Bacterial community diversity in Dermatophagoides farinae using high-throughput sequencing / 中国血吸虫病防治杂志

Objective To investigate the bacterial community diversity in Dermatophagoides farinae. Methods Laboratory-cultured D. farinae was collected, and the composition of microbial communities was determined by sequence analyses of the V4 region in the bacterial 16S ribosomal RNA (16S rRNA) gene on an Illumina PE250 high-throughput sequencing platform. Following quality control and filtering of the raw sequence files, valid reads were obtained and subjected to operational taxonomic units (OTU) clustering and analysis of the composition of microbial communities and alpha diversity index using the Usearch software, Silva database, and Mothur software. Results A total of 187 616 valid reads were obtained, and 469 OTUs were clustered based on a sequence similarity of more than 97%. OTU annotation showed that the bacteria in D. farinae belonged to 26 phyla, 43 classes, 100 orders, 167 families and 284 genera. The bacteria in D. farinae were mainly annotated to five phyla of Proteobacteria, Firmicutes, Bacteroidota, Actinobacteriota, and Acidobacteriota, with Proteobacteria as the dominant phylum, and mainly annotated to five dominant genera of Ralstonia, norank-f-Mitochondria, Staphylococcus and Sphingomonas, with Wolbachia identified in the non-dominant genus. Conclusions A high diversity is identified in the composition of the bacterial community in D. farinae, and there are differences in bacterial community diversity and abundance among D. farinae.

DNA barcoding of 4 species of cheyletid mites based on COI and 18S rRNA gene sequences / 中国血吸虫病防治杂志

Objective To analyze the sequences of mitochondrial cytochrome C oxidase subunit I gene (COI) and 18S ribosomal RNA gene (18S rRNA), so as to identify the feasible DNA barcodes for 4 species of cheyletid mites and improve the DNA barcoding database for cheyletid mites. Methods Cheyletid mite samples were collected from small-scale flour mills in Fuyang, Wuhu and Tongling cities of Anhui Province from May 2018 to July 2019, extracted and morphologically identified. Then, genomic DNA was extracted from a single cheyletid mite, and the COI and 18S rRNA gene sequences were obtained by PCR amplification, cloning and sequencing. The obtained sequences were aligned using the BLAST software. Multiple sequence alignment was done using the software ClustalX version 1.83 using the known gene sequences from cheyletid mites. The genetic distance was calculated using the software MEGA X, and the phylogenetic tree was created using the maximum likelihood method. Results The DNA barcoding results of Cheyletus malaccensis, C. carnifex and Cheletomorpha lepidopterorum were consistent with the morphological identification, while no sequences pertaining to Eucheyletia reticulate were retrieved in the GenBank database. The proportions of A + T were 69.6% and 55.1% in the COI and 18S rRNA sequences of 4 cheyletid mites species, respectively, and the numbers of base substitutions were 137 and 46, respectively. There were 154 to 321 and 58 to 99 inter-species variation loci in the COI and 18S rRNA gene sequences of 4 cheyletid mites species, respectively, and the intra-species genetic distance was all 0.020 or less in the COI and 18S rRNA gene sequences of 4 cheyletid mites species, with inter-species genetic distance of 0.235 to 0.583 and 0.078 to 0.114, respectively. Phylogenetic analysis based on COI and 18S rRNA genes showed that all four species of cheyletid mites were clustered into a branch with a 100% supportive rate, which was consistent with the morphological identification. Conclusion Mitochondrial COI gene is superior to 18S rRNA gene as DNA barcodes for 4 species of cheyletid mites, which is more suitable to be used to investigate the phylogenetic relationship of at genus and species levels.

Human skin infestation caused by Haemolaelaps casalis: a case report / 中国血吸虫病防治杂志

Our study reports a case of acarodermatitis caused by Haemolaelaps casalis. By morphological observations, the mites seized were identified as Haemolaelaps casalis (deutonymph) which could attack humans resulting in acarodermatitis characterized with the symptoms of papules and blisters in different degrees. The patient was treated with 15% calamine lotion and anti-inflammatory and antipruritic drugs. Meanwhile, the mites were eliminated in the bedroom. After the treatment for one week, the patient was cured. Haemolaelaps casalis, which had been found in the indoor mattress, could attack humans and cause acarodermatitis. We should strengthen the work of anti-mite in domestic environment.