Molecular Epidemiology of Plasmid-Mediated Types 1 and 3 Fimbriae Associated with Biofilm Formation in Multidrug Resistant Escherichia coli from Diseased Food Animals in Guangdong, China.

Types 1 and 3 fimbriae in Enterobacteriaceae play versatile roles in bacterial physiology including attachment, invasion, cell motility as well as with biofilm formation and urinary tract infections. Herein, we investigated the prevalence and transmission of plasmid-mediated types 1 and 3 fimbriae from 1753 non-duplicate Enterobacteriaceae from diseased food Animals. We identified 123 (7.01%) strong biofilm producers and all was identified as E. coli. WGS analysis of 43 selected strong biofilm producers revealed that they harbored multiple ARGs, including ESBLs, PMQR and mcr-1. The gene clusters mrkABCDF and fimACDH encoding types 1 and 3 fimbriae, respectively, were identified among 43 (34.96%) and 7 (5.7%) of 123 strong biofilm isolates, respectively. These two operons were able to confer strong biofilm-forming ability to an E. coli weak-biofilm forming laboratory strain. Plasmid analysis revealed that mrk and fim operons were found to co-exist with ARGs and were primarily located on IncX1 and IncFII plasmids with similar backbones, respectively. mrkABCDF operons was present in all of 9457 Klebsiella pneumoniae using archived WGS data, and shared high homology to those on plasmids of 8 replicon types and chromosomes from 6 Enterobacteriaceae species from various origins and countries. In contrast, fimACDH operons was present in most of Enterobacter cloacae (62.15%), and shared high homology to those with only a small group of plasmids and Enterobacteriaceae species. This is the first comprehensive report of the prevalence, transmission and homology of plasmid-encoded type 1 and 3 fimbriae among the Enterobacteriaceae. Our findings indicated that plasmid-encoded mrkABCDF and fimACDH were major contributors to enhanced biofilm formation among E. coli and these two operons, in particular mrk could be as a potential anti-biofilm target. IMPORTANCE Biofilms allow bacteria to tolerate disinfectants and antimicrobials, as well as mammalian host defenses, and are therefore difficult to treat clinically. Most research concerning biofilm-related infections is typically focused on chromosomal biofilm-associated factors, including types 1 and 3 fimbriae of biofilm-forming Enterobacterium. However, the transmission and homology of the mobile types 1 and 3 fimbriae among Enterobacteriaceae is largely unknown. The findings revealed that the plasmid-encoded type 3 fimbriae encoded by mrkABCDF and type 1 fimbriae encoded by fimACDH were major contributors to enhancing biofilm formation among strong biofilm E. coli from diseased food producing animals. Additionally, mrk operon with high homology at an amino acid sequence was present both on plasmids of various replicon types and on chromosomes from diverse Enterobacteriaceae species from numerous origins and countries. These findings provide important information on the transmission of the mobile types 1 and 3 fimbriae among Enterobacteriaceae, indicating a potential antibiofilm target.

Phylogenomic analysis of Salmonella Indiana ST17, an emerging MDR clonal group in China.

OBJECTIVES: To reconstruct the genomic epidemiology and evolution of MDR Salmonella Indiana in China. METHODS: A total of 108 Salmonella Indiana strains were collected from humans and livestock in China. All isolates were subjected to WGS and antimicrobial susceptibility testing. Phylogenetic relationships and evolutionary analyses were conducted using WGS data from this study and the NCBI database. RESULTS: Almost all 108 Salmonella Indiana strains displayed the MDR phenotype. Importantly, 84 isolates possessed concurrent resistance to ciprofloxacin and cefotaxime. WGS analysis revealed that class 1 integrons on the chromosome and IncHI2 plasmids were the key vectors responsible for multiple antibiotic resistance gene (ARG) [including ESBL and plasmid-mediated quinolone resistance (PMQR) genes] transmission among Salmonella Indiana. The 108 Salmonella Indiana dataset displayed a relatively large core genome and ST17 was the predominant ST. Moreover, the global ST17 Salmonella Indiana strains could be divided into five distinct lineages, each of which was significantly associated with a geographical distribution. Genomic analysis revealed multiple antimicrobial resistance determinants and QRDR mutations in Chinese lineages, which almost did not occur in other global lineages. Using molecular clock analysis, we hypothesized that ST17 isolates have existed since 1956 and underwent a major population expansion from the 1980s to the 2000s and the genetic diversity started to decrease around 2011, probably due to geographical barriers, antimicrobial selective pressure and MDR, favouring the establishment of this prevalent multiple antibiotic-resistant lineage and local epidemics. CONCLUSIONS: This study revealed that adaptation to antimicrobial pressure was possibly pivotal in the recent evolutionary trajectory for the clonal spread of ST17 Salmonella Indiana in China.

