Population structure of food-borne Staphylococcus aureus in China / 中华流行病学杂志

Objective: To understand the population structure of food-borne Staphylococcus (S.) aureus in China. Methods: Whole genome sequencing was used to analyze 763 food-borne S. aureus strains from 16 provinces in China from 2006 to 2020. Multilocus sequence typing (MLST), staphylococcal protein A gene (spa) typing, and staphylococcal chromosome cassettemec (SCCmec) typing were conducted, and minimum spanning tree based on ST types (STs) was constructed by BioNumerics 7.5 software. Thirty-one S. aureus strains isolated from imported food products were also included in constructing the genome phylogenetic tree. Results: A total of 90 STs (20 novel types) and 160 spa types were detected in the 763 S. aureus isolates. The 72 STs (72/90, 80.0%) were related to 22 clone complexes. The predominant clone complexes were CC7, CC1, CC5, CC398, CC188, CC59, CC6, CC88, CC15, and CC25, accounting for 82.44% (629/763) of the total. The STs and spa types in the predominant clone complexes changed over the years. The methicillin-resistant S. aureus (MRSA) detection rate was 7.60%, and 7 SCCmec types were identified. The ST59-t437-Ⅳa (17.24%, 10/58), ST239-t030-Ⅲ (12.07%, 7/58), ST59-t437-Ⅴb (8.62%, 5/58), ST338-t437-Ⅴb (6.90%, 4/58) and ST338-t441-Ⅴb (6.90%, 4/58) were the main types in MRSA strains. The genome phylogenetic tree had two clades, and the strains with the same CC, ST, and spa types clustered together. All CC7 methicillin sensitive S. aureus strains were included in Clade1, while 21 clone complexes and all MRSA strains were in Clade2. The MRSA strains clustered according to the SCCmec and STs. The strains from imported food products in CC398, CC7, CC30, CC12, and CC188 had far distances from Chinese strains in the tree. Conclusions: In this study, the predominant clone complexes of food-borne strains were CC7, CC1, CC5, CC398, CC188, CC59, CC6, CC88, CC15, and CC25, which overlapped with the previously reported clone complexes of hospital and community-associated strains in China, suggesting that close attention needs to be paid to food, a vehicle of pathogen transmission in community and food poisoning.

Prediction of superantigen active sites and clonal expression of staphylococcal enterotoxin-like W / 中华流行病学杂志

Objective: The docking and superantigen activity sites of staphylococcal enterotoxin-like W (SElW) and T cell receptor (TCR) were predicted, and its SElW was cloned, expressed and purified. Methods: AlphaFold was used to predict the 3D structure of SElW protein monomers, and the protein models were evaluated with the help of the SAVES online server from ERRAT, Ramachandran plot, and Verify_3D. The ZDOCK server simulates the docking conformation of SElW and TCR, and the amino acid sequences of SElW and other serotype enterotoxins were aligned. The primers were designed to amplify selw, and the fragment was recombined into the pMD18-T vector and sequenced. Then recombinant plasmid pMD18-T was digested with BamHⅠand Hind Ⅲ. The target fragment was recombined into the expression plasmid pET-28a(+). After identification of the recombinant plasmid, the protein expression was induced by isopropyl-beta-D- thiogalactopyranoside. The SElW expressed in the supernatant was purified by affinity chromatography and quantified by the BCA method. Results: The predicted three-dimensional structure showed that the SElW protein was composed of two domains, the amino-terminal and the carboxy-terminal. The amino-terminal domain was composed of 3 α-helices and 6 β-sheets, and the carboxy-terminal domain included 2 α-helices and 7 antiparallel β-sheets composition. The overall quality factor score of the SElW protein model was 98.08, with 93.24% of the amino acids having a Verify_3D score ≥0.2 and no amino acids located in disallowed regions. The docking conformation with the highest score (1 521.328) was selected as the analysis object, and the 19 hydrogen bonds between the corresponding amino acid residues of SElW and TCR were analyzed by PyMOL. Combined with sequence alignment and the published data, this study predicted and found five important superantigen active sites, namely Y18, N19, W55, C88, and C98. The highly purified soluble recombinant protein SElW was obtained with cloning, expression, and protein purification. Conclusions: The study found five superantigen active sites in SElW protein that need special attention and successfully constructed and expressed the SElW protein, which laid the foundation for further exploration of the immune recognition mechanism of SElW.

