Evaluation of interactions between strains of S. aureus isolated from different clinical specimens with peripheral blood phagocytic cells

The aim of this study was to investigate the interactions occurring between peripheral blood phagocytes and strains of S. aureus isolated from different clinical specimens (blood, respiratory tract, pus). To evaluate the sensitivity of microorganisms to bactericidal activity of phagocytes, monocytes and granulocytes separated from peripheral blood by standard density gradient and by counter-current centrifugal elutriation were incubated with suspensions of opsonized bacteria. In parallel, the viability of phagocytes was examined by flow cytometry, and the ability of bacteria to trigger reactive oxygen intermediates (ROI) production was evaluated by chemiluminescence measurement. To investigate efficiency of phagocytosis, bacteria were labelled with fluorescein isothiocyanate (FITC) and the percentage of cells containing FITC-labelled bacteria was analysed by flow cytometry. The data obtained show that strains of S. aureus originated from different clinical specimens, differ in their sensitivity to bactericidal activity of phagocytes--strains isolated from the blood show the highest, but strains isolated from respiratory tract show the lowest sensitivity for killing. These strains differ too in their ability to trigger monocyte CL response. Contrary, there was no difference in toxicity of bacteria against phagocytes. Strains isolated from peripheral blood showed significant negative correlation between the ability to trigger CL response and toxicity against phagocytes.     

老年气管插管患者下呼吸道感染细菌分布及 耐药性分析

目的研究老年气管插管患者下呼吸道感染的病原菌分布及耐药情况,为临床插管前预防性经验用药提供参考。方法回顾性分析2014-2016年上海市虹口区江湾医院老年气管插管患者的病原菌分布及耐药性情况。结果 560例标本中共检出177株致病菌,其中革兰阴性杆菌121株(68.36%),以肺炎克雷伯菌、铜绿假单胞菌为主;除鲍曼不动杆菌/溶血不动杆菌外,其他革兰阴性杆菌对亚胺培南、美罗培南敏感性均较高。革兰阳性球菌检出52株(29.38%),以金黄色葡萄球菌为主(其中MRSA 37株),对万古霉素敏感性较高。另外分离到真菌4株。结论气管插管患者下呼吸道感染致病菌以肺炎克雷伯菌、铜绿假单胞菌、金黄色葡萄球菌为主。在临床应用中,应根据本地区、本医院的病原菌分布状况和细菌耐药情况,给予适当药物,预防感染。     

Surface properties of Staphylococcus aureus affecting chemiluminescence response of human phagocytes

To assess the surface properties of Staphylococcus aureus affecting the response of human phagocytes, the effects of the organisms with different surface properties on the chemiluminescence (CL) response of human phagocytes were examined. The magnitude of the phagocytic CL response to hydrophobic strains was significantly greater than that to hydrophilic strains, while no significant difference in the CL response was seen between protein A-deficient strains and their parent strains. The CL response to the hydrophilic organisms prepared from a hydrophobic strain by trypsin treatment decreased significantly. These results suggest that the phagocytic CL response to staphylococci depends on the hydrophobicity of the surface, but not on the presence of protein A. Two protein A-deficient strains which were isolated from protein A-positive strains showed identical hydrophobicity with their parent strains. All of the hydrophilic strains isolated from hydrophobic strains possessed protein A identical to that of their parent strains. Moreover, a hydrophilic strain could be isolated from a protein A-deficient, hydrophobic strain. These results strongly suggest that protein A is not solely responsible for the surface hydrophobicity of S. aureus.     

Characteristics of Staphylococcus aureus, isolated from airways of cystic fibrosis patients, and their small colony variants

