合肥市产超广谱β-内酰胺酶菌株的SHV型耐药基因分布和耐药性分析

目的了解1999～2000年合肥市临床分离的产超广谱β-内酰胺酶(ESBLs)肺炎克雷伯菌和大肠埃希菌中,SHV型β-内酰胺酶基因型分布情况和耐药性分析。方法标本为安徽省细菌耐药性监控中心所留取的1999年9月～2000年9月从合肥市4家大医院临床分离的、已被证实产ESBLs的98株肺炎克雷伯菌和大肠埃希菌,采用聚合酶链反应(PCR)扩增产SHV型β-内酰胺酶菌株基因片段,克隆入pGEM-Teasy载体,双脱氧链终止法测定核苷酸序列以鉴定基因型。按照2005年CLSI推荐标准,用琼脂稀释法分别测定临床分离菌株和转移结合子对11种不同抗菌药物的MIC值,并比较分析两者的不同结果。结果98株产ESBLs菌株中有29株产SHV型β-内酰胺酶,其中SHV-1型8株,SHV-11型5株,SHV-12型11株,SHV-18型1株,SHV-28型1株,SHV-89型3株[序列号为(DQ193536)]。临床分离株的MIC结果显示对哌拉西林,头孢噻肟,头孢曲松的敏感率低;转移结合子的敏感性较临床分离菌株有所上升。结论合肥市部分医院产SHV型β-内酰胺酶肺炎克雷伯菌和大肠埃希菌检出率较高,我们在国内外首次报道了SHV-89;并且本地区产SHV型β-内酰胺酶菌株的耐药性较高。     

肺炎克雷伯氏菌SHV-28编码基因的克隆、测序及基因定位

以临床分离的一株肺炎克雷伯氏菌99-799株为研究对象，对其所产生的一种β-内酰胺酶编码基因的序列、亚型及基因定位进行研究。采用聚合酶链反应(PCR)，用β-内酰胺酶通用引物、blasHv引物扩增获得β-内酰胺酶及SHV型酶编码基因的片段，将SHV型酶PCR扩增产物克隆入pUCm—T载体，以双脱氧链终止法测定核苷酸序列，再通过GeneBank进行同源性检测确定其亚型和基因所在位置。肺炎克雷伯氏菌99—799株所含的一种β-内酰胺酶基因型为SHV型，与SHV-28编码基因序列完全相同，且位于细菌150bp的大质粒上，说明重庆地区有SHV-28亚型的存在。     

粘质沙雷菌中SHV型β-内酰胺酶编码基因的克隆及序列分析

目的研究重庆地区临床分离的粘质沙雷菌E121编码超广谱β-内酰胺酶（ESBLs）的基因。方法PCR扩增ESBLs编码基因片段，克隆入pUCm—T载体，双脱氧链终止法测定核苷酸序列并确定亚型，等电聚焦测定β-内酰胺酶的等电点（pI）。结果PCR扩增结果显示粘质沙雷菌E121产生的ESBLs为SHV型，其基因片段含756个核苷酸，GenBank查询其核苷酸序列与SHV-28型ESBLs完全相同。该耐药株至少含有等电点pI约为5．4和8．2的两种β-内酰胺酶。结论重庆地区粘质沙雷菌E121所产ESBLs亚型为SHV-28。     

