ABSTRACT
Three Gram-stain-positive, catalase-negative, α-haemolytic, chain-forming and coccus-shaped microorganisms (strains Z15T, Z1 and Z2) were isolated from feces of Tibetan antelopes collected from the Qinghai-Tibet plateau, PR China. The results of 16S rRNA gene sequence studies indicated that Z15T shared 94.5, 93.1 and 92.2â% similarity with Streptococcus pantholopis DSM 102135T, Streptococcus ursoris NUM 1615T and Streptococcus dentapri NUM 1529T, respectively. rpoB and groEL-based sequence analysis of our three novel isolates revealed interspecies divergence of 16.7 and 14.3â% from Streptococcus pantholopis DSM 102135T. The genomic DNA G+C content of Z15T is 42.48 mol%. Z15T has an average nucleotide identity (ANI) value of 81.19â% with S. pantholopis DSM 102135T and a DNA-DNA relatedness value of less than 70â% in the in-silico DNA-DNA hybridization (isDDH) with other species of genus Streptococcus deposited in the GenBank database. A whole-genome phylogenetic tree based on 246 core genes of 78 genomes of members of the genus Streptococcusindicated that Z15T represents a member of genus Streptococcus but one well separated from the currently recognized species. Z15T contains C18â:â1ω7c (25.5â%), C18â:â1ω9c (19.6â%), C16â:â0 (17.5â%) and C16â:â1ω9c (13.3â%) as its major cellular fatty acids. According to the morphological, biochemical and molecular phylogenetic features of the three novel isolates, they represent a novel species of the genus Streptococcus, and Streptococcus chenjunshii sp. nov. is thus proposed. The type strain is Z15T (=CGMCC 1.16529=DSM 106182).
Subject(s)
Antelopes/microbiology , Phylogeny , Streptococcus/classification , Animals , Bacterial Typing Techniques , Base Composition , DNA, Bacterial/genetics , Fatty Acids/chemistry , Feces/microbiology , Genes, Bacterial , Nucleic Acid Hybridization , RNA, Ribosomal, 16S/genetics , Sequence Analysis, DNA , Streptococcus/isolation & purification , TibetABSTRACT
OBJECTIVE: This study aimed to evaluate the genetic diversity, virulence, and antimicrobial resistance of Aeromonas isolates from clinical patients, tap water systems, and food. METHODS: Ninety Aeromonas isolates were obtained from Ma'anshan, Anhui province, China, and subjected to multi-locus sequence typing (MLST) with six housekeeping genes. Their taxonomy was investigated using concatenated gyrB-cpn60 sequences, while their resistance to 12 antibiotics was evaluated. Ten putative virulence factors and several resistance genes were identified by PCR and sequencing. RESULTS: The 90 Aeromonas isolates were divided into 84 sequence types, 80 of which were novel, indicating high genetic diversity. The Aeromonas isolates were classified into eight different species. PCR assays identified virulence genes in the isolates, with the enterotoxin and hemolysin genes act, aerA, alt, and ast found in 47 (52.2%), 13 (14.4%), 22 (24.4%), and 12 (13.3%) of the isolates, respectively. The majority of the isolates (≥ 90%) were susceptible to aztreonam, imipenem, cefepime, chloramphenicol, gentamicin, tetracycline, and ciprofloxacin. However, several resistance genes were detected in the isolates, as well as a new mcr-3 variant. CONCLUSIONS: Sequence type, virulence properties, and antibiotic resistance vary in Aeromonas isolates from clinical patients, tap water systems, and food.
Subject(s)
Aeromonas , Drinking Water/microbiology , Drug Resistance, Bacterial , Food Microbiology , Genetic Variation , Gram-Negative Bacterial Infections/microbiology , Aeromonas/drug effects , Aeromonas/genetics , Aeromonas/isolation & purification , Aeromonas/pathogenicity , Anti-Bacterial Agents/pharmacology , China , Species Specificity , VirulenceABSTRACT
OBJECTIVE: To establish a database and to understand the molecular epidemiological features of non-O157 Shiga toxin-producing Escherichia coli (STEC) isolates from different animal reservoirs and patients. METHODS: Pulsed-field gel electrophoresis (PFGE) was performed according to the PulseNet protocol with minor modifications. A dendrogram was constructed using the BioNumerics. RESULTS: Under the PulseNet protocol, 62 PFGE patterns were obtained from 76 non-O157 STEC isolates and then divided into A to M groups. Isolates from different sources were widely distributed in different groups, but were predominant seen in certain groups. CONCLUSION: The non-O157 STEC isolates in China were highly polymorphic. PulseNet protocol seemed to be suitable for the typing of Chinese non-O157 STEC isolates.