[Population structure of food-borne Staphylococcus aureus in China].

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].

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 ß-sheets, and the carboxy-terminal domain included 2 α-helices and 7 antiparallel ß-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.

Age-, sex- and glucose-dependent correlation of plasma soluble vascular adhesion protein-1 concentration with cardiovascular risk factors and subclinical atherosclerosis.

OBJECTIVE: Soluble vascular adhesion protein-1 (sVAP-1) may act as a biomarker for atherosclerosis and cardiovascular diseases. The associations of sVAP-1 concentration with cardiovascular risk factors and subclinical atherosclerosis at the population level have not been reported. PATIENTS AND METHODS: This cross-sectional study included 834 asymptomatic subjects (49.1 ± 9.3 years). sVAP-1 was measured by enzyme-linked immunosorbent assay. Subclinical atherosclerosis was assessed by brachial-ankle pulse wave velocity (baPWV) and carotid intima-media thickness (CIMT). RESULTS: sVAP-1 increased with age. Women had a higher concentration than men in age > 40 years. In women, sVAP-1 was negatively associated with estradiol (p < 0.01) and body mass index (BMI) (p < 0.05). In men, sVAP-1 was negatively associated with apolipoprotein A (ApoA) (p < 0.01), alcohol intake (p < 0.01) and uric acid (p < 0.05), but positively associated with ApoB/ApoA (p < 0.05). In hyperglycemia subjects, sVAP-1 positively correlated with fasting plasma glucose (p < 0.05) and hemoglobin A1c (p < 0.05), but in normoglycemic subjects, sVAP-1 negatively correlated with BMI (p < 0.01), triglyceride (p < 0.05), alcohol intake (p < 0.05). sVAP-1 independently influenced CIMT (ß = 0.001, p = 0.040) and carotid plaques [odds ratio 1.380 (95% confidence interval 1.051-1.813, p = 0.021)] in hyperglycemia, and baPWV (ß = 31.605, p = 0.014) in age > 55 years. CONCLUSIONS: sVAP-1 concentration correlates with cardiovascular risk factors and subclinical atherosclerosis in an age-, sex- and glucose-dependent manner.

The development and implementation of an obstetric cell salvage service.

Cell salvage in obstetric haemorrhage is now endorsed by a number of organisations. Most of the literature has focused on isolated case series and safety. We describe how cell salvage, including a quality assurance process conducted prior to clinical implementation, was introduced to our stand-alone obstetric hospital which had no previous experience of this technique. An implementation committee was established and 25 quality assurance and familiarisation cases were initially conducted. As part of this process the alpha fetoprotein, haematocrit, free plasma haemoglobin, potassium and Kleihauer tests were performed when enough blood was available for processing. Our guidelines for clinical use included women at greatly increased risk of obstetric haemorrhage and women at increased risk of haemorrhage who refused traditional transfusion. After the successful completion of this process, cell salvage was signed off for clinical use in March 2007 and was used on 51 occasions between March 2007 and July 2009. Twenty-one patients had salvaged blood re-transfused and for seven patients this was their only red blood cell replacement. The median blood loss in patients re-transfused was 3000 ml (range <500 to 8500 ml), with the median volume re-transfused 359 mi (range 60 to 1300 ml). There was one episode of unexplained hypotension associated with administration of salvaged blood. We have successfully introduced obstetric cell salvage into clinical practice. A quality assurance process prior to implementation was beneficial for the staff involved. Despite targeting a high-risk obstetric population, our re-transfusion rates are approximately 40%. No serious adverse events have been recorded. We recommend that in units that already provide intraoperative cell salvage in a non-obstetric setting, extending the service into obstetric situations should be considered. Units that routinely care for high-risk obstetric patients should also consider the introduction of such a service. Post transfusion Kleihauer testing should be performed as soon as possible in Rhesus-negative mothers who deliver a Rhesus-positive foetus, so that appropriate anti-D prophylaxis can be administered.

Assessment of a mutation in the H5 domain of Girk2 as a candidate for the weaver mutation.

A mutation in the GIRK2 inwardly rectifying K+ channel was mapped recently to the region of mouse chromosome 16 containing the wv gene and shown to occur in mutant but not in wild-type mice. We demonstrate tight linkage of the Girk2 mutation to the wv phenotype and refine the localization of the weaver (wv) gene on recombinational and physical maps. This linkage between Girk2 and wv has existed since at least 1988 in descendants of the original mutation maintained in C57BL/6 animals. Girk2 is shown to be transcribed in brain before the first recognized manifestation of the wv phenotype and in cultures of granule cells (GCs) isolated from cerebellum at postnatal day 8. Wild-type GCs grown in this culture system display an important developmental property--the ability to extend neurites. However, no inwardly rectifying K+ current is detected in GCs cultured from either wv/wv or +/+ cerebellum under a variety of conditions that activate related channels in other tissues. This suggests that if the Girk2 mutation is responsible for the wv phenotype, it does not act by altering these electrical properties of developing GCs.