肺炎克雷伯菌临床分离株产广谱和超广谱β-内酰胺酶的基因型研究

目的 了解产ESBLs肺炎克雷伯菌临床分离株的耐药性及其基因型分布特征,指导临床进行抗感染治疗,更好地控制耐药菌株的播散.方法 对38株经双纸片试验确认为ESBLs表型阳性的肺炎克雷伯菌采用纸片扩散法进行药物敏感性试验;采用PCR法对ESBLs阳性株进行TEM型、SHV型、CTX-M型、VEB型和PER型ESBL基因检测,对PCR阳性产物进行测序确定基因型别;同时采用PCR法检测整合酶基因,对PCR产物进行测序确定整合酶类别.结果 38株产ESBLs的肺炎克雷伯菌对青霉素类和头孢菌素类耐药性十分严重,对庆大霉素和复方磺胺甲嚼唑的耐药率也均＞90%,未检测到耐亚胺培南和美罗培南的菌株.38株ESBLs阳性菌株检测到3种ESBLs型,分别为TEM型、SHV型和CTX-M型,VEB型和PER型没有被检出.CTX-M型、TEM型和SHV型阳性率分别为92.1%(35/38)、84.2%(32/38)、76.3%(29/38).整合酶基因阳性率为94.7%(36/38).经测序,所有TEM型均为TEM-1广谱β内酰酶.29株SHV型阳性的PCR产物经测序证实,SHV-12有19株,SHV-11有4株,SHV-2有3株,SHV-28有2株及SHV-1有1株.35株CTX-M型中,CTX-M-14有22株,CTX-M-15有13株.同时检测到3种基因的有22株(57.9%),同时检测到2种基因的有14株(36.8%).整合酶基因PCR产物经测序为Ⅰ类整合子.结论 产ESBLs肺炎克雷伯菌临床分离株的耐药性及多重耐药性严重,Ⅰ类整合子是其多重耐药和耐药性传播的主要原因;CTX-M-14及SHV-12为肺炎克雷伯菌产ESBLs的主要基因型.     

广州地区泌尿系统感染产超广谱β-内酰胺酶肺炎克雷伯菌的耐药特征和基因分型

目的：了解本地区泌尿系统感染产超广谱β-内酰胺酶（ESBLs）肺炎克雷伯菌耐药特征及其基因型分布。方法：收集广州地区13家医院2001年7月～2003年8月间临床分离的尿培养阳性肺炎克雷伯菌130株,采用NCCLs规定的ESBLs初筛和确证试验方法检测ESBLs,用K-B琼脂扩散法进行药物敏感试验,并应用聚合酶链反应（PCR）方法对所分离的产ESBLs菌株进行SHV、CTX-M基因型检测。结果：产ESBLs肺炎克雷伯菌检出率为41．5％（54株）,其中66．7％（36株）携带CTX-M基因,53．7％（29株）携带SHV型基因,并有20．4％（11株）同时携带CTX-M基因和SHV型基因。产酶株的耐药率明显高于非产酶株,产ESBLs细菌对青霉素类、环丙沙星及头孢菌素类耐药率较高（高达75．9～99．7％1,加酶抑制剂克拉维酸或他唑巴坦后耐药率有明显下降。结论：广州地区泌尿系统感染的产ESBLs肺炎克雷伯菌具有多重耐药的特点。其中CTX-M型是流行的基因型。     

大肠埃希氏菌及肺炎克雷伯氏菌超广谱β-内酰胺酶基因的核苷酸序列测定及分子进化树的构建

了解四川大学华西医院产ESBLs肺炎克雷伯氏菌和大肠埃希氏菌的TEM或SHV型ESBLs，并探讨ESBLs进化及分类关系。方法 对用PCR法扩增的产ESBLs比大肠埃希氏菌及肺炎克雷伯氏菌的TEM型及SHV型ESBLs基因进行核苷酸序列测定，通过网上相似性检索确定其编码酶的亚型，并利用生物信息学软件ClustalX1．8构建分子进化树，对ESBLs进化及分类关系进行探讨。结果 本研究检出的ESBLs亚型为SHV—2和TEM—19。根据进化和同源关系，ESBLs可分为了TEM型、SHV型、CTX—M型、OXA型及一些不属于上述任何一个家族的类型，其中CTX—M族酶分为四组。结论 本研究检出的ESBLs比亚型以SHV—2为主。本研究构建的ESBLs的分子进化树较好地反映了ESBLs的进化和分类关系，是其分类研究的新手段。     