Physiological and symbiotic variation of a long-term evolved Rhizobium strain under alkaline condition.

Physiological variation and adaptation of the long-term evolved rhizobia to alkaline environments where no host plant existence and the stability of their symbiotic properties when they are reinoculated to legume host remain unclear. A highly effective N2-fixing Rhizobium yanglingense strain CCBAU 01603 was used as the ancestral strain and was cultured continuously with/without addition of extra alkaline reagent (KOH) in laboratory conditions for approximately 500 generations. Total 60 evolved clones obtained were checked for their adaptation to higher alkaline pH level and inoculated to their host plant Caragana microphylla to evaluate their symbiotic efficiencies. Most of the evolved clones showed increased adaptation to higher alkaline pH but all of them decreased symbiotic efficiencies, resulting in the formation of irregular root nodules with lower nitrogenase activity, production of abnormal bacteroids, and accumulation more starch grains in uninfected nodule cells. Further demonstration of lower symbiotic efficiencies came from the down-regulated expression of genes related to nitrogen fixation in the bacteroids by transcriptome comparison. In addition, genes related to transporters and other diverse functions were up- or down-regulated in the evolved clones in free-living conditions (like yjiS gene) or in symbiotic situations, demonstrating the significant variations in cellular physiology and symbiosis. Our study revealed that the enhancement of alkaline adaptation but loss of symbiotic efficiencies of the evolved clones had happened during the long-term evolution in alkaline environments where no selective pressures from host plant, offering new insight into the molecular mechanism and direction of rhizobial evolution in nature.

Efficacy of S-1 vs capecitabine for the treatment of gastric cancer: a meta-analysis.

AIM: To rationally evaluate the effect of S-1 vs capecitabine for the treatment of gastric cancer. METHODS: MEDLINE, EMBASE, Cochrane Controlled Trials Register, Google Scholar, and China Journal Full Text Database were accessed to collect clinical randomized controlled trials regarding the effect of S-1 vs capecitabine for the treatment of gastric cancer patients. Statistical analysis was performed by meta-analysis. Four randomized controlled trials met the inclusion criteria. RESULTS: Compared with capecitabine regimens, the 1-year survival rate in gastric cancer patients was 0.80 (95%CI: 0.52-1.21, P = 0.29). The overall response rate of S-1 vs capecitabine was 0.94 (95%CI: 0.59-1.51, P = 0.93). Compared with capecitabine regimens, the most frequent hematologic toxicities were neutropenia (OR = 0.99, 95%CI: 0.65-1.49, P = 0.94) and thrombocytopenia (OR = 0.72, 95%CI: 0.31-1.67, P = 0.44). The most frequent non-hematologic toxicities included nausea (OR = 0.85, 95%CI: 0.56-1.28, P = 0.43) and hand-foot syndrome (OR = 0.16, 95%CI: 0.10-0.27, P < 0.00001). CONCLUSION: The existing studies suggest that S-1 is not more effective than capecitabine in the treatment of gastric cancer patients, but does exhibit less toxicity with regard to hand-foot syndrome.

[Optimize the preparation process of Erigeron breviscapus sustained-release pellets based on artificial neural network and particle swarm optimization algorithm].

