[Virtual screen of effective AChE inhibitory constituents from Glycyrrhizae Radix et Rhizoma based on pharmacophore and molecular docking].

This research is to predict anti-Alzheimer's disease active constituents on the target of acetylcholinesterase(AChE) from Glycyrrhizae Radix et Rhizoma with the help of pharmacophore and molecular docking. AChE ligand-based pharmacophore model was set up and the molecular library of the constituents from Glycyrrhizae Radix et Rhizoma were established by collecting literature. Then the constituents from Glycyrrhizae Radix et Rhizoma were screen for the potential AChE inhibitory potency in silico through matching with the best pharmacophore model. The flexible docking was used to evaluate the interactions between compounds screened from pharmacophore model and AChE protein(PDB ID:4 EY7). The interactions were expressed including but not limited to CDOCKER interaction energy, hydrogen bonds and non-bonding interactions. The molecular library of Glycyrrhizae Radix et Rhizoma contains 44 chemical constituents. As for the pharmacophore model, six kinds of potential AChE inhibitory constituents from Glycyrrhizae Radix et Rhizoma were considered to be the promising compounds according to the results of searching 3 D database of pharmacophore model. The molecular docking was possessed and the interaction patterns were given to show the detail interactions. The compounds screening from the pharmacophore model were consistent with the existing studies to some degree, indicating that the virtual screen protocols of AChE inhibitory constituents from Glycyrrhizae Radix et Rhizoma based on pharmacophore and molecular docking was reliable.

[Nasopharyngeal carriage rate, antimicrobial resistance and serotype distribution of Streptococcus pneumoniae among children with upper respiratory infection].

OBJECTIVE: To investigate nasopharyngeal carriage rate, antimicrobial resistance and serotype distribution of Streptococcus pneumoniae among children with upper respiratory infection. METHODS: Nasopharygeal swabs were collected from children with upper respiratory infection visiting the outpatient department of Beijing Children's Hospital between March 2013 and February 2014. The antibiotic susceptibility was tested by Etest method, and the serotype was determined by Quellung reaction. RESULTS: The nasopharyngeal carriage rate for Streptococcus pneumoniae was 23.8% (699/2 941). One hundred isolates were randomly chosen for antimicrobial susceptiblity test and serotyping. Up to 98.0% isolates were susceptible to parenteral penicillin. The susceptible rate against oral penicillin, however, was 33.0%. The non-susceptible rate to erythromycin and azithromycin was 97.0%. The multi-drug resistance rate was up to 86.0%. The common serotypes were 6A(12.0%), 19F(12.0%), 6B(10.0%), 23F(9.0%) and 14(8.0%). The coverage rates of 7-, 10- and 13-valent pneumococcal conjugate vaccine were 41.0%, 42.0% and 59.0% respectively. CONCLUSIONS: About 25% of children with upper respiratory infection are nasopharyngeal colonized by Streptococcus pneumoniae. The isolates show a high antimicrobial resistance. The 13-valent pneumococcal conjugate vaccine covers about 60.0% of the isolates.

Molecular characteristics of erythromycin-resistant Streptococcus pneumoniae from pediatric patients younger than five years in Beijing, 2010.

BACKGROUND: Streptococcus pneumoniae is the main pathogen that causes respiratory infections in children younger than five years. The increasing incidence of macrolide- and tetracycline-resistant pneumococci among children has been a serious problem in China for many years. The molecular characteristics of erythromycin-resistant pneumococcal isolates that were collected from pediatric patients younger than five years in Beijing in 2010 were analyzed in this study. RESULTS: A total of 140 pneumococcal isolates were collected. The resistance rates of all isolates to erythromycin and tetracycline were 96.4% and 79.3%, respectively. Of the 135 erythromycin-resistant pneumococci, 91.1% were non-susceptible to tetracycline. In addition, 30.4% of the erythromycin-resistant isolates expressed both the ermB and mef genes, whereas 69.6% expressed the ermB gene but not the mef gene. Up to 98.5% of the resistant isolates exhibited the cMLSB phenotype, and Tn6002 was the most common transposon present in approximately 56.3% of the resistant isolates, followed by Tn2010, with a proportion of 28.9%. The dominant sequence types (STs) in all erythromycin-resistant S. pneumoniae were ST271 (11.9%), ST81 (8.9%), ST876 (8.9%), and ST320 (6.7%), whereas the prevailing serotypes were 19F (19.3%), 23F (9.6%), 14 (9.6%), 15 (8.9%), and 6A (7.4%). The 7-valent pneumococcal conjugate vaccine (PCV7) and 13-valent pneumococcal conjugate vaccine (PCV13) coverage of the erythromycin-resistant pneumococci among the children younger than five years were 45.2% and 62.2%, respectively. ST320 and serotype 19A pneumococci were common in children aged 0 to 2 years. CC271 was the most frequent clonal complex (CC), which accounts for 24.4% of all erythromycin-resistant isolates. CONCLUSIONS: The non-invasive S. pneumoniae in children younger than five years in Beijing presented high and significant resistance rates to erythromycin and tetracycline. The expressions of ermB and tetM genes were the main factors that influence pneumococcal resistance to erythromycin and tetracycline, respectively. Majority of the erythromycin-resistant non-invasive isolates exhibited the cMLSB phenotype and carried the ermB, tetM, xis, and int genes, suggesting the spread of the transposons of the Tn916 family. PCV13 provided higher serotype coverage in the childhood pneumococcal diseases caused by the erythromycin-resistant isolates better than PCV7. Further long-term surveys are required to monitor the molecular characteristics of the erythromycin-resistant S. pneumoniae in children.