The colonization of respiratory tract by Staphylococcus aureus is a frequent feature of cystic fibrosis (CF), especially in pediatric patients. The formation of small colony variants (SCVs), which produce reduced amounts of alpha-toxin, is one of the proposed ways of staphylococcal accommodation in an intracellular niche. The aim of the present study was to compare some properties of S. aureus SCVs and their parent strains. A site-directed S. aureus hemB mutant and parent strain 8325-4 were included in the study (control pair). Normal and SCV strain pairs from CF patients as well as control strains were tested for the susceptibility to defensins, killing activity of professional phagocytes and adhesion to A549 cell line. Because S. aureus are exposed to many cationic proteins in the host, we challenged a clinical isolate with minimal subinhibitory concentration (subMIC) of protamine and found that hemin and menadione auxotrophic SCVs emerged. SCVs were more resistant than normal strains to protamine but not to dermaseptin. The susceptibility to the bactericidal activity of magainin was the same for normal and SCV strains. The protamine resistance of normal as well as SCVs was strongly enhanced by high salt concentration. The adhesion of some SCVs to A549 cells was higher than adhesion of parental strains. However, the number of adherent bacteria (SCVs) was diminished in the presence of hemin for hemin auxotrophs. The uptake of SCVs by granulocytes was lower than ingestion of normal strains, but SCVs were killed with equal or greater potency. SCVs are adapted to intracellular survival and persistence in the host under certain circumstances. The ability to form a variant subpopulation affords S. aureus additional survival options.     

下呼吸道感染患者病原菌分布及耐药性

目的分析下呼吸道感染患者病原菌分布及耐药性,指导临床合理用药。方法收集我院2013年至2015年院内感染患者痰标本进行细菌培养和药物敏感性试验。结果 3年共收集下呼吸道痰液标本21 615份,分离病原菌5 621株,阳性率为26.0%;其中革兰阴性(G~-)菌4 249株,占75.6%,以铜绿假单胞菌居多(20.7%);真菌764株,占13.6%,以白假丝酵母居多(12.6%);革兰阳性(G~+)菌608株,占10.8%,以金黄色葡萄球菌居多(9.9%)。药物敏感试验结果显示:G~-杆菌对亚胺培南、美洛培南耐药率最低,对青霉素类、喹诺酮类和部分三代头孢类等抗菌药耐药率较高(50.0%)。G~+球菌对万古霉素、利奈唑胺耐药率为零,对青霉素类、喹诺酮类和红霉素等抗菌药耐药率较高(40.0%)。结论下呼吸道感染患者病原菌以G~-杆菌为主,耐药性呈增长趋势,临床应加大病原菌分布检测及其耐药性监测力度,及时调整抗菌药物用药。     

小儿呼吸道感染常见病原菌及药敏结果分析

目的:了解小儿下呼吸道感染的常见病原菌及其对抗菌药物的敏感性.方法:对北京市和平里医院儿科两年来确诊治疗的156例小儿呼吸道感染患儿的痰标本进行培养及药敏试验.结果:156例标本检出致病菌98株,其中G-杆菌71株(72.4％),G+球菌23株(23.5％),真菌4株(4.1％),主要致病菌依次为肺炎克雷伯菌26株,大肠埃希菌20株.流感嗜血杆菌13株,金黄色葡萄球菌7株,肺炎链球菌5株.药敏结果显示,G-杆菌对亚胺培南均敏感,其次为头孢西丁、庆大霉素,G+球菌对万古霉素均敏感,对头孢西丁、庆大霉素、环丙沙星、阿米卡星有较高的敏感性.结论:革兰阴性杆菌为本地区小儿呼吸道感染的主要致病菌,真菌的感染率也呈上升趋势,临床上应及时检测,合理用药.     

232株金黄色葡萄球菌的临床分布特征及耐药性分析

目的了解金黄色葡萄球菌(金葡菌)临床分离株的感染分布特点及耐药现状,以便为临床感染治疗及预防提供帮助。方法收集南昌大学第二附属医院2007年1月至2009年12月临床分离的非重复金葡菌232株。常规方法进行菌株分离,血浆凝固酶、金葡菌单克隆抗体及Vitek-32型仪进行菌株鉴定,纸片扩散法测定菌株对抗菌药物的敏感性,头孢西丁法检测耐甲氧西林金葡菌(MRSA),WHONET5.5软件分析数据。结果下呼吸道标本中分离的金葡菌最多,占44.0%,其次是脓液(20.3%)和血液(18.1%)。232株金葡菌中共检测到MRSA 131株(56.6%),金葡菌对青霉素的耐药率最高(90.0%),对庆大霉素、左氧氟沙星、克林霉素、红霉素和四环素的耐药率均50.0%;耐药率在10.0%~50.0%的有阿米卡星、复方磺胺甲噁唑和夫西地酸;对替考拉宁耐药率非常低(1.3%);未出现耐万古霉素的菌株。结论下呼吸道及皮肤软组织是金葡菌的主要感染部位;金葡菌对临床常用抗菌药物的耐药率近3年来趋于稳定,糖肽类抗菌药物对其仍有非常强的抗菌活性。     

