人苍白杆菌脂多糖的制备及致病性的初步研究

目的 对该院脑膜炎患者脑脊液中分离鉴定的人苍白杆菌进行脂多糖内毒素活性的初步研究。方法 用酚水法提取脂多糖作相关生物学活性试验。结果 人苍白杆菌脂多糖具有内毒素生物学活性,但其活性较大肠埃希菌脂多糖弱。结论 分离的人苍白杆菌脂多糖具有内毒素的活性,可能是该菌重要的致病因子,但其毒性低于大肠埃希菌脂多糖。     

116例人苍白杆菌的耐药率及临床危险因素分析

目的探讨人苍白杆菌血流感染的临床特点、危险因素分布及耐药特点,为有效预防和治疗该菌血流感染提供科学依据。方法回顾性统计分析2012年1月至2014年12月广州医学院第三附属医院北院收治的116例血液细菌培养为人苍白杆菌感染的临床和检验资料。结果本研究血流感染人苍白杆菌病例中,性别分布为:男性占52.59%(61/116),女性占47.41%(55/116);年龄分布为:6岁以下47.41%(55/116),50岁以上22.41%(26/116),19~49岁17.24%(20/116),6~18岁12.93%(15/116);科室分布为:儿科占45.69%(53/116),重症监护病房(ICU)占28.45%(33/116),移植科占9.48%(11/116),肾内科占6.03%(7/116),泌尿外科占3.45%(4/116),神经内科占0.86%(1/116)。人苍白杆菌对青霉素和第1、2、3代头孢菌素类、氨曲南耐药性较高,对4代头孢菌素头孢吡肟的敏感性较高,对亚胺培南、环丙沙星100.0%敏感。结论人苍白杆菌对大多数β-内酰胺类抗菌药物耐药率较高,治疗应首选喹诺酮类、碳青霉烯类等抗菌药物。预防该菌的医院血流感染,应尽量减少不必要的侵入性操作,加强抗菌药物的合理规范使用。     

Characterization of a versatile rhizospheric organism from cucumber identified as Ochrobactrum haematophilum

Several rhizobacteria play a vital role in promoting plant growth and protecting plants against fungal diseases and degrading pesticides in the environment. In this study, a bacterial strain, designated H10, was isolated from the rhizosphere at Laixi in Shandong Province, China, and was identified as Ochrobactrum haematophilum based on API 20 NE tests and 16S rRNA gene sequence analysis. The plant growth‐promoting characteristics of the strain were further characterized, and the results showed that strain H10 produces siderophore, indol‐3‐acetic (IAA) and solubilized phosphate but lacks 1‐aminocyclopropane‐1‐carboxylate (ACC) deaminase activity. Inoculation with the strain was found to significantly increase (p < 0.05) the growth of cucumber in pot experiments. Strain H10 was assessed in vitro for antagonism against several pathogenic fungi and showed high antifungal activity. The cell‐free culture filtrates, which had high extracellular chitinase, β;‐1,3‐glucanase and protease activities, could inhibit the growth of all pathogenic fungi tested, indicating that growth suppression was partly due to extracellular antifungal metabolites present in the culture filtrates. Changes in hyphal morphology were observed in phytopathogenic fungi after treatment with the culture filtrates. Additionally, strain H10 was able to degrade 80%, 85% and 58% of the pesticides chlorpyrifos, β;‐cypermethrin and imidacloprid, respectively, within 60 h in liquid culture. The inoculation of strain H10 into soil treated with 100 mg kg^–1of the three pesticides accordingly resulted in a higher degradation rate than in noninoculated soils. These results highlight the potential of this bacterium for use as a biofertilizer and biopesticide and suggest that it may provide an alternative to the use of chemical fertilizers and pesticides in agriculture. Additionally, it may represent a bioremediation agent that can remove contaminating chemical pesticide residues from the environment. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Isolation,identification, and characterization of diesel‐oil‐degrading bacterial strains indigenous to Changqing oil field,China

In the present study, 12 indigenous diesel‐oil‐degrading bacteria were isolated from the petroleum‐contaminated soils of the Changqing oil field (Xi’an, China). Measurement of the diesel‐oil degradation rates of these strains by the gravimetric method revealed that they ranged from 42% to 66% within 2 weeks. The highest degradation rates were observed from strains CQ8‐1 (66%), CQ8‐2 (62.6%), and CQ11 (59%), which were identified as Bacillus thuringiensis, Ochrobactrum anthropi, and Bordetella bronchialis, respectively, based on their 16S rDNA sequences. Moreover, the physiological and biochemical properties of these three strains were analyzed by Gram staining, catalase, oxidase, and Voges–Proskauer tests. Transmission electron microscopy showed that all three strains were rod shaped with flagella. Gas chromatography and mass spectrometric analyses indicated that medium‐ and long‐chain n‐alkanes in diesel oil (C11–C29) were degraded to different degrees by B. thuringiensis, O. anthropi, and B. bronchialis, and the degradation rates gradually decreased as the carbon numbers increased. Overall, the results of this study indicate strains CQ8‐1, CQ8‐2, and CQ11 might be useful for environmentally friendly and cost‐effective bioremediation of oil‐contaminated soils.     