Extraction optimization and purification of anthocyanins from Lycium ruthenicum Murr. and evaluation of tyrosinase inhibitory activity of the anthocyanins.

The aim of this study was to extract and purify anthocyanins from Lycium ruthenicum Murr. and evaluate their tyrosinase inhibitory activity. Response surface methodology was devoted to optimize enzyme-assisted extraction of anthocyanins from L. ruthenicum dried fruits. Extraction at 38 °C for 37 min using water-containing pectinase (52.04 mg/100 g dried fruit) rendered an anthocyanin extraction yield of 19.51 ± 0.21 mg/g. The purified anthocyanins were separated from the extract by macroporous resin XDA-6. Antioxidant tests in vitro suggested that the extract and the purified anthocyanins exhibited a potent 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging capacity, 2,2-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS) radical scavenging capacity, hydroxyl radical scavenging capacity, superoxide radical scavenging capacity, and total reducing power. Thirteen anthocyanins from L. ruthenicum dried fruits were analyzed by HPLC-MS. Moreover, the purified anthocyanins had inhibitory effect on tyrosinase monophenolase (IC50 = 1.483 ± 0.058 mg/mL), and the type of inhibition was competitive inhibition (Ki = 39.83 ± 1.4 mg/mL). The maximum inhibitory activity of the purified anthocyanins (3.00 mg/mL) on tyrosinase diphenolase was 42.16 ± 0.77%, and the type of inhibition was anticompetitive inhibition (Kis = 2.387 ± 0.10 mg/mL). PRACTICAL APPLICATION: The anthocyanins from L. ruthenicum dried fruits can be used as tyrosinase inhibitors in medicine, cosmetics, and food preservation industries.

Genetic analysis of group A streptococcus isolates recovered during acute glomerulonephritis outbreaks in Guizhou Province of China.

In this study, 68 group A streptococcus (GAS) isolates associated with two outbreaks of acute glomerulonephritis (AGN) in China were analyzed by emm typing. A total of 11 different emm types were identified. Analysis of emm type distribution suggested that AGN outbreaks in two counties were caused by emm60.1- and emm63.0-type GAS. These two types were further characterized by pulsed-field gel electrophoresis, multilocus sequence typing, sof sequence typing, and PCR-based identification of streptococcal pyrogenic exotoxin A, B, and C (speA, speB, and speC) genes. In antimicrobial susceptibility tests, all outbreak strains were resistant to erythromycin and tetracycline, and the rates of resistance of nonoutbreak strains to the two antibiotics were 63.6% and 90.9%. This study is also the first to report a nephritogenic M63 GAS strain.

Characterization of multidrug-resistant and metallo-beta-lactamase-producing Pseudomonas aeruginosa isolates from a paediatric clinic in China.