表皮葡萄球菌对大鼠变应原敏感性的影响

目的筛选具有较好抑制金黄色葡萄球菌效果的表皮葡萄球菌,研究通过鼻腔进行表皮葡萄球菌调节观察大鼠对变应原敏感性的效果。方法由鼻腔拭子稀释液分离筛选得到的9株表皮葡萄球菌(Staphylococcus epidermidis),使用上清液抑制法选取抑制金黄色葡萄球菌效果最好的表皮葡萄球菌做体内实验。将Wistar大鼠分为阴性组、模型组、表葡调节组。模型组、表葡调节组使用OVA建立呼吸道炎症模型,使用表皮葡萄球菌DMSA16001进行滴鼻调节2周,同时用PBS进行滴鼻对照。统计抓鼻和喷嚏数,用ELISA进行肺灌洗液(BALF)和外周血IgE的检测。结果 (1)不同株的表皮葡萄球菌均对金黄色葡萄球菌有抑制作用,表皮葡萄球菌DMSA16001对金黄色葡萄球菌的抑制率最高。(2)与模型组相比,表葡调节组的抓鼻数显著下降(t=2.173,P=0.049),喷嚏数有下降趋势,表葡调节组的肺灌洗液和外周血血清的IgE水平均呈现下降趋势。结论对金黄色葡萄球菌有抑制作用的表皮葡萄球菌能使OVA造模的哮喘大鼠对变应原敏感性降低。     

ICU机械通气并发下呼吸道医院感染病原菌的调查分析

目的：分析ICU机械通气并发下呼吸道医院感染病原学构成及耐药情况。为临床防治提供依据。方法：对我院1996年6月-1999年6月3间ICU收住的98例机械通气合并下呼吸道医院感染患者的致病菌及药敏结果进行回顾性调查。结果：共检出致病毒128株,其中革兰阴性细菌（G^-菌）占66.4%（85株）,革兰阳性细菌（G^ 菌）占25.8%(33株）,真菌占7.8%(10株）;前四位致病菌分别为铜绿假单胞菌（24株）,革兰阳性细菌（G^ 菌）占25.8%(33株）,真菌占7.8%(10株）;前四位致病菌分别为铜绿假单胞菌（24株）,金黄色葡萄球菌（22株）,不动杆菌属（21株）,肠杆菌属（18株）,药敏结果显示这类菌株多重耐药现象严重。结论：ICU机械通气并发下呼吸道医院感染病原体构成以G^-菌为主,其药敏试验呈多重耐药,临床应重视病原学检查,开展细菌耐药性监测,合理使用抗菌药物。     

深圳市人民医院近五年临床分离金黄色葡萄球菌的 分布及耐药性分析

目的分析医院感染患者金黄色葡萄球菌的临床分布特征及耐药性变化,为临床治疗金黄色葡萄球菌感染提供依据。方法回顾性分析2012年1月至2016年12月我院从临床各类标本中分离获得的1 141株金黄色葡萄球菌,统计其在各类标本和病区中的分布特点,并用K-B法测定该菌对常用抗菌药物的敏感性。结果 5年中共分离出1 141株金黄色葡萄球菌,标本来源构成比最多的是伤口分泌物(43.3%)、呼吸道标本(24.0%)和血液标本(10.2%)。耐甲氧西林金黄色葡萄球菌(MRSA)共有339株,占29.7%。各年MRSA的检出数依次为53株(31.9%)、51株(26.0%)、82株(35.2%)、81株(30.3%)和72株(26.0%)。MRSA主要分离自神经外科(13.8%)、呼吸监护室(10.6%)、重症监护室(8.8%)和骨科(7.7%)。MRSA对抗菌药物的耐药性普遍高于MSSA,二者比较差异有统计学意义(P0.05)。未发现对万古霉素、利奈唑胺、替考拉宁耐药的金黄色葡萄球菌。结论 MRSA感染多发生于长期使用抗菌药物,有皮肤软组织伤口及侵入性操作的科室及患者。MRSA具有多重耐药性,应严格掌握抗菌药物的使用适应证;同时临床治疗应根据药物敏感性报告针对性地合理用药,以便及时有效地控制感染并防止耐药菌株的扩散。     

Anti-MRSA activity of alkyl gallates.