新生儿医院产超广谱β-内酰胺酶肺炎克雷伯菌感染分离株耐药性及基因类型检测

目的 了解新生儿医院感染产超广谱β-内酰胺酶（ESBLs）肺炎克雷伯菌分离株的耐药状况及β-内酰胺酶编码基因TEM、SHV、OXA、PER、GES、VEB、CTX型存在状况。方法 将我院2004年7月新生儿病房感染的14株肺炎克雷伯菌用全自动微生物鉴定和药敏分析配套卡进行抗生素敏感性检测和ESBLs检测，并采用聚合酶链反应及序列分析方法分析菌株内的超广谱β-内酰胺酶基因型。结果 14株产ESBLs的肺炎克雷伯菌药敏结果一致，氨苄西林、头孢曲松、头孢唑林、头孢他啶均耐药对阿莫西林／克拉维酸、哌拉西林／三唑巴坦也耐药，对亚胺培南敏感。均检出blacTX-M和blaTEM基因，未检出blasm,、扰noxA、blaPER、扰nGES和blaVEB基因。对blarm和blacTX-M基因扩增产物测序，经BLAST程序分析基因为TEM-1和CTX-M-3型。结论 本院感染流行的ESBLs肺炎克雷伯菌耐第三代头孢菌素和耐酶抑制剂，基因类型为TEM-1和CTX-M-3。新生儿属于ESBLs的高危人群，新生儿病房产超广谱β-内酰胺酶菌感染应引起各方关注。     

产ESBLs肺炎克雷伯菌的耐药基因研究

目的研究产ESBLs肺炎克雷伯菌临床分离株的耐药性以及ESBLs的基因表型.方法对500株产ESBLs肺炎克雷伯菌的可疑临床分离株进行ESBLs确证,并采用琼脂稀释法进行药敏试验;采用聚合酶链（PCR）反应分析368株产ESBLs肺炎克雷伯菌株的ESBLs基因（blaTEM、blaSHV和blaCTX-M）,分析产ESBLs肺炎克雷伯菌的耐药性及ESBLs的基因表型情况.结果产ESBLs肺炎克雷伯菌筛选试验初步筛出500株,通过进一步确认试验368 （77.2％）株确认为出产ESBLs菌;368株产ESBLs肺炎克雷伯菌株中有158株（40.93％）检测到blasHv,165株（42.75％）检测到blaTEM,173株（44.82％）检测到blacTX-M;除阿米卡星、加替沙星、环丙沙星、左旋氧氟沙星外,产ESBLs肺炎克雷伯菌株和不产ESBLs肺炎克雷伯菌株对其他8种抗生素的耐药率不同（P＜ 0.01）;结论产ESBLs肺炎克雷伯菌其耐药性高于非产ESBLs肺炎克雷伯菌;我院ESBLs肺炎克雷伯菌blaCTX-M比例略高.     

一种新β-内酰胺酶亚型SHV-56的发现及其临床意义

目的 分析产超广谱β-内酰胺酶(ESBLs)鲍曼不动杆菌SHV型β-内酰胺酶(BLA)的编码基因并确定其亚型。方法 采用聚合酶链反应(PCR)扩增BLA编码基因片段，双脱氧链终止法测定核苷酸序列、确定亚型。结果 临床分离的鲍曼不动杆菌HZ29株产生SHV型BLA，其扩增片段含825个核苷酸，核苷酸及相应的氨基酸序列经GenBank查询无相同序列，为新发现的一种BLA亚型，其序列已以SHV-56名称在美国核酸数据库GenBank成功登录(GenBank注册号：AY352599)。结论 临床分离的鲍曼不动杆菌HZ29株所产SHV型BLA为一种新发现的BLA亚型。     

肺炎克雷伯氏菌K99-1029中的ESBLs基因型分析

目的 了解华山医院临床分离的肺炎克雷伯氏菌K99—1029菌株产生的超广谱β—内酰胺酶(ESBLs)的基因型。方法 编码框以外设计引物、PCR扩增K99—1029转移接合子中的ESBLs全编码基因，克隆人pHSG398质粒、表达，并对PCR产物进行测序分析其基因型。结果 K99—1029转移接合子所产生的三种酶编码基因序列分别与GenBank中TEM—1、SHV—12、CTX—M—3编码基因序列的同源性为100％；产SHV—12或门CTX—M—3克隆菌株对多数β—内酰胺类抗生素耐药，SHV—12和CTX—M—3对多数β—内酰胺类抗生素具有水解作用，CTX—M—3对头孢噻肟的水解能力明显强于头孢他啶；产TEM—1克隆菌株仅对青霉素类耐药，TEM—1对青霉素类有明显的水解作用。结论 临床分离的肺炎克雷伯氏菌K99—1029菌株同时产生TEM—1、SHV—12、CTX-M—3型酶，可导致对大多数的β—内酞胺类抗生素产生耐药性。     