BACKGROUND: In the present study, we characterized multidrug-resistant Pseudomonas aeruginosa (MDRP) clinical isolates from a paediatric facility and investigated the types and features of the metallo-beta-lactamases (MBLs) produced by carbapenem-resistant strains. METHODS: Four hundred and ninety-eight strains of Pseudomonas aeruginosa were isolated from patients at Beijing Children's Hospital between January 2005 and December 2006. The minimal inhibition concentrations (MICs) of the strains for 13 antibiotics were measured. A combination of the E test and PCR amplification/DNA sequencing was used to define the carbapenem-resistant strains. RESULTS: We found that 24.1% (120/498) of the isolates were MDRP. The frequencies of resistance to imipenem and meropenem were 34.2% and 35.8%, respectively, and the MIC50 and MIC90 values for the two antibiotics were identical at 4 microg/ml and 32 microg/ml, respectively. The detection rate for carbapenem resistance was 49.2% (59/120). Among the 59 carbapenem-resistant Pseudomonas aeruginosa strains, 39 (66.1%) were positive for the MBL genotype; 35 (89.7%) strains carried the bla(IMP) gene and 4 (10.3%) strains carried the bla(VIM) gene. Neither bla(SPM) nor bla(GIM) was amplified from any of the 59 isolates. DNA sequencing revealed that IMP-1 was present in 35 IMP-producing isolates and VIM-2 was detected in four VIM-producing isolates. CONCLUSIONS: These MDRP isolates exhibited high frequencies of resistance to carbapenems among clinical isolates from a paediatric facility in Beijing, China. The production of MBL appears to be an important mechanism for carbapenem resistance in Pseudomonas aeruginosa.

[Surveillance of antibiotic resistance of Streptococcus pneumoniae isolated from hospitalized patients with pneumonia in four children's hospitals in China].

OBJECTIVE: To investigate the antimicrobial resistance of Streptococcus pneumoniae (S.pneumoniae) isolated from Chinese children with pneumonia. METHODS: Hypopharyngeal aspirate specimens were collected from hospitalized children with pneumonia who were admitted to the children's hospital located in Beijing, Shanghai, Guangzhou or Shanghai from February 16, 2006 to February 16, 2007. The minimum inhibitory concentration (MIC) of S.pneumoniae isolates against penicillin, amoxicillin, cefuroxime (sodium), ceftriaxone, erythromycin, vancomycin, ofloxacin and imipenem was determined by E-test method. RESULTS: A total of 279 S.pneumoniae isolates were obtained. Eighty-six percent of the isolates were not susceptive to penicillin, and 23.3% was resistant to penicillin. The rate of susceptibility of the isolates to amoxicillin was 92.1%, and to cefuroxime and ceftriaxone was 19.0% and 75.3%, respectively. The isolates also showed a high susceptibility to vancomycin (99.6%) and ofloxacin (97.8%). Seventeen point six percent of the isolates were not susceptive to imipenem, and most of those were intermediate. Almost of all isolates were resistant to erythromycin. There were some distinct regional differences in the susceptibility to antimicrobials tested except for erythromycin, vancomycin and ofloxacin. CONCLUSIONS: The S.pneumoniae isolates from Chinese children with pneumonia were susceptive to amoxicillin, vancomycin and ofloxacin, but were not susceptive or resistant to penicillin, cefuroxime and erythromycin. The isolates kept susceptibility to ceftriaxone and imipenem to a certain extent.

[Transfer of erythromycin-resistance among strains and species of bacteria: plasmid conjugation method in enterococcal isolates].

OBJECTIVE: To study if the resistance to macrolide in Enterococcus can be transferred between strains, and species of the same and different genera. METHODS: Agar dilution was used to screen 30 enterococcal isolates that were resistant to erythromycin. Conjugation was performed by filter mating method. The 30 donor bacteria included 13 strains of Enterococcus faecalis, 16 strains of E. faecium, and 1 strain of E. hirae. The recipient bacteria included 1 strain of E. faecalis sensitive to erythromycin and resistant to tetracycline, and 1 strain of Staphylococcus aureus with the MIC against erythromycin of 0.25 approximately 1 microg/ml. Polymerase chain reaction was used to test the existence of ermB gene and the tranposons Tn1545 and Tn917 in the enterococcal isolates before and after filter mating. RESULTS: The transfer rate between different strains and species of the same genus were all 100%. The MIC(50) and MIC(90) against erythromycin of 13 conjugates were both 512 microg/ml, and Tn1545 and Tn917 were found in the ermB gene of 12 conjugates. 17 conjugates were obtained from 16 strains of donor E. faecium and 1 strain of E. hirae with the MIC(50) and MIC(90) both of 512 microg/ml. The ermB gene was found in 16 of the 17 conjugates, and 11 of the 16 conjugates showed the existence of Tn1545 and Tn917, Tn1545 existed in the ermB gene of 4 conjugates, and Tn917 existed in the ermB gene of 1 conjugate. 30 conjugates of Staphylococcus aureus were obtained by plasmid conjugation and transfer with a transfer rate of 100% and the MIC(50) and MIC(90) both of 512 microg/ml. The ermB gene was found in 28 of the 30 conjugates. Both Tn1545 and Tn917 were found in the ermB gene of 23 of the 28 conjugates, Tn1545 was found in the ermB gene of 4 conjugates, and Tn917 was found in the ermB gene of 1 conjugate. CONCLUSION: The resistance to macrolide of Enterococcus, related with the existence of ermB gene and transposons Tn1545 and Tn917, can be transferred between strains and species of same and different genera.

