大肠埃希菌氨基糖苷酰基转移酶基因型研究

目的：了解大肠埃希菌的耐药谱、氨基糖苷酰基转移酶基因（aac）的分布规律及其与氨基糖苷类抗生素耐药的相关性。方法：琼脂稀释法测定无菌体液分离的44株大肠埃希菌对阿米卡星等12种抗生素的耐药性，聚合酶联反应（PCR）法测定酰基转移酶基因型aac（3）-Ⅰ、Ⅱ和aac（6’）-Ⅰ。结果：大肠埃希菌超广谱β-内酰胺酶（ESBLs）的发生率为45．45％（20／44），对亚胺培南（IPM）、关罗培南（MEM）的耐药率为0，对哌拉西林／他唑巴坦、头孢他啶的耐药率较低（〈20％），对左氟沙星、环丙沙星的耐药率较高（〉60％），对氨基糖苷类阿米卡星、庆大霉素、妥布霉素的耐药率分别为18．18％、56．82％、61．36％。氨基糖苷类耐药模式TG（妥布霉素、庆大霉素）〉TGA（妥布霉素、庆大霉素、阿米卡星）〉T（妥布霉素）〉G（庆大霉素），分别占36．36％、18．189／5、6．82％、2．27％。氨基糖苷酰基转移酶基因检出以aac（3）-Ⅱ最高，占52．27％（23／44），aac（6＇）-Ⅰ次之，占29．55％（13／44），aac（3）-Ⅱ和aac（6’）-Ⅰ同时检出者占15．91％（7／44），未检出aac（3）-Ⅰ。ESBLs阳性株的aac（3）-Ⅱ、aac（6’）-Ⅰ检出率分别为60％、50％，高于ESBLs阴性株的45．81％、12．51％。TG模式与其耐药基因aac（3）-Ⅱ符合率较高为93．75％（15／16）。结论：本地分离大肠埃希菌氨基糖苷类耐药模式以TG为主，酰基转移酶基因以aac（3）-Ⅱ为主，aac（6’）-Ⅰ次之，aac（3）-Ⅰ罕见。     

1990-2004年上海地区临床分离大肠埃希菌耐药性变迁

目的 了解临床分离大肠埃希菌对抗菌药耐药性变迁情况。方法 对1990至2004年上海地区11所医院的细菌耐药监测资料中大肠埃希菌临床分离株的耐药性变迁情况进行分析，细菌药敏采用Kirby-Bauer法。结果 临床分离大肠埃希菌33495株对21种抗菌药药敏试验结果显示，该菌对大多常用抗菌药的耐药性在15年间呈上升趋势。对氨苄西林、哌拉西林的耐药率自69．0％和30．0％分别增至85．0％和71．4％。对头孢菌素类中的头孢唑啉（24．0％-48．3％）、头孢呋辛（18．0％-45．7％）、头孢克洛（33．3％-46．8％）的耐药率均增长，尤其是头孢噻肟的耐药率自1990年的6.0％增至2004年的35．2％。对氟喹诺酮类的耐药性15年间明显增高，且各品种间呈交叉耐药，自1990年的11．0％增至2004年的55．4％。对庆大霉素的耐药率缓慢上升（44．0％-54．0％）。大肠埃希菌对四环素、氯霉素、磺胺甲晤唑／甲氧苄啶（SMZ／TMP）耐药率始终较高。头孢他啶、头孢吡肟、亚胺培南、阿米卡星、β内酰胺类／β内酰胺酶抑制剂复方、呋喃妥因则保持了对大肠埃希菌的良好抗菌活性。产超广谱B内酰胺酶（ESBL）大肠埃希菌所占比例在2000-2004年间逐渐上升，自14．7％增至36．5％，产ESBL菌株耐药性均明显高于非产ESBL者。结论 临床分离的大肠埃希菌对常用抗菌药的耐药性在1990-2004年的15年间普遍呈明显增高趋势。 床分离的大肠埃希菌对常用抗菌药的耐药性在1990--2004年的15年间普遍呈明显增高趋势。     

美英欧药典微生物限度标准的浅析

本文就USP,BP和EuP收载的微生物限度分类列表,并进行了系统的对比分析.前者品种项下的微生物限度分级有11级,是否必要?后者微生物限度分级有5级,更适用.指出ChP微生物限度存在的差距,为药典修订和发展提供依据.     