Genetic characterisation of CTX-M-15-producing Klebsiella pneumoniae and Escherichia coli strains isolated from stem cell transplant patients in Tunisia

Characterisation of extended-spectrum beta-lactamase (ESBL) genes and their genetic environments as well as the presence of integrons were analysed in nine Klebsiella pneumoniae and two Escherichia coli ESBL-positive isolates recovered in the Centre of Bone Marrow Transplantation of Tunisia. All strains harboured the bla(CTX-M-15) gene and presented minimum inhibitory concentrations for cefotaxime and ceftazidime of 256-1024mgL(-1) and 16-512mgL(-1), respectively, and eight of them showed different pulsed-field gel electrophoresis patterns. The bla(OXA-1) and bla(TEM-1) genes were detected in eight and ten strains, respectively. In addition, bla(SHV-1), bla(SHV-11) and bla(SHV-27) were found in six, one and one K. pneumoniae strains, respectively. The new variant bla(SHV-103) was characterised in one K. pneumoniae strain. The intI1 gene was detected in eight K. pneumoniae strains and the dfrA5+ereA2 and aadA gene cassettes were found in one and five strains, respectively. All strains harboured a 70kb plasmid, and its transference in addition to bla(CTX-M-15), bla(TEM-1b) and bla(OXA-1) genes was demonstrated from three K. pneumoniae to E. coli. ISEcp1 and orf477 were located upstream and downstream, respectively, of the bla(CTX-M-15) gene in 10 strains. The occurrence of the bla(CTX-M-15) gene in unrelated strains might have originated from the dissemination of mobile genetic elements in which ISEcp1 may have played an important role.     

A Klebsiella pneumoniae producing three kinds of class A beta-lactamases encoded by one single plasmid isolated from a patient in Huashan Hospital, Shanghai, China

A Klebsiella pneumoniae strain was isolated from a sputum specimen of a patient in the intensive care unit in 1999 in Shanghai Huashan Hospital, China. The isolate was confirmed as an extended-spectrum beta-lactamase (ESBL) producing strain by double-disk synergy test. The results of susceptibility test showed that it was resistant to most beta-lactams (including third generation cephalosporins) and non-beta-lactam antimicrobial agents. Transconjugants were obtained at a frequency of 10(-4). A plasmid of about 60 kb was obtained from the transconjugant by plasmid extraction. Three major nitrocefin-hydrolysing bands with pIs of 5.4, 8.2 and 8.4, were shown in extracts of the transconjugant. Partial gene amplification products of bla(TEM), bla(SHV), and CTX-M-1 group gene were obtained from the isolate as well as its transconjugant. The entire bla(TEM), bla(SHV), and bla(CTX-M) in the transconjugant were amplified by PCR and the PCR products were cloned into a pHSG398 vector. Afterwards, the susceptibility of transformants and activities of beta-lactamases of transformants on antibiotics were tested. The PCR products were directly sequenced, analysed and identified as TEM-1, SHV-12, and CTX-M-3 genes. These results confirm that this strain of Klebsiella pneumoniae produces SHV-12, CTX-M-3 ESBLs and TEM-1 beta-lactamase, encoded by one single plasmid, which is responsible for the resistance of this strain to most beta-lactams.     

Dissemination of CTX-M type beta-lactamases in Enterobacteriaceae isolates in the People's Republic of China

Previously there have been a number of reports of extended spectrum beta-lactamase (ESBL) producing isolates of the family Enterobacteriaceae in Asia. We first reported the occurrence of bla(CTX-M) in Guangzhou, China, subsequently there have been reports of bla(CTX-M) from a number of other south Asian countries. Initial surveillance study data suggested that bla(CTX-M) might be widely distributed in China. This study examines the type of bla(CTX-M) occurring in other major population centres in China. Initial disk diffusion method susceptibility testing (NCCLS) selected ESBL producing Escherichia coli and Klebsiella pneumoniae isolates from Beijing and near Wuhan, PRC. After screening in both China and the UK, 13 isolates producing CTX-M ESBLs were identified and studied, 11 also produced TEM-1, and 4 also produced SHV-1. Sequence analysis of the bla(CTX-M) containing isolates revealed these isolates contained two different bla(CTX-M), three with bla(CTX-M-3) and 10 with bla(CTX-M-14). After comparison with other previously published studies in the English language, we conclude that the most prevalent bla(CTX-M) so far reported in Asia are bla(CTX-M-14) and bla(CTX-M-3).     

