肺炎克雷伯菌耐药机制的研究进展

肺炎克雷伯菌是临床分离和医院获得性感染最常见的致病菌之一,其主要耐药机制包括产生抗菌药物灭活酶、抗菌药物渗透障碍(生物被膜和外膜孔蛋白缺失)、药物作用靶位的改变、主动外排泵系统的亢进作用、整合子等。肺炎克雷伯菌耐药机制的研究对于控制耐药菌的播散和合理使用抗生素都具有重要的意义。本文就上述耐药机制的研究进展进行综述。     

358株肺炎克雷伯菌的临床分布及耐药性分析

目的分析肺炎克雷伯菌的临床分布及耐药情况,为临床合理使用抗生素提供依据。方法采用回顾性调查的方法对358株肺炎克雷伯菌的标本来源及耐药性进行分析。结果 358株肺炎克雷伯菌中,产ESBLs阳性142株,阳性率为39.7%;ESBLs阳性的肺炎克雷伯菌对所测抗菌药物耐药性显著高于产ESBLs阴性菌,并且出现2株对亚胺培南耐药的肺炎克雷伯菌。结论产ESBLs肺炎克雷伯菌在医院感染中十分流行,多重耐药明显。     

克雷伯菌肺炎患儿外周血中Th17细胞及白细胞介素的变化

目的观察Th17细胞及白细胞介素-17(IL-17)、IL-21和IL-22在克雷伯菌肺炎(KP)患儿外周血中的变化,探讨其在克雷伯菌肺炎临床诊治中的意义。方法采用流式细胞术(FACS)检测36例KP患儿与32例健康儿童外周血Th17淋巴细胞亚群的表达情况。酶联免疫吸附法(ELISA)检测血清中IL-17、IL-21和IL-22的水平。结果 KP组外周血Th17细胞占CD4+T细胞8.15%±3.46%,显著高于健康组5.37%±4.12%(P<0.01)。KP组血清IL-17水平高于健康组(23.13±6.27 pg/mL比12.53±6.64 pg/mL,P<0.05);IL-21和IL-22表达水平与健康组相比差异无显著性(P>0.05)。结论儿童KP感染者外周血Th17细胞比例明显升高,并伴有IL-17水平的升高,提示Th17细胞及其产生的细胞因子IL-17在克雷伯菌肺炎免疫失调过程中起着重要作用。     

环丙沙星体外诱导肺炎克雷伯菌耐药机制的研究

目的：探讨环丙沙星体外诱导敏感肺炎克雷伯菌（KPn）耐药的分子机制。方法对临床分离的敏感肺炎克雷伯菌体外使用环丙沙星,采用多步法诱导耐药,并随机选择10对临床分离敏感菌和诱导后高度耐药菌进行GyrA 基因 QRDR（喹诺酮抗性区,quinolone resistant-determining region）的聚合酶链式反应（PCR）扩增、SDS-PAGE 电泳鉴定外膜外排泵蛋白 TolC 及膜孔蛋白 porin 蛋白的表达。结果诱导后的 KPn 均成为耐药菌,其中高度耐药菌占73．81％。10株诱导的耐药菌中 Ser83突变率为30％;膜孔蛋白 porin 表达均减少,外排泵蛋白 TolC表达均增多。结论环丙沙星的使用与 KPn 耐药密切相关,并可引起 KPn 多种耐药分子产生。     

耐碳青酶烯类肺炎克雷伯菌的替加环素MIC药敏试验和临床特点分析

目的:应用微量肉汤稀释法(MIC)药敏试验测定耐碳青霉烯类肺炎克雷伯菌对替加环素的耐药率,并分析耐药菌的临床特点。方法:搜集2014年11月-2016年4月本院微生物室从不同病区各种临床标本分离的耐碳青酶烯类肺炎克雷伯菌38株(CRKP),应用微量肉汤稀释法进行替加环素药敏试验,从患者年龄、性别、标本类型、原发病、抗生素使用情况等方面对比,分析临床特点与替加环素耐药的相关性。结果:在38株CRKP中筛选到6耐替加环素耐药菌,耐药率为15.8%。耐药性与患者年龄有关(P<0.05),与性别、标本类型、原发病、抗生素使用情况无关(P>0.05)。结论:耐替加环素的耐碳青霉烯类肺炎克雷伯菌已经出现,耐药株多见于老年患者。     

