产超广谱β内酰胺酶菌株中质粒头孢菌素酶的研究

目的 调查产超广谱β内酰胺酶(ESBLs)的大肠埃希菌和肺炎克雷伯菌中质粒头孢菌素酶(AmpC酶)的发生率及其基因型。方法 收集北京朝阳医院2001年1～12月头孢西丁耐药的产ESBLs的24株大肠埃希菌、8株肺炎克雷伯菌,采用等电聚焦电泳测定β内酰胺酶的等电点;接合试验证实酶基因有无可转移性;脉冲场凝胶电泳(PFGE)确定耐药株的亲缘关系;对AmpC酶基因进行多重PCR及序列分析确定其基因型。结果 2001年北京朝阳医院ESBLs的发生率,大肠埃希菌为16.8％(49／292),肺炎克雷伯菌为160.5％(35／212);ESBLs株中质粒AmpC酶的发生率,大肠埃希菌为2．0％(1／49),肺炎克雷伯菌为17．1％(6／35)。这7株菌均产生DHA-1型AmpC酶;1株肺炎克雷伯菌可将头孢西丁耐药性传给受菌体。该7株菌都产TEM-1酶、5株产CTX-M-3型ESBL、2株产SHV-12型ESBL;该7株菌携带质粒2～5个,且都有约33～36kb的大质粒。PFGE发现这7株菌来自多个不同的克隆株。结论 北京朝阳医院ESBL阳性的大肠埃希菌和肺炎克雷伯菌中,有7株既产DHA-1型质粒AmpC酶,又产CTX-M-3或SHV-12 ESBL。这7株菌来自多个不同的克隆株。     

大肠埃希菌和肺炎克雷伯菌质粒中AmpC酶基因型的检测

目的探讨台州地区大肠埃希菌和肺炎克雷伯菌临床分离株质粒介导的AmpC酶基因型流行状况。方法应用VITEK-60型全自动细菌鉴定仪鉴定细菌,按NCCLS推荐的确证试验测定β-内酰胺酶(ESBLs);采用头孢西丁纸片扩散法筛选疑产AmpC酶阳性菌株,并通过酶粗提物头孢西丁三维试验、接合试验和PCR测序等实验分析该菌株的基因型及基因表型。结果299株大肠埃希菌和肺炎克雷伯菌ESBLs检出率为19.73%(59/299),AmpC酶纸片扩散法筛选阳性率为12.04%(36/299),且36株AmpC酶筛选阳性菌株均为ESBLs阳性株;该菌株中有15株经三维试验证实为AmpC酶阳性,阳性率5.02%(15/299);15株产AmpC菌经接合试验得到15株接合子,经PCR及测序证实与原菌株表型基本一致。质粒型AmpC基因中13株为CIT型,2株为DHA型。结论台州地区大肠埃希菌和肺炎克雷伯菌临床分离株中已出现质粒携带的AmpC基因,基因型以CIT型为主,其次是DHA型。AmpC基因可能与编码ESBLs的基因存在于同一质粒上,编码的AmpC酶的质粒可在细菌间传递。     

可疑产碳青霉烯酶肠杆菌的耐药性及与β-内酰胺酶的关系

目的观察本地区可疑产碳青霉烯酶肠杆菌的耐药性及与B．内酰胺酶的关系。方法采用VITEK-2全自动细菌鉴定仪检测55株可疑产碳青霉烯酶肠杆菌对21种抗生素的药敏情况,以改良Hodge试验进行碳青霉烯酶筛选,以纸片扩散初筛试验、扩散确证试验进行超广谱B-内酰胺酶（ESBLs）表型检查,以头孢西丁三维试验进行头孢菌毒酶（AmpC酶）p-内酰胺酶表型检查,PCR法检测β-内酰胺酶基因表达并进行产物测序。结果55株菌株对青霉素类、头孢菌素类抗生素耐药率高达87％以上,对亚胺培南、美洛培南、丁胺卡那霉素耐药率在30％以下;β-内酰胺酶表型阳性率为74．54％,主要来自产ESBLs＋AmpC酶菌株,其次为单产ESBLs酶和单产AmpC酶菌株;肺炎克雷伯菌碳青霉烯酶、DHA、CIT、TEM、CTX．M型β-内酰胺酶基因阳性率分别为7．27％、16．36％、27．27％、27．27％、16．36％。结论本地区耐碳青霉烯类抗生素的菌株呈不断增加趋势,目前尚缺乏有效治疗产酶细菌所致感染的方法;菌株耐碳青霉烯类药物的主要原因并非产碳青霉烯酶,而可能为同时产ESBLs＋AmpC酶或存在其他耐药机制。     

