Plasmonic probing of the adhesion strength of single microbial cells

Probing the binding between a microbe and surface is critical for understanding biofilm formation processes, developing biosensors, and designing biomaterials, but it remains a challenge. Here, we demonstrate a method to measure the interfacial forces of bacteria attached to the surface. We tracked the intrinsic fluctuations of individual bacterial cells using an interferometric plasmonic imaging technique. Unlike the existing methods, this approach determined the potential energy profile and quantified the adhesion strength of single cells by analyzing the fluctuations. This method provides insights into biofilm formation and can also serve as a promising platform for investigating biological entity/surface interactions, such as pathogenicity, microbial cell capture and detection, and antimicrobial interface screening.

Microorganisms can form biofilms, which are widely distributed and present on biotic and abiotic surfaces in natural, industrial, and medical settings (1–3). Initial bacterial adhesion to surfaces is the most crucial step in biofilm formation. The transition from initial weak, reversible interactions between a bacterium and a surface to irreversible adhesion involves complex physicochemical forces, including specific receptor-ligand forces, nonspecific hydrophobic, and electrostatic forces (4). Understanding and managing bacterial adhesion, especially at single-cell level, is a cross-disciplinary challenge (5, 6).While many methods have been developed for study of bacterial adhesion, most technologies are based on ensemble analysis of a vast population of cells, which washes out heterogeneity and microscopic information of single bacterial cells, and cannot measure the forces driving cell adhesion. Several methods are now available to study bacterial adhesion at the single-cell level (7–9). For example, atomic force microscopy (AFM) measures interfacial forces by mechanically moving one cell with the AFM probe (7, 10). Optical tweezers are another force spectroscopy method with an intense laser field that uses microbeads attached to the cell (11, 12). These methods measure one single cell at one time, thus having limited throughput. Additionally, they exert external forces on the cell and interfere with the intrinsic feature of bacterial adhesion.Here, we aim to probe the interfacial forces by measuring intrinsic fluctuations of bacteria attached to the surface using plasmonic interferometric imaging technique. Unlike AFM or optical tweezers, this method enabled us to perform high-throughput tracking of many single bacterial cells, to determine the potential energy profile for each bacterial cell and obtain the elastic parameters. To probe the tiny vertical fluctuations, we imaged the interferometric pattern of bacterial cells scattering the planar plasmonic wave propagating on the surface. The plasmonic scattering intensity was extremely sensitive to the vertical distance, allowing precise tracking of the fluctuations. From the fluctuation analyses, we obtained the interfacial energy profiles and elasticity of microbial binding, which were essential properties in understanding microbial adhesion. The derived binding constant can be used to quantify bacterial adhesion strength. Thus, the knowledge obtained can help understand biofilm formation and be used in the design of artificial surfaces to minimize or maximize bacterial adhesion.     

老年人下呼吸道嗜麦芽窄食单胞菌感染的临床分析

目的 探讨老年人下呼吸道嗜麦芽窄食单胞菌感染的危险因素及该菌对常用抗生素的敏感性。方法 分析40例老年下呼吸道嗜麦芽窄食单胞菌感染患者的临床资料，用K-B法测定该菌的体外药物敏感性。结果 全部患者均有基础疾病，其中慢性阻塞性肺疾病(COPD)20例(50．0％)，混合感染17例(42．5％)。均有抗生素应用史，70．0％的患者机体免疫功能低下，30．0％的患者曾有侵袭性治疗，平均住院时间达41．7d。临床症状及X线表现符合下呼吸道感染。药敏试验提示该菌呈现多重耐药，复方磺胺甲噁唑、环丙沙星、左氧氟沙星、阿米卡星、庆大霉素及氧氟沙星为较敏感抗生素。结论 老年下呼吸道嗜麦芽窄食单胞菌感染多发生于患有各种基础疾病、免疫功能低下及长期应用抗菌药物者，细菌耐药现象严重，诊断及治疗应根据病原学检查及药物敏感试验。     

Microorganisms in the Female Genital Tract during Pregnancy: Tolerance versus Pathogenesis