肺炎支原体265株耐药结果分析

目的:为了了解本地区肺炎支原体的对抗生素的耐药情况,为临床医师治疗用药提供依据。方法:采用口痰或咽拭子进行肺炎支原体半定量培养鉴定加药敏试验,并对培养阳性的265株肺炎支原体对14种抗生素的耐药情况进行统计分析。结果:265株肺炎支原体对14种抗生素的耐药率分别为:强力霉素(63.40%)、乙酰螺旋霉素(44.91%)、美满霉素(43.02%)、莫西沙星(43.02%)、克林霉素(34.72%)、交沙霉素(34.34%)、依托红霉素(28.68%)、环丙沙星(28.68%)、阿奇霉素(28.68%)、左氧氟沙星(27.17%)、克拉霉素(26.79%)、加替沙星(26.79%)、罗红霉素(25.66%)、红霉素(24.53%)。结论:本地区肺炎支原体耐药性已经日趋严重,临床医师在治疗支原体肺炎时应该重视药敏结果,选择合理有效的抗生素,是减少耐药菌株的重要手段。     

219株铜绿假单胞菌感染分布与耐药性分析

目的:了解铜绿假单胞菌的感染情况及其耐药性,为临床合理应用抗生素提供科学依据。方法:收集本院临床分离铜绿假单胞菌,分析其科室分布、标本来源及耐药情况。结果:铜绿假单胞菌主要分布于干诊三病房(53.9%),主要以痰液分离最多(91.3%);其耐药率分别为:复方新诺明(100%)、头孢噻肟(83.94%)、庆大霉素(53.42%)、头孢他啶(51.83%)、氨曲南(50.55%)、头孢西林(50.27%)、环丙沙星(48.62%)、左氧氟沙星(44.95%)、妥布霉素(43.38%)、头孢吡肟(42.66%)、阿米卡星(26.30%)、哌拉西林/他唑巴坦(22.57%)、美罗培南(16.90%)、亚胺培南(14.39%)。结论:铜绿假单胞菌的耐药机制复杂,应加强医院耐药菌株的监测,指导临床合理使用抗生素,采取有效的防范措施最大限度减少铜绿假单胞菌感染。     

改良吸引连接管放置装置对神经外科重症患者致病菌感染的影响

目的:探讨神经外科采用改良吸引连接管放置装置进行吸痰对致病菌感染及不良反应发生率的影响。方法:回顾性分析2017年9月-2018年2月本院颅脑手术重症患者139例的临床资料为对照组,2018年3-8月颅脑手术重症患者153例的临床资料为观察组。两组均以按需吸痰法吸痰,对照组采用传统的吸引连接管处理方式,观察组采用改良吸引连接管放置装置处理。观察两组痰培养阳性率及痰中多重耐药菌的数量、不良反应发生率。结果:观察组致病菌阳性率为13.07%,低于对照组的66.19%(X~2=86.903,P=0.000),且两组致病菌均以肺炎克雷伯菌为主;观察组不良反应发生率为18.95%,低于对照组的38.13%,差异有统计学意义(X~2=13.260,P=0.000)。结论:采用改良吸引连接管放置装置可有效降低致病源阳性率,减少交叉感染和环境污染,并明显降低了不良反应发生率,为患者改善预后提供了有效措施。     

解放军第264医院165例多重耐药菌的分布及耐药性分析

目的:研究医院多重耐药菌的临床分布及对抗生素的耐药情况,指导临床合理的应用抗菌药物。方法:将2016年度检验科微生物室出具的多重耐药药敏结果,按照病原菌种类、标本来源、对抗生素的耐药情况进行统计分析。结果:本院2016年共检出165例多重耐药菌,其中革兰阴性菌占56.36%,革兰阳性菌占43.64%。居前5位的依次是表皮葡萄球菌、铜绿假单胞菌、大肠埃希菌、金黄色葡萄球菌和鲍曼不动杆菌。产ESBLs阴性菌株除对碳青霉烯类敏感之外,对其他常用抗菌药物普遍耐药。结论:规范抗生素在临床的合理应用,根据药敏结果谨慎选择抗菌药物,从源头上减少多重耐药的发生。     