产质粒介导Ⅰ型头孢菌素酶细菌的耐药性及基因型研究

目的 了解华南地区产β内酰胺酶中质粒介导的Ⅰ型头孢菌素(AmpC)酶细菌的耐药性及其基因型特征。方法 收集革兰阴性菌临床分离无重复菌株共1187株，采用头孢西丁三维试验检测AmpC酶，Kirby-Bauer琼脂扩散法检测耐药性；质粒结合试验，聚合酶链反应(PCR)通用引物扩增各组基因及测序以确定AmpC酶基因型。结果 革兰阴性菌头孢西丁三维试验阳性率为5．9％(70／1187)，其中质粒介导的AmpC β内酰胺酶的检出率为大肠杆菌4．2％(19／451)，克雷伯菌属4．7％(16／339)，肠杆菌属2．1％(4／190)，产碱杆菌属5．3％(1／19)，不动杆菌属2．2％(1／45)，总检出率为3．5％(41／1187)。药敏显示结合子对头霉素和氨苄西林耐药，对头孢吡肟和亚胺培南敏感。PCR扩增和测序结果证实为blaDHA-1基因和blaACT-1。基因，主要分布于克雷伯菌属和大肠杆菌属。结论 华南地区质粒介导AmpC酶的基因型以DHA-1和ACT-1为主。第四代头孢菌素和碳青霉烯类药物可作为治疗产质粒介导的AmpC酶细菌感染的有效药物。     

一株产DHA-1型质粒AmpC酶肺炎克雷伯菌的耐药基因鉴定及药物敏感性测定

目的对一株头孢西丁耐药肺炎克雷伯菌进行耐药基因鉴定及药物敏感性测定。方法对临床分离的一株头孢西丁耐药肺炎克雷伯菌,采用PCR扩增及测序,检测细菌的耐药基因特性,接合实验验证质粒的传递性,等电聚焦电泳（IEF）测定细菌β-内酰胺酶的等电点。结果该株肺炎克雷伯菌产生TEM-1、DHA-1和SHV-12三种3-内酰胺酶,其耐药基因blaDHA-1可通过质粒传递。结论我院已发现同时携带DHA-1型质粒AmpC酶及SHV-12型ESBL的肺炎克雷伯菌;临床应及时准确进行鉴定及药敏实验,为合理使用抗菌药物提供依据。     

大肠埃希菌和肺炎克雷伯菌中质粒AmpCβ内酰胺酶基因型的检测

目的了解产质粒介导的AmpC酶大肠埃希菌和肺炎克雷伯菌的耐药性和基因型。方法收集2002年1月至2004年5月间呼吸科临床标本中分离的大肠埃希菌和肺炎克雷伯菌共110株，用酶提取物三维试验检测AmpC酶；用等电聚焦电泳、耐药质粒电转化试验、聚合酶链反应（PCR）及测序确定AmpC酶基因型。结果大肠埃希菌和肺炎克雷伯菌中AmpC酶检出率分别为9．30％（4／43），4．48％（3／67）。药敏试验结果显示产酶株对头孢西丁全部耐药，对第三代头孢菌素、酶抑制剂、氨曲南、阿米卡星及环丙沙星均有不同程度耐药，对头孢吡肟及亚胺培南较敏感。7株产AmpC酶菌株中有5株通过电转化试验可将头孢西丁耐药性传递给受体菌，经PCR扩增和测序证实为质粒介导DHA-1型AmpC酶。结论临床分离的大肠埃希菌和肺炎克雷伯菌中已经出现产质粒介导AmpC酶菌株，其耐药性能够水平传播，给临床抗感染治疗带来重大威胁。     