A series of alkyl gallates (3,4,5-trihydroxybenzoates) was found to show antibacterial activity against Gram-positive bacteria including methicillin resistant Staphylococcus aureus (MRSA) strains. For example, dodecyl (C(12)) gallate (1) exhibited bactericidal activity against MRSA ATCC 33591 strain with the minimum bactericidal concentration (MBC) of 25 microg/mL (74 microM). The time-kill curve study showed that dodecyl gallate is bactericidal against this MRSA strain. This bactericidal activity comes in part from its ability to inhibit respiratory electron transport systems. The length of the alkyl chain is not a major contributor but plays an important role in eliciting the activity.     

医院内感染的病原菌分布及其耐药谱的分析

本文统计了我院１９９２年８月—１９９４年７月两车间医院内感染病原菌的分离结果,分离出病原菌２５种７５８株,其中革兰氏阳性菌１６３株（占２１．５１％）,革兰氏阴性菌３７８株（占４９．８７％）,真菌２１７株（占２８．６２％）。院感病原菌依次为,白色念珠菌、绿脓假单胞菌表、葡菌、肺炎克雷伯氏菌、酵母菌及大肠艾希氏菌等,显示了真菌及表葡菌在院内感染中已经上升到不可忽略的地位。用１８种常用抗生素,对除真菌外的上述病原菌５４１株做耐药谱测定,并发现除了表葡菌及多数革兰氏阴性菌对喹谱酮类及少数头孢三代抗生素尚属敏感外,大部分均具有越来越广泛的耐药性。     

神经外科颅内出血患者下呼吸道感染病原菌的耐药性监测

目的了解神经外科重症监护室（NICU）颅内出血患者下呼吸道感染病原菌的种类及耐药情况,为临床合理用药提供依据。方法对2010年1月至2011年1月颅内出血的患者,其下呼吸道感染病原菌的种类及耐药性进行回顾性分析。结果分离出的374例病原菌中以革兰阴性杆菌为主,占81．8％,革兰阳性球菌占4．0％,真菌占14．2％。分离率较高的细菌依次为鲍曼不动杆菌、铜绿假单胞菌、肺炎克雷伯菌、嗜麦芽窄食单胞菌、金黄色葡萄球菌。其中,产超广谱β-内酰胺酶（ESBLs）的肺炎克雷伯菌的检出率为50．0％;耐甲氧西林金黄色葡萄球菌（MRSA）的检出率为73．3％。鲍曼不动杆菌和铜绿假单胞菌对丁胺卡那、妥布霉素、多粘菌素B有较好的敏感性;而金黄色葡萄球菌对复方新诺明、呋喃妥因、万古霉素耐药率较低。结论NICU颅内出血患者下呼吸道感染以多重耐药的革兰阴性杆菌为主,临床应根据药敏结果合理用药,控制和减少感染的发生。     

小儿下呼吸道感染痰培养标本病原菌构成分析

目的了解小儿下呼吸道感染病原菌的分布及对常用抗菌药物的耐药状况。方法对2710例小儿下呼吸道感染患者痰标本进行培养,用VITEK-2Compact微生物鉴定系统鉴定菌种和药敏试验,WHO-NET5．4软件对数据进行分析。结果共分离病原菌675株,革兰阴性杆菌457株,占67．7％,主要为大肠埃希菌、肺炎克雷伯菌;革兰阳性球菌159株,占23．5％,主要为金黄色葡萄球菌、肺炎链球菌;真菌59株,占8．7％,主要为白色假丝酵母菌。结论小儿下呼吸道感染病原菌以革兰阴性杆菌为主,耐药性较为严重,应不断加强耐药性监测,合理使用抗菌药物。     

The bactericidal effects of the respiratory burst and the myeloperoxidase system isolated in neutrophil cytoplasts