吡嗪酰胺耐药对初治菌阳肺结核疗效的影响

目的:探讨吡嗪酰胺耐药对初治菌阳肺结核疗效的影响效果。方法:选取2014年1月-2015年5月本院收治的90例初治菌阳肺结核患者,对其按照药物敏感性试验结果进行分组,其中对吡嗪酰胺敏感同时采用吡嗪酰胺治疗的患者作为研究组,对吡嗪酰胺敏感但不采用吡嗪酰胺治疗的患者作为对照一组,对吡嗪酰胺耐药同时采用吡嗪酰胺治疗的患者作为对照二组,对其药物疗效进行对比分析。结果:研究组患者治疗2个月后的痰菌转阴率、病灶吸收率及空洞缩小率分别为80.00%、85.00%及85.00%,其中痰菌转阴率、病灶吸收率与对照二组对应指标比较差异均有统计学意义(P<0.05);研究组的痰菌转阴率和空洞缩小率与对照一组对应指标比较差异均有统计学意义(P<0.05)。结论:在初治菌阳肺结核患者过程中,对吡嗪酰胺敏感的患者使用该药,其痰菌转阴率、病灶吸收率及空洞缩小率较好,可促进患者病情稳定,早日康复痊愈,值得在临床中推广应用。     

Influence of Asellus aquaticus on Escherichia coli, Klebsiella pneumoniae, Campylobacter jejuni and naturally occurring heterotrophic bacteria in drinking water

Water lice, Asellus aquaticus (isopoda), frequently occur in drinking water distribution systems where they are a nuisance to consumers and water utilities. Whether they are solely an aesthetic problem or also affect the microbial water quality is a matter of interest. We studied the influence of A. aquaticus on microbial water quality in non-chlorinated drinking water in controlled laboratory experiments. Pure cultures of the indicator organisms Escherichia coli and Klebsiella pneumoniae and the pathogen Campylobacter jejuni as well as naturally occurring heterotrophic drinking water bacteria (measured as heterotrophic plate counts, HPC) were investigated in microcosms at 7 °C, containing non-sterilised drinking water, drinking water sediment and A. aquaticus collected from a non-chlorinated ground water based drinking water supply system. Concentrations of E. coli, K. pneumoniae and C. jejuni decreased over time, following a first order decay with half lives of 5.3, 18.4 and 1.3 days, respectively. A. aquaticus did not affect survival of indicators and pathogens substantially whereas HPC were influenced by presence of dead A. aquaticus. Growth rates increased with an average of 48% for bacteria grown on R-2A agar and an average of 83% for bacteria grown on yeast extract agar when dead A. aquaticus were present compared to no and living A. aquaticus present. A. aquaticus associated E. coli, K. pneumoniae and C. jejuni were measured (up to 25 per living and 500 per dead A. aquaticus) and so were A. aquaticus associated heterotrophic bacteria (>1.8*10⁴ CFU per living and >6*10⁴ CFU per dead A. aquaticus). A. aquaticus did not serve as an optimised habitat that increased survival of indicators and pathogens, since A. aquaticus associated E. coli, K. pneumoniae and C. jejuni were only measured as long as the bacteria were also present in the water and sediment.     

Factors influencing inactivation of Klebsiella pneumoniae by chlorine and chloramine

Inactivation of Klebsiella pneumoniae cultures by chlorine and chloramine was evaluated under different growth conditions by varying nutrient media dilution, concentrations of essential inorganic nutrients (FeCl3, MgSO4, phosphate, and ammonium salts), and temperature. All inactivation assays were performed at room temperature (22-23 degrees C) and near neutral pH (7.2-7.5). C*T(99.9) values for chlorine increased >20-fold and for chloramine increased 2.6-fold when cells were grown in 100-fold diluted nutrient broth (2NB) solutions (final TOC of 35-40 mg/L). Background levels of Mg: 6.75 x 10(-2) mM and Fe: 3.58 x 10(-5) mM or high levels of FeCl3 (0.01 mM) and MgSO4 (1 mM) during growth resulted in the highest resistances to chlorine with C*T(99.9) values of 13.06 (+/-0.91) and 13.78 (+/-1.97) mg-min/L, respectively. Addition of low levels of FeCl3 (0.001 mM) and MgSO4 (0.1 mM) to K. pneumoniae cultures during growth resulted in the lowest bacterial resistances to inactivation; C*T(99.9) values ranged from 0.28 (+/-0.06) to 1.88 (+/-0.53)mg-min/L in these cultures. Increase in growth temperature from 22.5 degrees C to 35 degrees C for unamended 2NB cultures resulted in a 42-fold decrease in C*T(99.9) values for chlorine. A similar change in temperature resulted in no significant change in C*T(99.9) values for chloramine. These results indicate that inactivation of K. pneumoniae cultures by chlorine was highly sensitive to changes in growth conditions unlike inactivation by chloramine.     