Antimicrobial susceptibility of Streptococcus sp. to quinupristin-dalfopristin in China / 生物医学与环境科学（英文）

This study aimed to determine the in vitro activity of quinupristin-alfopristin against Streptococcus sp. isolated in China. This agent is not yet available for clinical use, but it has been tested against a high proportion of resistant Staphylococcus aureus strains. A total of 156 streptococcal isolates, which were recovered from various geographic areas and diseases, were tested using the Etest (AB Biodisk, Solna, Sweden). Quinupristin-alfopristin showed excellent activity against all of the tested streptococci isolates. These results provide useful data for the clinical use of quinupristin-alfopristin in China.

Molecular epidemiological characteristics of Streptococcus pyogenes strains involved in an outbreak of scarlet fever in China, 2011 / 生物医学与环境科学（英文）

<p><b>OBJECTIVE</b>To investigate molecular characterization of streptococcus pyogenes isolates involved in an outbreak of scarlet fever in China in 2011.</p><p><b>METHODS</b>Seventy-four Streptococcal pyogenes involved in an outbreak of scarlet fever were isolated from pediatric patients in the areas with high incidence in China from May to August of 2011. Emm genotyping, pulsed-field gel electrophoresis (PFGE), superantigen (SAg) genes and antimicrobial susceptibility profiling were analyzed for these isolates.</p><p><b>RESULTS</b>A total of 4 different emm types were identified. Emm12 was the most prevalent type which contained four predominating PFGE patterns corresponding to four different virulence and superantigen profiles. Emm12 (79.7%) and emm1 (14.9%) accounted for approximately 94% of all the isolates. The speA gene was all negative in emm12 isolates and positive in emm1 isolates. All strains were resistant to erythromycin, and 89.4% of them were resistant to erythromycin, tracycline, and clindamycin simultaneously.</p><p><b>CONCLUSION</b>Several highly diversified clones with a high macrolide resistance rate comprise a predominant proportion of circulating strains, though no new emm type was found in this outbreak. The data provide a baseline for further surveillance of scarlet fever, which may contribute to the explanation of the outbreak and development of a GAS vaccine in China.</p>

Proteome analysis of Neisseria meningitidis serogroup strains C associated with outbreaks in China / 生物医学与环境科学（英文）

<p><b>OBJECTIVE</b>During 2003-2005, an outbreak of meningitis due to Neisseria meningitidis serogroup C occurred in China. With the aim to find strain clues result in the final epidemics, the ancestral strain 053442, a clinical isolate, and a carrier strain 053426 with different gene type were analyzed.</p><p><b>METHODS</b>Clinical strain 053442 and carrier strain 053426 were cultured on GC agar plates under the same condition. Two-dimensional electrophoresis was performed using the pH 3-10 nonlinear IPG strips of 24 cm length, and all the protein spots were identified by matrix-assisted laser desorption/ionization time of flight spectrometry.</p><p><b>RESULTS</b>502 and 380 protein spots were identified in 053426 and 053442 respectively, relating to 266 and 202 different genes covering a wide range of cellular functions. The express volume and number of proteins involved in energy metabolism, protein synthesis and amino acid biosynthesis in 053426 were higher than in 053442. Virulence factor Opa, Opc and a series of proteins involved in pilus assembly and retraction were identified in 053442, which appear to be of primary importance in colonization and invasion of human cells. Compared to 053442, virulence protein species were less in 053426, with lower express volumes too. No Opa and Opc were detected in 053426.</p><p><b>CONCLUSIONS</b>The different protein expression profiles of the clinical strain 053442 and carrier strain 053426 in the present study provide some clues of the different pathogenicity of the two strains, which may account for result in the final epidemics.</p>