96株大肠埃希菌耐药性及其产ESBLs、AmpC酶菌株基因型检测

目的 了解大肠埃希菌耐药现状及其及产超广谱β-内酰胺酶（ESBLs）和AmpCβ-内酰胺酶（AmpC酶）菌株基因型,以指导临床医师合理使用抗菌药物。方法自本院尿路感染患者标本中分离大肠埃希菌96株,采用确证试验和改良三维试验检测其ESBLs、AmpC酶表达情况,用K-B法测定其对亚胺培南等16种抗菌药物的敏感性,用PCR法检测TEM、SHV、PER、CTX-M-1群、CTX-M-2群、CTX—M-3群、DHA和ACT-1基因型分布情况,用接合转移试验了解耐药基因转移方式。结果96株大肠埃希菌单产ESBLs30株,同时产ESBLs和AmpC酶4株,单产AmpC酶2株;产ESBLs大肠埃希菌对氨苄西林、头孢唑啉、头孢呋辛、头孢噻肟四种抗生素耐药率达到100％,而对左氧氟沙星、复方新诺明和呋喃妥因的耐药率亦〉80％,对亚胺培南和美罗培南均敏感;ESBLs基因型以CTX—M和TEM型为主,AmpC酶基因为DHA型,两酶能通过接合转移方式将质粒携带的耐药性传递至受体菌。结论大肠埃希菌所致感染对碳青霉烯类药物较为敏感;临床应及时了解本地区产ESBLs、AmpC酶大肠埃希菌的耐药表型和基因型,以指导临床合理使用抗生素、延缓细菌耐药性产生、控制耐药菌株播散和流行。     

革兰阴性杆菌产AmpC酶及超广谱β-内酰胺酶的研究

为探讨临床分离的对第三代头孢菌素耐药的革兰阴性杆菌AmpCβ－内酰胺酶（AmpC)和超广谱β－内酰胺酶（ESBLs)的分布情况，采用头孢西丁三维试验检测AmpC酶，纸片确证试验和头孢曲松三维试验检测ESBLs。结果显示，227株革兰阴性杆菌中产AmpC酶者97株（占42．6％），产ESBLs者38株（占16．7％）。提示AmpC酶和ESBLs是导致革兰阴性杆菌耐药的两类主要酶。AmpC酶和ESBLs的单克隆抗体有望为这类细菌感染的免疫生物治疗提供新方法。     

铜绿假单胞菌耐药性与产β内酰胺酶的关系

目的分析临床分离的93株铜绿假单胞菌的耐药性与β内酰胺酶类型的关系。方法采用K-B法测定亚胺培南等16种抗菌药物对93株铜绿假单胞菌的体外抗菌活性；采用等电聚焦电泳(isoelectric focusing，IEF)、三维试验、2-巯基丙酸抑制试验、聚合酶链反应(PCR)分析β内酰胺酶类型。结果阿米卡星敏感性最高为82．8％，其次依次为头孢吡肟(81．7％)、头孢哌酮／舒巴坦(81．7％)、头孢他啶(80．6％)、美罗培南(77．4％)、亚胺培南(71．0％)。三维试验结果表明，14株(15．1％)产碳青霉烯酶，其中2株产金属酶；15株(16．1％)产AmpC酶，其中2株同时产AmpC酶和超广谱β内酰胺酶(ESBLs)。等电聚焦电泳显示产AmpC的细菌均具有9．0的条带；19号和54号菌株有一个6．3的条带。2．巯基丙酸抑制试验筛选金属酶2株阳性，与三维试验结果相符。设计金属酶VIM-2特异性引物，PCR反应结果阳性，经克隆测序证实为VIM-2型金属酶。结论铜绿假单胞菌感染中产B内酰胺酶较常见，其中产碳青霉烯酶和AmpC酶占一定比率，是造成临床上铜绿假单胞菌对碳青霉烯类和头孢菌素第3、4代耐药的主要原因。     

耐多药大肠埃希菌AmpC酶基因型及耐药性

目的探讨临床分离耐多药大肠埃希菌(E.coli)产AmpCβ-内酰胺酶(AmpC酶)现状。方法初筛试验及三维试验:检测产AmpC酶菌株;纸片扩散法(K-B法):测定临床分离71株大肠埃希菌对头孢噻肟(CTX)等10种抗菌药物的抗菌活性;PCR技术检测三维实验阳性菌株的AmpC酶基因。阳性扩增片段送上海生工生物技术公司进行基因测序。结果在71株大肠埃希菌中粗筛阳性产AmpC酶菌株共11株,通过头孢西丁三维试验分离出产AmpC酶的菌株8株,占总菌株数11.27%。药敏结果显示对亚胺培南全敏感,对阿米卡星等9种抗菌药物均有不同程度耐药;耐药模式中以耐多药菌株24株(33.80%);产AmpC酶菌株对多种常用抗生素的耐药率明显高于非产AmpC酶菌株(P<0.05);检测发现2株质粒AmpC酶基因阳性。结论大肠埃希菌的多重耐药的现象突出;产AmpC酶菌株的耐药率明显高于非产AmpC酶菌株;质粒介导的AmpC酶的基因型表现为DHA-1。     

