Active Surveillance, Drug Resistance, and Genotypic Profiling of Staphylococcus aureus Among School-Age Children in China.

Methicillin-susceptible (MSSA) and methicillin-resistant Staphylococcus aureus (MRSA) nasal colonization predisposes individuals for endogenous infections and is a major threat to children. Recently, oxacillin/cefoxitin-susceptible mecA-positive S. aureus (OS-MRSA) has been reported worldwide. Herein, a prospective, cross-sectional study was conducted across five schools, representing three educational stages, in Guangzhou, China. Nasal swabs from 2,375 students were cultured for S. aureus and all isolates were subjected to antibiotic susceptibility testing phenotypically and confirmed by femB and mecA genetic detection; all the isolates were classified as MSSA, MRSA, or OS-MRSA. All strains were also analyzed by multi-locus sequence typing. Among the 2,375 swabs, S. aureus was detected in 744 children (31.3%, 95% CI: 25.9-36.7%), of whom 72 had MRSA (3.0%, 95% CI: 0.6-5.4%) and 4 had OS-MRSA (0.2%, 95% CI: 0.1-0.3%), of which an oxacillin- and cefoxitin-susceptible MRSA strain was identified. The prevalence of S. aureus and MRSA was higher in younger children. The highest percentage of drug resistance of the S. aureus isolates (n = 744) was to penicillin (85.5%), followed by erythromycin (43.3%) and clidamycin (41.0%). The most prevalent sequence types (STs) were ST30, ST45, and ST188 in MSSA, accounting for 38.7% of the total isolates, whereas ST45, ST59, and ST338 accounted for 74.6% of the MRSA isolates and ST338 accounted for 50.0% of the OS-MRSA isolates. The MRSA and OS-MRSA isolates (n = 76) were grouped into three clades and one singleton, with clonal complex (CC) 45 as the most predominant linkage. The top nine multi-locus sequence typing-based CCs (CC30, CC45, CC5, CC1, CC15, CC944, CC398, CC59, CC7) represented 86.7% of all S. aureus isolates. All CC30 isolates were resistant to erythromycin and clidamycin, and almost all these isolates were also resistant to penicillin (99.2%). The CC45 and CC59 isolates exhibited high resistance rates to oxacillin at 31.5 and 59.0%, respectively. This study provides updated data valuable for designing effective control strategies to mitigate the burden of disease and to improve the adequacy of empirical antimicrobial treatments for potentially harmful infections.

Oral administration of recombinant Bacillus subtilis spores expressing mutant staphylococcal enterotoxin B provides potent protection against lethal enterotoxin challenge.

Pathogenicity of Staphylococcus aureus is induced by staphylococcal enterotoxin B (SEB). A mutant form of SEB (mSEB) is immunogenic as well as less toxic. Recombinant mSEB and SEB were expressed in pET28a prokaryotic plasmids. Tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) levels in mSEB-stimulated macrophages were lower than those in SEB-stimulated macrophages (p < 0.001, p < 0.01 respectively). Using CotC as a fusion protein, we constructed recombinant Bacillus subtilis spores expressing mSEB on the spore surface and evaluated their safety and protective efficacy via mouse models. Oral administration of mSEB-expressing spores increased SEB-specific IgA in feces and SEB-specific IgG1 and IgG2a in the sera, compared with mice in naïve and CotC spore-treated groups (p < 0.001, p < 0.01, p < 0.001 respectively). Six weeks following oral dosing of recombinant spores, significant differences were not found in the serum biochemical indices between the mSEB group and the naïve and CotC groups. Furthermore, oral administration of mSEB spores increased the survival rate by 33.3% in mice intraperitoneally injected with 5 µg of wild-type SEB plus 25 µg lipopolysaccharide (LPS). In summation, recombinant spores stably expressing mSEB were developed, and oral administration of such recombinant spores induced a humoral immune response and provided protection against SEB challenge in mice.

Prevalence, Characterization, and Drug Resistance of Staphylococcus Aureus in Feces From Pediatric Patients in Guangzhou, China.