Extended-spectrum beta-lactamases in Shigella flexneri from Argentina: first report of TOHO-1 outside Japan

A 9-year nation wide survey of the presence of extended-spectrum β-lactamases (ESBLs) in Shigella flexneri is described. Ten of 9033 (0.1%) isolates produced ESBLs, which were characterized by isoelectric focusing, PCR and DNA sequencing. These were CTX-M-2 (five isolates), TOHO-1 (one isolate), SHV-2 (two isolates) and PER-2 (two isolates, the first report in S. flexneri world wide). The emergence of each ESBL type in S. flexneri was not restricted to a particular region of Argentina. TOHO-1 showed a more basic isoelectric point (8.4) than that previously found (7.8) and its encoding gene (bla_TOHO-1a) harboured a silent change, G825A, relative to the reported bla_TOHO-1. All the ESBL-encoding genes were transferred to Escherichia coli by conjugation. PFGE analysis indicated that the 10 ESBL-producing S. flexneri isolates were subtypes of a unique clone.     

Carriage of genes for various extended-spectrum β-lactamases: a novel resistance strategy of Klebsiella pneumoniae in Poland

Among 110 randomly sampled strains from a collection of 247 extended-spectrum β-lactamase (ESBL)-producing clinical isolates of Klebsiella pneumoniae collected from hospitalised children in three paediatric hospitals in Poland, 64 strains (58.2%) with multiple ESBLs were found, including five non-clonal strains (4.5%) harbouring bla genes for ESBLs of three families (CTX-M, SHV and TEM). This is the first report of the emergence of triple ESBL-producing K. pneumoniae in Poland. In addition, K. pneumoniae strains harbouring bla genes for TEM-130 and TEM-132 ESBLs were detected in Poland for the first time. Epidemiological analysis of the multiple ESBL-producing K. pneumoniae isolates by pulsed-field gel electrophoresis (PFGE) revealed a relatively high genetic diversity between isolates producing the same combination of enzymes. Clonally related strains were uncommon.     

3株含qnr基因肺炎克雷伯菌中超广谱β-内酰胺酶的检测

目的了解临床分离含qnr基因,(质粒介导的喹酮类耐药基因)肺炎克雷伯菌中超广谱β-内酰胺酶的基因型别。方法琼脂稀释法测定3株临床分离含qnr基因肺炎克雷伯菌对β-内酰胺类、喹诺酮类抗菌药物的耐药性,NCCLS表型确证试验进行产ESBLs菌株的表型鉴定、采用TEM、SHV、CTX-M-1组、CTX-M-2组、CTX-M-13组、OXA-1组、OXA-2组、OXA-10组、PER-1、VEB-1β-内酰胺酶通用引物以及TEM、CTX-M-13组、OXA-1组全编码基因引物、I类整合酶基因引物进行PCR检测和DNA序列分析;同时对这些菌株进行PFGE检测。结果3株临床分离含qnr基因肺炎克雷伯菌均为产ESBLs菌株,ESBLs基因型别为CTX-M-14,其中2株细菌同时产生TEM-1型广谱β-内酰胺酶、1株同时产生TEM-1和OXA-30型广谱β-内酰胺酶,I类整合酶基因均为阳性;这些菌株对青霉素类、一代、二代、三代头孢菌素(头孢噻肟)以及多种喹诺酮类均显示耐药。3株菌株中有2株的PFGE谱型相同。结论临床分离含qnr基因肺炎克雷伯菌可同时产生CTX-M-14超广谱β-内酰胺酶,引起多重耐药,并存在克隆传播,临床应加强检测。     

