is not only a medical but also a forensic task when it comes to legal investigations. In this study, we evaluated 46 autopsied cases where there was clear evidence of physical neglect during the last period of the deceased's life. The age of the deceased ranged from 21 to 96 years; most of them were female (71.7%). The majority of cases (89.9%) took place in a domestic environment, with partners or relatives providing care. The most frequent post-mortem findings were pressure sores, followed by inflammatory skin changes, and signs of malnutrition and dehydration. Neglect was the cause or co-cause of death in 23% of the cases. More than half of the deceased showed severe contamination of the skin surface by excrement, and in almost 40% of the cases, fly infestation was found. The majority of insects belonged to the group of house flies (Diptera: Muscidae), mainly the common house fly, Musca domestica. By analyzing the entomological evidence, it was possible to prove an insect infestation period of at least several days ante-mortem. Since the period of neglect may be relevant in terms of legal proceedings, the present work demonstrates the particular importance of insect traces in providing this evidence. While prosecution and conviction of caregivers remain challenging, it is all the more essential that entomology and legal medicine collaborate on the analysis of findings of neglect.

Versatility of Stenotrophomonas maltophilia: Ecological roles of RND efflux pumps

S. maltophilia is a widely distributed bacterium found in natural, anthropized and clinical environments. The genome of this opportunistic pathogen of environmental origin includes a large number of genes encoding RND efflux pumps independently of the clinical or environmental origin of the strains. These pumps have been historically associated with the uptake of antibiotics and clinically relevant molecules because they confer resistance to many antibiotics. However, considering the environmental origin of S. maltophilia, the ecological role of these pumps needs to be clarified. RND efflux systems are highly conserved within bacteria and encountered both in pathogenic and non-pathogenic species. Moreover, their evolutionary origin, conservation and multiple copies in bacterial genomes suggest a primordial role in cellular functions and environmental adaptation. This review is aimed at elucidating the ecological role of S. maltophilia RND efflux pumps in the environmental context and providing an exhaustive description of the environmental niches of S. maltophilia. By looking at the substrates and functions of the pumps, we propose different involvements and roles according to the adaptation of the bacterium to various niches. We highlight that i°) regulatory mechanisms and inducer molecules help to understand the conditions leading to their expression, and ii°) association and functional redundancy of RND pumps and other efflux systems demonstrate their complex role within S. maltophilia cells. These observations emphasize that RND efflux pumps play a role in the versatility of S. maltophilia.

Molecular identification of the potentially forensically relevant cluster flies Pollenia rudis (Fabricius) and Pollenia vagabunda (Meigen) (Diptera: Polleniidae) — non-recorded species in Algeria

Cluster flies are represented by the genus Pollenia Robineau-Desvoidy, 1830 of the family Polleniidae Brauer and Bergenstamm, 1889. Their larvae are known to be internal parasites or predators of earthworms. Herein, we report for the first time the occurrence of the cluster flies Pollenia rudis Fabricius, 1794 and Pollenia vagabunda (Meigen, 1826) (Diptera: Polleniidae) on carcasses in Algeria and identify them through DNA barcoding. A region of the mitochondrial cytochrome c oxidase I gene (COI) was amplified and sequenced. Genetic distances were determined. A phylogenetic tree was constructed with the maximum parsimony method using 10 000 bootstrap replicates. A total number of 157 adults of P. rudis were collected together with 325 adults of Pollenia vagabunda. The occurrence of Pollenia on animal carcasses does not seem to be correlated with a particular stage of decomposition. All the sequences were correctly identified using the BLASTn tool from the GenBank database and the BOLD identification engine. Intra- and interspecific sequence divergence values were less than 1% and greater than 3%, respectively. COI barcodes obtained from this study were robust enough to identify and distinguish unambiguously between P. rudis and P. vagabunda. In the tree-based analysis, the cluster flies were all assigned to their respective species separately from each other confirming the morphological identification. These results provide DNA barcodes that contribute to the growth of reference databases and allow fast and accurate identification.

An Examination of Flying Insects in Seven Hospitals in the United Kingdom and Carriage of Bacteria by True Flies (Diptera: Calliphoridae, Dolichopodidae, Fanniidae, Muscidae, Phoridae, Psychodidae, Sphaeroceridae)

Insects are efficient vectors of bacteria and in the hospital environment may have a role in spreading nosocomial infections. This study sampled the flying insect populations of seven hospitals in the United Kingdom and characterized the associated culturome of Diptera, including the antibiotic resistance profile of bacterial isolates. Flying insects were collected in seven U.K. hospitals between the period March 2010 to August 2011. The bacteria carried by Diptera were isolated using culture-based techniques, identified and characterized by antimicrobial susceptibility testing. A total of 19,937 individual insects were collected with Diptera being the most abundant (73.6% of the total), followed by Hemiptera (13.9%), Hymenoptera (4.7%), Lepidoptera (2.9%), and Coleoptera (2%). From Diptera, 82 bacterial strains were identified. The majority of bacteria belonged to the Enterobacteriaceae (42%), followed by Bacillus spp. (24%) and Staphylococcus spp. (19%). Less abundant were bacteria of the genus Clostridium (6%), Streptococcus (5%), and Micrococcus (2%). A total of 68 bacterial strains were characterized for their antibiotic resistance profile; 52.9% demonstrated a resistant phenotype to at least one class of antibiotic. Staphylococcus spp. represented the highest proportion of resistant strains (83.3%), followed by Bacillus spp. (60%) and Enterobacteriaceae (31.3%). Diptera were the predominant flying insects present in the U.K. hospital environments sampled and found to harbor a variety of opportunistic human pathogens with associated antimicrobial resistance profiles. Given the ability of flies to act as mechanical vectors of bacteria, they present a potential to contribute to persistence and spread of antimicrobial-resistant pathogenic bacteria in the hospital environment.

Population and temperature effects on Lucilia sericata (Diptera: Calliphoridae) body size and minimum development time

Understanding how ecological conditions influence physiological responses is fundamental to forensic entomology. When determining the minimum postmortem interval with blow fly evidence in forensic investigations, using a reliable and accurate model of development is integral. Many published studies vary in results, source populations, and experimental designs. Accordingly, disentangling genetic causes of developmental variation from environmental causes is difficult. This study determined the minimum time of development and pupal sizes of three populations of Lucilia sericata Meigen (Diptera: Calliphoridae; from California, Michigan, and West Virginia) at two temperatures (20 degrees C and 33.5 degrees C). Development times differed significantly between strain and temperature. In addition, California pupae were the largest and fastest developing at 20 degrees C, but at 33.5 degrees C, though they still maintained their rank in size among the three populations, they were the slowest to develop. These results indicate a need to account for genetic differences in development, and genetic variation in environmental responses, when estimating a postmortem interval with entomological data.