耐头孢西丁革兰阴性杆菌高产AmpC酶发生率及其基因型和耐药性

目的了解耐头孢西丁革兰阴性杆菌高产AmpC酶发生率及其基因型分布和耐药性状况。方法收集2004年9月-2005年3月分离自南京军区福州总院、福建省立医院、解放军476医院、福州?第二医院住院患者155株耐头孢西丁无重复革兰阴性杆菌,采用酶提取物三维试验检测AmpC酶;API药敏试验板和K-B法测定高产AmpC酶菌株对抗菌药物的敏感性;质粒转化试验定位耐药基因;PCR通用引物扩增AmpC酶与ESBLs基因及其序列测定,确定其基因亚型。结果在155株菌中有36株高产AmpC酶,高产AmpC酶发生率23.2%,分布在13种菌种中,其中大肠埃希菌、肺炎克雷伯菌、鲍氏不动杆菌和阴沟肠杆菌的发生率,分别为29.3%、13.9%、6/10、2/6。在36株高产AmpC酶菌株中检测出DHA-1型2株(肺炎克雷伯菌)、CMY-2型4株(大肠埃希菌),新发现基因CMY-22型1株(大肠埃希菌,GenBank登录号:DQ256079),5株携带CMY基因的大肠埃希菌分别同时带有TEM-1型广谱酶,TEM-144(新发现基因,GenBank登录号:DQ256080)、CTX-M-27、和CTX-M-14超广谱β-内酰胺酶。高产AmpC酶菌株耐药性严重,且呈多重耐药,但对亚胺培南和美罗培南的敏感率>87%。结论耐头孢西丁革兰阴性杆菌高产AmpC酶发生率较高,菌种分布较宽,耐药性强,治疗相关菌造成的感染应以亚胺培南和美罗培南为首选药物。福州地区临床分离株发现产DHA-1型AmpC酶肺炎克雷伯菌、产CMY-2型和CMY-22型AmpC酶大肠埃希菌。CMY-2型和CTX-M-27型为中国大陆首次报告,CMY-22型和TEM-144型为国内外首次发现。     

Characterization of SHV-5 beta-lactamase-producing Klebsiella pneumoniae in an intensive care unit

OBJECTIVE: To perform the molecular characterization of Klebsiella pneumoniae isolates from pediatric patients and health care workers at the intensive care unit of a tertiary care hospital in Mexico City. MATERIAL AND METHODS: Fifteen Klebsiella pneumoniae isolates collected during an outbreak in June 1996 were analyzed; eight were from patients and seven from health care workers of Mexico's Children's Hospital. Characterization of isolates was carried out by pulsed field gel electrophoresis (PFGE), random amplified polymorphic DNA polymerase chain reaction (RAPD-PCR) and serotyping, beta-Lactamase isoelectric focusing (IEF), and nucleotide sequencing of PCR products. RESULTS: Serotype 61 was predominant and correlated with genomic fingerprints of RAPD and PFGE in 11 of 15 isolates. One SHV-5-producer predominant clone with a high case-fatality rate was identified. CONCLUSIONS: Molecular biology techniques are useful tools to characterize the K. pneumoniae clone isolated from patients and health care workers, suggesting potential cross-transmission. These data call for strengthening control programs to prevent dissemination of nosocomial infections in the studied hospital.     

Prevalent phenotypes and antibiotic resistance in Escherichia coli and Klebsiella pneumoniae at an Indian tertiary care hospital: plasmid-mediated cefoxitin resistance.