基质辅助激光解吸电离飞行时间质谱在鉴定儿童血流感染少见苍白杆菌的应用及耐药情况分析

目的 快速鉴定和分析儿童血流感染少见苍白杆菌及其耐药情况分析。 方法 收集某儿童医院儿童血流感染的临床标本中分离的苍白杆菌26株,运用基质辅助激光解吸电离飞行时间质谱(matrix-assisted laser desorption/ionization time-of-flight mass spectrometry,MALDI-TOF MS)技术,对其进行检测,并结合测序结果分析确定菌株;根据药敏实验结果,用PCR法分析其耐药情况。 结果 26株实验菌株最后通过MALDI-TOF MS和16S rRNA基因测序技术,有25株被鉴定为解糖精假苍白杆菌,药敏结果显示它们对哌啦西林/他唑巴坦、喹诺酮类、氨基糖苷类和复方新诺明的耐药率为0.0%。而对氨曲南耐药率为100.0%,其他β-内酰胺类抗菌药物有不同的耐药率。AmpC和AmpR耐药基因检测均为阴性。 结论 MALDI-TOF MS能够快速鉴定临床少见苍白杆菌,儿童血流感染的解糖精假苍白杆菌不产头孢菌素酶,结合药敏分析结果及儿童用药特点,建议使用哌啦西林/他唑巴坦。     

30株苍白杆菌的分离鉴定和药物敏感性分析

目的分析临床苍白杆菌分离株的种型特征和药物敏感性。方法收集临床分离苍白杆菌共30株。用手工生化试验、Vitek 2 Compact GN鉴定卡、API 20NE鉴定试条进行生化鉴定,扩增16S rRNA基因并进行测序鉴定和序列分析。用Vitek 2Compact AST-GN13药敏鉴定卡进行微量稀释法的药敏实验。结果经生化鉴定和基因测序,17株为人苍白杆菌、10株为中间苍白杆菌、1株为嗜血苍白杆菌、1株疑为苍白杆菌属内未分类的新种、1株为解糖精假苍白杆菌。药敏试验显示对喹诺酮类和亚胺培南的敏感率分别为100%和93.3%;对三代头孢类抗菌药物和哌拉西林/他唑巴坦的耐药率为93.3%和96.7%;对氨基糖苷类抗菌药物敏感性因菌种而异,人苍白杆菌对阿米卡星、庆大霉素和妥布霉素的敏感率分别为94.1%、88.2%和94.1%,而中间苍白杆菌为0%、10%和0%,差异具有统计学意义(χ2=14.50,P0.05)。结论临床苍白杆菌感染主要由人苍白杆菌和中间苍白杆菌引起,二者对氨基糖苷类抗菌药物敏感率的差异可用于其种型的区分。     

人苍白杆菌分离株部分生物学性状的研究

目的 对本院分离鉴定的1株人苍白杆菌进行16s rRNA基因序列分析以及脂多糖内毒素活性和外膜蛋白免疫性的初步研究。方法 采用自行设计的引物对菌株做PCR扩增和16s rRNA基因序列测定；用酚水法提取脂多糖作相关生物学活性试验；提取外膜蛋白组分免疫动物，观察其对羊布氏杆菌是否有交叉保护作用。结果 本院分离的人苍白杆菌与购自美国苍白杆菌ATCC菌株和购自北京的羊布氏杆菌之间核苷酸序列具有高度同源性（〉98％）；人苍白杆菌脂多糖具有内毒素生物学活性，但较大肠埃希菌脂多糖为弱；以人苍白杆菌外膜蛋白免疫小鼠不能抵御布氏杆菌的攻击。结论 我院分离的人苍白杆菌在遗传学上与羊布氏杆菌具有非常密切的亲缘关系，但其外膜蛋白组分对羊布氏杆菌无交叉保护作用。人苍白杆菌脂多糖具有内毒素的活性，可能是一种重要的致病因子，但其毒性低于大肠埃希菌脂多糖。     

儿童感染人苍白杆菌的耐药性及DHA-1基因检出

目的初步探讨败血症患儿血标本分离的人苍白杆菌耐药机制。方法采用VITEK2compact全自动微生物鉴定药敏系统对败血症患儿分离的病原菌进行鉴定和药敏试验;聚合酶链反应(PCR)法对人苍白杆菌受试株进行AmpC、AmpR、DHA-1、AcrA、RamA、OprD、TEM、SHV等多重耐药基因检测,扩增产物经纯化后测序并进行序列分析。结果从败血症患儿的血标本中检出155株人苍白杆菌,从中随机选取30株进行检测。30株试验菌株中,有20株耐哌拉西林/他唑巴坦,其中16株(80.00%,16/20)扩增出人苍白杆菌AmpC/R基因,2株(10.00%,2/20)扩增出DHA-1基因。30株受试菌均未扩增出AcrA、RamA、OprD、TEM、SHV等基因。将155株人苍白杆菌根据其是否耐哌拉西林/他唑巴坦,分成耐药组(126株)和非耐药组(29株),其中耐药组菌株对氨苄西林、第一～三代头孢菌素、氨曲南等几乎100%耐药,但对左氧氟沙星、亚胺培南、美罗培南、环丙沙星、阿米卡星、庆大霉素等耐药率(0.00%～1.59%)低。结论产AmpC/R是儿童感染人苍白杆菌耐多种抗菌药物的机制,重症患儿可选用亚胺培南。应加强对人苍白杆菌耐药性的监测,防止DHA基因在革兰阴性杆菌中流行。