OBJECTIVE: To optimize the preparation process of Erigeron breviscapus sustained-release pellets. METHODS: A mathematical model of relationship between the independent variables and dependent variable of the preparation process of Erigeron breviscapus sustained-release pellets was established by using back-propagation (BP) artificial neural networks (ANN), and the preparation process parameters were optimized with particle swarm optimization (PSO) algorithm. RESULTS: The pellets prepared according to the optimized preparation process parameters had significant effect of sustained-releasing. Drug release from the pellets was controlled by both diffusion and matrix corrosion. CONCLUSION: Combining BP ANN modeling with PSO algorithm provides an effective way to solve the multi-dimensional optimization problem of complicated nonlinear systems in pharmaceutical technology.

[Optimization of the matrix formulation of compound Die Da Zhen Tong cataplasm by uniform design].

OBJECTIVE: To optimize the matrix formulation of compound Die Da Zhen Tong cataplasm. METHODS: The optimal preparation was selected by U17 (17(16)) uniform design, independent variables were the percentage ratio of the matrix formulation component part in compound Die Da Zhen Tong cataplasm,and the viscosity, continued viscosity and overall desirability used as indexes were dependent variables. RESULTS: The percentage of the matrix formulation component part in compound Die Da Zhen Tong cataplasm was, NP-700: carbomer 980: PVP K-90: dihydroxy aluminum: tartaric: kaolinite: sorbitol: glycerin = 5: 1. 2: 2.5: 0.25: 0.15:4: 12: 5. CONCLUSION: The optimized cataplasm has good viscosity, continued viscosity and high overall desirability.

A tyrosine decarboxylase catalyzes the initial reaction of the salidroside biosynthesis pathway in Rhodiola sachalinensis.

Salidroside, the 8-O-ß-D-glucoside of tyrosol, is the main bioactive component of Rhodiola species and is found mainly in the plant roots. It is well known that glucosylation of tyrosol is the final step in the biosynthesis of salidroside; however, the biosynthetic pathway of tyrosol and its regulation are less well understood. A summary of the results of related studies revealed that the precursor of tyrosol might be tyramine, which is synthesized from tyrosine. In this study, a cDNA clone encoding tyrosine decarboxylase (TyrDC) was isolated from Rhodiola sachalinensis A. Bor using rapid amplification of cDNA ends. The resulting cDNA was designated RsTyrDC. RNA gel-blot analysis revealed that the predominant sites of expression in plants are the roots and high levels of transcripts are also found in callus tissue culture. Functional analysis revealed that tyrosine was best substrate of recombinant RsTyrDC. The over-expression of the sense-RsTyrDC resulted in a marked increase of tyrosol and salidroside content, but the levels of tyrosol and salidroside were 274 and 412%, respectively, lower in the antisense-RsTyrDC transformed lines than those in the controls. The data presented here provide in vitro and in vivo evidence that the RsTyrDC can regulate the tyrosol and salidroside biosynthesis, and the RsTyrDC is most likely to have an important function in the initial reaction of the salidroside biosynthesis pathway in R. sachalinensis.

Characterization of glycosyltransferases responsible for salidroside biosynthesis in Rhodiola sachalinensis.

Salidroside, the 8-O-ß-D-glucoside of tyrosol, is a novel adaptogenic drug extracted from the medicinal plant Rhodiola sachalinensis A. Bor. Due to the scarcity of R. sachalinensis and its low yield of salidroside, there is great interest in enhancing production of salidroside by biotechnological manipulations. In this study, two putative UDP-glycosyltransferase (UGT) cDNAs, UGT72B14 and UGT74R1, were isolated from roots and cultured cells of methyl jasmonate (MeJA)-treated R. sachalinensis, respectively. The level of sequence identity between their deduced amino acid sequences was ca. 20%. RNA gel-blot analysis established that UGT72B14 transcripts were more abundant in roots, and UGT74R1 was highly expressed in the calli, but not in roots. Functional analysis indicated that recombinant UGT72B14 had the highest level of activity for salidroside production, and that the catalytic efficiency (Vmax/Km) of UGT72B14 was 620% higher than that of UGT74R1. The salidroside contents of the UGT72B14 and UGT74R1 transgenic hairy root lines of R. sachalinensis were also ∼420% and ∼50% higher than the controls, respectively. UGT72B14 transcripts were mainly detected in roots, and UGT72B14 had the highest level of activity for salidroside production in vitro and in vivo.