BACKGROUND: The beta-lactam antibiotics, in combination with aminoglycosides, are among the most widely prescribed antibiotics. However, because of extensive and unnecessary use, resistance to these drugs continues to increase. In recent years, resistance in the Indian bacterial population has increased markedly, the majority showing complex mechanisms. Due to increased transcontinental movement of the human population, it would be wise to know the prevalence and resistance complexity of these strains, well in advance, in order to formulate a policy for empirical therapy. METHODS: One hundred and eighty-one isolates of Escherichia coli and 61 isolates of Klebsiella pneumoniae obtained from 2655 non-repeat samples of pus (912) and urine (1743) were studied, and their resistance rates and patterns were noted. The isolates were analyzed for prevalent aminoglycoside and cephalosporin resistance phenotypes and for the presence of extended spectrum beta-lactamase (ESBL) and AmpC enzymes by spot-inoculation and modified three-dimensional tests developed in our laboratory. Fourteen isolates of E. coli and six of K. pneumoniae, resistant to all of the antibiotics tested, were selected for plasmid screening, curing, and transconjugation experiments, and for comparative evaluation of the double disk synergy test (DDST) and modified three-dimensional test (TDT) for detection of beta-lactamases. RESULTS: Urinary E. coli isolates showed maximum susceptibility to amikacin (57.1%), followed by tobramycin (38.5%) and gentamicin (31.9%). Eighteen (19.8%) isolates were susceptible to cefotaxime, whereas 11 (12.1%) were susceptible to ceftriaxone. The K. pneumoniae isolates from urine samples showed maximum susceptibility to tobramycin (63.6%) followed by amikacin (54.5%). Of the K. pneumoniae isolates, 31.8% were susceptible to cefotaxime and 13.6% were susceptible to ceftriaxone. A more or less similar trend of antibiotic susceptibility was noted in E. coli and K. pneumoniae isolates from pus samples. Twenty-six (14.4%) E. coli and 15 (24.6%) K. pneumoniae isolates were found to be ESBL-producers by NCCLS-ESBL phenotypic confirmatory test. Eighteen (9.9%) E. coli and 19 (31.1%) K. pneumoniae isolates were found to be AmpC enzyme-producers by our modified TDT. The simultaneous occurrence of ESBL and AmpC enzymes was noted in 7.7% and 9.8% isolates of E. coli and K. pneumoniae, respectively. CONCLUSIONS: The prevalence of multidrug-resistant bacterial isolates is quite high in our bacterial population. On comparative evaluation of DDST and TDT in resistant isolates, TDT was found to be the better method, detecting ESBLs in 80% of isolates compared to 15% with DDST. A 19.9-kb plasmid was consistently present in all the screened isolates of E. coli and K. pneumoniae, and was inferred to encode cefoxitin and tetracycline resistance based on curing and transconjugation experiments.     

产超广谱β-内酰胺酶大肠埃希菌及肺炎克雷伯菌的耐药基因序列分析

目的　了解四川大学华西医院产超广谱 β 内酰胺酶 (ESBLs)肺炎克雷伯菌和大肠埃希菌的TEM及SHV型ESBLs亚型 ,并分析其耐药性。方法　采用聚合酶链反应 (PCR)扩增分离四川大学华西医院住院患者的产ESBLs大肠埃希菌与肺炎克雷伯菌株的TEM型及SHV型ESBLs基因并测序 ,用琼脂稀释法测定头孢他啶和头孢噻肟等 8种抗菌药物的最小抑菌浓度 (MIC)值。结果　所有产ESBLs株均耐头孢噻肟 ,11株耐氨曲南 ,2株分别耐头孢他啶和头孢吡肟 ,对环丙沙星、阿米卡星及头孢西丁耐药的分别为 11株、5株和 3株。 12株ESBLs菌中 10株产SHV 2 ,2株产TEM 19。结论　本研究中的产ESBLs株以耐头孢噻肟和氨曲南为主 ,其中绝大多数为多重耐药株 ,产SHV 2和TEM 19是其对头孢噻肟及氨曲南等氧亚胺基 β 内酰胺酶类抗生素耐药的原因之一     

Spread ofklebsiella pneumoniae producing SHV-5 beta-lactamase among hospitalized patients

Summary The first outbreak of infections caused by an SHV-5 producing strain ofKlebsiella pneumoniae is reported. Within a period of 1 year and 9 months, multiresistantK. pneumoniae strains caused severe infections, mostly of the lower respiratory tract, in 22 patients. The strains were resistant to penicillins, third-generation cephalosporins, aztreonam, chloramphenicol, tetracycline and co-trimoxazole. The resistance determinants were transferable toEscherichia coli. All isolates produced a beta-lactamase with a pI of 8.2. Ceftazidime was hydrolyzed at this band. These characteristics, together with the resistance phenotype, are identical to those of a reference strain producing the beta-lactamase SHV-5. TheK. pneumoniae strains of all patients were identical in their capsular serotype (K1), plasmid pattern and plasmid fingerprint after digestion with Dra I restriction endonuclease. We conclude that this outbreak was caused by the spread of one clone ofK. pneumoniae producing SHV-5 beta-lactamase among patients of different wards. Our results indicate a real risk for failure of therapy by third-generation cephalosporins in intensive care patients due to SHV-5 producing pathogens.