Multilocus sequence typing of methicillin-resistant Staphylococcus aureus / 中华预防医学杂志

<p><b>OBJECTIVE</b>To analyze multilocus sequence typing (MLST) of methicillin-resistant Staphylococcus aureus (MRSA) strains in 2000 and 2005, and get a primary knowledge of MLST Characterization of MRSA.</p><p><b>METHODS</b>Sequence analysis was conducted on seven allelic genes of 29 methicillin-resistant Staphylococcus aureus strains and 2 methicillin-sensitive Staphylococcus aureus (MSSA) strains and the allelic profiles were gained from internet database.</p><p><b>RESULTS</b>All 12 MRSA strains in 2000 were sequence type (ST) 239 and 10 MRSA strains in 2005 were ST239, while 7 MRSA strains in 2005 were new types, ST5 (41.18%, 7/17). ST6 and ST630 were allelic profiles of 2 MSSA strains. ST239 was the most prevalent allelic profile (75.86%, 22/29), while ST5 was the second prevalent allelic profile (24.14%, 7/29) among all isolates.</p><p><b>CONCLUSION</b>ST239 and ST5 are the most prevalent MRSA clones in this research. MRSA strains have different allelic profile from MSSA strains. MLST might provide an unambiguous method for assigning MRSA and MSSA isolates to known clones or assigning them as novel clones via the internet. Further studies need to be taken by increasing strains.</p>

Monosaccharide composition analysis and its content determination of polysaccharides from Rhaponticum uniforum / 中国中药杂志

<p><b>OBJECTIVE</b>To analyze the monosaccharide composition in the polysaccharides from Rhaponticum uniforum, determine the content of monosaccharide, and provide some references for further research.</p><p><b>METHOD</b>The monosaccharide composition was determined by high performance anion exchange chromatography with pulsed amperometric detection (HPAEC-PAD). Phenol-sulfuric acid method was used for the determination of the content of polysaccharide.</p><p><b>RESULT</b>The monosaccharides composition in polysaccharides from R. uniforum are glucose, arabonose and fructose. Their molar ratios are 1 : 1.61 : 2.21. The content of polysaccharide is 95.78%, taking the mixture of monosaccharide compositions as reference substances.</p><p><b>CONCLUSION</b>HPAEC-PAD can be used to analyze the monosaccharide composition in the polysaccharide with high precision, and the method of phenol-sulfuric acid is simple, convenient and reliable.</p>

Sequence analysis on sorbitol fermentation related genes in Vibrio cholerae / 中华流行病学杂志

<p><b>OBJECTIVE</b>To Investigate the differences of sorbitol fermentation related genes and optimize molecular analysis method for distinguishing an epidemic with nonepidemic strains of Vibrio cholerae.</p><p><b>METHODS</b>Sequence analysis on four genes of sugar fermentation stimulation protein, periplasmic maltose-binding protein, periplasmic phosphate-binding protein and periplasmic amino acid-binding protein.</p><p><b>RESULTS</b>In this study, the following data was noticed: for O1 serogroup El Tor biotype V. cholerae, twenty-four epidemic and eight nonepidemic strains were chosen; For O139 serogroup V. cholerae, five epidemic and four nonepidemic strains were chosen. With those genes of sugar fermentation stimulation protein, there were three point mutations. The 106th, 150th, 378th oligonucleotide in epidemic strains were A, A and T, comparing to the nonepidemic strains which were G, G and C. When comparing the protein sequences, epidemic strains had a Threonine at 36th amino acid, whereas nonepidemic strains had an Alanine. The results in O139 serogroup were consistent with those in O1 serogroup El Tor biotype strains. Another two point mutations were found in the genes of periplasmic maltose-binding protein. The 999th, 1003rd oligonucleotides in epidemic strains were A and C, while in nonepidemic which were G and T. For the gene of periplasmic amino acid-binding protein, two point mutations were noticed. The 504th and 690th oligonucleotides in epidemic strains were T and C, but were C and T in nonepidemic. However, no amino acid differences were found in periplasmic maltose-binding protein and periplasmic amino acid-binding protein. For periplasmic amino acid-binding protein gene, there was no difference on oligonucleotide between epidemic and nonepidemic strains.</p><p><b>CONCLUSION</b>Results suggested that SNPs in these genes might serve as a useful tool to distinguish the epidemic strains from nonepidemic strains. The 36th amino acid mutation of sugar fermentation stimulation protein in epidemic and nonepidemic strains might change the activity of the protein which might be associated with sorbitol fermentation.</p>

