Comparison of microbiota, antimicrobial resistance genes and mobile genetic elements in flies and the feces of sympatric animals

Abstract

Flies are well-known vectors of bacterial pathogens, but there are little data on their role in spreading microbial community and antimicrobial resistance. In this study, we compared the bacterial community, antimicrobial resistance genes (ARGs) and mobile genetic elements (MGEs) in flies with those in the feces of sympatric animals. A 16S rRNA-based microbial analysis identified 23 bacterial phyla in fecal samples and 25 phyla in flies; all the phyla identified in the fecal samples were also found in the flies. Bray–Curtis dissimilarity analysis showed that the microbiota of the flies were more similar to the microbiota of the feces of their sympatric animals than those of the feces from the three other animal species studied. The qPCR array amplified 276 ARGs/MGEs in fecal samples, and 216 ARGs/MGEs in the flies, while 198 of these genes were identified in both flies and feces. Long-term studies with larger sample numbers from more geospatially distinct populations and infection trials are indicated to further evaluate the possibility of flies as sentinels for antimicrobial resistance.

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

“…This aspect is very important, since it is known that the insect presence can have an influence on the microbial composition of the feeding substrate. Concerning the blowfly’s ability to perform the microbiome exchange in and from the living environment, carrying and transmitting pathogens, was demonstrated by the same microbial patterns identified both in flies and the feces of sympatric animals 9 . Additionally, during the decomposed tissue pre-digestion, blowflies secrete certain enzymes that have antimicrobial actions, thus having the potential to alter the microbial pattern of the substrate 36 , 57 .…”

“…Regarding the overall microbiome characterization, studies investigating the fly’s bacterial content showed that Proteobacteria, Firmicutes, Bacteroidetes and Actinobacteria prevailed in both blowfly and housefly life stages 9 , 13 , 46 , while another study 36 revealed that Flavobacteria dominated the pupa stage. Singh and collaborators research 36 showed that the microbiome pattern was specific and similar for the adult and larva stages, being characterized by Firmicutes with Lactobacillales, for the pupa being dominated by Proteobacteria with the greatest order and family diversity, and for the teneral stage prevailing Actinobacteria with Corynebacteriales.…”

“…Although a bacterial diversity delimitation, characteristic for certain stages of development could be emphasized, this was not reflected in the diversity dynamics of the liver samples, which were dominated by Firmicutes. Most studies revealed Gammaproteobacteria as the main class identified from the blowfly specimens 9 , 11 , 33 , 35 , with a relative abundance of up to 81% 11 . Furthermore, in Maleki-Ravasan et al 11 Morganellaceae represented the most abundant family detected both by culture-dependent and independent methods, while in the current survey Lactobacillaceae dominated, along with Corynebacteriaceae.…”

“…Meanwhile, as flies feed and breed, they acquire a part of the microbiome of the living environment 8 . As such, blowflies that feed on decomposed human or animal remains are responsible for transmitting pathogens, most species being vectors for important bacteria, such as Streptococcus , Staphylococcus , and Clostridium 9 . Several studies emphasized the high dispersion ability of blowflies of spreading foodborne pathogens such as various Salmonella serotypes 10 , Escherichia coli 11 , Campylobacter species 12 , and Helicobacter pylori 13 .…”

“…At the opposite pole, several bacterial taxa such us Staphylococcus or Bacillus species 21 can inhibit the larval growth. In spite of a wealth of information on the vector capacity of flies 9 , very little is known about their role in the environmental bacterial spread, as well as in the bacterial transfer throughout the development cycle of various insect species. As microbes rely on insects for spatial and temporal dispersion, all pathogenic bacteria have many more opportunities to be transferred into the environment given the adults capacity of traveling long distances 7 .…”