Microorganisms in the pregnant female genital tract are not always associated with pathology. The factors that influence the maternal response to microorganisms remain ill defined. We review the state of knowledge of microbe–host interactions in gestational tissues and highlight mechanisms that promote tolerance or pathogenesis. Tolerance to microorganisms is promoted during pregnancy by several mechanisms including upregulation of anti‐inflammatory mediators, induction of endotoxin tolerance, and possibly by regulation of autophagy. Conversely, an altered vaginal microbiota or a pre‐existing viral presence may result in induction of excessive inflammation and preterm labor. Although infections play a prevalent role in preterm birth, microbes are present in gestational tissues of women with healthy outcomes and may provide beneficial functions. The complex interactions between different microbial species and the maternal immune system during gestation remain incompletely elucidated.     

1764例血培养病原菌分布及耐药性分析

目的：了解血培养中常见病原菌的组成以及各类病原菌对抗菌药物的耐药性,为临床医生合理选用抗菌药物解决患者病痛提供依据。方法收集临床送检的血培养标本,应用法国生物梅里埃公司 BacT／Alert3D 全自动血培养仪、配套培养基、鉴定仪系统鉴定菌种及药敏试验。结果1764份血培养分离出病原菌179株,其阳性率为10．1％,其中革兰阳性菌68株（38．0％）,革兰阴性菌111株（62．0％）;病原菌中占首位的是大肠埃希菌,其次是凝固酶阴性菌、肺炎克雷伯菌、铜绿假单胞菌。药敏结果显示绝大部分检出的病原菌均有耐药情况出现。结论临床医生应重视患者早期的血培养检验,并严格根据药敏结果合理使用抗菌药物。对血培养的检测应更加规范,从而提高病原菌的检出率,并及时检测病原菌变化及耐药趋势。     

与隐形眼镜相关的感染性角膜炎-埃及5年流行病学研究

目的：研究埃及Tanta大学医院与隐形眼镜相关的感染性角膜炎患者的不同流行病学特点,评估这类疾病各方面的特点,以提高患者对这类疾病的认识,找出可行的解决方案。

方法：选取我院2009-01/2013-12期间在眼科门诊就诊的所有角膜炎患者仔细检查,并对所有与隐形眼镜相关的感染性角膜炎患者进一步检查和调查。

结果：本研究期间,总共108 496位有不同主诉的患者中,1463例(1.3%)患有不同形式的角膜炎,其中151例(0.1%)为隐形眼镜相关感染性角膜炎。结果发现患有隐形眼镜相关感染性角膜炎常见的年龄群<30岁,大多数是学生(64%),家庭人数多且较为拥挤,农村居民高于城市居民,患者采用户外水源及污水处理不卫生。从病史分析发现：隐形眼镜相关感染性角膜炎通常为彻夜使用,储存或者配戴不卫生,或者隐形眼镜来源不安全,例如化妆品商店和理发店。结膜囊微生物培养结果提示阳性率92%,阴性率8%。大多数培养阳性的病例是由细菌和真菌混合感染引起,共53例(38.1%),单纯细菌感染43例(30.9%),真菌31例( 22.3%),阿米巴12例(8.6%)。

结论：与隐形眼镜相关的感染性角膜炎常见于学生群体,与农村生活、户外供水、不卫生的污水处理等危险因素有关。彻夜配戴、储存或配戴不卫生及隐形眼镜来源不安全都可增加隐形眼镜相关感染性角膜炎的发病率。     