Primary analysis on protein maps of Helicobacter pylori strains associated with gastric carcinoma / 中华流行病学杂志

<p><b>OBJECTIVE</b>To identify specific proteins of Helicobacter pylori (H. pylori) that associated with gastric carcinoma.</p><p><b>METHODS</b>The whole-cell proteins of H. pylori were separated by two-dimensional electrophoresis (2-DE). The protein maps of four H. pylori strains associated with gastric carcinoma and nine strains that isolated from patients with non-gastric carcinoma were then compared by ImageMaster 2D v3.1. MALDI-TOF mass spectrometry was performed to identify the proteins of interest. The proteins were searched by software mascot and identified by peptide fingerprint map.</p><p><b>RESULTS</b>Three proteins seemed to be associated with gastric carcinoma including acylneuraminate cytidylyltransferase with Mowse score 79 with the sequence coverage of 32%. The other two had no unambiguous protein to match.</p><p><b>CONCLUSION</b>Acylneuraminate cytidylyltransferase seemed to be a specific H. pylori protein associated with the presence of gastric carcinoma. Other two were novel proteins that might be associated with gastric carcinoma. However, the mechanism needs to be explored.</p>

In-vitro activity of rabeprazole, lansoprazole, and esomeprazole against Helicobacter pylori / 中华流行病学杂志

<p><b>OBJECTIVE</b>To investigate the antimicrobial activity of Pariet, Tekpron, Nexium, respectively, against Helicobacter pylori (H. pylori) in vitro.</p><p><b>METHODS</b>Antimicrobial effects of these medicines were evaluated through detection of MICs for 3 H. pylori strains isolated from different countries.</p><p><b>RESULTS</b>The MIC(99) contents were 2.25 mg/L, 42.5 mg/L and 360 mg/L, respectively, for the three medicines. The strains under testing exhibited the same susceptibility to each medicine. Nexium did not inhibit the bacteria under the concentration of 3.6 - 36 mg/L with more and bigger H. pylori colonies seen when compared with controls.</p><p><b>CONCLUSIONS</b>The growth inhibitory activity appeared to be different among the three PPI medicines under investigation, with Rabeprazole the most potential agent of the three. Data suggested that the action of growth inhibition in vitro was resting on the characteristic of the given PPI as well as the supplements of the medicine.</p>

Study on optimization of expression, purification, properties and biological function of recombinant human sBLyS / 生物工程学报

The prokaryotic expression plasmid pET-30a(+)/sBLyS was constructed and transformed into E. coli BL21 (lambda DE3). The recombinant protein was found to be highly expressed by the plight of soluble part and inclusion body. For the sake of enhancing the proportion of the soluble part, inducement at 16 degrees C for 12 h was ascertained. The expressing product was then purified by Ni2+ affinity chromatography gel. PI of the recombinant human sBLyS(rhsBLyS) is about 7.1-7.3 and it assembles into a homotrimer. The effect of rhsBLyS on B lymphocytes by MTT method told us the B lymphocytes' proliferating capacity dose depended on concentration and also stimulating time of the rhsBLys. With rhsBLyS(2 micrograms/mL) stimulating 3 days, B lymphocytes can proliferate the most.