mCIM试验检测临床产碳青霉烯酶革兰阴性杆菌的应用价值

目的评估改良碳青霉烯灭活试验(mCIM)在检测临床产碳青霉烯酶革兰阴性杆菌中的应用价值。方法采用mCIM、改良Hodge(MHT)及Carba NP试验分别检测106株碳青霉烯酶基因阳性的革兰阴性杆菌(36株肠杆菌科细菌、26株铜绿假单胞菌及44株鲍曼不动杆菌),并比较差异。同时,收集湘雅医院2016年1月-12月临床分离的非重复性耐碳青霉烯类革兰阴性杆菌106株,同期随机选取100株分离的碳青霉烯类敏感菌株作为对照组,mCIM试验检测碳青霉烯酶,PCR检测碳青霉烯酶基因,分析其敏感性及特异性。结果 (1)106株碳青霉烯酶基因阳性菌株,mCIM试验:肠杆菌科细菌的敏感性、特异性为88.9%(32/36),铜绿假单胞菌均为阴性。MHT试验:肠杆菌科细菌的敏感性、特异性为77.8%(28/36),铜绿假单胞菌的敏感性、特异性为69.2%(18/26)。Carba NP试验:肠杆菌科细菌的敏感性、特异性为97.2%(35/36),铜绿假单胞菌的敏感性、特异性为57.7%(15/26)。鲍曼不动杆菌3种方法均为阴性。肠杆菌科细菌中,MHT与Carba NP试验差异有统计学意义(χ~2=6.222,P=0.028),MHT与mCIM试验差异无统计学意义(χ~2=1.600,P=0.343),Carba NP与mCIM试验差异无统计学意义(χ~2=1.934,P=0.357);铜绿假单胞菌中,MHT与Carba NP试验阳性,二者差异无统计学意义(χ~2=0.746,P=0.565)。(2)144株临床分离肺炎克雷伯菌(碳青霉烯类耐药及敏感菌株分别为44株、100株),采用美罗培南和亚胺培南分别做mCIM试验,其敏感性和特异性均为100%,且与PCR的结果一致。结论 mCIM试验在肠杆菌科细菌中敏感性高、特异性强,操作简单,结果易于判断,具有良好的临床应用价值。     

A polyphasic taxonomic study of thermophilic bacilli from shallow, marine vents

Eighty-seven thermophilic, aerobic, spore-forming bacteria were isolated from shallow, marine, thermal vents of the Eolian Islands (Italy) and tested for a broad spectrum of phenotypic characteristics. A numerical taxonomy study was performed on these isolates and 8 thermophilic Bacillus and Geobacillus reference strains by 89 selected features. Results from cluster analysis showed the formation of nine clusters. Most of the isolates (83%) fell into several phenetically well distinguished clusters, loosely related to Geobacillus thermodenitrificans. The remaining isolates grouped together with different reference strains. Eighteen isolates, representative of the different clusters, were selected for subsequent genotypic characterisation, including partial 16S rDNA sequence analysis of 18 strains and almost complete 16S rDNA sequences of 9 strains. Subsequent DNA/DNA reassociation studies and determination of the base composition of DNA identified seven isolates as Geobacillus thermodenitrificans, two isolates as G. thermoleovorans and one isolate as Bacillus pallidus. Four isolates represented two novel species of Bacillus. The remaining four represented novel Geobacillus species, one of which has recently been described as Bacillus vulcani DSMZ 13174 T.     

