High-throughput metagenome analysis of the Sarcoptes scabiei internal microbiota and in-situ identification of intestinal Streptomyces sp.

Abstract

Multiple parasitic arthropods of medical importance depend on symbiotic bacteria. While the link between scabies and secondary bacterial infections causing post infective complications of Group A streptococcal and staphylococcal pyoderma is increasingly recognized, very little is known about the microbiota of Sarcoptes scabiei . Here we analyze adult female mite and egg metagenome datasets. The majority of adult mite bacterial reads matched with Enterobacteriaceae (phylum Proteobacteria), followed by Corynebacteriaceae (phylum Actinobacteria). Klebsiella was the most dominant genus (78%) and Corynebacterium constituted 9% of the assigned sequences. Scabies mite eggs had a more diverse microbial composition with sequences from Proteobacteria being the most dominant (75%), while Actinobacteria, Bacteroidetes and Firmicutes accounted for 23% of the egg microbiome sequences. DNA sequences of a potential endosymbiont, namely Streptomyces , were identified in the metagenome sequence data of both life stages. The presence of Streptomyces was confirmed by conventional PCR. Digital droplet PCR indicated higher Streptomyces numbers in adult mites compared to eggs. Streptomyces were localized histologically in the scabies mite gut and faecal pellets by Fluorescent In Situ Hybridization (FISH). Streptomyces may have essential symbiotic roles in the scabies parasite intestinal system requiring further investigation.

Understanding the role of the Scabies mite microbiota in the development of novel control strategies

“…As previously mentioned, Corynebacterium was found to be associated with the mite internal microbiota [35]. Interestingly the in vivo study reflected this finding.…”

“…was associated with both, scabies eggs and mites [35]. In situ hybridization (FISH) clearly localised Streptomyces and Klebsiella to the mite guts and faeces, however, neither were detected within or on the surface of eggs [35]. This may tell us that Streptomyces and Klebsiella species dominate and are adapted to the mite intestinal environment.…”

“…The study by Swe et al, predicted through Kraken analysis, and confirmed by PCR, that Streptomyces sp. was associated with both, scabies eggs and mites [35]. In situ hybridization (FISH) clearly localised Streptomyces and Klebsiella to the mite guts and faeces, however, neither were detected within or on the surface of eggs [35].…”

“…Using this porcine scabies model, Swe et al isolated female mites and eggs from crusted skin lesions, washed them to remove external microorganisms, and extracted DNA. Illumina sequencing highlighted marked differences between the bacterial species present in the adult mites versus the eggs [35]. 89% of the adult female microbiome was comprised of the phylum Proteobacteria, with Klebsiella being the most abundant in this phylum at 78%.…”

“…It was suggested by Swe at el., that Streptomyces, as a known producer of enzymes that degrade complex carbohydrates, may assist in the digestion of skin and serum, which is the proposed nutrient source of Sarcoptes mites [39]. It is also possible that the presence of Streptomyces may inhibit unfavourable bacteria through the production of anti-microbial compounds, thus making it an important component of the mite gut microflora, and a potential therapeutic target [35].…”