Neutrophil polymorphonuclear leucocytes kill bacteria by oxygen-dependent and oxygen-independent mechanisms. Many potentially toxic mechanisms have been described, but the complexity of the phagosomal environment and the synergy between oxidative and non-oxidative systems hamper the investigation of individual bactericidal mechanism in whole cells. Neutrophil cytoplasts are greatly depleted of granule proteins and permit the investigation of the bactericidal effects of the respiratory burst in isolation. In this study they have been used to examine the role of the respiratory burst and myeloperoxidase in oxygen-dependent killing of Staphylococcus aureus. Cytoplasts generated oxygen radicals at comparable rates to human neutrophils and phagocytosed but did not kill S. aureus. The selective reconstitution of the myeloperoxidase-hydrogen peroxide-halide system by coating bacteria with myeloperoxidase conferred on cytoplasts the ability to kill intracellular bacteria. However, extracellular killing by diffusible bactericidal factors was not detected in this system.     

Respiratory burst activity of Atlantic cod (Gadus morhua L.) blood phagocytes differs markedly from that of rainbow trout

In the present study we investigated the respiratory burst (RB) activity of Atlantic cod (Gadus morhua L.) blood phagocytes and we evaluated how the RB activity of cod blood cells differ from that of trout. The RB activities were measured directly from highly diluted whole blood as luminol-amplified chemiluminescence (CL) under various conditions. Studies regarding the blood dilutions for cod whole blood chemiluminescence measurements (WBCL) revealed that at a final blood dilution of 1.5 microl ml(-1) or less the CL response was strictly proportional to the number of phagocytes. This range of blood dilution did not markedly differ from that of trout. However, the opsonisation capacity of cod plasma was markedly poorer. The RB activity of phagocytes was most active at 15 degrees C when heterologous cod serum was used as a source of opsonin, whereas at final blood dilution of 8.0 microl ml(-1) (when homologous cod plasma was at a higher concentration) the highest RB activity was observed at 10 degrees C. Aeromonas salmonicida strain MT004 (As MT004) induced higher RB activity than the two known pathogens for cod, atypical A. salmonicida and Vibrio anguillarum. Cod blood phagocytes were more responsive to plastic surfaces and the adhesion response of phagocytes was partly inhibited but did not totally vanish even at a final gelatin concentration of 0.4%. Moreover, cod serum enhanced the adherence of phagocytes and cod blood phagocytes also showed slow spontaneous degranulation. Finally, within the tested anticoagulants (heparin, Na-citrate, EDTA) heparin treated blood phagocytes generated the highest RB activity.     

社区老年人上呼吸道定植菌调查及药敏分析

调查社区老年人上呼吸道的定植菌情况,能够了解引起社区老年人呼吸道感染的危险因素,分析主要定植菌的药敏结果,指导社区老年人呼吸道感染的经验治疗。取社区老年人咽喉部拭子进行细菌分离培养及鉴定,调查呼吸道定植菌情况,并对主要定植菌进行药敏试验,细菌鉴定应用法国生物梅里埃公司的细菌鉴定仪VITEK2和API系统,药敏试验采用K-B纸片琼脂扩散法,结果统计应用WHONET5.4软件。对706例社区老年人上呼吸道标本进行分离培养,有274份标本生长了致病菌或条件致病菌,其中248份标本有一种细菌生长,26份标本生长2种细菌,总体阳性率为38.8%。共分离9种细菌,居首位的细菌是肺炎克雷伯菌151株,占21.4%,其次为副流感嗜血杆菌74株,占10.5%,第3位的是β-溶血链球菌31株,占4.4%。75株肺炎克雷伯菌的药敏结果显示全部为敏感株,从药敏表型分析具有较高的同源性。老年人群上呼吸道定植菌以革兰阴性杆菌尤其以肺炎克雷伯杆菌为主,并对常用抗菌药物有高度敏感性,一旦发生定植菌感染应选择合适的抗菌药物并给予恰当的治疗方案,防止细菌产生耐药性。     

Killing of Escherichia coli by mononuclear phagocytes and neutrophils stimulated in vitro with beta-1,3-D-polyglucose derivatives.