Phylogenetic diversity of thermophilic carbohydrate degrading bacilli from Bulgarian hot springs

Phylogenetic diversity of culturable bacteria from genus Bacillus and related genera, isolated from 18 Bulgarian hot springs was investigated in association with their functional diversity. Sixty-seven thermophilic and facultative thermophilic strains were isolated under aerobic conditions at 60°C. Sixty-six of them belonged to eight species in four genera from Bacillus group: Anoxybacillus, Geobacillus, Brevibacillus and Bacillus. Representatives of the genus Anoxybacillus predominated. Based on phylogenetic analysis (<97% sequence similarity) four strains belonged to groups representing potentially novel species. Producers of carbohydrases, degrading 12 from the tested 13 substrates were isolated. About half of the isolates degraded amylose by exo- or endo-mechanism of action of their enzymes. The isolates degrading hemicellulose carbohydrates like arabinan, arabinoxylan, β-glucan, galactan, galactomannan and xyloglucan were reached to. Some of the microorganisms were able to uptake microbial polysaccharides like curdlan and gellan and their enzymes were between first reported thermostable enzymes in their groups, like gellan lyase and curdlan lyase A relation between species affiliation and their functional activity was observed—all A. gonensis strains were producer of amylolytic enzymes, most of Brevibacillus ruber strains were able to grow in a minimal medium with xanthan.     

Use of DIR-PCR for elaboration of molecular markers of intraspecies bacterial groups as exemplified by <Emphasis Type="Italic">Bacillus thuringiensis</Emphasis>

A recently developed PCR-fingerprinting method, the so-called DIR (diverged inverted repeats)-PCR, was used for quick search for molecular markers of Bacillus thuringiensis subspecies carrying the cry1 genes. The analysis of the fingerprints obtained with this method made it possible to reveal PCR fragments characteristic of the subspecies that produce proteins toxic for insects of the order Lepidoptera. Cloning and sequencing of these fragments allowed systems of SCAR (sequence characterized amplified region) primers to be designed, which are specific to the above group of B. thuringiensis strains. Comparison of the specific fragments with sequences available in the GenBank database revealed their homology with the rpoC gene family and the adjacent spacer region, suggesting chromosomal localization of these markers. This increases the reliability of the designed system of SCAR primers, because plasmids may be lost or transferred by transformation between closely related strains. It was demonstrated that the DIR-PCR method allows markers to be elaborated that are linked to diagnostic genotypic and phenotypic characteristics of bacteria.     

若干需氧芽孢杆菌芽孢脂肪酸成分分析

51株需氧芽孢杆菌纯化后的芽孢培养物经处理抽提全细胞脂肪酸甲酯 ,用于气相色谱分析 ,同时以相应的繁殖体作为对照。芽孢脂肪酸成分的重现性实验发现 ,芽孢的脂肪酸成分比较稳定。将脂肪酸百分含量编制成原始数据矩阵 ,以 Statistica5.0统计软件进行聚类分析 ,得到两张分别基于芽孢脂肪酸成分和繁殖体脂肪酸成分的实验菌株树状聚类图。通过对比这两张图可以得出一些有意义的结论 ,同时也说明芽孢脂肪酸分析可望成为需氧芽孢杆菌化学分类的新手段。     

恶性淋巴瘤组织切片中结核菌L型的检出及其意义

本文应用Ｉｎｔｅｎｓｉｆｉｅｄｋｉｎｙｏｕｎ（ＩＫ）改良抗酸染色和结核菌抗休免疫组织化学染色检测了５１例恶性淋巴瘤组织功片内结核菌及其Ｌ型感染率。结果发现５１例恶性淋巴瘤组织功片中,ＩＫ染色阳性２５例（４９％）,免疫组化染色阳性２６例（５０．９％）,并发现结核菌Ｌ型感染与恶性淋巴瘤的疗效有关（Ｐ＜０．０１）。故认为恶性淋巴瘤中,结核菌Ｌ型感染是一个值得进一步研究的课题。     