清热合剂对上呼吸道感染常见致病菌的体外抑菌试验

目的观察清热合剂对上呼吸道感染常见致病菌的体外抑菌活性。方法上呼吸道感染常见致病菌163株中不产超广谱β-内酰胺酶(ESBLs)革兰阴性菌74株(大肠埃希菌33株,肺炎克雷伯菌24株,铜绿假单胞菌17株);产ESBLs革兰阴性菌10株(大肠埃希菌6株,肺炎克雷伯菌4株);革兰阳性菌79株[耐甲氧西林金黄色葡萄球菌(MRSA)11株、甲氧西林敏感金黄色葡萄球菌(MSSA)46株,肺炎链球菌22株]。采用琼脂稀释法对清热合剂进行定量抑菌试验,配制含有不同药物浓度的琼脂平板,在平板上接种待测菌株菌悬液,孵育后观察含药平板,记录最低抑菌浓度(MIC)。结果清热合剂对大肠埃希菌、肺炎克雷伯菌、铜绿假单胞菌等革兰阴性菌的MIC90分别为88、176、22 g/L,其对产ESBLs与不产ESBLs革兰阴性菌的抑菌效果一致;不同浓度药物对铜绿假单胞菌的累积抑菌率均最高。清热合剂对MSSA、MRSA和肺炎链球菌等革兰阳性菌的MIC90分别为11、11、22 g/L,MRSA的MIC90与MSSA相同,但MIC50略高于MSSA;不同浓度药物对MSSA和MRSA的累积抑菌率均高于肺炎链球菌,对MSSA与MRSA的累积抑菌率相近。结论清热合剂对上呼吸道感染常见的致病菌除肺炎克雷伯菌之外均有一定的抑菌作用,对革兰阳性菌的抑菌效果明显优于革兰阴性菌。     

Electronic Public Health Registry of Extensively Drug-Resistant Organisms,Illinois, USA

In response to clusters of carbapenem-resistant Enterobacteriaceae (CRE) in Illinois, USA, the Illinois Department of Public Health and the Centers for Disease Control and Prevention Chicago Prevention Epicenter launched a statewide Web-based registry designed for bidirectional data exchange among health care facilities. CRE occurrences are entered and searchable in the system, enabling interfacility communication of patient information. For rapid notification of facilities, admission feeds are automated. During the first 12 months of implementation (November 1, 2013–October 31, 2014), 1,557 CRE reports (≈4.3/day) were submitted from 115 acute care hospitals, 5 long-term acute care hospitals, 46 long-term care facilities, and 7 reference laboratories. Guided by a state and local public health task force of infection prevention specialists and microbiologists and a nonprofit informatics entity, Illinois Department of Public Health deployed a statewide registry of extensively drug-resistant organisms. The legal, technical, and collaborative underpinnings of the system enable rapid incorporation of other emerging organisms.     

基层医院ICU与非ICU主要革兰阴性杆菌分布与耐药性差异

目的了解医院重症监护室(ICU)与非ICU主要革兰阴性(G-)杆菌的分布及耐药性,为临床合理使用抗菌药物提供依据。方法对某院2011—2013年住院患者送检标本中培养分离的G-菌标本来源及耐药性进行统计分析,比较ICU与非ICU的差异。结果 25 153份标本共分离G-菌3 875株,分离率15.41%;其中ICU1 121份标本中分离G-菌527株,分离率47.01%,非ICU24 032份标本分离G-菌3 348株,分离率13.93%,两者比较差异有统计学意义(χ2=899.32,P0.001)。大肠埃希菌和肺炎克雷伯菌产超广谱β-内酰胺酶(ESBLs)菌株检出率:ICU分别为56.00%(28/50)、70.65%(65/92),非ICU分别为52.81%(517/979)和40.37%(241/597)。ICU中铜绿假单胞菌、鲍曼不动杆菌、大肠埃希菌、肺炎克雷伯菌对亚胺培南的耐药率分别为36.59%、88.54%、10.00%、10.87%,均高于非ICU同类菌的耐药率,分别为20.21%、61.15%、1.74%、2.85%。结论 ICU主要G-杆菌的耐药率高于非ICU,且以多重耐药的非发酵菌为主。临床治疗应区别对待,以减少耐药菌的产生。     

对几种蒙药成方剂型微生物检查的分析

目的：通过对4种蒙药成方剂型进行质量检查,分析微生物超标的直接原因。方法：按照《中国药典》2010版第一部附录制剂通则及微生物限度检查法进行实验。结果：4个制剂微生物均不符合规定。结论：与方内糖类和淀粉类成分有关。