Background: Staphylococcus aureus (S. aureus) is a major pathogen of human infections. Its fecal carriage serves as a risk factor for nosocomial transmission and disease development. However, the rate of S. aureus fecal carriage among Chinese children has not yet been reported. Therefore, we sought to investigate the prevalence, characterization, and drug resistance of S. aureus isolated from pediatric patients' feces in Southern China. Methods: Fecal samples (2059) from pediatric patients in three centers in Guangzhou were cultured. From which, 412 S. aureus isolates were identified via selective mediums and automated VITEK Mass Spectrometer analysis. Antibiotic susceptibility was determined and DNA sequencing of seven housekeeping genes were used for multilocus sequence typing analysis. Results: The fecal carriage rates were 20.0% for S. aureus and 4.5% for methicillin-resistant S. aureus (MRSA). Moreover, S. aureus fecal carriage was positively correlated with outpatient status and gastroenteritis diagnosis. Moreover, age-related patterns were observed with respect to prevalence of S. aureus. Besides, a total of 76 sequence types (STs) were identified, including 25 newly assigned STs and 28 clonal complexes (CCs). ST188, ST6, and ST15 were the most prevalent methicillin-sensitive S. aureus (MSSA) clones, while ST59 and ST45 were the major MRSA clones. S. aureus isolates also exhibited high rates of penicillin (84.2%), erythromycin (38.8%), and clindamycin (35.9%) resistance. Specifically, all ST30 and ST338 isolates were resistant to erythromycin and clindamycin, 61% of ST7 were resistant to tetracycline, and 84% of ST45 exhibited resistance and intermediate resistance to rifampicin. Also, CC59 (ST338 and ST59) and CC45 exhibited different antibiotic resistance patterns. Conclusion: These results demonstrate the colonization dynamics and molecular epidemiology of S. aureus in child feces in Southern China. Further, they suggest an urgency for strengthening the surveillance programs in China and provide important information for the prevention and treatment of S. aureus infection.

ETS2 promotes epithelial-to-mesenchymal transition in renal fibrosis by targeting JUNB transcription.

Epithelial-to-mesenchymal transition (EMT) plays an important role in the progression of renal tubulointerstitial fibrosis, a common mechanism leading to end-stage renal failure. V-ets erythroblastosis virus E26 oncogene homolog 2 (ETS2), a transcription factor, exhibits diverse roles in pathogenesis; however, its role in renal fibrosis is not yet fully understood. In this study, we detected the expression of ETS2 in an animal model of renal fibrosis and evaluated the potential role of ETS2 in tubular EMT induced by TGF-ß1. We found that ETS2 and profibrogenic factors, alpha-smooth muscle actin (α-SMA) and fibronectin (FN), were significantly increased in the unilateral ureteral obstruction (UUO)-induced renal fibrosis model in mice. In vitro, TGF-ß1 induced a high expression of ETS2 dependent on Smad3 and ERK signaling pathway in human proximal tubular epithelial cells (HK2). Knockdown of ETS2 abrogated TGF-ß1-mediated expression of profibrogenic factors vimentin, α-SMA, collagen I, and FN in HK2 cells. Mechanistically, ETS2 promoted JUNB expression in HK2 cells after TGF-ß1 stimulation. Furthermore, luciferase and Chromatin Immunoprecipitation (ChIP) assays revealed that the binding of ETS2 to three EBS motifs on the promoter of JUNB triggered its transcription. Notably, silencing JUNB reversed the ETS2-induced upregulation of the profibrogenic factors in HK2 cells after TGF-ß1 stimulation. These findings suggest that ETS2 mediates TGF-ß1-induced EMT in renal tubular cells through JUNB, a novel pathway for preventing renal fibrosis.

Oral administration of recombinant Bacillus subtilis spores expressing Helicobacter pylori neutrophil-activating protein suppresses peanut allergy via up-regulation of Tregs.

BACKGROUND: Helicobacter pylori neutrophil-activating protein (NAP) is an immune modulator with anti-Th2 inflammation activity that can be used to prevent IgE-mediated allergic reactions. Cholera toxin B (CTB) is a mucosal adjuvant that can induce antigen tolerance. Bacillus subtilis spores are an ideal vehicle for the oral delivery of heterologous antigens. OBJECTIVE: We investigated the therapeutic effect of recombinant NAP B subtilis spores on peanut allergies in a mouse model. METHODS: Female C3H/HeJ mice were sensitized and challenged with peanut extract by oral administration. Before challenge, recombinant NAP and CTB-NAP (CNAP) spores were orally administered to sensitized mice for 4 weeks. Faecal peanut-specific IgA and serum-specific IgE, IgG1, and IgG2a levels were measured, and the intestinal microbiota was analysed. Mice were intraperitoneally injected with anti-CD25 antibodies for regulatory T cell (Treg) depletion to evaluate the efficacy of Tregs in preventing peanut allergy. After challenge, anaphylactic reactions, plasma histamine, Tregs, and splenocyte interleukin (IL)-10, IL-4, IL-5 and interferon-γ (IFN-γ) levels were evaluated. RESULTS: After 4 weeks of recombinant spore treatment, faecal IgA levels and serum IgG2a levels were increased, while serum IgG1 and IgE levels were reduced. Intestinal microbiota analysis revealed that CNAP spores increased the taxonomic abundance of Firmicutes at the phylum level and Clostridia at the class level. After challenge, the administration of NAP or CNAP spores to mice was found to ameliorate anaphylactic reactions and decrease plasma histamine levels. Administration of NAP or CNAP spores also enhanced IL-10 and IFN-γ secretion, and suppressed IL-4 and IL-5 secretion. The protective effect of CNAP spores was more pronounced than that of NAP spores; this therapeutic effect was lost after Treg depletion. CONCLUSIONS AND CLINICAL RELEVANCE: Recombinant NAP spores successfully suppressed Th2 inflammation via the up-regulation of Tregs; this may serve as a novel therapeutic approach for treating food allergies.