Extraction optimization and identification of anthocyanins from Nitraria tangutorun Bobr. seed meal and establishment of a green analytical method of anthocyanins.

This study aimed to extract and identify anthocyanins from Nitraria tangutorun Bobr. seed meal and establish a green analytical method of anthocyanins. Ultrasound-assisted extraction of anthocyanins from N. tangutorun seed meal was optimized using response surface methodology. Extraction at 70°C for 32.73 min using 51.15% ethanol rendered an extract with 65.04mg/100g of anthocyanins and 947.39mg/100g of polyphenols. An in vitro antioxidant assay showed that the extract exhibited a potent DPPH radical-scavenging capacity. Eight anthocyanins in N. tangutorun seed meal were identified by HPLC-MS, and the main anthocyanin was cyanidin-3-O-(trans-p-coumaroyl)-diglucoside (18.17mg/100g). A green HPLC-DAD method was developed to analyse anthocyanins. A mixtures of ethanol and a 5% (v/v) formic acid aqueous solution at a 20:80 (v/v) ratio was used as the optimized mobile phase. The method was accurate, stable and reliable and could be used to investigate anthocyanins from N. tangutorun seed meal.

[Carrier rate of Streptococcus pneumoniae and susceptibility thereof to antimicrobial drugs among children in China: a surveillance study in Beijing, Shanghai, and Guangzhou 2000-2002].

OBJECTIVE: To investigate the carrier rate of Streptococcus pneumoniae and the susceptibility of S. pneumoniae to 10 different antimicrobial drugs among children in China. METHODS: Nasopharageal swab specimens were collected from randomly selected 3578 out-patients with upper respiratory infection aged 1 month to 5 years in Beijing, Shanghai, and Guangzhou 2000-2002 so as to isolate S. pneumoniae. The susceptibility of these strains to erythromycin and beta-lactam antibiotics (penicillin, amoxicillin/clavulanic acid, cefaclor, cefuroxime and ceftriaxone) was determinated by E-test MIC method, and the susceptibility to chloramphenicol, tetracycline, sulfamethoxazole/trimethoprim and ciprofloxacin was determinated by disk diffusion method. RESULTS: A total of 892 strains of S. pneumoniae were isolate from the 3578 children with a carrier rate of 24.9% (9.0%-36.0%). 634 isolates of S. pneumoniae were tested to examine their susceptibility to chloramphenicol, 199 to ciprofloxacin, and 887 to the other 8 antimicrobial drugs. The insusceptibility rate of S. pneumoniae to penicillin was 39.9%, and the resistance rate was 6.4%. The resistance rate to cefaclor was 20.4%. The insusceptibility rate to cefuroxime was 19.0%. The susceptibility rate to amoxicillin/clavulanic acid was 98.5% and that to ceftriaxone was 97.2%. More than 80% of the isolates were resistant to erythromycin, tetracycline, and sulphamethoxazole/trimethoprim. Chloramphenicol resistance was less common (32.3%) than the resistance to other non-beta-lactam antibiotics, except for ciprofloxacin to which the resistance rate was 2.0%. The national insusceptibility rates for beta-lactam antibiotics did not vary significantly during the three years with the widest varying range of 5.1% for penicillin (38.1%-43.2%). Each of the three cities had their different varying patterns of antimicrobial susceptibility, especially for beta-lactam antibiotics. Multi-drug resistance was common (88.7%). Strains of S. pneumoniae insusceptible to penicillin were significantly more common than those susceptible to penicillin (99.1% vs. 78.8%, chi(2) = 50.36, P < 0.001), and strains of S. pneumoniae insusceptible to erythromycin were significantly more common than those susceptible to erythromycin too (95.8% vs. 17.1%, chi(2) = 360.26, P < 0.001). CONCLUSION: Antimicrobial resistant S. pneumoniae has already become a serious problem in China. Ongoing surveillance study on the antimicrobial resistance of S. pneumoniae is necessary for appropriate antimicrobial use in clinical work and modification of medical strategies for people's health.