Decolorization and biodegradation of methyl red by Klebsiella pneumoniae RS-13

Bacterial strains isolated from dye-contaminated sludge decolorized a toxic azo dye, namely, methyl red (MR). Klebsiella pneumoniae RS-13 was selected because of its better abilities to completely decolorize and degrade MR under aerobic conditions. Effects of physico-chemical parameters, such as: temperature and aeration, concentrations of glucose, ethanol, ammonium sulfate and pH of the culture medium on the MR degradation by the bacterium and a previously isolated aerobic MR-degrading bacterium, Acetobacter liquefaciens S-1, were determined. K. pneumoniae RS-13 had higher MR degradation ability than A. liquefaciens S-1. Under optimal conditions, K. pneumoniae RS-13 completely decolorized and degraded 100 mg l⁻¹ of MR in cultural medium. The high MR degradation ability and low nutrient and environmental requirements of K. pneumoniae RS-13 enable this bacterium to be used in the treatment of industrial effluent containing azo dyes.     

Zinc-induced antibiotic resistance in activated sludge bioreactors

Increased levels of bacterial resistance to antibiotics noted in recent decades poses a significant obstacle to the effective treatment and prevention of disease. Although overuse of antibiotics in agriculture and medicine is partially responsible, environmental exposure to heavy metals may also contribute to antibiotic resistance, even in the absence of antibiotics themselves. In this study, a series of eight lab-scale activated-sludge reactors were amended with Zn and/or a suite of three antibiotics (oxytetracycline, ciprofloxacin, and tylosin), in parallel with unamended controls. Classical spread-plating methods were used to assess resistance to these compounds in culturable bacteria over 21 weeks. After seven weeks of general acclimation and development of baseline resistance levels (phase 1), 5.0 mg/L Zn was added to half of the reactors, which were then operated for an additional 7 weeks (phase 2). For the final seven weeks (phase 3), two of the Zn-amended reactors and two of the control reactors were amended with all three antibiotics, each at 0.2 mg/L. Zn amendment alone did not significantly change resistance levels at the 95% confidence level in phase 2. However, tylosin resistance increased significantly during phase 3 in the Zn-only reactors and resistance to all three antibiotics significantly increased as a consequence of combined Zn+antibiotic amendments. Ambient dissolved Zn levels in the reactors were only 12% of added levels, indicating substantial Zn removal by adsorption and/or precipitation. These results show that sub-toxic levels of Zn can cause increased antibiotic resistance in waste treatment microbial communities at comparatively low antibiotic levels, probably due to developed cross-resistance resulting from pre-exposure to Zn.     

再生骨料对混凝土的抗氯离子渗透性能影响

利用III级再生粗、细骨料制备C30和C40两种强度等级再生骨料混凝土,并分别掺加0和30%粉煤灰。测定该混凝土电通量,并分析再生粗、细骨料对混凝土抗氯离子性能影响规律。试验结果表明:随着再生骨料替代率增加,混凝土抗氯离子渗透性能逐渐减低,且对C40混凝土抗氯离子渗透性能影响较小;再生骨料混凝土中掺入30%粉煤灰,可有效改善其抗氯离子渗透性能。     

掺和料对混凝土抗硫酸盐侵蚀性能的影响

对掺入高活性特细掺和料（FC掺和料）的混凝土进行硫酸盐侵蚀试验，试验表明在混凝土中掺加适量FC料，可以提高混凝土的耐腐蚀性能。从微观孔结构分析了FC掺和料提高高性能混凝土抗硫酸盐腐蚀性能的机理。指出硫酸根离子（SO^2－4）在混凝土中起到了激发FC掺和料及腐蚀混凝土的双重作用。     

Wastewater treatment contributes to selective increase of antibiotic resistance among Acinetobacter spp.

