ABSTRACT
Pure bacterial cultures were isolated from different tissues of moribund Megalobrama terminalis from a high mortality event that occurred at a farm in Foshan, China. Two isolates (F2 and F3) were identified as Streptococcus dysgalactiae subsp. dysgalactiae based on morphological and biochemical detection as well as molecular analysis. In brain heart infusion broth, the best growth conditions of isolate F3 were 35ºC, salinity 5 and pH 7. Furthermore, infection with isolate F3 (1.2 × 106 CFU/fish) led to the death of M. terminalis and zebrafish (Danio rerio). However, isolate F3 had no obvious pathogenicity to tilapia (GIFT, Oreochromis niloticus). When the water temperature was 29ºC, the corresponding mortality rates for zebrafish infected by isolate F3 were higher than those at 23ºC. Culture for 24 and 72 hr with isolate F3 resulted in the same mortality rates for zebrafish. The antimicrobial susceptibility assay revealed that isolate F3 was susceptible to ampicillin, florfenicol and several other antibiotics but resistant to nalidixic acid, streptomycin, sulfamethoxazole/trimethoprim, neomycin and amikacin. To our knowledge, this is the first report that S. dysgalactiae infected the subtropical freshwater fish M. terminalis, which indicates that this bacterium is a potential threat to subtropical freshwater fish.
Subject(s)
Cyprinidae , Fish Diseases/microbiology , Streptococcal Infections/veterinary , Streptococcus/physiology , Streptococcus/pathogenicity , Animals , Anti-Bacterial Agents/pharmacology , China , Cichlids , Drug Resistance, Bacterial , Phylogeny , Streptococcal Infections/microbiology , Streptococcus/classification , Streptococcus/drug effects , ZebrafishABSTRACT
<p><b>BACKGROUND</b>Rheumatoid arthritis (RA) is characterized by inflammation of the synovial membrane, leading to invasion of synovial tissue into the adjacent cartilage matrix with degradation of articular cartilage and bone as a consequence. Dickkopf-1 (DKK-1) and osteoprotegerin (OPG) have been demonstrated to be key molecules involved in bone erosion and bone remodeling. The aim of this study was to explore the potential role of DKK-1 and OPG in different stage of RA.</p><p><b>METHODS</b>The protein levels of DKK-1 and OPG were detected by ELISA. The serum samples were collected from 300 patients with RA and 60 healthy controls. Of which, 150 RA patients were defined as early RA (disease duration < or = 1 year), and other 150 RA patients were defined as longlasting RA (disease duration > or = 5 years). At the time of serum sampling, various clinical and laboratory parameters were assessed. The correlations of DKK-1 or OPG and clinical/laboratory parameters were analyzed.</p><p><b>RESULTS</b>The serum level of DKK-1 was elevated in patients with longstanding RA compared with healthy controls, while no significant difference was observed between the two groups in the level of OPG. In contrast, in early RA patients, the circulating OPG was elevated, while there was no significant difference between the two groups in expression of DKK-1. The serum DKK-1 was correlated with Sharp score and DAS28 in longstanding RA patients. In early RA, age was the only parameter that was significantly related to serum OPG.</p><p><b>CONCLUSIONS</b>There was a cross-talk between DKK-1 and OPG, which involved in bone destruction in RA. In different stage of RA, DKK-1 and OPG may play different roles in the pathogenesis of RA.</p>
