Isolation Of Streptococcus Pantholopis Sp. Nov. From Tibetan Antelope And Analysis Of Shiga Toxin-producing Escherichia Coli Among Wild And Domestic Animals In China

Almost all of the new pathogens emerged to cause significant public health problems in recent years were from animals that lived in the special geographical and ecological environment. In this study, we focused on the finding of novel bacteria in the Tibetan antelope (Pantholops hodgsonii) in Qinghai-Tibetan plateau, China, and on the distribution and genetic ralatedeness of Shiga toxin-producing Escherichia coli (STEC) in wild animals in this very special ecological environments.Two bacterial strains were isolated from fecal samples of the Tibetan antelopes. Cells stain Gram-positive, are non-spore-forming cocci,0.4-0.7 μm in diameter and occur in pairs or short chains. Colonies on blood agar are small, raised, and adherent with irregular margins,0.75-1.00 mm in diameter and a-haemolytic at 37℃ for 48 h. Cells are facultatively anaerobic, catalase-negative and non-motile. Growth occurs at 22,30,37 and 42℃ but not at 4 or 15℃. Growth occurs in the presence of 3.5% NaCl but not in broth containing 4.5 or 6.5% NaCl. Comparative 16S rRNA gene sequencing studies confirmed that the organisms were members of the genus Streptococcus, but they did not correspond to any recognized species of the genus, being most closely related to Streptococcus ursoris NUM 1615T(93.4%16S rRNA gene sequence similarity). On the basis of their genotypic and phenotypic differences to other existing Streptococcus species, the two isolates represent a novel species of the genus Streptococcus, for which the name Streptococcuspanlholopis sp. nov. is proposed. The complete genome of the type strain TA 26T has been sequenced. The circular chromosome of TA26T comprises 2,241,302 bp with an overall G+C content of 42 mol%. The genome encompasses 2,251CDSs,66 tRNAs, and 15 rRNAs, with 5 copies each of 16S,23S, and 5S rRNA genes. It also contains 7 incomplete prophages. Digital DNA-DNA hybridization studies showed less than 70% DNA-DNA relatedness between strain TA 26T and other species of the genus Streptococcus deposited in GenBank database, supporting a novel species status of the strain. Several putative virulence-associated factors including PavA, an adherence factor associated with pneumococcal infections, and Hyaluronic acid capsule, a universal adhesin for attachment in genus Streptococcus were predicted in the genome, indicating the pathogenic potential of the novel Streptococcus pantholopis sp.We also investigated the distribution of the STEC in various wild animals including plateau pikas, Tibetan antelopes, marmota himalayana, yaks in Qinghai-Tibetan plateau, as well as domestic animals and raw meats in China. We found that STEC strains are widely distributed in all those animals in this study. The isolation rates of STEC in plateau pika, Tibetan antelope, marmota himalayana, cattle and raw meats are 1.97%,1.07%,2.47%,5.0% and 6.8% respectively. This study found that the wild animals in Qinghai-Tibetan plateau serve as important reservoir of STEC. We investigated the characteristics of STEC strains from plateau pikas by serotyping, virulence profiles analysis, antimicrobial susceptibility test, MLST and PFGE, finding that STEC strains from pikas were phenotypically and genetically diverse, and showed low pathogenic potential. STEC strains from plateau pika and yaks in the same geographical and ecological environment shared nine identical STs (ST40, ST297, ST737, ST906, ST1001, ST3686, ST3692, ST3883. ST3884). the same predominated serotype O2:H45, and similar virulence profiles, implying strains are widely transformed in different animals in this region. Based on MLST analysis between all animal-derived STEC strains isolated in this study with HUSEC collection and STEC of 026, O45,0103, O111, O121,0145 and 0157 serogroups, we found various animal-derived STEC isolates in this study including plateau pika, Tibetan antelope, marmota himalayana, yak, goat and raw meats shared same ST or showed close relationship with those human pathogenic strains, indicating those animal-derived STEC isolates may have the potential to cause human diseases, thus emphasizing the need to detect and monitor STEC in animals and meat in China.