丙磺舒对阿莫西林在家兔体内的药动学影响

目的:观察丙磺舒对阿莫西林在健康家兔体内药动学的影响.方法:采用微生物杯碟法测定兔血清中阿莫西林的浓度.结果:阿莫西林单剂量肌内注射后,吸收迅速,Tmax=(0.78±0.09)h,Cmax=(0.87±0.30)μg·mL-1,其代谢模型为一级速率一房室模型.当阿莫西林和丙磺舒等剂量伍用时丙磺舒对阿莫西林药动学参数的影响达到最大值:阿莫西林的t1/2由(2.06±0.09)h延长至(5.50±0.52)h,AUC由(4.07±0.05)μg·mL-1·h增加至(13.75±3.09)μg·mL-1·h,Cmax由(0.87±0.30)μg·mL-1增加至(6.30±1.46)μg·mL-1,且三者统计学差异极显著(P<0.01).结论:丙磺舒对阿莫西林的药动学参数的影响呈S型,当两者等剂量伍用时影响最大.     

A non‐fatal case of invasive zygomycete (Lichtheimia corymbifera) infection in an allogeneic haematopoietic cell transplant recipient

Post‐transplant infections in allogeneic haematopoietic cell transplant (allo‐HCT) recipients often have severe consequences. This is especially the case when dealing with zygomycete infections where the result is often fatal. A major problem when dealing with zygomycete infections is the need for an accurate and fast diagnosis as the phylum is highly resistant towards the conventional antifungals. We herein describe a non‐fatal case of Lichtheimia corymbifera infection in an allo‐HCT recipient.     

Bacterial flagella explore microscale hummocks and hollows to increase adhesion

Biofilms, surface-bound communities of microbes, are economically and medically important due to their pathogenic and obstructive properties. Among the numerous strategies to prevent bacterial adhesion and subsequent biofilm formation, surface topography was recently proposed as a highly nonspecific method that does not rely on small-molecule antibacterial compounds, which promote resistance. Here, we provide a detailed investigation of how the introduction of submicrometer crevices to a surface affects attachment of Escherichia coli. These crevices reduce substrate surface area available to the cell body but increase overall surface area. We have found that, during the first 2 h, adhesion to topographic surfaces is significantly reduced compared with flat controls, but this behavior abruptly reverses to significantly increased adhesion at longer exposures. We show that this reversal coincides with bacterially induced wetting transitions and that flagellar filaments aid in adhesion to these wetted topographic surfaces. We demonstrate that flagella are able to reach into crevices, access additional surface area, and produce a dense, fibrous network. Mutants lacking flagella show comparatively reduced adhesion. By varying substrate crevice sizes, we determine the conditions under which having flagella is most advantageous for adhesion. These findings strongly indicate that, in addition to their role in swimming motility, flagella are involved in attachment and can furthermore act as structural elements, enabling bacteria to overcome unfavorable surface topographies. This work contributes insights for the future design of antifouling surfaces and for improved understanding of bacterial behavior in native, structured environments.     

Microbial transformation of asiatic acid by Alternaria longipes

Asiatic acid is a major pentacyclic triterpene isolated from Centella asiatica. It shows a variety of bioactivities. In order to obtain its derivatives, potentially useful for detailed pharmacological studies, the substrate was subjected to incubations with selected micro-organisms. In this work, asiatic acid was converted into three new compounds: 2α,3β,23,30-tetrahydroxyurs-12-ene-28-oic acid (1), 2α,3β,22β,23-tetrahydroxyurs-12-ene-28-oic acid (2), and 2α,3β,22β,23,30-pentahydroxyurs-12-ene-28-oic acid (3) by the fungus Alternaria longipes AS 3.2875. The structures of the three metabolites were determined by 1D and 2D NMR spectral data.     