[Role of allograft inflammatory factor-1 in regulating the proliferation, migration and apoptosis of colorectal cancer cells].

OBJECTIVE: To investigate the role of allograft inflammatory factor-1 (AIF-1) in colorectal cancer (CRC) progression and explore the possible mechanism. METHODS: The expression levels of AIF-1 in 70 CRC tissues and paired adjacent tissues were detected using immunohistochemistry and Western blotting, and the correlation of AIF-1 expression with the clinicopathological features of the patients was analyzed. In the CRC cell line SW480, the functional role of AIF-1 in regulating tumor progression was investigated by transfecting the cells with an AIF-1-overexpressing plasmid (AIF-1) and a negative control plasmid (NC). EdU proliferation assay and flow cytometry were used to assess the cell proliferation and cell cycle changes; Transwell migration assay and Annexin V-APC/7-AAD apoptosis assay kit were used to analyze the cell migration and apoptosis. The changes in the biological behaviors of the cells were observed after application of SB203580 to block the p38 MAPK pathway. The expression levels of CDK4, cyclin D1, P21, P27, MMP2, MMP9, Bax, Bcl2, Bcl-xl, p38 and p-p38 were detected using Western blotting. RESULTS: AIF-1 was down-regulated in CRC tissues compared with the adjacent normal tissues, and its expression level was positively correlated with lymph node metastasis (P=0.008), TNM stage (P=0.003) and tumor size (P=0.023). Overexpression of AIF-1 in SW480 cells significantly reduced EdU-positive cells and caused obvious cell cycle arrest in G1 phase (P<0.05). AIF-1 overexpression resulted in significantly lowered protein expressions of CDK4 and cyclin D1, enhanced expressions of P21 and P27, attenuated cell migration ability (P<0.001), and decreased protein levels of MMP2 and MMP9. AIF-1 overexpression also induced obvious apoptosis of SW480 cells (P<0.01), significantly increased the protein levels of Bax and p-p38, and decreased the protein levels of Bcl-2 and Bcl-xl; SB203580 significantly attenuated the apoptosis-inducing effect of AIF-1 overexpression. CONCLUSION: AIF-1 plays the role of a tumor suppressor in CRC by inhibiting cell proliferation, suppressing cell migration and inducing cell apoptosis. AIF-1 overexpression promotes the apoptosis of CRC cells by activating the p38 MAPK pathway.

Glia maturation factor beta is required for reactive gliosis after traumatic brain injury in zebrafish.

Gliosis is a hallmark of neural pathology that occurs after most forms of central nervous system (CNS) injuries including traumatic brain injury (TBI). Identification of genes that control gliosis may provide novel treatment targets for patients with diverse CNS injuries. Glia maturation factor beta (GMFB) is crucial in brain development and stress response. In the present study, GMFB was found to be widely expressed in adult zebrafish telencephalon. A gmfb mutant zebrafish was created using CRISPR/cas9. In the uninjured zebrafish telencephalon, glial fibrillary acidic protein (GFAP) fibers in gmfb mutants were disorganized and shorter than wild type zebrafish. After TBI, transformation of quiescent type I radial glial cells (RGC) to proliferative type II RGCs was significantly suppressed in the gmfb mutant. RGC proliferation and hypertrophy post-TBI was reduced in gmfb mutants, indicating that reactive gliosis was attenuated. TBI-induced acute inflammation was also found to be alleviated in the gmfb mutant. Morphological changes also suggest attenuation of microglial reactive gliosis. In a mouse model of TBI, GMFB expression was increased around the injury site. These GMFB+ cells were identified as astrocytes and microglia. Taken together, the data suggests that GMFB is not only required for normal development of GFAP fibers in the zebrafish telencephalon, but also promotes reactive gliosis after TBI. Our findings provide novel information to help better understand the reactive gliosis process following TBI.