Staphylococcus aureus, or methicillin-resistant S. aureus (MRSA), is a significant pathogen in both nosocomial and community infections. Community-associated MRSA (CA-MRSA) strains tend to be multi-drug resistant and to invade hospital settings. This study aimed to assess the antimicrobial resistance and molecular characteristicsof nasal S. aureus among newlyadmitted inpatients.In the present study, 66 S. aureus isolates, including 10 healthcare-associated MRSA (HA-MRSA), 8 CA-MRSA, and 48 methicillin-sensitive S. aureus (MSSA) strains, were found in the nasal cavities of 62 patients by screening 292 newlyadmitted patients. Antimicrobial resistance and molecular characteristics of these isolates, including spa-type, sequence type (ST) and SCCmec type, were investigated. All isolates were sensitive to linezolid, teicoplanin, and quinupristin/dalfopristin, but high levels of resistance to penicillin and erythromycin were detected. According to D-test and erm gene detection results, the cMLSB and iMLSB phenotypes were detected in 24 and 16 isolates, respectively. All 10 HA-MRSA strains displayed the cMLSB phenotypemediated by ermA or ermA/ermC, while the cMLSB CA-MRSA and MSSA strains carried the ermB gene. Molecular characterization revealedall 10 HA-MRSA strains were derived from the ST239-SCCmec III clone, and four out of eight CA-MRSA strains were t437-ST59-SCCmec V. The results suggest that patients play an indispensable role in transmitting epidemic CA-MRSA and HA-MRSA strains.
Anti-Bacterial Agents/*pharmacology ; Bacterial Proteins/genetics ; Drug Resistance, Multiple, Bacterial/genetics ; Humans ; Inpatients ; Methicillin-Resistant Staphylococcus aureus/*drug effects/genetics/isolation & purification ; Methyltransferases/genetics ; Microbial Sensitivity Tests ; Nasal Cavity/*microbiology ; Staphylococcal Infections/diagnosis/microbiology ; Staphylococcus aureus/*drug effects/genetics/isolation & purification

目的：探讨沉默 G 蛋白偶联受体激酶 3（G protein-coupled receptor kinase 3，GRK3）对口腔鳞状细胞癌（oral squamous cell carcinoma，OSCC）细胞增殖、迁移和侵袭的影响及其可能的机制。方法：利用 Oncomine 数据库分析 GRK3 在正 常口腔组织及 OSCC 组织中的表达水平。用 RNA 干扰技术敲降 GRK3 在 OSCC 细胞 WSU-HN6 和 CAL27 中的表达，用 qPCR 法验证干扰效率后，采用 CCK-8 法和流式细胞术分别检测敲降 GRK3 对 OSCC 细胞增殖和凋亡的影响，Transwell 小室 法检测对 OSCC 细胞迁移、侵袭能力的影响，qPCR 法检测对 OSCC 细胞周期、上皮间质转化（epithelial to mesenchymal transition，EMT）和基质金属蛋白酶（matrix metallopeptidase，MMP）相关分子 mRNA 水平表达的影响，WB 法检测 EMT 及 MMP 相关分子的蛋白表达水平变化。结果：OSCC 组织中 GRK3 的表达水平显著高于正常口腔组织（P<0.01）。转染 si-GRK3 后，OSCC 细胞中 GRK3 mRNA 表达水平均下调 70% 以上。敲降 GRK3 可显著抑制 OSCC 细胞的增殖、迁移和侵袭能力（均 P<0.01），对细胞凋亡无显著影响（P>0.05）。敲降 GRK3 表达后，OSCC 细胞的 G0/G1 期比例显著增高（t=5.799，P<0.01），细胞 周期蛋白 D1（Cyclin D1）、Cyclin D3、周期蛋白依赖性激酶 2（cyclin-dependent kinases 2，CDK2）和 CDK4 基因的 mRNA 表达降 低（均 P<0.05）；EMT 相关分子波形蛋白（Vimentin）、Zeb1 和 Slug 表达降低，E-钙黏蛋白（E-Cadherin）表达升高（均 P<0.05）； MMP3 和 MMP9 表达降低（均 P<0.05），MMP2 和 MMP7 表达无明显变化（均 P>0.05）。结论：GRK3 可通过调节细胞周期促 进 OSCC 细胞的增殖能力，并通过调控 EMT 和 MMP 增强细胞的迁移和侵袭能力。