Characterization of house fly microbiota and antibiotic resistant bacterial species they are harbourin

Abstract

Housefly (Musca domestica L.) is an insect belonging to the order Diptera, family Muscidae. This insect can frequently carry bacteria in their digestive tract or on the body surface. Accurate identification of houseflies is an essential factor for both epidemiological studies and the precise formulation of vector control strategies. Thus, numerous publications have reported on pathogenic bacteria including those of antimicrobial resistant isolated from housefly samples. Houseflies are highly mobile and can spread pathogenic bacteria by mechanical contact with the substrates and the habitat of houseflies harbours a diverse microbial community. The rapid adaptation process of ingested microbes in the insect gut may involve gene transfer including antibiotic resistant determinants among different bacterial strains. Hence, the aim of this study was to determine the occurrence and characterize houseflies sampled from the hospices and to detect microbial pathogens together with their associated resistant genes of medical and veterinary importance that they are harbouring.A systemic review and meta-analysis were conducted using published articles from 1980 to 2020 retrieved from electronic databases assessed for eligibility according to Preferred Reporting Items for Systemic Reviews and Meta-Analysis guidelines. Seventy-eight studies were included in the review with only 44 studies eligible for meta-analysis with only five pathogenic bacterial species including Escherichia coli, Enterococcus faecium, Klebsiella pneumoniae, Pseudomonas aeruginosa and Staphylococcus aureus being focused on for meta-analysis. Houseflies collected from hospices were identified using published species identification keys to confirm the observed features and to supplement the morphological observation, PCR targeting the 16S rRNA, CO1 and ITS2 genes were conducted to identify and characterize houseflies to species level. The bacterial communities harboured by houseflies were determined using NGS platform, whilst the antibiotic resistance and virulence genes from microbial communities associated with houseflies were detected by PCR assays.The systematic review revealed that houseflies carried a considerable number of susceptible and antibiotic-resistant bacteria, including multiple-antibiotic resistant strains. Majority of studies have used culture methods for the detection of bacteria from houseflies. A total of ii 657 houseflies were collected comprising of 306 (46.6%), 258 (39.3%) and 93 (14.2%) fromSparrow hospice, Lebone hospice, and from Sunflower hospice respectively. The morphological identification of houseflies was successful and further supported by amplification of 16S rRNA, CO1 as well as ITS2 gene fragments. Generated sequences for the targeted gene fragments matched with Musca domestica and all sequences were deposited to the GenBank database. The microbiota composition at the phylum, class, order and genus level were assessed. The most abundant phyla detected were Proteobacteria, followed by Firmicutes and Bacteroidetes. Multiple species of bacteria were identified to genus level present in some housefly samples from some hospices. The samples from Lebone and Sparrow hospice were significantly more diverse as compared to those from Sunflower hospice. The tested housefly samples shared some of the bacterial species, if not all. Antibiotic resistant genes detected from the housefly DNA in this study included ermB, tetA, blaSHV and blaTEM genes associated to resistance for erythromycin, tetracycline, and beta-lactams antibiotics, respectively. There were no virulence genes detected for the selected bacterial pathogens from housefly samples in all three hospices investigated. The systematic review and meta-analysis have provided global overview on the carriage of considerable bacterial pathogens including antibiotic resistant bacteria detected in houseflies from different regions of the world. The identification of housefly by morphological and molecular identification in this study, confirmed the importance of considering both techniques for identification of houseflies. The application of DNA barcoding can delineate the limitations between species and allocate taxonomic status to unidentified species from known species. Generated data from this study showed that houseflies collected from different hospices are associated with highly diverse microbial communities and some with antibiotic resistant genes detected. As such, this insect poses tremendous health risk in hospices and surrounding communities since they are potential vector of pathogenic microorganisms. It is recommended that there should be formulation of vector control strategy to ensure that houseflies are controlled both inside and outside the hospice facility. There should be continuous education on the proper use of antibiotics especially at the human care centres. Furthermore, there is need to do further researcher for genotyping the bacteria of medical importance carried by the hospice houseflies