The occurrence and spread of multi-drug resistant bacteria is a pressing public health problem. The emergence of bacterial resistance to antibiotics is common in areas where antibiotics are heavily used, and antibiotic-resistant bacteria also increasingly occur in aquatic environments. The purpose of the present study was to evaluate the impact of the wastewater treatment process on the prevalence of antibiotic resistance in Acinetobacter spp. in the wastewater and its receiving water. During two different events (high-temperature, high-flow, 31 °C; and low-temperature, low-flow, 8 °C), 366 strains of Acinetobacter spp. were isolated from five different sites, three in a wastewater treatment plant (raw influent, second effluent, and final effluent) and two in the receiving body (upstream and downstream of the treated wastewater discharge point). The antibiotic susceptibility phenotypes were determined by the disc-diffusion method for 8 antibiotics, amoxicillin/clavulanic acid (AMC), chloramphenicol (CHL), ciprofloxacin (CIP), colistin (CL), gentamicin (GM), rifampin (RA), sulfisoxazole (SU), and trimethoprim (TMP). The prevalence of antibiotic resistance in Acinetobacter isolates to AMC, CHL, RA, and multi-drug (three antibiotics or more) significantly increased (p < 0.01) from the raw influent samples (AMC, 8.7%; CHL, 25.2%; RA, 63.1%; multi-drug, 33.0%) to the final effluent samples (AMC, 37.9%; CHL, 69.0%; RA, 84.5%; multi-drug, 72.4%), and was significantly higher (p < 0.05) in the downstream samples (AMC, 25.8%; CHL, 48.4%; RA, 85.5%; multi-drug, 56.5%) than in the upstream samples (AMC, 9.5%; CHL, 27.0%; RA, 65.1%; multi-drug, 28.6%). These results suggest that wastewater treatment process contributes to the selective increase of antibiotic resistant bacteria and the occurrence of multi-drug resistant bacteria in aquatic environments.     

泊松效应对打桩桩侧阻力的影响

讨论了管桩在打桩时压力波和拉力波分别产生的正负泊松效应对桩侧阻力的影响。通过分析桩土界面处桩土单元的受力情况，以粘性土抗剪强度公式为主要理论依据，推导给出了受泊松效应影响的打桩桩侧阻力公式，最后由一算例来测试泊松效应对打桩侧阻力的影响。计算结果表明，泊松效应对打桩侧阻力的影响很小，可以忽略不计。     

Influence of strain histories on liquefaction resistance of sand

The liquefaction resistance of sand increases with cyclic pre-shearing and pre-shaking as a result of earthquakes if the strain level in the pre-shearing is small. When larger shear strains are imposed, liquefaction resistance decreases. These complicated effects of pre-shearing histories on the liquefaction resistance are investigated in this study through a series of cyclic triaxial tests. Various combinations of cyclic stress amplitude and number of cycles of pre-shearing are examined. The tested sand is Toyoura Sand at 45% relative density, under a confining pressure of 50 kPa. Test results indicate that for the range of shear strain amplitude in pre-shearing smaller than 0.35%, the liquefaction resistance increases with pre-shearing. The increase in the liquefaction resistance depends strongly on the volumetric strain in the pre-shearing, and several effects of the shear stress amplitude and number of cycles can be negligible. Small volumetric strain of the order of 1% doubled the liquefaction resistance. Meanwhile, in the range of shear strain amplitude larger than 0.6%, the liquefaction resistance decreases. The liquefaction resistance decreases as the shear strain amplitude increases. Shear strain amplitude is one of the factors dominating this degrading effect, and the volumetric strain exerts beneficial effects to a certain extent. In this study, another series of tests are conducted to investigate the combined effects of small and large strain amplitude pre-shearing. It is observed that small shear strain pre-shearing cycles subsequent to large shear strain cycles erased the degrading effect of the latter. However, a large shear strain pre-shearing after small strain cycles degrades the beneficial effect of the small shear strain pre-shearing cycles previously applied to the specimens; however, the effects of the former small strain pre-shearing remains.     

渗克宝渗透结晶型掺和剂对混凝土耐化学侵蚀和冻融循环的影响

对加入渗克宝渗透结晶型掺和剂的砂浆试件进行吸水率、耐化学侵蚀和冻融循环测试,研究了添加掺和剂对前后试件的吸水率、抗压强度和抗渗压力的影响。结果表明:渗克宝渗透结晶型掺和剂可以有效防止水的侵入,明显降低水泥基材料的吸水率;赋予混凝土优良的耐化学侵蚀和抗冻融循环能力,提高混凝土的耐久性。