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Ausbreitung eines SHV-5-betalaktamase-produzierenden Stammes von Klebsiella pneumoniae unter hospitalisierten Patienten

Zusammenfassung Wir berichten über das in Deutschland erstmalig gehäufte Auftreten von Infektionen verursacht durch einen Stamm vonKlebsiella pneumoniae, der die plasmidische Betalaktamase SHV-5 produziert. Innerhalb eines Beobachtungszeitraumes von einem Jahr und neun Monaten verursachte dieser Stamm bei 22 Patienten schwere nosokomiale Infektionen zumeist der tiefen Atemwege. Der Erreger war resistent gegenüber Penicillinen, Cephalosporinen der dritten Generation, Aztreonam, Chloramphenicol, Tetrazyklin und Co-trimoxazol. Die Resistenzdeterminanten waren aufEscherichia coli übertragbar. Alle Isolate produzierten eine Betalaktamase mit einem isoelektrischen Punkt von 8,2, die Ceftazidim hydrolysierte. Diese Merkmale zusammen mit dem Resistenz-Phänotyp sind identisch mit denen eines mitgeführten Referenzstammes, der die Betalaktamase SHV-5 produziert. AlleK. pneumoniae-Stämme waren identisch in ihrem Kapsel-Serotyp, ihrem Plasmidmuster und ihrem Plasmid-Fingerprint (nach Verdauen mit der Restriktionsendonuclease Dra I). Wir schließen daraus, daß dieser Ausbruch von Infektionen durch einen einzigen Klon eines betalaktamase-produzierendenK. pneumoniae-Stammes verursacht wurde, der sich über verschiedene Stationen verbreitete. Diese Ergebnisse signalisieren das Risiko von Therapiemißerfolgen in Deutschland bei empirischem Einsatz von Drittgenerations-Cephalosporinen bei Infektionen mitK. pneumoniae.

     

SHV-type extended-spectrum beta-lactamase (ESBL) are encoded in related plasmids from enterobacteria clinical isolates from Mexico

OBJECTIVE: In this work we report the molecular characterization of beta-lactam antibiotics resistance conferred by genes contained in plasmids from enterobacteria producing extended-spectrum beta-lactamases (ESBL). MATERIAL AND METHODS: Fourteen enterobacterial clinical isolates selected from a group of strains obtained from seven different hospitals in Mexico during 1990-1992 and 1996-1998 were analyzed at the Bacterial Resistance Laboratory (National Institute Public Health, Cuernavaca). Molecular characterization included PFGE, IEF of beta-lactamases, bacterial conjugation, PCR amplification and DNA sequencing, plasmid extraction and restriction. RESULTS: Isolates were genetically unrelated. ESBL identified were SHV-2 (5/14) and SHV-5 (9/14) type. Cephalosporin-resistance was transferable in 9 of 14 (64%) clinical isolates with only one conjugative plasmid, DNA finger printing showed a similar band pattern in plasmids. CONCLUSIONS: The dissemination of cephalosporin resistance was due to related plasmids carrying the ESBL genes.     

Comparison of the E-test method with an automated bacterial identification and antimicrobial susceptibility detection system for screening extended-spectrum beta-lactamase producers

Some automated systems used in clinical microbiology laboratories are able to detect products responsible for antimicrobial resistance. In this study, 626 isolates (436 Escherichia coli, 134 Klebsiella pneumoniae and 56 Klebsiella oxytoca strains) were examined for the presumptive detection of extended-spectrum beta-lactamase (ESBL) production by 2 methods: the Sceptor system (BD, Sparks, MD, USA) and the E-test. ESBL production was detected in 26 E. coli strains (5.96%), 60 K. pneumoniae strains (44.77%) and 15 K. oxytoca strains (26.78%) by ceftazidime/ceftazidime-clavulanate E-test. Using the E-test, ESBL production was detected in 25 of 201 E. coli strains (12.43%), 55 of 75 K. pneumoniae (73.33%) and 14 of 27 K. oxytoca strains (51.85%) that were alerted as ESBL-producing strains by the Sceptor system. ESBL positivity was detected in 1 E. coli, 5 K. pneumoniae and 1 K. oxytoca strains, that were not warned as being ESBL producers by the Sceptor system. These data suggest that clinical microbiology laboratories should not only rely on these rapid automated systems but also use another method for screening ESBL producers, such as the E-test. The rates of these ESBL-producing isolates in this study were lower than those in other studies reported from other parts of Turkey, but higher than those reported from the USA and Europe.