Prevalence of plasmid-mediated quinolone resistance determinants qnr and aac(6')-Ib-cr in Escherichia coli and Klebsiella pneumoniae producing extended-spectrum β-lactamases in Spain

The presence of the plasmid-mediated quinolone resistance determinants qnrA, qnrB, qnrS and aac(6')-Ib-cr was evaluated in a collection of 382 isolates of extended-spectrum β-lactamase (ESBL)-producing Escherichia coli and Klebsiella pneumoniae collected between February and March 2006 for the nationwide Spanish GEIH-ESBL 2006 project. In total, 14 isolates (3.7%) were positive for qnr genes (3 qnrA1, 5 qnrB-like and 6 qnrS1) and 62 isolates (16.2%) were positive for the mutant variant of aac(6')-Ib-cr. The Aac(6')-Ib-cr enzyme was the most prevalent plasmid-mediated mechanism of quinolone resistance in Spain. Most of the Aac(6')-Ib-cr-producing E. coli isolates (94.2%) carried two mutations in gyrA and two in parC, whilst only 57.2% of K. pneumoniae harbouring this enzyme were gyrA and/or parC mutants. Most qnr plasmids were transferable, but only four were conjugative. Plasmid incompatibility groups were identified for only four plasmids, belonging to FIA, HI2 and I1γ. The most prevalent ESBLs associated with qnr plasmids belonged to the SHV and CTX-M families. The present study highlights the broad geographical spread of qnr-like determinants in Spain and their association with the SHV-12 and CTX-M-9 ESBLs in human clinical isolates.     

SHV-type beta-lactamases.

The group of plasmid-mediated SHV b-lactamases includes SHV-1 and at least twenty-three variants, most of which possess extended-spectrum (ES) activity against the newer broad-spectrum cephalosporins. Their likely ancestor is a chromosomal penicillinase of Klebsiella pneumoniae. SHV enzymes belong to the molecular class A of serine b-lactamases and share extensive functional and structural similarity with TEM b-lactamases. The three-dimensional structure of the SHV-1 b-lactamase possesses an active site wider than that of TEM-1 b-lactamase by 0.7 to 1.2 A. This results in subtle, yet important, differences in the positioning of critical active-site residues. SHV-1 b-lactamase behaves as a typical penicillinase hydrolyzing penicillins and early generation cephalosporins. SHV-1 b-lactamase has spread, via plasmids, to virtually all enterobacterial species but is encountered mostly in K. pneumoniae. ES SHV b-lactamases are found with increasing frequency in K. pneumoniae and other enterobacterial isolates and are now considered the most prevalent ES b-lactamases. These ES SHV b-lactamases confer a wide spectrum of resistance to b-lactams, including the new generation cephalosporins and monobactams, and are usually encoded by self-transmissible multi-resistant plasmids that are highly mobile. Extension of the hydrolytic spectrum of ES SHV enzymes to include oximino-b-lactams is seen as a result of substitutions of critical amino acid residues that alter the properties of the active site. These mutational changes, however, result in diminished hydrolytic activity against penicillins and an increased susceptibility to mechanism-based inhibitors. Understanding the substrate evolution, properties and modes of spread of these clinically important b-lactamases can help in formulating effective antibiotic policies and developing new antimicrobial agents.     

肺炎克雷伯菌产超广谱β-内酰胺酶基因分型研究

目的调查广州地区下呼吸道感染肺炎克雷伯菌产超广谱β-内酰胺酶(ESBL)的分离率及各种基因型的流行病学分布。方法收集广州地区13家医院2001-10～2002-12临床分离的肺炎克雷伯菌511株,采用美国临床实验室标准化委员会规定的ESBL表型筛选和确证试验确定ESBL的发生率、PCR扩增对产ESBL菌初步分型,然后对部分PCR扩增阳性产物测序,序列分析进一步确定基因型。结果肺炎克雷伯菌产ESBL分离率为40.1%。TEM型49株占21.9%,均为TEM-1型;CTX-M型59株占28.8%;SHV型96株占46.8%。结论SHV型是广州地区下呼吸道感染肺炎克雷伯菌产ESBL流行的常见基因型。