肿瘤患者感染三种常见革兰阴性杆菌耐药性分析

目的分析肿瘤患者临床分离的革兰阴性杆菌分布及其主要菌株的耐药性,为指导临床合理用药提供依据。方法对2014年1月~2015年12月恶性肿瘤患者感染分离的1478株革兰阴性杆菌及其主要菌株的耐药性进行回顾性分析。结果分离的1478株革兰阴性杆菌中,以大肠埃希菌(568/1478)38.43%、肺炎克雷伯菌(338/1478)22.87%、铜绿假单胞菌(216/1478)14.61%3种为主。这3种革兰阴性杆菌均呈多药耐药性;除亚胺培南对革兰阴性杆菌有较好的抗菌活性外,其它药物均显示有一定的耐药性,其中对派拉西林的耐药率在91%以上,头孢他啶、头孢噻肟、复方新诺明等药物的耐药率在70%以上。结论肿瘤患者感染革兰阴性杆菌耐药现象严重,尤其是感染产超广谱β-内酰胺酶(ESBLs)的大肠埃希菌和肺炎克雷伯菌呈多重耐药,实验室应加强对革兰阴性杆菌耐药性的监测,以指导临床合理选用抗菌药物。     

Bacterial cyclodextrin glucanotransferase

Cyclodextrin glucanotransferase (CGTase, Ec 2.4.1.19) is an enzyme which catalyze intramolecular (cyclizing) and intermolecular (coupling, disproportionation) transglycosylation as well as having a hydrolytic action on starch and cyclodextrins. By a cyclizing reaction, the enzyme converts starch and related -1, 4-glucans to cyclodextrins which are widely utilized in food, pharmaceutical, and chemical industries. The present review attempts to summarize the reported data concerning the bacterial producers of CGTase, growth cultural conditions providing optimal enzyme biosynthesis in batches, repeated batch and continuous cultivation of free and immobilized cells, as well as some physicochemical and biochemical characteristics of the enzyme, CGTase immobilization, and enzyme structure.     

有益芽孢杆菌受体菌研究

采用酸性茚三酮法测定了30株有益芽胞杆菌的赖氨酸产量,然后在不同的溶菌酶浓度下,对赖氨酸产量超过0．07g/L的21株菌进行原生质体转化质粒pUB110,测定原生质体形成率、原生质体再生率及转化频率,结果6103,6104,6120,6129四株菌的转化频率较高。最后,采用经典遗传学方法选育AEC抗性突变株,使赖氨酸积累提高。其中,B.licheniformis 6104诱变菌株610401能积累赖氨酸2．91g/L ,比出发菌株提高了17倍左右,转化率也提高了一个数量级。通过质粒的再转化试验及传代稳定性试验,进一步证实B.licheniformis 6104及其 突变菌株610401是较好的受体菌,尤其是用于赖氨酸合成酶基因的表达。     

引起儿童下呼吸道感染的革兰阴性杆菌构成及耐药性分析

【摘 要】 目的 了解引起儿童下呼吸道感染的革兰阴性杆菌的构成情况及优势菌的耐药状况。方法 对2011年1月至2013年5月深圳市龙华新区观澜人民医院儿科门诊及住院患者痰标本分离的革兰阴性杆菌的构成及耐药情况进行回顾性分析。结果 引起儿童下呼吸道感染的革兰阴性杆菌以肺炎克雷伯菌（KPN）、大肠埃希菌（ECO）和流感嗜血杆菌（HI）为主，分别占28.9%、26.8%和22.3%；KPN对AMP和CZO的耐药率均为100%，对CAZ、FEP、CTT、TZP、CIP、IPM、TOB、MEM、LVF、AMK耐药率均在10%以下；ECO对AMP和CZO的耐药率分别为100%和74.1%，对CAZ、FEP、TOB、AMK、NIT、CTT、TZP、IPM、MEM耐药率均10%以下；HI对SXT和AMP的耐药率分别为64.8%和34.0%，对其余9种抗生素的耐药率均在10%以下；KPN和ECO的超广谱β-内酰胺酶（ESBLs）的检出率分别为29.5%和29.2%；ESBLs菌株对AMP、CZO和CRO的耐药率均在97%以上，对TOB、AMK、CTT、TZP、IPM、MEM耐药率均在6%以下。结论 引起儿童下呼吸道感染的革兰阴性杆菌种类多，耐药性强。临床医生应加强病原菌监测，根据患儿痰培养结果，合理选用抗生素，以减少耐药菌株的产生。