浅析药品微生物限度检查与食品微生物检验的借鉴

浅析药品微生物限度检查法与食品微生物检验的实用性与指导意义。从实验操作和实验思路两方面提出可行性的参考方案。药品微生物限度检查法与食品微生物检验拥有各自的特点,通过交互补充,共同进步。     

产β 内酰胺酶葡萄球菌在临床标本中的检出及耐药性

目的了解某院产β 内酰胺酶葡萄球菌在临床标本中的检出及耐药现状，为防治葡萄球菌感染提供依据。方法回顾性分析该院2005-2010年临床各科送检标本分离的1 725株产β 内酰胺酶葡萄球菌的临床和实验室资料。结果近6年产β 内酰胺酶葡萄球菌总检出率为94.83%（1 725/1 819），各年度（2005-2010年）检出率分别为88.68%（94/106）、89.69%（174/194）、91.72%（155/169）、97.58%（242/248）、96.10%（591/615）、96.30%（469/487），有逐年上升趋势（χ2=51.11, P<0.01）；各菌种以松鼠葡萄球菌β 内酰胺酶阳性率最高（99.50%，198/199），耳葡萄球菌最低（80.37%，86/107），种间差异有统计学意义（χ2＝58.08，P<0.01）。药敏结果显示，除万古霉素、利奈唑烷、呋喃妥因和利福平外，产β 内酰胺酶葡萄球菌对青霉素、氨苄西林、氨苄西林/舒巴坦、苯唑西林、头孢唑林、环丙沙星、四环素、克林霉素、红霉素、庆大霉素和复方磺胺甲口恶唑呈高度耐药（耐药率51.74%～100.00%）和多重耐药，且产酶菌的耐药性均高于非产酶菌（χ2在7.00～485.39之间，P<0.01）。苯唑西林耐药菌株占产β 内酰胺酶金黄色葡萄球菌和凝固酶阴性葡萄球菌的72.86%和78.30%，是产酶葡萄球菌的主要组成菌群。结论产β 内酰胺酶葡萄球菌的高检出率和对临床常用抗菌药物的高耐药率形势严峻，加强对产酶细菌的监测，遏制其快速增长非常必要。     

Microbial life at ?13 °C in the brine of an ice-sealed Antarctic lake

The permanent ice cover of Lake Vida (Antarctica) encapsulates an extreme cryogenic brine ecosystem (−13 °C; salinity, 200). This aphotic ecosystem is anoxic and consists of a slightly acidic (pH 6.2) sodium chloride-dominated brine. Expeditions in 2005 and 2010 were conducted to investigate the biogeochemistry of Lake Vida’s brine system. A phylogenetically diverse and metabolically active Bacteria dominated microbial assemblage was observed in the brine. These bacteria live under very high levels of reduced metals, ammonia, molecular hydrogen (H₂), and dissolved organic carbon, as well as high concentrations of oxidized species of nitrogen (i.e., supersaturated nitrous oxide and ∼1 mmol⋅L⁻¹ nitrate) and sulfur (as sulfate). The existence of this system, with active biota, and a suite of reduced as well as oxidized compounds, is unusual given the millennial scale of its isolation from external sources of energy. The geochemistry of the brine suggests that abiotic brine-rock reactions may occur in this system and that the rich sources of dissolved electron acceptors prevent sulfate reduction and methanogenesis from being energetically favorable. The discovery of this ecosystem and the in situ biotic and abiotic processes occurring at low temperature provides a tractable system to study habitability of isolated terrestrial cryoenvironments (e.g., permafrost cryopegs and subglacial ecosystems), and is a potential analog for habitats on other icy worlds where water-rock reactions may cooccur with saline deposits and subsurface oceans.