Emergence of ehrlichiosis by a new tick-borne Ehrlichia species in China.

OBJECTIVES: From March to June 2021, the reported number of clinically diagnosed endemic typhus in Anhui and Hubei provinces of China nearly increased four-fold compared with the monthly average numbers in last 5 years. An etiological and epidemiological investigation was initiated. METHODS: The clinical specimens from the reported patients and the potential vector ticks were collected for molecular and serological detection, as well as cell culturing assay to identify the potential pathogen. RESULTS: Polymerase chain reaction and sequence analysis of rrs and groEL showed that the pathogen from these patients was Ehrlichia sp., isolated from Haemaphysalis longicornis attached to these patients. The phylogenetic analysis based on 39 Ehrlichia genomes suggested that it should be taxonomically classified as a novel species, tentatively named "Candidatus Ehrlichia erythraense". A total of 19 of 106 cases were confirmed as Candidatus Ehrlichia erythraense infections by polymerase chain reaction, sequencing, and/or serological tests. The most frequent symptoms were fever (100%), rashes (100%), asthenia (100%), anorexia (100%), and myalgia (79%). CONCLUSION: The occurrence of the disease presenting with fever and rashes in Anhui and Hubei provinces was caused by a novel species of the genus Ehrlichia; physicians need to be aware of this newly-discovered pathogen to ensure appropriate testing, treatment, and regional surveillance.

Flaviflexus equikiangi sp. nov. isolated from faeces of Equus kiang (Tibetan wild ass) and carrying a class 1 integron gene cassette in its genome.

Two Gram-stain-positive, catalase-negative, non-spore-forming, cocci-shaped strains (dk850T and JY899) were isolated from the feces of Equus kiang in the Qinghai-Tibet Plateau of China. 16S rRNA gene sequence-based phylogenetic analyses showed that strains dk850T and JY899 belong to the genus Flaviflexus, closest to F. salsibiostraticola KCTC 33148T, F. ciconiae KCTC 49253T and F. huanghaiensis H5T. The DNA G + C content of strain dk850T was 62.9%. The digital DNA-DNA hybridization values of strain dk850T with the closely related species were below the 70% threshold for species demarcation. The two strains grew best at 28°C on brain heart infusion (BHI) agar with 5% sheep blood. All strains had C18:1ω9c and C16:0 as the major cellular fatty acids. MK-9(H4) was the major menaquinone in strain dk850T. The major polar lipids included diphosphatidylglycerol and an unidentified phospholipid. Strains dk850T and JY899 were identified as carrying a class 1 integron containing the aminoglycoside resistance gene aadA11, both strains were resistant to spectinomycin and streptomycin. Based on several lines of evidence from phenotypic and phylogenetic analyses, strains dk850T and JY899 represent a novel species of the genus Flaviflexus, for which the name Flaviflexus equikiangi sp. nov. is proposed. The type strain is dk850T(= CGMCC 1.16593T = JCM 33598T).

Mycolicibacterium baixiangningiae sp. nov. and Mycolicibacterium mengxianglii sp. nov., two new rapidly growing mycobacterial species.

Four bacterial strains (LJ126T/S18 and Z-34T/S20) recovered from faecal samples of Tibetan antelopes on the Qinghai-Tibet Plateau of China were analysed using a polyphasic approach. All four isolates were aerobic, short rod-shaped, non-motile, Gram-stain-positive, acid-fast and fast-growing. Phylogenetic analyses based upon 16S rRNA and whole-genome sequences showed that the two pair of strains formed two distinct branches within the evolutionary radiation of the genus Mycolicibacterium. Strains LJ126T/S18 and Z-34T/S20 were most closely related to Mycolicibacterium austroafricanum CCUG 37667T, Mycobacterium aurum NCTC 10437T, Mycobacterium pyrenivorans DSM 44605T, Mycobacterium monacense JCM 15658T, Mycolicibacterium sarraceniae JCM 30395T, Mycolicibacterium tokaiense JCM 6373T and Mycobacterium murale JCM 13392T, but readily distinguished from the known species by a combination of chemotaxonomic and phenotypic features and by low average nucleotide identity values (74.4-84.9 %). Consequently, the two strain pairs are considered to represent different novel species of Mycolicibacterium for which the names Mycolicibacterium baixiangningiae sp. nov. and Mycolicibacterium mengxianglii sp. nov. are proposed, with LJ126T (=CGMCC 1.1992T=KCTC 49535T) and Z-34T (=CGMCC 1.1993T=DSM 106172T) as the respective type strains.