Human monocytes, human peritoneal macrophages, mouse peritoneal macrophages and human peripheral neutrophils pretreated with beta-1,3-D-polyglucose derivatives showed pronounced bactericidal capacity to Escherichia coli compared to control cells. The increased bactericidal capacity was detectable in mononuclear phagocytes over a wide range of concentrations of bacteria. Granulocytes, however, showed bactericidal capacity only at low concentrations of bacteria. The pretreated mononuclear phagocytes released significant amounts of IL-1 and PGE2. However, there was no significant release of tumor necrosis factor (TNF). By incubating unstimulated cells with purified IL-1 and TNF, the bactericidal activity of neutrophils and mononuclear phagocytes was enhanced. Our data indicate that the inability of neutrophils stimulated with beta-1,3-D-polyglucose derivatives to kill large numbers of bacteria could be overcome by a combined treatment with purified IL-1 or TNF in addition to beta-1,3-D-polyglucose derivatives. By incubating unstimulated cells with medium from beta-1,3-D-polyglucose-treated human peritoneal macrophages, the bactericidal activity of the cells was enhanced to the same extent as cells pretreated with purified TNF and IL-1. Cells incubated with IL-1-depleted medium from beta-1,3-D-polyglucose-treated human peritoneal macrophages, showed reduced bactericidal activity compared to cells incubated with undepleted medium. These studies demonstrate that beta-1,3-D-polyglucose-treated mononuclear phagocytes and neutrophils show enhanced bactericidal activity. The enhanced activity is partly caused by stimulation of the cells with IL-1 released from mononuclear phagocytes and partly by other unknown effects of beta-1,3-D-polyglucose derivatives on both mononuclear phagocytes and neutrophils.     

News & Notes: Adhesiveness of Bacteroides fragilis Strains Isolated from Feces of Healthy Donors, Abscesses, and Blood

Bacteroides fragilis strains attached to oral epithelial cells (ECs) and the cell line Intestine 407 and associated with human phagocytes with different efficiencies depending on their source. The 58%, 75%, and 40% of strains isolated from feces, abscesses, and blood respectively adhered to ECs with good efficiency (11–40 bacteria/cell). Of the strains from feces and abscesses, 17% and 20% exhibited a high adherence (>40 bacteria/cell); however, none of the blood isolates presented this property. Similar results were obtained with the cell line Intestine 407 and human phagocytes. Of the isolates from feces, abscesses, and blood, 20%, 56%, and 71% respectively also exhibited hemagglutination ability, indicating that this property is a virulence trait more frequently present among pathogenic isolates than in commensal strains.     

In vitro effect of subinhibitory concentrations of ceftazidime and meropenem on the serum sensitivity of Pseudomonas aeruginosa strains

The aim of this study was to determine the effect of subminimal inhibitory concentrations (subMICs) of ceftazidime, meropenem and gentamicin on the in vitro serum sensitivity of Pseudomonas aeruginosa strains isolated from a variety of isolation sites at two medical wards and an intensive care unit in a government university hospital in Croatia. A total of 20 serum-resistant P aeruginosa strains isolated from different clinical specimens were selected. Bacteria were exposed to 1/2, 1/4, 1/8, 1/16, and 1/32 x MIC of each antibiotic tested. Sensitivity of P. aeruginosa strains to bactericidal activity of normal human serum before and after bacterial exposure to subMICs was determined. Significant difference in serum sensitivity of the strains was observed after the bacteria were exposed to subMICs of ceftazidime and meropenem (p < 0.01), while the exposure to subMICs of gentamicin did not affect significantly the resistance of tested strains to the serum bactericidal activity. Comparing the number of serum-resistant strains before and after exposure to subMICs of antibiotics, statistically significant differences were determined (p < 0.01) after exposure of the strains to 1/2, 1/4, 1/8 and 1/16 x MIC of meropenem, and after exposure to 1/2, 1/4 and 1/8 x MIC of ceftazidime. SubMICs of ceftazidime and meropenem affected not only the resistance to serum bactericidal activity of bacteria, but also their morphology. The alterations in bacterial morphology caused by subMICs of ceftazidime and meropenem could be connected with consecutive bacterial serum sensitivity.